A method for manufacturing a work roller for rolling metal products, a rolling mill, a metal strip, a work roller, and the use of a work roller.

Abstract

The present invention relates to a work roller for rolling metal articles, particularly for rolling metal strips, wherein the work roller has - a base body made of metal, and - an abrasion protection layer disposed at least partially on the base body, the abrasion protection layer being a thermal spray protection layer, and the abrasion protection layer having a thickness of 70 μm or less, preferably 40 μm or less, and particularly preferably 15 μm or less.

Description

[Technical Field]

[0001] The present invention relates to a work roller for rolling metal products, particularly for rolling metal strips, wherein the work roller has a base body made of metal and an abrasion protection layer disposed at least partially on the base body, the abrasion protection layer being a thermal spray protection layer.

[0002] Furthermore, this invention relates to a rolling mill.

[0003] Furthermore, the present invention relates to a metal strip that is cold-rolled using a work roller.

[0004] Furthermore, the present invention relates to a method for manufacturing a work roller.

[0005] The present invention also relates to the use of work rollers.

[0006] The type of work roller described at the beginning, or the method for manufacturing this type of work roller, is known from the prior art.

[0007] To extend the service life of the work rollers as mentioned at the beginning, the surface of this type of work roller is provided with an appropriate wear protection layer, and at the same time, this wear protection layer can create a specified surface texture on the band.

[0008] Since wear protection layers can exhibit various wear characteristics when combined with the high loads in the rolling process, various influencing factors must also be considered when designing wear protection layers.

[0009] In the normal case, a suitable wear protection layer includes a hard chromium coating. However, this hard chromium coating is also prone to generating fine cracks, which is also considered to adversely affect the service life and corrosion resistance. When manufacturing a conventionally known chromium-based wear protection layer, especially when manufacturing a hard chromium layer, hexavalent chromium (Cr-6) has been used until now. During that time, it has been found that Cr-6 is carcinogenic and / or acts as a mutagen.

[0010] There are also various methods for attaching a wear protection layer to the working roller.

[0011] The problem underlying the present invention is to provide an improved or alternative form to the prior art.

[0012] According to a first aspect, the problem of the present invention is solved by a working roller for rolling a metal product, particularly for rolling a metal strip. The working roller has a base body made of metal and a wear protection layer disposed at least partially on the base body. The wear protection layer has a layer thickness of 70 μm or less, preferably 40 μm or less, and particularly preferably 15 μm or less.

[0013] When the wear protection layer is manufactured with a layer thickness of 70 μm or less, preferably 40 μm or less, and particularly preferably 15 μm or less, the working roller as described at the beginning can be manufactured at a very low cost.

[0014] The wear protection layer as described at the beginning is relatively complex in its structure, and accordingly, the manufacturing, especially the preparation of the materials therefor, is cost-intensive.

[0015] Conventionally, only a relatively thick wear protection layer has been successfully provided for the working roller as described at the beginning. The conventional wear protection layer has a layer thickness far exceeding 80 μm.

[0016] For cost reasons alone, it is desirable to provide the thinnest possible wear protection layer on the work rollers.

[0017] It has been found that a thin abrasion protection layer is advantageous if it has a fine-grained microstructure consisting of hard phase particles and matrix particles.

[0018] In particular, very small hard phase particles, and consequently the resulting particle size, are advantageous with respect to the wear protection layer.

[0019] For other favorable values ​​regarding the thickness of the wear protection layer, and consequently other favorable values ​​regarding the properties of the wear protection layer, please refer to Table 1.

[0020] Furthermore, by using the values ​​mentioned above for the thickness of the wear protection layer, it is possible to realize a particularly robust wear protection layer, resulting in a suitably long-lasting wear protection layer and / or a wear protection layer that is relatively unaffected by peak loads.

[0021] In this case, it is necessary to consider that the cohesive force will decrease if a relatively thin layer is selected. This increases the adhesion to the wear protection layer. Experiments have shown that this can result in improved wear properties, reduced delamination resistance, and improved impact stiffness. In this case, it has been demonstrated that very low values ​​for the thickness of the wear protection layer reverse the trend in delamination resistance and / or impact stiffness of the wear protection layer.

[0022] Since we were able to prove that the delamination resistance can be increased as the value of residual stress in the wear protection layer increases, it is thought that the reason for this reversal of the trend is that the magnitude of residual stress in the wear protection layer decreases due to relatively low values ​​for the thickness of the wear protection layer.

[0023] Furthermore, even with relatively low layer thicknesses, a more homogeneous distribution of elements in the wear protection layer, as well as an improved distribution of individual metallurgical phases within the wear protection layer, can be achieved. Experiments have shown that the homogeneity of the element distribution in the wear protection layer decreases as the layer thickness increases.

[0024] Regarding the precipitation of elemental tungsten (W) and / or ditungsten carbide (W2C), experiments have shown that precipitation may increase with increasing layer thickness.

[0025] During the application of the abrasion protection layer, a relatively thin abrasion protection layer results in a relatively low maximum temperature within the abrasion protection layer. This is because a relatively thin abrasion protection layer can be cooled more rapidly both on the base body side and on the side of the abrasion protection layer opposite the base body side. The maximum temperature of the abrasion protection layer during the thermal spraying process increases, and this promotes the precipitation of elemental tungsten (W) and / or ditungsten carbide (W2C). Furthermore, it has been demonstrated that the rate of cooling of the abrasion protection layer during the thermal spraying process, as the cooling rate increases, can potentially reduce the precipitation of elemental tungsten (W) and / or ditungsten carbide (W2C).

[0026] Furthermore, it was observed that as the thickness of the abrasion protection layer increases, the minimum achievable arithmetic roughness of the surface of the abrasion protection layer may increase, and / or the homogeneity of the thickness distribution of the abrasion protection layer may deteriorate more significantly. Therefore, relatively high thicknesses of the abrasion protection layer may contribute to higher post-processing costs for the abrasion protection layer before it is used for its designated application.

[0027] [Table 1]

[0028] Table 1: Layer thickness of abrasion protection layer (μm): Cohesive force, abrasion resistance, delamination resistance, element distribution (homogeneity), residual stress, stiffness against impact, tungsten precipitate and phase distribution, and cost for each abrasion protection layer (each evaluated on a scale from 0 to 10 using separate scales from minimum (0) to maximum (10) (scale symbol: kg) and from neutral (0) to best (10) (scale symbol: nb)).

[0029] Simply by appropriately selecting the thickness of the wear protection layer, the work roller described at the beginning can be advantageously developed; therefore, the features related to this, or combinations thereof, are already advantageous even without the other features of the present invention.

[0030] Furthermore, it is advantageous if the wear protection layer has a thickness of 2 μm or more, preferably 5 μm or more, and particularly preferably 6 μm or more and 8 μm or more.

[0031] This ensures that the base body is reliably covered with a wear-protective layer.

[0032] Furthermore, this layer thickness, in relation to the wear protection layer proposed in this invention, can still guarantee a good service life.

[0033] The abrasion protection layer preferably has a chromium content of 90% by weight or less, preferably 60% by weight or less, and particularly preferably 30% by weight or less.

[0034] For other favorable values ​​regarding the chromium content of the abrasion protection layer, and consequently other favorable values ​​regarding the properties of the abrasion protection layer, please refer to Table 2.

[0035] The wear protection layer of this invention is used to protect work rollers from wear.

[0036] When the wear protection layer is configured as proposed, improved wear resistance of the work roller base body can be ensured.

[0037] On the other hand, the risk of serious carcinogenic and / or mutagenic effects on living organisms, particularly workers or operators, can be eliminated or at least significantly reduced.

