High-wear-resistance and high-accident-resistance forged semi-steel blooming roller and forging method thereof

Abstract

The invention relates to a high-wear-resistance and high-accident-resistance forged semi-steel cogging roller and a forging method thereof, belongs to the technical field of forging processes, and solves the problems that a cogging roller in the prior art is poor in wear resistance and toughness matching degree and cannot have good wear resistance and toughness at the same time. The invention provides a forging method of a semi-steel cogging roller. A steel ingot is subjected to heat treatment, pre-drawing, upsetting, drawing, blanking, heating and heat preservation to obtain a semi-steel cogging roller finished product. The hardness of the forged semisteel cogging roller prepared by the preparation method is 35-60 HSD; the room-temperature yield strength is 480-800 MPa, the tensile strength is 800-1300 MPa, the wear resistance and toughness matching degree is good, and the accident resistance is remarkably improved; the strength index is reduced slowly at high temperature, and hot cracks are not easy to generate; and the hardness difference of the surface within the range of 200mm is less than or equal to 3HS, so that deep hole grooves are formed.

Description

Technical Field

[0001] The invention relates to the technical field of forging technology, in particular to a forged semi-steel blanking roller with high wear resistance and high accident resistance and a forging method thereof. Background Art

[0002] The blanking roll is the first roll in the steel rolling production line. The working conditions are relatively bad and hot cracks are prone to occur. Therefore, the roll surface is required to have sufficient thermal strength, high wear resistance, heat resistance, and impact resistance. At present, the materials used for hot rolling blanking rolls in China include forged steel 60CrMnMo, 60CrNiMo, ductile iron, 75CrNiMo cast steel, cast semi-steel, etc. Although the forged steel 60CrMnMo and 60CrNiMo hot rolling work rolls have high toughness, they have poor wear resistance. The use layer is mainly pearlite structure, which is very easy to crack. The high temperature strength index decreases a lot, and the plasticity index increases, resulting in plastic deformation of the roll surface and wrinkles; ductile iron has poor wear resistance; cast steel, cast semi-steel and other materials have poor toughness and are prone to roll breakage accidents.

[0003] Therefore, it is necessary to develop a blanking roller with good matching of wear resistance, strength, plasticity, toughness and high accident resistance. Summary of the invention

[0004] In view of the above analysis, an embodiment of the present invention aims to provide a forged semi-steel blanking roller with high wear resistance and high accident resistance and a forging method thereof, so as to solve the problem that the wear resistance and strength, plasticity and toughness of the existing blanking rollers are poorly matched and cannot have good wear resistance and strength, plasticity and toughness at the same time.

[0005] The present invention provides a forging method for a semi-steel blanking roller, which specifically comprises the following steps:

[0006] S1: The first fire: the steel ingot is quickly put into the furnace and heat treated according to the preset step-type heating curve. After the heat treatment is completed, the ingot is taken out of the furnace, the edges are chamfered, the jaws are pressed, and the bottom of the ingot and the jaws are gas-cut to discard the material.

[0007] S2 second fire: After the steel ingot treated in S1 is heated and kept warm, the heating temperature is Tstart ± 10℃, and the holding time is 30 to 60 minutes per 100mm of the average water riser diameter of the steel ingot. After it is taken out of the furnace, the upper and lower V-shaped anvils are used to pre-draw it to the diameter required by the process at a pre-drawing ratio of 1.0 to 1.5;

[0008] S3 third fire: After the steel ingot treated in S2 is heated and kept warm, the heating temperature is Tstart ± 10℃, and the holding time is 2 to 5 hours per 100mm of the pre-drawn diameter. After it is taken out of the furnace, it is upset to the height required by the process according to the upsetting ratio of 1.5 to 2.0;

[0009] S4 fourth fire: After the steel ingot treated in S3 is heated and kept warm, the heating temperature is Tstart ± 10℃, and the holding time is 30 to 60 minutes per 100mm of height after upsetting. After it is taken out of the furnace, it is drawn to the diameter required by the process using upper and lower V-shaped anvils according to the KD drawing ratio of 1.5 to 2.5;

[0010] S5 Fifth Fire: After the steel ingot treated in S4 is heated and kept warm, the heating temperature is Tstart ± 10℃, and the holding time is 2 to 5 hours for every 100mm of the drawing diameter. After it is taken out of the furnace, it is continued to be drawn by KD to the large circle diameter of the blank. The two ends of the blank are cut according to the length required by the process, and the water riser roll neck is pinched by KD to obtain the semi-finished blank roll;

[0011] S6 Sixth fire: After the semi-finished blank roll is heated and kept warm, the heating temperature is T start ± 10 ℃, and the holding time is 30 to 60 minutes per 100mm of the roll neck diameter size after heating. After coming out of the furnace, KD stretches the roll necks at both ends to the roll neck size of the blank figure, and rounds the finished blank roll;

[0012] Among them, Tstart is the starting forging temperature, ranging from 1100 to 1200℃.

