A composite descaling roller with axial homogeneity and its manufacturing method

Abstract

This invention discloses an axially homogeneous composite descaling roller and its manufacturing method. The manufacturing method includes: performing a base layer weld on the surface of a base roller and a wear-resistant layer weld on the base layer surface; performing the base layer weld on the surface of the base roller in a circumferential welding manner perpendicular to the axis of the base roller, wherein the base layer weld is performed by fusion-penetration plasma arc welding; and performing the wear-resistant layer weld on the base layer surface in a manner parallel to the axis of the base roller, wherein the wear-resistant layer weld is performed by coaxial powder feeding plasma arc welding. This effectively solves the problems that traditional roll welding methods cannot fully meet the service conditions of descaling rollers, and that are prone to surface peeling and severe wear.

Description

Technical Field

[0001] This invention relates to the field of metal material processing technology, and in particular to a composite hard alloy descaling roller used in the descaling roller conveyor for producing medium and heavy steel plates from continuously cast billets, plates, etc., and its manufacturing method. Background Technology

[0002] Descaling rollers are key components for ensuring the surface quality of hot-rolled steel sheets, and their surface quality and service life play a crucial role in steel product production. During high-pressure water descaling, the combined effects of frictional wear, erosion wear, and high-temperature fatigue can easily cause severe wear on the surface of the descaling rollers. Improving the surface quality and service life of descaling rollers is an effective means to further ensure the normal production of steel products and reduce their economic costs.

[0003] Currently, the main focus is on the optimization and improvement of rolling mill rolls. Based on roll optimization technology, there are two main directions for optimizing the quality and lifespan of rolls. One is to optimize the roll material by designing different composition systems to further improve the quality of the rolls. The other is to optimize its overall structure by using different methods to form surface functional composite layers, thereby improving its toughness and wear resistance. After years of development, composite structures are now widely used to improve the performance of rolling mill rolls.

[0004] Current research on optimized roll structures and their fabrication methods reveals that the main methods for preparing composite functional layers include centrifugal casting, nesting, welding, and spray deposition. Among these, welding represents the primary development direction for composite roll fabrication.

[0005] The working environment and function of descaling rolls are similar to those of rolling mill rolls, yet there are significant differences. Both rolling mill rolls and descaling rolls support and transport continuously cast billets and plates, and are subjected to pressure and temperature changes. However, descaling rolls experience lower pressure but greater temperature fluctuations during operation. Simultaneously, the pressure-bearing surface of descaling rolls is smaller, while the degree of oxide scale buildup is greater. Traditional rolling mill roll welding methods cannot fully meet the service conditions of descaling rolls, easily leading to surface peeling and severe wear, significantly affecting their surface quality and service life. Therefore, the development of composite cemented carbide descaling roll technology using welding methods, specifically tailored to the service environment of descaling rolls, is of great significance. Summary of the Invention

[0006] In view of this, the present invention provides a method for manufacturing an axially homogeneous composite descaling roller, which solves the problems that the traditional roll welding method cannot fully meet the service conditions of the descaling roller and is prone to surface peeling and severe wear.

[0007] In addition, the present invention also provides a dephosphorization roller manufactured by the above method.

[0008] The first aspect is a method for manufacturing an axially homogeneous composite descaling roller, comprising:

[0009] The base roller surface is subjected to a bottom layer weld overlay and a wear-resistant layer weld overlay is performed on the bottom layer surface;

[0010] The underlayer welding is performed on the surface of the base roller using a circumferential welding method perpendicular to the axis of the base roller. The underlayer welding is performed by welding wire cladding using a penetration-type plasma arc welding method.

[0011] The wear-resistant layer is welded onto the surface of the base layer in a manner parallel to the axis of the base roller, and the wear-resistant layer is welded and clad using a coaxial powder feeding plasma arc welding method.

[0012] In this disclosure and possible embodiments, during the underlayer welding, the welding current is 50-100A, the plasma gas flow rate is 1-1.5L / min, the shielding gas flow rate is 15-20L / min, and the weld cladding thickness is 3-5mm.

[0013] In this disclosure and possible embodiments, the method of performing the underlayer welding in a circumferential welding manner perpendicular to the base roller axis includes:

[0014] While the base roller rotates circumferentially around its axis, the plasma welding gun is positioned directly above the base roller and cladding is performed. After the base roller rotates one revolution, the plasma welding gun is moved along the axial direction to the next adjacent position, and the base roller surface at that position is clad in the same manner. This process is repeated until the entire surface of the base roller is clad; the overlap rate of the cladding is 10-20%.