[0038] The wear protection layer proposed here eliminates the need for chromium, particularly hard chromium, which was previously primarily required for wear protection layers. This allows for the provision of the work roller, and especially the wear protection layer itself, as freely as possible, preferably completely freely, and provides at least uniform, or even improved, quality characteristics, such as improved surface quality, improved service life, and other improved characteristics of the work roller. These characteristics will be described in more detail below.

[0039] In all cases, this wear protection layer ensures a uniform roughness on the work roller surface that lasts as long as possible, and this work roller surface has an equal influence over the longest possible period on the desired target amount for the metal product to be rolled, for example, the surface of the metal product to be manufactured, in particular the roughness and texture or smoothness of the metal strip to be manufactured, with respect to the rolling process.

[0040] In particular, a suitably constructed wear protection layer for the work roller already solves the problem of the present invention by itself.

[0041] Herein, it should be noted that within the framework of this patent specification, indefinite articles and descriptions of an indefinite number such as "one" and "two" should, in most cases, be interpreted as minimal descriptions unless it is clear from the context of a particular section or a specific sentence that only "exactly one" or "exactly two" is intended, meaning they should also be interpreted as "at least one" or "at least two."

[0042] It should be noted here that, within the framework of this patent specification, the expression “in particular” should always be understood to mean that a preferred feature as an option is introduced by this expression. This expression should not be interpreted as “moreover” or “that is.”

[0043] Here, as the nickel content increases, the wear resistance decreases, so in particular, the nickel content should be adjusted to be relatively low, and especially, it should have a nickel content of 90% by weight or less, preferably 60% by weight or less, and most preferably 30% by weight or less.

[0044] For other favorable values ​​regarding the nickel content of the wear protection layer, and consequently other favorable values ​​regarding the properties of the wear protection layer, please refer to Table 2.

[0045] As can be seen from Table 2, a relatively high chromium content and / or a relatively low nickel content can improve the wear resistance of the wear protection layer, and in this case, a relatively low chromium content and a relatively low nickel content can improve or avoid the mutagenic and / or carcinogenic effects on the surrounding environment.

[0046] Experiments have demonstrated that the residual stress resulting in the wear protection layer can be influenced by selecting the chromium and / or nickel content of the wear protection layer. Herein, within the framework of this specification, the term residual stress should always be understood as residual compressive stress unless explicitly stated otherwise.

[0047] Other features, effects, advantages, or disadvantages can be seen in the description in Table 2 below.

[0048] [Table 2]

[0049] Table 2: Chromium and / or Nickel Content (Weight %): Residual Compressive Stress and Abrasion Resistance (Each evaluated on a scale from 0 to 10 using separate scales from minimum (0) to maximum (10) (scale symbol: kg) and from neutral (0) to best (10) (scale symbol: nb))

[0050] The level of residual compressive stress in the wear protection layer can also support the wear resistance of the wear protection layer. The generation of residual compressive stress in the wear protection layer favorably bonds the wear protection layer to the base body, thereby ultimately improving the stability and / or quality of the layer, particularly its adhesive tensile resistance. Therefore, reducing the nickel content in particular can favorably affect the adhesive tensile resistance of the wear protection layer.

[0051] Furthermore, in some cases, microscopic cracks that occur in the wear protection layer can be closed again by residual compressive stress in the wear protection layer, thereby advantageously reducing or preventing the extension of the microscopic cracks that may occur.

[0052] Experiments demonstrated that increasing the chromium content in the wear protection layer can raise the level of observable residual stress in the wear protection layer, while increasing the nickel content in the wear protection layer can lower the level of observable residual stress in the wear protection layer.

[0053] Furthermore, the wear protection layer has an arithmetic mean roughness value R a When the outer surface has a roughness of 0.01 μm or more, preferably 0.5 μm or more, and particularly preferably 1.5 μm or more, and / or the abrasion protection layer has an arithmetic mean roughness value R a It is advantageous when the outer surface has a thickness of 17 μm or less, preferably 10 μm or less, and particularly preferably 6 μm or less.

[0054] Arithmetic mean roughness value R of the outer surface of the wear protection layer aFor other favorable values ​​relating to this, and consequently to other favorable values ​​relating to the properties of the wear protection layer, please refer to Table 3.

[0055] Using the roughness values ​​shown herein, the roughness R of the wear protection layer of the work roller of this application is determined. a This can be individually adjusted to meet the requirements of the products that can be processed using it, thereby controlling the surface roughness R of the product. a In particular, the surface roughness of the strip material can be determined almost arbitrarily. In other words, this allows the factory to provide a roughness R of the wear protection layer of the product to be sold. a It can be adjusted.

[0056] [Table 3]

[0057] Table 3: Arithmetic mean roughness R of the outer surface of the abrasion protection layer a (μm): Adjustability of rolled product roughness, paintability of rolled product, texture of rolled product, deep drawing and press working characteristics of rolled product, adjustability of rolling force, and porosity of wear protection layer (each evaluated on a scale from 0 to 10 using separate scales from minimum (0) to maximum (10) (scale symbol: kg) and from neutral (0) to best (10) (scale symbol: nb)).

[0058] The ability to specifically determine the surface roughness of a product is particularly advantageous for various product characteristics, such as the paintability of the product, the feel of the product, the deep drawing and / or press working characteristics of the product, and the adjustability of the rolling force.

[0059] Furthermore, the arithmetic mean roughness value R of the surface of the wear protection layer a An interaction exists between this and the achievable porosity of the wear protection layer.

[0060] Even with only the characteristics regarding the arithmetic mean roughness value, the working roller as described at the beginning can be advantageously developed. Therefore, the characteristics regarding this, or the combination of those characteristics, are already advantageous even without other characteristics of the present invention.

[0061] The arithmetic mean roughness value R of the outer surface of the wear protection layer a A low value can bring about an improved texture of the working roller, an improved texture of the strip material rolled by the working roller, and an advantageous adjustability of the rolling force.

[0062] The arithmetic mean roughness value R of the outer surface of the wear protection layer a An intermediate value (see Table 3) can contribute to the best conditions for the paintability of the metal products rolled by the working roller.

[0063] The arithmetic mean roughness value R of the outer surface of the wear protection layer a A relatively high value (see Table 3) can improve the deep drawing characteristics and / or press working characteristics of the metal products rolled by the working roller, as well as the adhesion of the coating portion of the strip.

[0064] The arithmetic mean roughness value R of the outer surface of the wear protection layer a The wear protection layer having a low value (see Table 3) of the arithmetic mean roughness value R contributes to a low porosity of the wear protection layer. Therefore, it has been found that when the value of the arithmetic mean roughness value R a is small, the adhesion tensile resistance of the wear protection layer depending on the porosity of the wear protection layer can also be improved.

[0065] Furthermore, it is advantageous when the wear protection layer has a particle diameter of 2 μm or more, preferably 5 μm or more, and / or a particle diameter of 50 μm or less, preferably 45 μm or less, particularly preferably 30 μm or less or 20 μm or less.

[0066] For another advantageous value regarding the particle diameter of the wear protection layer, and thus another advantageous value regarding the characteristics of the wear protection layer related thereto, see Table 4.

[0067] In the spirit of this invention, the term "particle size" refers to the average diameter or average area of ​​crystallites (particles) in a polycrystalline metal on the polished surface. The particle size of the abrasion protection layer proposed herein is determined by the size of the particles of the starting material that provides the coating material for forming the abrasion protection layer during thermal spraying. Therefore, the term "particle size" is particularly strongly correlated with the particle size of the powder particles of the starting material powder.