[0013] Specifically, the steel ingot is a cast steel ingot made of semi-steel material, and its composition is as follows by mass percentage: C 1.0-1.6%, Si 0.2-0.7%, Mn 0.4-1.0%, Cr 1.0-2.0%, Ni 0.1-1.0%, Mo 0.2-0.8%, P, S≤0.02%, and the rest are iron and other impurity elements; and Cu+Pb+Sb+As+Bi+Sn+Zn<0.2% among the impurity elements.

[0014] Specifically, the step heating curve in step S1 is:

[0015] Preheating stage: heat the steel ingot to Tpre and keep it warm, where Tpre is 750-850℃;

[0016] Homogenization diffusion stage: heat the steel ingot to Texpand ±10℃ and keep it warm, with a heating rate of ≤50℃ / h, where Texpand = Tstart +30℃;

[0017] Initial forging stage: slowly cool the steel ingot to Tstart ±10℃ and keep it warm, with a cooling rate of ≤50℃ / h.

[0018] Furthermore, the holding time in the preheating stage is h1, the holding time in the homogenization diffusion stage is h2, and the holding time in the initial forging stage is h3; h1, h2, and h3 are determined according to the diameter of the steel ingot, h1 is 40 to 80 minutes per 100 mm, h2 is 2 to 5 hours per 100 mm, and h3 is 1 to 2 hours per 100 mm.

[0019] Specifically, the final forging temperature of each step is ≥850°C.

[0020] Specifically, the specific operations and parameters of step S2 are: the pressing amount ≥ 20% of the blank height, 90° flipping, and one pass of pressing with the staggered anvil.

[0021] Specifically, the specific operations and parameters of step S4 are: the pressing amount ≥ 20% of the blank height, 90° flipping, and odd-even anvil arrangement.

[0022] Specifically, after the finished blank roller is obtained in step S6, the blank roller is cooled to 600±10°C and then placed in a post-forging furnace; the purpose of cooling to 600±10°C and then placing it in a post-forging furnace is to speed up the cooling speed and avoid the precipitation of network carbides or excessive precipitation temperature.

[0023] Specifically, the total forging ratio of the forging method is ≥3.

[0024] The invention provides a forged semi-steel blank opening roller with high wear resistance and high accident resistance. The blank opening roller is made by the forging method. The hardness of the forged semi-steel blank opening roller is 35-60HSD, and a large amount of free carbides improve the wear resistance; the room temperature yield strength reaches 480-800MPa, and the tensile strength reaches 800-1300MPa; the hardness difference within 200mm of the surface is ≤3HS, and it is suitable for opening deep hole grooves.

[0025] At high temperatures, the strength index decreases slowly, the hot strength is high, the plastic index does not change much, the softening phenomenon is light, and plastic deformation is not easy to occur during high-temperature rolling. While ensuring strength, the plastic toughness is taken into account, and the wrinkles, bulges, and steel sticking in the roll hole groove are improved. At the same time, since the semi-steel roll is composed of uniform pearlite matrix and carbide from the surface to the inside, the hardness difference within the range of 200mm on the surface is ≤3HS, which is especially suitable for steel rolls with deep hole grooves.

[0026] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0027] 1. The present invention provides a forging method specifically used for forging semi-steel blanking rolls, which has a good effect on improving the segregation of steel ingots and preventing surface and core cracks.

[0028] Traditional materials for blanking rolls are forged steel 60CrMnMo, 60CrNiMo, ductile iron, 75CrNiMo cast steel, cast semi-steel, etc. Although forged steel 60CrMnMo and 60CrNiMo hot rolling work rolls have high toughness, their wear resistance is poor. The use layer is mainly composed of pearlite structure, which is very easy to crack. The high-temperature strength index decreases significantly, and the plasticity index increases, resulting in plastic deformation of the roll surface and wrinkles. Ductile iron has poor wear resistance. Cast steel, cast semi-steel and other materials have poor toughness and are prone to roll breakage accidents.