[0015] In this disclosure and possible embodiments, a double-wire welding cladding is used for the bottom layer. The welding wire material is 0Cr18NiMo and the diameter is 1-2mm. The double wires are horizontally parallel and fed in the opposite direction to the welding direction, and the distance between them and the base roller is 1-1.5mm. At the same time, the tip of the welding wire is kept at the center of the plasma arc during the welding cladding process.

[0016] In this disclosure and possible embodiments, a hot wire system is used to preheat the bottom layer welding wire, the distance L between the preheating end and the plasma welding gun nozzle is 10-20 mm, and the outlet temperature T is 150-200°C.

[0017] In this disclosure and possible embodiments, a method for welding the wear-resistant layer parallel to the axis of the base roller includes:

[0018] After completing a single-pass wear-resistant layer cladding by moving from one edge of the base roller along a direction parallel to the roller axis to the other edge, the base roller is rotated and the welding gun returns to the starting side of the base roller to perform the next cladding pass.

[0019] In this disclosure and possible embodiments, the coaxial powder-fed plasma arc welding has a welding current of 120–150 A, a powder feed rate of 30–50 rad / min, an overlap rate of 20–25%, and a weld overlay thickness of 2–5 mm; and / or,

[0020] Wear-resistant layer cladding is performed using Ni-based alloy powder and WC powder. The composition and content of the mixed Ni-based alloy powder and WC powder are as follows: W 60wt%~65wt%, C 1.5wt%~3.5wt%, Cr 4.0wt%~8.0wt%, Si 1.0wt%~3.0wt%, Fe 1.0wt%~3.0wt%, B 0.5wt%~2.5wt%, with the balance being Ni.

[0021] In this disclosure and possible embodiments, the particle size of both the Ni-based alloy powder and the WC powder is 50–100 μm.

[0022] In this disclosure and possible embodiments, before performing the underlayer welding, the surface of the base roller is milled to ensure the flatness of the base roller surface and the coaxiality of the axis; if the diameter of the processed base roller is set as d and the diameter of the finished dephosphorization roller is set as D, then 10mm≤Dd≤20mm.

[0023] Secondly, the axially homogeneous composite descaling roller is manufactured according to the method described in the first aspect.

[0024] The beneficial effects of this invention are as follows:

[0025] The manufacturing method of the axially homogeneous composite descaling roller of the present invention firstly sets an underlayer between the base roller and the wear-resistant layer. This underlayer is a composition transition layer. By setting the underlayer, the cladding depth of the base roller is reduced, the degree of reaction between the cladding metal and the base roller is controlled, the influence of the chemical composition of the base roller on the wear-resistant layer is reduced, and the overall toughness of the wear-resistant layer is appropriately improved. At the same time, the method of performing underlay welding perpendicular to the axis of the base roller on the surface of the base roller and cladding welding of the wear-resistant layer parallel to the axis of the base roller is adopted. The purpose is to change the grain growth direction of the underlayer and the wear-resistant layer, change the bonding mechanism of the two cladding metals, and make them staggered at 90°, thereby improving the bonding quality and bearing capacity between the two metals. In addition, the hardness of the wear-resistant layer along the axis of the base roller is more uniform. Therefore, by using the above-mentioned staggered cladding method, on the one hand, the bonding strength and toughness are improved, and on the other hand, the axial performance stability of the cladding surface is improved, so that the Rockwell hardness value fluctuation is no greater than 5. This effectively avoids cracks and detachment defects caused by large stress differences due to high temperature fatigue and wear on the axial surface in contact with high-temperature materials. Attached Figure Description

[0026] The above and other objects, features, and advantages of this disclosure will become clearer from the following description of embodiments with reference to the accompanying drawings, in which:

[0027] Figure 1 This is a schematic diagram of the bottom layer soldering method in an embodiment;

[0028] Figure 2 This is a schematic diagram of the wear-resistant layer overlay welding method in an embodiment. Detailed Implementation

[0029] The present disclosure is described below based on embodiments; however, it is worth noting that the present disclosure is not limited to these embodiments. In the detailed description of the present disclosure below, certain specific details are described in detail. However, those skilled in the art will fully understand the present disclosure for the parts not described in detail.