[0068] Here, the term "delamination" specifically refers to the unintended separation of the wear protection layer from the base body surface.

[0069] In the spirit of this invention, the term "element distribution" refers to the volumetric ratio of the hard phase and the matrix, where the volumetric ratio can be determined, for example, by using a microscope after coating the base body.

[0070] In the spirit of this invention, the terms "matrix" or "matrix material" refer to the structure of the applied abrasion protection layer.

[0071] The matrix of the wear protection layer may have iron and / or nickel and / or cobalt and / or molybdenum and / or boron and / or tungsten.

[0072] By using iron as a component of the matrix of the wear protection layer, it is advantageous to achieve a relatively inexpensive matrix for the wear protection layer. This is particularly advantageous when the work roller wears out faster than its wear protection layer corrodes.

[0073] By using nickel as a component of the matrix of the wear protection layer, the chemical resistance of the matrix can be improved. Depending on the alloy of the wear protection layer, using a matrix containing nickel makes the wear protection layer as a whole chemically stable and particularly corrosion resistant.

[0074] Cobalt, as a component of the matrix of the wear protection layer, can improve the temperature resistance of the wear protection layer. Advantageously, cobalt can improve the hardness of the matrix, and consequently, the overall hardness of the wear protection layer.

[0075] The use of molybdenum as a component of the matrix can improve the chemical and / or thermal resistance of the wear protection layer, particularly the matrix.

[0076] Similarly, if the matrix contains tungsten, it is considered advantageous for the temperature resistance of the matrix, and by extension, the entire wear protection layer.

[0077] It was found that the adhesion properties of the matrix, and consequently the adhesion properties of the wear protection layer itself, can be improved by using boron as a component of the matrix.

[0078] Furthermore, the matrix of the wear protection layer may contain manganese, copper, chromium, and / or silicon, thereby allowing for further optimization of the matrix of the wear protection layer in terms of its ductility, hardness, chemical resistance, machinability, friction properties, temperature resistance, adhesion resistance, and the like.

[0079] In this relationship, the “hard phase” is either embedded in the relatively soft material of the wear protection layer, particularly in the relatively soft matrix or relatively soft matrix material of the wear protection layer, or is embedded “floating” within it.

[0080] The hard phase suitable for the wear protection layer may, in particular, be an oxide, carbide, or boride hard phase, which advantageously possess high hardness. For example, a compound consisting of silicon and carbon that forms silicon carbide (SiC) can be used.

[0081] Here, the term "adhesion tensile resistance" refers to the resistance to adhesion acting on the abrasion protection layer.

[0082] Here, "adhesion" refers to the ability of the wear protection layer to adhere to the base body of the work roller.

[0083] In this context, the term "aggregation," as further mentioned below, refers to the ability of individual layers of the wear protection layer or the mutual adhesion of the coating layers.

[0084] Here, the term "phase" generally refers to the state of one or more elements. In particular, an intermetallic phase refers to a compound of at least two metals, especially a homogeneous chemical compound.

[0085] The particle size of the abrasion protection layer, particularly the average particle size of the hard phase of the abrasion protection layer, and especially the average particle size of the hard phase elements of the abrasion protection layer, affect several properties of the abrasion protection layer. The particle size can be influenced by the thermal spraying process parameters of the abrasion protection layer, particularly through the average diameter of the powder used.

[0086] In particular, particle size can advantageously affect the homogeneity of the wear protection layer, especially the homogeneity of the distribution of coating elements within the wear protection layer, particularly the distribution of hard phase elements within the wear protection layer, and also the homogeneity of the thickness of the wear protection layer. Experiments confirmed that the homogeneity described above can be improved as the particle size decreases.

[0087] Furthermore, the roughness R of the abrasion protection layer depends on the particle size. a , in particular the arithmetic mean roughness value R a This can have an effect on the arithmetic mean roughness value R of a wear-protective layer that has not undergone post-treatment after thermal spraying, especially with relatively small particle sizes. a A relatively low value can be achieved.

[0088] The particle size can affect the residual stress in the wear protection layer. In this case, a relatively small particle size can improve the residual stress in the wear protection layer, and a relatively high residual stress in the wear protection layer can improve the adhesion tensile resistance. It has been found that reducing the particle size can also reduce the risk of the wear protection layer peeling off from the base body of the work roller. However, the particle size can also further affect the delamination resistance by influencing the porosity of the wear protection layer.

[0089] [Table 4]

[0090] Table 4: Particle size of the abrasion protection layer (μm): Roughness of the abrasion protection layer, roughness of the product (strand) processed by the work roller, residual stress, porosity, hardness, peak number, homogeneity, in particular homogeneity of the distribution of coating elements within the abrasion protection layer, homogeneity of the thickness of the abrasion protection layer, (coating) element distribution, adhesion tensile strength, and delamination strength (each evaluated on a scale from 0 to 10 using separate scales from minimum (0) to maximum (10) (scale symbol: kg) and from neutral (0) to best (10) (scale symbol: nb)).

[0091] On the other hand, the particle size achieved within the abrasion protection layer can affect the motion of the coating material and the temperature of the coating material particles during the thermal spraying process and when it is applied to the base body surface. As the average powder diameter, and consequently the particle size of the abrasion protection layer, increases, the particle velocity decreases and the adhesion ability decreases, assuming the same heat transfer. Consequently, the adhesion tensile strength of the abrasion protection layer may also decrease with increasing particle size.

[0092] During thermal spraying of the wear protection layer, it was found that as the average diameter of the powder used increases, and therefore as the particle size of the wear protection layer increases, the amount of powder particles adhering to the surface decreases, which can impair the homogeneity of the element distribution.

[0093] The higher the thermal energy of the powder particles during thermal spraying of the wear protection layer, the greater the risk of undesirable precipitation of elemental tungsten particles and / or ditungsten carbide (W2C).

[0094] Particle size not only affects roughness and residual stress, but can also affect the porosity of the wear protection layer. In particular, relatively large particle sizes increase the porosity of the wear protection layer, which can reduce its hardness and / or delamination resistance.

[0095] Furthermore, particle size can also affect the number of peaks in the wear protection layer, and consequently, the roughness of the metal strip processed by the work roller. In this case, the optimal number of peaks can be achieved in the intermediate range of particle sizes considered here, and therefore the roughness of the metal strip processed by the work roller can also take an optimal value in the intermediate range of particle sizes considered here.

[0096] The characteristics related to particle size alone are advantageous enough to develop the work roller described at the beginning, so these characteristics, or combinations thereof, are already advantageous even without the other features of the present invention.

[0097] Particularly preferably, the wear protection layer contains tungsten carbide (WC) in a proportion of 50% by weight or more, preferably 60% by weight or more, and particularly preferably 70% by weight or more.

[0098] Within the scope of this specification, tungsten carbide (WC) is explicitly understood to mean tungsten monocarbide (WC).

[0099] The hardness of the wear protection layer can be advantageously increased by the weight ratio of tungsten carbide in the wear protection layer, particularly tungsten carbide as a component of the hard phase of the wear protection layer. In this case, the hardness of the wear protection layer can be further increased by increasing the proportion of monotungsten carbide (WC) in the wear protection layer.

[0100] The abrasion protection layer may, advantageously, contain tungsten carbide (WC) in a proportion of 2% by weight or more, preferably 20% by weight or more, and particularly preferably 25% by weight or 30% by weight or more. More advantageously, the abrasion protection layer may contain tungsten carbide (WC) in a proportion of 40% by weight or more, preferably 45% by weight or more, and particularly preferably 65% ​​by weight or 70% by weight or more. Particularly advantageously, the abrasion protection layer may contain tungsten carbide (WC) in a proportion of 75% by weight or more, preferably 80% by weight or more, and particularly preferably 85% by weight or more or 87% by weight or more.