[0029] In order to provide a forged semi-steel blanking roller with high wear resistance and high accident resistance, the present invention selects semi-steel material as raw material. The semi-steel material has good comprehensive performance, good strength and toughness, high and relatively uniform hardness, and has the potential to make rolling rollers; however, the semi-steel material has a high carbon content, serious ingot segregation, and serious original shrinkage porosity. The conventional forging method sacrifices the pass reduction in order to control surface cracks, and the qualified rate of the products produced is extremely low, the product performance stability is poor, and the performance of the material cannot be fully exerted.

[0030] After the steel ingot is ingoted, it is heated by a step-type heating curve to prevent cracks on the surface and core of the steel ingot due to structural stress and temperature stress. At the same time, high-temperature diffusion improves element segregation. In particular, the special step-type heating curve provided by the present invention has a better effect.

[0031] After the steel ingot is heated and taken out of the furnace for the first time, a pre-drawing process is set up. The pre-drawing breaks the cast structure on the surface of the steel ingot through a small deformation, reduces the occurrence of upsetting cracks, and prepares the organization for subsequent high-temperature diffusion.

[0032] Furthermore, the final forging temperature of each fire is strictly controlled to be ≥850℃, and the forging is stopped before carbides precipitate on the surface to avoid forging cracks caused by network carbides.

[0033] The forging method increases the holding time during heating before the upsetting fire and the KD compaction fire, respectively, in order to achieve high-temperature diffusion, reduce element segregation, make the structure uniform, and improve the toughness and strength of the product through long-term holding.

[0034] The forging method provided by the present invention can well compact the defects in the center of the steel ingot, refine the grains, and improve the toughness and strength of the product.

[0035] 2. The forged semi-steel blanking roller provided by the present invention has good wear resistance and a high degree of matching with strength, plasticity and toughness.

[0036] The selected forged semi-steel material has a high carbon content and contains a large amount of free carbides in its structure, which makes it more wear-resistant. The room temperature yield strength reaches 480-800MPa, and the tensile strength reaches 800-1300MPa. It has high thermal strength and is not prone to plastic deformation during high-temperature rolling. It ensures strength while taking into account plastic toughness, and improves the phenomena of wrinkles, protrusions, and steel sticking in the roller holes and grooves.

[0037] The forged semi-steel blanking roller provided by the present invention has a structure composed of uniform pearlite matrix and carbide from the surface to the inside, a hardness difference of ≤3HS within 200mm of the surface, and almost no hardness drop within the working layer. It is particularly suitable for preparing steel rolling rollers with deep hole grooves.

[0038] In the present invention, the above-mentioned technical solutions can also be combined with each other to achieve more preferred combination solutions. Other features and advantages of the present invention will be described in the subsequent description, and some advantages can become obvious from the description, or can be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained through the contents particularly pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like components throughout the drawings.

[0040] Figure 1 It is a schematic diagram of a step heating curve;

[0041] Figure 2 This is a blank process diagram of a semi-steel blanking roll in Example 1;

[0042] Figure 3 This is a heating curve process diagram of the first fire in Example 1;

[0043] Figure 4 This is a blanking diagram of the semi-steel blanking roll in Example 1;

[0044] Figure 5 This is a blank process diagram of a semi-steel blanking roll in Example 2;

[0045] Figure 6 This is a heating curve process diagram of the first fire in Example 2;

[0046] Figure 7 This is a blanking diagram of a semi-steel blanking roll in Example 2;

[0047] Figure 8 This is a blank process diagram of a semi-steel blanking roll in Example 3;

[0048] Fig. 9 This is a heating curve process diagram of the first fire in Example 3;

[0049] Fig.10 This is the cutting diagram of the semi-steel blanking roller in Example 3. DETAILED DESCRIPTION

[0050] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not used to limit the scope of the present invention.

[0051] Traditional materials for blanking rolls are forged steel 60CrMnMo, 60CrNiMo, ductile iron, 75CrNiMo cast steel, cast semi-steel, etc. Although forged steel 60CrMnMo and 60CrNiMo hot rolling work rolls have high toughness, their wear resistance is poor. The use layer is mainly composed of pearlite structure, which is very easy to crack. The high-temperature strength index decreases significantly, and the plasticity index increases, resulting in plastic deformation of the roll surface and wrinkles. Ductile iron has poor wear resistance. Cast steel, cast semi-steel and other materials have poor toughness and are prone to roll breakage accidents.