[0030] Furthermore, those skilled in the art should understand that the accompanying drawings are for illustrative purposes, features, and advantages of this disclosure only, and are not actually drawn to scale. Also, unless the context explicitly requires it, the words "comprising," "including," and similar terms throughout the specification and claims should be interpreted as encompassing rather than exclusive or exhaustive; that is, meaning "including but not limited to."

[0031] This disclosure provides a detailed description of the method for manufacturing an axially homogeneous composite descaling roller according to the present invention through the following Examples 1-4, and provides a comparative explanation through Comparative Examples 1 and 2. In Comparative Example 1, a wear-resistant layer is directly welded using a circumferential welding method without a transition layer. In Comparative Example 2, both transition layer welding and wear-resistant layer welding processes are employed, and both are performed using a circumferential welding method.

[0032] The method for manufacturing an axially homogeneous composite descaling roller according to Examples 1-4 specifically includes the following steps:

[0033] (1) Select the base roller for the descaling roller:

[0034] The base roller material selected is 42CrMo, and its chemical composition and content are as follows: C 0.38~0.45wt%, Si 0.17~0.37wt%, Mn 0.50~0.80wt%, S≤0.035wt%, P≤0.035wt%, Cr 0.90~1.20wt%, Mo 0.15~0.25wt%.

[0035] The chemical composition of the base rollers in Examples 1-4 and Comparative Examples 1-2 is shown in Table 1:

[0036] Table 1. Chemical composition of the base roller (wt%)

[0037] Example 1 0.39 0.20 0.56 0.031 0.032 0.92 0.18 Example 2 0.42 0.30 0.65 0.028 0.032 1.03 0.20 Example 3 0.41 0.25 0.62 0.030 0.031 1.12 0.22 Example 4 0.40 0.31 0.68 0.031 0.030 1.08 0.21 Comparative Example 1 0.39 0.20 0.56 0.031 0.032 0.92 0.18 Comparative Example 2 0.42 0.30 0.65 0.028 0.032 1.03 0.20

[0038] (2) Surface treatment of the base roller surface:

[0039] In Examples 1-4 and Comparative Examples 1-2, the surface of the base roller is milled to ensure its surface flatness and coaxiality. Let the diameter of the processed base roller be d, and the diameter of the finished dephosphorization roller be D, then 10mm ≤ Dd ≤ 20mm.

[0040] The purpose of setting Dd to 10-20mm is to approximate the size requirements of the finished descaling roller after welding and cladding. If Dd is set too small, the wear-resistant layer will be too thin after milling after welding and cladding, which will not meet the service requirements; if Dd is set too large, the size of the finished descaling roller will not be achieved after welding and cladding.

[0041] (3) Apply a base layer of weld overlay to the surface of the base roller:

[0042] In Examples 1-4 and Comparative Example 2, the bottom layer cladding was performed using a penetration-type plasma arc welding method with DC positive polarity. The welding parameters were: welding current 50–100 A, plasma gas flow rate 1–1.5 L / min, and shielding gas flow rate 15–20 L / min. The aim was to utilize the characteristics of plasma welding technology, increasing the energy density of the plasma arc through compression, to achieve double-wire cladding under relatively low heat input conditions, thus reducing the impact on the microstructure and properties of the base roller material.

[0043] The thickness of the weld overlay is controlled to be 3-5 mm. The purpose is to form a compositional transition layer between the base roller and the wear-resistant layer. This reduces the influence of the base roller composition on the wear-resistant layer and appropriately improves the overall toughness of the wear-resistant layer. If the thickness of the underlay weld overlay is too small, the above effect cannot be guaranteed; if the thickness of the underlay weld overlay is too large, it will seriously reduce the overall strength of the descaling roller surface and affect its service life.

[0044] like Figure 1 As shown, embodiments 1-4 employ a circumferential welding method perpendicular to the base roller axis for the underlayer cladding. During the cladding process, the base roller rotates circumferentially around its axis while the welding torch is positioned directly above the base roller for cladding. After the base roller completes one rotation, the welding torch is moved to the next adjacent position along the axial direction, and the same method is used to clad the surface of the base roller at that adjacent position. This process is repeated until the entire surface of the base roller is clad; the overlap rate of the cladding is controlled to be 10-20%.