[0101] The abrasion protection layer can be further improved if it contains tungsten precipitates in a proportion of 50% by weight or less, preferably 33% by weight or less, and particularly preferably 10% by weight or less or 5% by weight or less, especially tungsten precipitates of elemental tungsten (W) and / or ditungsten carbide (W2C).

[0102] [Table 5]

[0103] Table 5: Tungsten precipitates in the abrasion protection layer (elemental tungsten and / or ditungsten carbide W2C) (weight %): Each of these is evaluated on a scale from 0 to 10 for the abrasion protection layer, including embrittlement, abrasion resistance, fracture toughness, adhesion tensile strength, service life, hardness, and layer adhesion (each using separate scales from minimum (0) to maximum (10) (scale symbol: kg) and neutral (0) to best (10) (scale symbol: nb)).

[0104] For other favorable values ​​regarding the weight percentage of tungsten precipitates in the abrasion protection layer, and consequently other favorable values ​​regarding the properties of the abrasion protection layer, please refer to Table 5.

[0105] Tungsten precipitates in the form of elemental tungsten (W) and / or ditungsten carbide (W2C) may result from the degradation of tungsten carbide (WC).

[0106] Tungsten precipitates in the abrasion protection layer, particularly in the form of elemental tungsten (W) and / or ditungsten carbide (W2C), can contribute to the embrittlement of the abrasion protection layer. As the proportion of tungsten precipitates increases, the abrasion resistance, fracture toughness, and / or adhesive tensile strength of the abrasion protection layer may decrease. Overall, a relatively high proportion of tungsten precipitates in the abrasion protection layer may result in a shorter service life.

[0107] However, it should also be noted that the hardness of the wear protection layer can be increased by increasing the "weight %" percentage of tungsten precipitates.

[0108] Furthermore, the proportion of tungsten precipitates within the abrasion protection layer can affect the interlayer adhesion between adjacent layers of the abrasion protection layer, particularly between individual layers of abrasion protection layers that are stacked vertically and not simultaneously adhered. However, as the proportion of tungsten precipitates increases, the interlayer adhesion may decrease.

[0109] To that extent, the wear protection layer must comply with the requirement that it have a regulated proportion of tungsten precipitates in "weight %".

[0110] The proportion of tungsten precipitates, particularly elemental tungsten (W) and / or ditungsten carbide (W2C) precipitates alone, is sufficient to favorably develop the work roller described at the beginning. Therefore, the features related to this, or combinations thereof, are already advantageous even without the other features of the present invention.

[0111] Furthermore, the wear protection layer has a load capacity of 60 N / mm 2 In summary, 70 N / mm is preferred. 2 In particular, 80 N / mm2 or 100 N / mm 2 Having the above-mentioned tensile strength for fixation is advantageous.

[0112] During a adhesion tensile test, it is possible to determine whether the inspected abrasion protection layer completely delaminates, partially delaminates, or does not delaminate at all after a test using a tensile force applied perpendicular to the abrasion protection layer. Therefore, adhesion tensile resistance is understood to be the tensile force value at which the abrasion protection layer does not delaminate at all at the inspected location. Accordingly, a relatively high value of adhesion tensile resistance is advantageous for the delamination resistance of the abrasion protection layer.

[0113] Furthermore, the wear protection layer has a load capacity of 55 N / mm 2 In summary, 65 N / mm² is preferred. 2 In particular, 75 N / mm 2 or 90 N / mm 2 It possesses the above-mentioned tensile strength for fixation.

[0114] The tensile strength of the wear protection layer alone is sufficient to develop the work roller described at the beginning of this text advantageously; therefore, the features related to this, or combinations thereof, are already advantageous even without the other features of the present invention.

[0115] Furthermore, it is advantageous if the wear protection layer has a porosity value of 1% or less, preferably 0.5% or less, and particularly preferably 0.1% or less.

[0116] [Table 6]

[0117] Table 6: Porosity (%) of the abrasion protection layer: Quality, corrosion resistance, delamination resistance, surface roughness, hardness, residual stress, and peak number (each evaluated on a scale from 0 to 10 using separate scales from minimum (0) to maximum (10) (scale symbol: kg) and from neutral (0) to best (10) (scale symbol: nb)).

[0118] For other favorable values ​​regarding the porosity of the abrasion protection layer, and consequently other favorable values ​​regarding the properties of the abrasion protection layer related to this porosity, please refer to Table 6.

[0119] The term "porosity" here refers to the number and / or size of pores in the abrasion protection layer, expressed in units of a percentage (%). This number can be determined, for example, by optical evaluation or by a penetration test, in which the drainage rate of the abrasion protection layer and / or the work roller equipped with the abrasion protection layer is examined under the influence of vacuum.

[0120] Experiments have demonstrated that, with respect to the required properties for work rollers, particularly corrosion resistance, delamination resistance, and hardness, the general quality of the wear protection layer on work rollers can be improved as the porosity of the wear protection layer decreases.

[0121] In particular, as the porosity value decreases, the corrosion resistance of the wear protection layer can be improved.

[0122] Similarly, a relatively low porosity value of the abrasion protection layer can have a positive effect on the adhesion tensile resistance or delamination resistance of the abrasion protection layer.

[0123] Similarly, the hardness of the wear protection layer can be increased as the porosity value decreases.

[0124] A low roughness value of the outer surface of the abrasion protection layer, particularly a low porosity value, can be advantageously achieved by additional application of the abrasion protection layer and / or removal of the outer layer of the abrasion protection layer, especially using a thermal spraying process.

[0125] Furthermore, the achievable residual stress value in the wear protection layer can also be increased by lowering the porosity.

[0126] Furthermore, we were able to demonstrate that a higher number of peaks can be achieved with a low porosity of the wear protection layer, particularly with the EDT texturing method, which allows for texturing of the surface of the wear protection layer by spark processing.

[0127] The porosity of the wear protection layer alone is sufficient to advantageously develop the work roller described at the beginning; therefore, the features related to this, or combinations thereof, are already advantageous even without the other features of the present invention.

[0128] Furthermore, it is advantageous if the abrasion protection layer has a permeability value of 1 barrer or less, preferably 0.5 barrer or less, and particularly preferably 0.1 barrer or less.

[0129] For other favorable values ​​regarding the permeability of the abrasion protection layer, and consequently other favorable values ​​regarding the properties of the abrasion protection layer related to this permeability, please refer to Table 7.

[0130] The permeability of the abrasion protection layer can also affect its quality. In other words, if the abrasion protection layer has low permeability, and especially low gas permeability in units of valves, then better layer quality can be achieved with respect to the abrasion protection layer.

[0131] Experiments have demonstrated that the general quality of the wear protection layer on work rollers can be improved as the permeability of the wear protection layer decreases, particularly in terms of the required properties of the work roller, such as corrosion resistance, delamination resistance, and hardness.

[0132] In particular, as the permeability value decreases, the corrosion resistance of the wear protection layer can be improved.

[0133] Similarly, a relatively low permeability value of the abrasion protection layer can have a positive effect on the adhesion tensile resistance or delamination resistance of the abrasion protection layer.

[0134] Similarly, the hardness of the wear protection layer can be increased as the permeability value decreases.

[0135] Here, the term "permeability" refers to the passability of the abrasion protection layer, which is mainly determined by the number of permeable or open holes in the abrasion protection layer, particularly the number of holes through which gas can pass.

[0136] [Table 7]

[0137] Table 7: Permeability of the abrasion protection layer (Valor): Quality, corrosion resistance, delamination resistance, surface roughness, hardness, residual stress, and peak number for each abrasion protection layer (each evaluated on a scale from 0 to 10 using separate scales from minimum (0) to maximum (10) (scale symbol: kg) and from neutral (0) to best (10) (scale symbol: nb)).

[0138] The permeability of the wear protection layer alone is sufficient to develop the work roller described at the beginning, so the features related to this, or combinations thereof, are already advantageous even without the other features of the present invention.

[0139] It is advantageous if the wear protection layer has a layer hardness value of 800 HV or higher, preferably 1000 HV or higher, particularly preferably 1100 HV or higher, and / or 1600 HV or lower, preferably 1500 HV or lower, particularly preferably 1400 HV or lower.

[0140] For other favorable values ​​regarding the hardness of the abrasion protection layer, which can be measured by the micro-identification method and measured in Vickers units, and for other favorable values ​​regarding the properties of the abrasion protection layer related to this hardness, please refer to Table 8.

[0141] [Table 8]

[0142] Table 8: Layer Hardness (HV) of the Abrasion Protection Layer: Abrasion resistance and adhesion tensile strength of the abrasion protection layer (evaluated on a scale from 0 to 10 using separate scales from minimum (0) to maximum (10) (scale symbol: kg) and from neutral (0) to best (10) (scale symbol: nb)).

[0143] The hardness values ​​shown here can favorably influence the wear resistance of the wear protection layer, or improve the wear resistance of the wear protection layer.

[0144] However, experiments have confirmed that the higher the hardness of the wear protection layer, the lower its tensile resistance to adhesion, particularly with respect to adhesion to the base body of the work roller.

[0145] Furthermore, by selecting the layer hardness, it is possible to favorably influence the residual stress generated in the wear protection layer, and the surface roughness R of the wear protection layer can also be adjusted. a It should be noted that this can similarly have a favorable impact on [the other party].

[0146] In particular, the ratio of the hard phase to the matrix, the precipitation of ditungsten carbide (W2C), porosity, and / or permeability affect the hardness of the wear protection layer of the work roller.

[0147] Furthermore, the interrelationships between layer hardness, the number of peaks in the wear protection layer, the porosity of the wear protection layer, and the homogeneity of the wear protection layer can also be advantageously utilized.

[0148] The selected layer hardness alone, with respect to the wear protection layer, allows for the advantageous development of the work roller described at the beginning; therefore, the features related to this, or combinations thereof, are already advantageous even without the other features of the present invention.

[0149] Furthermore, it is advantageous if the wear protection layer has a deviation of 40% or less, preferably 30% or less, and particularly preferably 20% or less from the weight ratio of the coating elements averaged over the total number of analysis points, at 80% or more of the analysis points, preferably 90% or more of the analysis points, and particularly preferably 95% or more of the analysis points, where the total number of analysis points is 5 or more, preferably 15 or more, and particularly preferably 25 or more, and in particular the coating elements are tungsten carbide (WC), aluminum oxide (Al2O3), zirconium oxide (ZrO2), chromium carbide (Cr3C2, Cr7C3 and / or Cr 23 It is one of C6 or vanadium carbide (VC).

[0150] For other favorable values ​​regarding the maximum deviation in the weight ratio of coating elements within the wear protection layer (homogeneity of the distribution of coating elements), and consequently other favorable values ​​regarding the quality-evaluated properties of the wear protection layer related to this maximum deviation, please refer to Table 9.

[0151] The homogeneity of the element distribution can also advantageously influence the properties of the wear protection layer.

[0152] By analyzing the homogeneity of element distribution, the composition of chemical elements, in particular, can be locally identified. In this case, both qualitative and quantitative analysis are possible.

[0153] This can be determined using microanalysis methods such as EDX analysis (Energy Dispersive X-ray Spectroscopy). EDX analysis allows for advantageous inspection of the coating composition. Unknown materials or impurities in terms of chemical elements can also be analyzed in this wear protection layer. Furthermore, the thickness of the wear protection layer can also be measured.

[0154] [Table 9]

[0155] Table 9: Homogeneity of element distribution (qualitative): For each wear protection layer, the homogeneity of the distribution of the hard phase in the matrix, hardness, porosity, residual (compressive) stress, delamination resistance, and thickness (each evaluated on a scale from 0 to 10 using separate scales from minimum (0) to maximum (10) (scale symbol: kg) and from neutral (0) to best (10) (scale symbol: nb)).

[0156] In general, the higher the heterogeneity of the starting material supplied to the thermal spraying process, the higher the heterogeneity of the resulting wear protection layer. Consequently, the ratio of the hard phase to the matrix of the wear protection layer becomes heterogeneous, and this heterogeneous ratio affects several properties of the wear protection layer.

[0157] The greater the heterogeneity of the ratio of the hard phase to the matrix, the lower the effective hardness of the wear protection layer. Furthermore, as the heterogeneity of the hard phase relative to the matrix increases, more vacancies are generated, which increase the porosity of the wear protection layer.

[0158] The homogeneity of the distribution of coating elements in the wear protection layer reduces the useful level of residual stress generated in the wear protection layer.

[0159] As a result, the homogeneity of the coating element distribution decreases, which also reduces the adhesion tensile strength of the wear protection layer, and this adhesion tensile strength decreases particularly with increased porosity and / or a decrease in the minimum residual stress level.

[0160] In particular, increased heterogeneity in the distribution of coating elements in the wear protection layer can lead to heterogeneity in the thickness of the wear protection layer.

[0161] The homogeneity of the wear protection layer alone is advantageous for developing the work roller described at the beginning, so the features related to this, or combinations thereof, are already advantageous even without the other features of the present invention.

[0162] Furthermore, the properties of the wear protection layer of the present invention can be affected if, at 80% or more of the measurement locations, preferably 90% or more of the measurement locations, and particularly preferably 95% or more of the measurement locations, there is a thickness deviation of 20% or less, preferably 10% or less, and particularly preferably 5% or less, from the average thickness of the wear protection layer over the total number of measurement locations, where the total number of measurement locations is 10 or more, preferably 25 or more, and particularly preferably 40 or more.

[0163] Preferably, the abrasion protection layer has a thickness tolerance of 1 μm or less, preferably 0.5 μm or less, and particularly preferably 0.2 μm or less.

[0164] Homogeneity of layer thickness is a particularly advantageous characteristic of abrasion protection layers. In other words, undulation on the surface of the abrasion protection layer is usually undesirable and is only desired in special cases. Therefore, for many embodiments of work rollers, an abrasion protection layer with a more uniform thickness and / or with only slight thickness deviations is advantageous.

[0165] Preferably, the abrasion protection layer has a thickness tolerance of 2 μm or less, preferably 0.75 μm or less, and particularly preferably 0.35 μm or less.

[0166] The thickness homogeneity proposed here, in particular, improves the roughness R of the wear protection layer. a and / or it can favorably influence the undulation of the wear protection layer.

[0167] The uniform thickness alone allows for the advantageous development of the work roller described at the beginning; therefore, the features related to this, or combinations thereof, are already advantageous even without the other features of the present invention.

[0168] Additionally, it is advantageous if the wear protection layer has a hard phase and a matrix, with the hard phase being contained within the matrix.

[0169] Experiments have shown that abrasion-protective layers with a hard phase are particularly resistant to abrasion and therefore have an improved service life, especially when at least one hard phase is incorporated into a matrix that is softer than that hard phase.