[0045] The welding parameters and base roll processing parameters used for the underlayer welding in Examples 1-4 are shown in Table 2:

[0046] Table 2 Welding parameters for the root pass and processing parameters for the base roller

[0047]

[0048] Embodiments 1-4 of this disclosure employ a dual-wire method for the root pass cladding. The welding wire is made of 0Cr18NiMo with a diameter of 1-2 mm. The two wires are horizontally parallel, fed in opposite directions along the welding direction, and spaced 1-1.5 mm apart from the base roller. During the cladding process, the tip of the welding wire is kept at the center of the plasma arc to ensure that the plasma arc primarily acts on the welding wire and secondarily on the base roller surface. This results in a small amount of melting on the base roller surface, ensuring effective cladding of the molten welding wire metal and reducing heat input to the base roller surface. If the welding wire diameter is too small or the distance to the base roller is too large, the heat input from the plasma arc to the base roller will be excessive, increasing the amount of melting on the base roller and severely affecting the composition of the root pass and reducing its mechanical properties. If the welding wire diameter is too large or the distance to the base roller is too small, the plasma arc cannot effectively melt the metal on the base roller surface, reducing its wetting and reaction with the root pass, and failing to form an effective metallurgical bond.

[0049] In embodiments 1-4, a hot wire system is used to preheat the welding wire for the bottom layer. The distance L between the preheating end and the plasma welding torch nozzle is 10-20 mm, and the exit temperature T is 150-200℃. The purpose is to ensure that the temperature of the welding wire entering the plasma arc is above 150℃, reducing its demand for arc melting energy, and allowing the welding wire to melt completely without increasing the plasma current, thereby further controlling the influence of the plasma arc on the base roller. If the temperature is too low, the plasma arc will not be able to melt the metal on the surface of the base roller after melting the welding wire, and an effective cladding weld cannot be formed. If the temperature is too high, the plasma arc will melt too much metal on the surface of the base roller after melting the welding wire, and the elements will enter the bottom layer, seriously reducing its mechanical properties.

[0050] The relevant parameters of the welding wire used for the root pass welding in Examples 1-4 and Comparative Example 2 are shown in Table 3:

[0051] Table 3 Welding wire related parameters

[0052]

[0053]

[0054] (4) Perform surface treatment on the underlayer layer after the base roller surface has been welded:

[0055] In this embodiment 1-4, the surface after the bottom layer cladding and overlay welding is milled to ensure its surface flatness and coaxiality.

[0056] (5) Apply wear-resistant layer welding to the surface of the base layer:

[0057] In Examples 1-4, coaxial powder-feeding plasma arc welding is used for cladding the wear-resistant layer. The welding parameters include a welding current of 120–150 A and a powder feed rate of 30–50 rad / min. The aim is to completely melt the Ni-based alloy powder and mix it with WC particles to form the wear-resistant layer. If the welding current is too low or the powder feed rate is too high, the Ni-based alloy powder cannot completely melt, and the underlayer metal cannot form an effective molten pool, resulting in poor density of the wear-resistant layer and an inability to form an effective metallurgical bond with the underlayer. Conversely, if the welding current is too high or the powder feed rate is too low, the amount of molten metal in the underlayer is too large or the number of shadow particles is too small, reducing the overall performance of the wear-resistant layer.

[0058] The purpose of controlling the cladding thickness to 2-5 mm is to avoid excessive differences in the microstructure between the center and edge of the weld pool. Through specific lap remelting cladding, the dendritic structure at the edge of the weld pool is optimized, and a specific thickness is selected to further improve the uniformity of the overall joint surface hardness. If the lap ratio or thickness is too small, the surface hardness value of the weld pool will vary greatly or the performance will fluctuate greatly. If the lap ratio or thickness is too large, the production efficiency and economic cost will increase significantly.

[0059] The relevant process parameters for the wear-resistant layer welding cladding in Examples 1-4 and Comparative Examples 1-2 are shown in Table 4:

[0060] Table 4. Relevant process parameters for wear-resistant layer welding cladding

[0061]

[0062] like Figure 2 As shown, in embodiments 1-4, the wear-resistant layer is welded and clad along the surface of the base roller from one side to the other in a manner parallel to the roller axis. During the welding and cladding process, the base roller is placed horizontally and fixed, and the welding torch is positioned directly above the base roller, moving from one edge of the base roller along a direction parallel to the roller axis to the other edge. After completing a single pass of welding and cladding, the base roller is rotated, and the welding torch returns to the starting side to perform the next pass of welding and cladding, controlling the welding overlap rate to be 20-25%.