[0170] Here, the hard phase refers to a phase that contains at least one particle of at least one type of oxide, carbide, and / or boride.

[0171] Particularly advantageous are the hard phases tungsten carbide (WC), aluminum oxide (Al2O3), zirconium oxide (ZrO2), chromium carbide (especially Cr3C2, Cr7C3 and / or Cr 23 C6) contains vanadium carbide (VC), silicon carbide (SiC), tungsten boride (WB), chromium oxide (especially CrO, Cr2O3, CrO2 and / or CrO3), titanium carbide (TiC), titanium oxide (especially TiO, Ti2O3 and / or TiO2), and / or molybdenum carbide (especially Mo2C and / or MoC).

[0172] Furthermore, it is advantageous if the wear protection layer has a hard phase and a matrix, and is particularly advantageous if the ratio of the hard phase to the entire layer system consisting of the hard phase and matrix is ​​40 volume% or more, preferably 50 volume% or more, and especially preferably 60 volume% or more, and / or particularly advantageous if the ratio of the hard phase to the entire layer system is 90 volume% or less, preferably 85 volume% or less, and especially preferably 80 volume% or less or 75 volume% or less.

[0173] For other favorable values ​​regarding the ratio of the hard phase to the matrix of the wear protection layer, and consequently other favorable values ​​regarding the properties of the wear protection layer related to this ratio, please refer to Table 10.

[0174] It should be noted that the term "ratio of hard phase to matrix" used here is understood to mean the proportion of the hard phase in the wear protection layer in a quantitative sense, that is, the ratio of the hard phase to the entire layer system consisting of the hard phase and the matrix.

[0175] The hard phase / matrix ratio can be used as a measure of the element distribution in the wear protection layer.

[0176] To that extent, it is advantageous when the hard phase and matrix exist in an optimal ratio relative to each other. This is because the more hard phase there is, the higher the hardness of the wear protection layer becomes.

[0177] [Table 10]

[0178] Table 10: Ratio of hard phase to matrix, i.e., ratio of hard phase to the entire layer system consisting of hard phase and matrix: hardness and roughness R for the wear protection layer, respectively. a Density, homogeneity of element distribution, homogeneity of layer thickness distribution, number of peaks, bonded tensile strength, residual stress, and porosity (each evaluated on a scale from 0 to 10 using separate scales from minimum (0) to maximum (10) (scale symbol: kg) and from neutral (0) to best (10) (scale symbol: nb)).

[0179] Furthermore, the higher the proportion of the hard phase, the more particles protrude from the wear protection layer, thereby affecting the surface roughness R of the wear protection layer. a It can have an effect.

[0180] In contrast, the following applies: The softer the abrasion protection layer, the denser it becomes, which can result in a thinner final thickness of the abrasion protection layer.

[0181] The softer the wear protection layer, that is, the lower the proportion of the hard phase, the more particles can adhere to the surface, which can affect the homogeneity of the elements and the homogeneity of the thickness of the wear protection layer.

[0182] Other interactions related to this hard phase / matrix ratio may occur in the wear protection layer with respect to peak number, adhesion, residual stress, and / or porosity.

[0183] The ratio of the hard phase to the entire layer system consisting of the hard phase and matrix alone is sufficient to advantageously develop the work roller described at the beginning; therefore, the features related to this, or combinations thereof, are already advantageous even without the other features of the present invention.

[0184] Particularly advantageous is that the wear protection layer is composed of elements such as tungsten carbide (WC), aluminum oxide (Al2O3), zirconium oxide (ZrO2), chromium carbide (Cr3C2, Cr7C3 and / or Cr 23 C6), having at least one, two, three, four, five, six, seven or more of the following: vanadium carbide (VC), silicon carbide (SiC), tungsten boride (WB), chromium oxide (CrO, Cr2O3, CrO2 and / or CrO3), titanium carbide (TiC), titanium oxide (TiO, Ti2O3 and / or TiO2), or molybdenum carbide (Mo2C and / or MoC), particularly tungsten carbide (WC), aluminum oxide (Al2O3), zirconium oxide (ZrO2), chromium carbide (Cr3C2, Cr7C3 and / or Cr 23 It contains at least one, two, three, four or more of C6 and / or vanadium carbide (VC).

[0185] In particular, other coating elements can influence the formation and properties of the wear protection layer of this invention.

[0186] For example, the following coating elements, namely tungsten carbide (WC), aluminum oxide (Al2O3), zirconium oxide (ZrO2), chromium carbide (Cr3C2, Cr7C3 and / or Cr 23C6), consisting of vanadium carbide (VC), silicon carbide (SiC), tungsten boride (WB), chromium oxide (CrO, Cr2O3, CrO2 and / or CrO3), titanium carbide (TiC), titanium oxide (TiO, Ti2O3 and / or TiO2), or molybdenum carbide (Mo2C and / or MoC), and in particular in all combinations and compositions, tungsten carbide (WC), aluminum oxide (Al2O3), zirconium oxide (ZrO2), chromium carbide (Cr3C2, Cr7C3 and / or Cr 23 The properties of all wear protection layers can be influenced by a coating element consisting of at least one, two, three, four or more of C6 and / or vanadium carbide (VC).

[0187] The hard phase and matrix can be used to further influence the wear protection layer.

[0188] Depending on the coating element, the ratio of the hard phase to the matrix can be favorably defined, as already explained above.

[0189] Typically, various coating elements are characterized by various properties, particularly by various hardnesses, and to that extent, one or more elements of the wear protection layer can favorably influence the hardness and other properties of the wear protection layer.

[0190] Furthermore, various coating elements can also affect the residual stress in the wear protection layer.

[0191] The selection of one or more elements of the wear protection layer alone can advantageously develop the work roller described at the beginning, so the features relating thereto, or combinations thereof, are already advantageous even without other features of the present invention.

[0192] Furthermore, the wear protection layer and / or base body have a -200 N / mm 2 In summary, preferably 0 N / mm 2In particular, 200 N / mm 2 If the residual compressive stress is greater than or equal to the above value, and / or the wear protection layer and / or base body is 2,000 N / mm 2 The following is preferably 1,500 N / mm 2 The following is particularly preferred: 1,000 N / mm 2 Having residual compressive stress of the following values ​​is advantageous.

[0193] For the time being, let's just say that negative values ​​of residual stress or residual compressive stress should be understood as residual tensile stress.

[0194] These values ​​make it possible to achieve improved wear resistance of the work roller, particularly through very tight connections or "bonding" of the wear protection layer in coated components such as the base body of the work roller of the present invention. To that extent, improved layer adhesion can be achieved by generating the proposed residual compressive stress.

[0195] Furthermore, the occurrence of cracks in the wear protection layer, particularly fine cracks, can be suppressed by using appropriate residual compressive stress.

[0196] Furthermore, in some cases, microcracks that develop in the wear protection layer can be closed again by residual compressive stress in the wear protection layer, thereby advantageously reducing or preventing the potential extension of these microcracks. Similarly, tensile residual stress may promote the extension of microcracks.

[0197] Furthermore, the growth of the wear protection layer is typically affected by unfavorable tensile residual stresses.

[0198] Furthermore, the adhesion tensile strength of the abrasion protection layer, the hardness of the abrasion protection layer, and the final thickness of the abrasion protection layer can be positively or negatively affected by the appropriately set residual stress, particularly as shown in Table 11 below.

[0199] These value ranges can be determined by various methods, however, they can be determined using the following methods: "ICP-sensor monitors the curvature by Tsui and Clyne mode" or "Rigaku stress analyzer of model STRAIN-FLEX MSF-2M", where residual compressive stress and residual stress are given in N / mm². 2 It is measured in units of [unit].

[0200] Other features, effects, advantages, or disadvantages can be seen in the description in Table 11 below.

[0201] The residual stress in the wear protection layer and / or base body, particularly the residual compressive stress in the wear protection layer and / or base body alone, is advantageous enough to develop the work roller described at the beginning; therefore, the features relating to this, or combinations thereof, are already advantageous even without the other features of the present invention.

[0202] [Table 11]

[0203] Table 11: Residual compressive stress (N / mm²) 2 ): For each abrasion protection layer, abrasion resistance, layer adhesion, layer adhesion strength, and adhesion tensile strength (each evaluated on a scale from 0 to 10 using separate scales from minimum (0) to maximum (10) (scale symbol: kg) and from neutral (0) to best (10) (scale symbol: nb)).

[0204] Furthermore, it is advantageous if the wear protection layer and / or base body have a peak number of RPc values ​​of 1 / cm or more, preferably 30 / cm or more, particularly preferably 60 / cm or more, and / or a peak number of RPc values ​​of 300 / cm or less, preferably 250 / cm or less, particularly preferably 200 / cm or less.

[0205] These values ​​regarding the number of peaks allow for the formation of a highly advantageous surface for the wear protection layer, and in particular, a highly advantageous texture on the surface of the wear protection layer.

[0206] In particular, this can also affect the adhesion between the wear protection layer and the base body.

[0207] However, it should be noted that a high number of peaks in the base body does not directly result in a high number of peaks in the wear protection layer. Accordingly, the number of peaks in the base body is not the only important factor when it comes to the number of peaks in the wear protection layer.

[0208] Arithmetic mean roughness value R a When R is relatively high, a relatively high number of peaks can be achieved, and in that case, a relatively low arithmetic mean roughness value R a Even so, we were able to prove that a high number of peaks can be achieved.

[0209] The number of peaks is expressed in units of "peaks / cm". Further details regarding the number of peaks can be found in DIN10049-2014.

[0210] The characteristics related to the number of peaks alone are sufficient to develop the work roller described at the beginning to an advantage; therefore, these characteristics, or combinations thereof, are already advantageous even without the other features of the present invention.

[0211] Particularly advantageous is that the wear protection layer contains oxides in a proportion of 5% by weight or less, preferably 3% by weight or less, and especially preferably 1.5% by weight or less, particularly chromium oxide (CrO, Cr2O3, CrO2 and / or CrO3) and / or aluminum oxide (Al2O3) and / or zirconium oxide (ZrO2) and / or titanium oxide (TiO, Ti2O3 and / or TiO2).

[0212] A relatively low percentage of oxides can be achieved, in particular, by having a thermal spraying apparatus with a lambda value of approximately 1 or 1.

[0213] Experiments revealed that increased oxide content may shorten the lifespan of the wear protection layer and / or, if the wear protection layer has a multilayer structure, may negatively affect the adhesion between adjacent layers.

[0214] Similarly, the base body has an arithmetic mean roughness value R of 0.1 μm or more, preferably 0.2 μm or more, and particularly preferably 0.3 μm or more. a If the outer surface to be coated is present, and / or the arithmetic mean roughness value R is 14 μm or less, preferably 4.0 μm or less, and particularly preferably 0.8 μm or less. a It was found to be advantageous when there is an outer surface to be coated.

[0215] Base body surface roughness R a This can advantageously affect the wear protection layer, for example, the final roughness R of the wear protection layer. a Furthermore, it can also affect its homogeneity. Here, the roughness R of the material to be coated (base body) a The larger the value, the roughness R of the surface of the wear protection layer. a The size also increases, and the roughness R of the material to be coated (base body) a The larger the deviation, the greater the variation in layer thickness, which can negatively affect the uniformity of the wear protection layer thickness.

[0216] Furthermore, the particle adhesion, and consequently the layer adhesion, of the wear protection layer on the base body surface may also be affected by the roughness of the base body surface.

[0217] The roughness R mentioned here pertains to the surface of the base body. a Various types of roughness can be produced, as described above R aThis can be partially achieved, for example, by polishing the uncovered surface (base body surface) of the work roller, with a roughness R of, for example, from 0.3 μm to 0.8 μm. a It is possible to achieve this.

[0218] Other features, effects, advantages, or disadvantages can be seen in Table 12 below.

[0219] [Table 12]

[0220] Table 12: Average roughness R of the abrasion protection layer a (μm): Layer roughness, layer thickness, homogeneity of the abrasion protection layer, residual stress of the abrasion protection layer, and adhesion tensile strength of the abrasion protection layer (each evaluated on a scale from 0 to 10 using separate scales from minimum (0) to maximum (10) (scale symbol: kg) and from neutral (0) to best (10) (scale symbol: nb)).

[0221] Arithmetic mean roughness value R a The features related to this alone are sufficient to advantageously develop the work roller described at the beginning; therefore, these features, or combinations thereof, are already advantageous even without the other features of the present invention.

[0222] It was found that the base body is suitable when it has a hardness value of 35 HRC or higher, preferably 40 HRC or higher, and particularly preferably 50 HRC or higher, and / or when it has a hardness value of 70 HRC or lower, preferably 65 HRC or lower, and particularly preferably 60 HRC or lower.

[0223] The other hardness values ​​mentioned here for the base body can, in particular, favorably influence or adjust the adhesion of the wear protection layer to the base body of the work roller.

[0224] If an excessively soft base body hardness is selected, unfortunately, components of the wear protection layer may penetrate the base body. If the base body hardness is excessively hard, there is a risk that the number of components of the coating material that are repelled by the base body during application of the coating material to the base body will be critically high.

[0225] Furthermore, the following points should be noted regarding the hardness of the base body: As the hardness of the base body increases, the tensile strength of the abrasion protection layer decreases, which can make the abrasion protection layer more prone to delamination from the base body.

[0226] As the hardness of the base body increases, the risk of more vacancies occurring in the bond between the base body and the wear protection layer increases, which in turn can increase the risk of delamination.

[0227] These types of vacancies often result in higher porosity, which can negatively impact the wear protection layer and the base body.

[0228] [Table 13]

[0229] Table 13: Base body hardness (HRC): Porosity, vacancy rate, bond tensile strength, residual stress, and layer thickness for the wear protection layer (each evaluated on a scale from 0 to 10 using separate scales from minimum (0) to maximum (10) (scale symbol: kg) and from neutral (0) to best (10) (scale symbol: nb)).

[0230] Furthermore, vacancies also affect the residual stress in the wear protection layer, and vice versa.

[0231] Furthermore, the adhesion mechanism in the thermal spraying process can affect the roughness and thickness of the wear protection layer.

[0232] The harder the abrasion protection layer becomes, the roughness R of the abrasion protection layer surface increases accordingly. a This could potentially have an impact.

[0233] The base body hardness HRC here is preferably measured by a macro-identification method.

[0234] Other features, effects, advantages, or disadvantages can be seen in the description in Table 13 below. The features related to the hardness of the base body alone are advantageous enough to develop the work roller described at the beginning, so these features, or combinations thereof, are already advantageous even without the other features of the present invention.

[0235] Furthermore, other components relating to the base body, such as the materials used in its manufacture, may have a favorable effect on the wear protection layer.

[0236] Furthermore, the dimensions selected for the base body, particularly its width, diameter, and length, as well as the support width between the base body's support points, can also affect the quality of the wear protection layer.