[0063] In Examples 1-4, Ni-based alloy powder and WC powder are used for wear-resistant layer cladding. The composition is: W 60-65wt%, C 1.5-3.5wt%, Cr 4.0-8.0wt%, Si 1.0-3.0wt%, Fe 1.0-3.0wt%, B 0.5-2.5wt%, with the balance being Ni. The purpose of using the above powder is to uniformly distribute WC particles in the Ni-based alloy cladding by plasma arc welding, and to use the tough matrix to solidify the WC particles to form a wear-resistant layer, thereby improving the surface hardness of the descaling roller.

[0064] The composition of the wear-resistant layer powder in Examples 1-4 and Comparative Examples 1-2 is shown in Table 5 below:

[0065] Table 5. Composition of wear-resistant layer powder (wt%)

[0066] Example 1 62 1.8 5.0 1.2 1.4 1.2 Balance Example 2 62 2.0 5.4 1.5 1.8 1.2 Balance Example 3 63 2.4 6.5 2.4 2.2 1.8 Balance Example 4 64 3.2 7.2 2.8 2.6 2.0 Balance Comparative Example 1 62 1.8 5.0 1.2 1.4 1.2 Balance Comparative Example 2 62 2.0 5.4 1.5 1.8 1.2 Balance

[0067] In Examples 1-4, the Ni-based alloy powder and WC powder used have a particle size of 50-100 μm. The aim is to ensure that the Ni-based alloy powder can effectively melt and mix with the WC powder under plasma arc irradiation to form a wear-resistant layer. If the powder particle size is too small, the economic cost will be greatly increased, and an effective hard phase interaction cannot be formed, reducing the wear resistance of the wear-resistant layer. If the powder particle size is too large, the Ni-based alloy powder cannot completely melt and mix with the WC particles, reducing the density of the wear-resistant layer.

[0068] (6) The composite descaling roller with the wear-resistant layer welded on is then surface-treated and ready for use:

[0069] In this embodiment 1-4, the surface of the composite dephosphorizing roller with the wear-resistant layer welded and clad is polished by milling to meet the finished product specifications and surface quality requirements, and the milling thickness is ≤1mm to ensure that the wear-resistant layer thickness is not less than 2mm.

[0070] (7) Rockwell hardness tests were performed on different locations of the dephosphorization rollers obtained in Examples 1-4 and Comparative Examples 1-2. The test results are shown in Table 6 below:

[0071] Table 6 Rockwell hardness of the finished surface of the dephosphorization roller at four equal divisions along the parallel axis.

[0072]

[0073]

[0074] As can be seen from Table 6:

[0075] The axially homogeneous composite descaling rollers of Embodiments 1-4 of this invention employ a method of performing a root pass weld perpendicular to the base roller axis and a wear-resistant layer cladding weld parallel to the base roller axis on the base roller surface. The aim is to alter the grain growth direction of the root pass and the wear-resistant layer, making them interlaced at 90° angles, thereby improving the bonding quality and load-bearing capacity between the two metal layers. Simultaneously, this makes the hardness of the wear-resistant layer more uniform along the base roller axis. Since the descaling roller operates in line contact when carrying high-temperature materials, with the material moving along the upper or lower tangent of the base roller axis, the uniformity of hardness of the wear-resistant layer along the base roller axis plays a crucial role in its service performance. If the hardness along the base roller axis is uneven, stress differences can easily occur during alternating high and low temperature transitions, leading to detachment. If the hardness is uniform along the axis of the base roller, it is not easy to cause detachment due to stress difference during the alternation of high temperature and low temperature. The descaling rollers of the above embodiments 1-4 of this disclosure have a Rockwell hardness ≥54 in the direction parallel to the axis and a fluctuation value ≤4, which shows good axial performance stability. Therefore, it can effectively avoid cracks and detachment defects caused by large stress difference due to high temperature fatigue and wear on the axial surface in contact with high temperature materials.