[0237] In any case, the aforementioned features allow for the customization of work rollers for rolling metal products, particularly the wear protection layer of the work rollers, to meet various individual needs while taking into account legal requirements to avoid hard chromium.

[0238] In another embodiment, the problem of the present invention is also solved by a rolling mill having a work roller that conforms to one of the features described herein.

[0239] The problem of the present invention is also solved for metal strips, which are cold-rolled using a work roller that conforms to one of the features described herein.

[0240] Advantageously, specific characteristics of the wear protection layer can be recognized based on the surface pattern achieved in the metal strip. In particular, the texturing of the wear protection layer of the work roller can be transferred from the surface of the work roller, especially the surface of the wear protection layer, to the surface of the metal strip when rolling the metal strip.

[0241] The problems of the present invention are also solved by a method for manufacturing a work roller of the present invention, wherein the wear protection layer is applied to a pre-provided base body by a thermal spraying process.

[0242] This makes it advantageous to manufacture work rollers equipped with a wear protection layer.

[0243] In particular, various powder compositions for forming process-specific wear protection layers can be applied concisely and precisely to the base body of the work roller using a thermal spraying process.

[0244] If the wear protection layer is smoothed by polishing after application, the wear protection layer can be further adapted to suit the work roller. For example, it should be noted that the surface roughness of the wear protection layer can be further adjusted by this polishing.

[0245] In particular, this type of method can be advantageously developed if a more homogeneous powder distribution can be achieved by increasing the number of powder conveyors. This can also further improve the quality of the wear protection layer on the work rollers.

[0246] It should be noted here that the method described herein can be further complemented by other technical features described herein, particularly the features of the work roller or its wear protection layer, thereby allowing the method to be advantageously further developed or the specifications of the method to be described or expressed more precisely.

[0247] In particular, the powder conveyor can be positioned above the burner (e.g., a high-velocity oxygen fuel (HVOF) burner or a high-velocity air fuel (HVAF) burner) for spraying the wear protection layer, thereby suitably increasing the static pressure for supplying the powder to the burner.

[0248] Furthermore, regarding the provision of powder, it is considered advantageous for the design of the wear protection layer of this invention if the powder capable of forming the wear protection layer is preheated.

[0249] By additionally sifting the powder, a homogeneous powder distribution can be achieved.

[0250] Similarly, preheating or sieving the powder appropriately can favorably influence the manufacturing of the wear protection layer, particularly in terms of warping / strand dimensions, to optimize residual stress related to the wear protection layer.

[0251] Furthermore, the problems of the present invention can also be solved by a working roller for cold rolling a metal strip, which conforms to one of the features described herein.

[0252] By using the work roller of this invention, it is possible to reliably form a high-quality surface, especially over a longer period of time, in cold-rolled metal strips.

[0253] The measures described above, particularly the selection of coating materials and, in particular, the selection of more complex coating parameters, can greatly contribute to providing the wear protection layer of this invention, which is of high quality and value for rolling metal strips.

[0254] Further advantages, details, and features of the present invention will become even clearer from the embodiments described below. [Brief explanation of the drawing]

[0255] [Figure 1]Schematic view of a working roller for rolling metal products, when a wear protection layer is being sprayed onto the base body of the working roller. [Figure 2] Schematic partial cross-sectional view of a part of the working roller of FIG. 1 having a first layer thickness. [Figure 3] Schematic partial cross-sectional view of a part of an alternative working roller having an even thinner layer thickness.

[0256] According to this sole figure, the manufacture of a working roller 1 for rolling metal products, in particular a metal strip (not shown), is schematically illustrated.

[0257] Here, the working roller 1 is processed by spraying. More precisely, a wear protection layer 2 is applied to the surface 3 of the base body 4 of the working roller 1.

[0258] Here, the spraying of the wear protection layer 2 is carried out using a suitable spraying device 5 having a burner 6, such as an HVOF burner or an HVAF burner. Above the burner 6, a plurality of powder conveyors 7 (shown only by way of example and numbered) are arranged, and at least some of them can preheat the powder 8.

[0259] Here, the powder 8 can be individually mixed by a number of powder components 9 as required by the gist of the present invention.

[0260] The powder conveyor 7 further has a screening device 10 for the powder 8 or its powder components 9.

[0261] Overall, using the spraying device 5, while the working roller 1 is rotating in the rotational direction 12 about its bearing axis 12, a coating material 11 of a particularly advantageous composition can be applied to the base body 4 of the working roller 1.

[0262] In the drawing of FIG. 2, a part of the working roller 1 is shown as a cross-sectional detail of the interface region 20 between the wear protection layer 2 and the base body 4.

[0263] In particular, the peaks 22 of the roughness of the interface surface 24 of the base body surface 3 (not re-labeled here) can be clearly seen, and the peaks 22 also form cavities 26 on the base body surface 3.

[0264] The peaks 22 and the cavities 26 form the roughness of the interface surface 24 shown as jagged lines (not re-labeled here).

[0265] The wear protection layer 2 has hard phase particles 28 (dashed structures) embedded and arranged in the matrix 30 of the wear protection layer 2.

[0266] In particular, it can be clearly seen how the hard phase particles 28 are pushed into and arranged in the cavities 26, and in this process, they are in frictional bonding contact with the side surfaces 32 of the peaks 22 over a large area.

[0267] In the interface region 20, a higher residual compressive stress can occur than in areas further away from the interface region 20.

[0268] Accordingly, due to the residually compressive stress adjusted to a high level, the wear protection layer 2 is pressed into the base body 2 even more strongly, and in particular, it is pushed into the cavities 26 even more powerfully, and the hard phase particles 28 of the wear protection layer 2 also interact much more closely with the side surfaces 32.

[0269] Generally, a particularly tight bond between the wear protection layer 2 and the base body 4 can be ensured, and thus a particularly good fixation tensile resistance can be ensured, especially due to the compressive residual stress between 500 N / mm2 and 1,500 N / mm2.

[0270] Even the hard phase particles 28 inside the matrix 30 are "bonded" tightly to each other by this type of residual compressive stress.

[0271] The wear protection layer 2 shown here is characterized by having an average layer thickness 40 of approximately 60 μm, which is far smaller than the average layer thickness 40 of over 80 μm that is common in conventional technology.

[0272] Such a layer thickness 40 according to the present invention is characterized by extremely low porosity, to the point of being almost nonexistent, and small hard phase particles 28 or relatedly small particle sizes (without further reference numbering).

[0273] In any case, the wear protection layer 2, with its small thickness of 60 μm, can be manufactured at a very low cost, especially due to its small material requirements.

[0274] Figure 3 shows an alternative work roller 1 with an even thinner wear protection layer 2, clearly having an even thinner layer thickness 40.

[0275] Furthermore, the thickness 40 of this even thinner wear protection layer 2 is only 7.5 μm on this alternative work roller 1.

[0276] Furthermore, this even thinner wear protection layer 2 also has significantly smaller hard phase particles 28 or related small particle sizes.

[0277] In any case, this even thinner wear protection layer 2 can be manufactured with even less material and, consequently, at an even lower cost. [Explanation of Symbols]

[0278] 1. Work roller 2. Abrasion protection layer 3 surface 4 Base Body 5. Equipment for thermal spraying 6. Powder conveyor 7 Sieve device 8 powder 9 Powdered ingredients 10 Sieve device 11 Coating materials 12 Rotation direction 20 Interface region 22 Peak 24 Interface 26 Cavity 28 Hard phase particles 30 Matrix 32 Side surface 40 Layer thickness

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