[0076] The embodiments described above are merely illustrative of implementation methods of this disclosure, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent disclosure. It should be noted that those skilled in the art can make various modifications, equivalent substitutions, and improvements without departing from the concept of this disclosure, and these all fall within the protection scope of this disclosure. Therefore, the protection scope of this patent disclosure should be determined by the appended claims.

Claims

1. A method for manufacturing an axially homogeneous composite descaling roller, characterized in that, include: The base roller surface is subjected to a bottom layer weld overlay and a wear-resistant layer weld overlay is performed on the bottom layer surface; The underlayer welding is performed on the surface of the base roller using a circumferential welding method perpendicular to the axis of the base roller. The underlayer welding is performed by welding wire cladding using a penetration-type plasma arc welding method. The wear-resistant layer is welded on the surface of the base layer in a manner parallel to the axis of the base roller, and the wear-resistant layer is welded and clad using a coaxial powder feeding plasma arc welding method. During the root pass welding, the welding current is 50 A to 100 A, the plasma gas flow rate is 1 L / min to 1.5 L / min, the shielding gas flow rate is 15 L / min to 20 L / min, and the weld cladding thickness is 3 mm to 5 mm. A double-wire welding process is used for the root pass welding, and the welding wire material is 0Cr18NiMo. The coaxial powder-feeding plasma arc welding has a welding current of 120 A to 150 A, a powder feeding rate of 30 rad / min to 50 rad / min, an overlap rate of 20% to 25%, and a weld overlay thickness of 2 mm to 5 mm. The wear-resistant layer was clad with Ni-based alloy powder and WC powder. The composition and content of the mixed powder of Ni-based alloy powder and WC powder were as follows: W 60 wt%~65 wt%, C 1.5 wt%~3.5 wt%, Cr 4.0 wt%~8.0 wt%, Si 1.0 wt%~3.0 wt%, Fe 1.0 wt%~3.0 wt%, B 0.5 wt%~2.5 wt%, with the balance being Ni.

2. The method for manufacturing the axially homogeneous composite descaling roller according to claim 1, characterized in that, The method of performing the underlayer welding in a circumferential welding manner perpendicular to the base roller axis includes: While the base roller rotates circumferentially around its axis, the plasma welding gun is positioned directly above the base roller and cladding is performed. After the base roller rotates one revolution, the plasma welding gun is moved along the axial direction to the next adjacent position, and the base roller surface at that position is clad in the same manner. This process is repeated until the entire surface of the base roller is clad. The overlap rate of the cladding is 10% to 20%.

3. The method for manufacturing the axially homogeneous composite descaling roller according to claim 2, characterized in that: The diameter of the welding wire is 1 mm to 2 mm; the two wires are horizontally parallel and fed in the opposite direction to the welding direction, and the distance between them and the base roller is 1 mm to 1.5 mm; at the same time, the tip of the welding wire is kept at the center of the plasma arc during the cladding process.

4. The method for manufacturing the axially homogeneous composite descaling roller according to claim 3, characterized in that: A hot wire system is used to preheat the bottom layer welding wire. The distance L between the preheating end and the plasma welding gun nozzle is 10 mm to 20 mm, and the exit temperature T is 150℃ to 200℃.

5. The method for manufacturing the axially homogeneous composite descaling roller according to any one of claims 1-4, characterized in that, A method for welding the wear-resistant layer in a manner parallel to the axis of the base roller includes: After completing a single-pass wear-resistant layer cladding by moving the welding torch from one edge of the base roller along a direction parallel to the roller axis to the other edge, the base roller is rotated, and the welding torch returns to the starting side of the base roller to perform the next cladding pass; the cladding overlap rate is 20% to 25%.

6. The method for manufacturing the axially homogeneous composite descaling roller according to claim 5, characterized in that: The particle size of both the Ni-based alloy powder and the WC powder is 50 μm to 100 μm.

7. The method for manufacturing the axially homogeneous composite descaling roller according to any one of claims 1-4 or 6, characterized in that: Before performing the bottom layer welding, the surface of the base roller is milled to ensure the flatness of the base roller surface and the coaxiality of the axis; the diameter of the base roller after processing is set as d, and the diameter of the finished dephosphorization roller is set as D, then 10mm≤Dd≤20mm.

8. An axially homogeneous composite descaling roller, characterized in that, The dephosphorization roller is: It is manufactured according to the method described in any one of claims 1-7.

Images