[0052] In order to provide a forged semi-steel blanking roller with high wear resistance and high accident resistance, the present invention selects semi-steel material as raw material. Semi-steel material has good comprehensive performance, good strength and toughness, high and relatively uniform hardness, and has the potential to make rollers; however, semi-steel material has high carbon content, serious ingot segregation, and serious original shrinkage porosity. Conventional forging methods sacrifice pass reduction to control surface cracks, and the qualified rate of the products produced is extremely low, the product performance stability is poor, and the performance of the material cannot be fully utilized. Therefore, it is necessary to develop a blanking roller forging method suitable for semi-steel material with good process stability.

[0053] The forging method provided by the present invention adopts a stepped heating curve for heating in the first fire, and increases the holding time before the upsetting fire and the KD compaction fire for forging, so as to prevent cracks from being generated on the surface and the core of the steel ingot due to tissue stress and temperature stress, and improve element segregation by high-temperature diffusion; after the steel ingot is heated and taken out of the furnace for the first time, a pre-drawing process is arranged to reduce the generation of upsetting cracks; the KD compaction and drawing fire adopts an odd-even pass anvil arrangement method, and the single pass reduction amount is ≥20%; at the same time, the anvil type is reasonably selected, the total fire times and the deformation amount of each fire time are reasonably arranged, and the generation of core cracks is avoided, and the finally produced product has good wear resistance and a high matching degree with strength, plasticity and toughness.

[0054] The present invention provides a forging method for a semi-steel blanking roller, which specifically comprises the following steps:

[0055] S1: The first fire: the steel ingot is quickly put into the furnace and heat treated according to the preset step-type heating curve. After the heat treatment is completed, the ingot is taken out of the furnace, the edges are chamfered, the jaws are pressed, and the bottom of the ingot and the jaws are gas-cut to discard the material.

[0056] S2 second fire: After the steel ingot treated in S1 is heated and kept warm, the heating temperature is Tstart ± 10℃, and the holding time is 30 to 60 minutes per 100mm of the average water riser diameter of the steel ingot. After it is taken out of the furnace, the upper and lower V-shaped anvils are used to pre-draw it to the diameter required by the process at a pre-drawing ratio of 1.0 to 1.5;

[0057] The purpose of this step is to break the cast structure on the surface of the steel ingot through a certain amount of deformation, thereby reducing the occurrence of upsetting cracks. On the other hand, pre-pulling can shorten the distance between dendrites and improve the subsequent high-temperature diffusion effect;

[0058] S3 third fire: After the steel ingot treated in S2 is heated and kept warm, the heating temperature is Tstart ± 10℃, and the holding time is 2 to 5 hours per 100mm of the pre-drawn diameter. After it is taken out of the furnace, it is upset to the height required by the process according to the upsetting ratio of 1.5 to 2.0;

[0059] After the first step of pre-drawing (i.e., the second fire), the cast structure of the ingot is improved to a certain extent, and the dendrite structure becomes denser. This step extends the holding time at the initial forging temperature. The purpose is to achieve high-temperature diffusion homogenization effect through long-term high-temperature holding, reduce the micro-segregation of elements between dendrites, and improve forging performance. The longer the high-temperature diffusion time, the better the diffusion effect. However, after diffusion to a certain extent, the element concentration gradient gradually decreases. At this time, increasing the diffusion time will slow down the homogenization effect, waste energy, and even lead to coarse grains. Therefore, the holding time cannot be insufficient or too long.

[0060] S4 fourth fire: After the steel ingot treated in S3 is heated and kept warm, the heating temperature is Tstart ± 10℃, and the holding time is 30 to 60 minutes per 100mm of the height after upsetting. After it is taken out of the furnace, it is drawn to the diameter required by the process using upper and lower V-shaped anvils according to the KD drawing ratio of 2.0 to 2.5;

[0061] After the upsetting in the last fire (the third fire), some axial defects have been initially improved. At the same time, upsetting increases the diameter of the blank, providing sufficient drawing amount for this fire. This fire sets a drawing amount of no more than 2.5. Insufficient drawing amount makes it difficult to compact the original defects in the core. Excessive drawing amount will cause cracks in the core. At the same time, the anvil arrangement method and the amount of pressing for each pass are specified to ensure that the defects in the core are completely compacted.

[0062] S5 Fifth Fire: After the steel ingot treated in S4 is heated and kept warm, the heating temperature is Tstart ± 10℃, and the holding time is 2 to 5 hours for every 100mm of the drawing diameter. After it is taken out of the furnace, it is continued to be drawn by KD to the large circle diameter of the blank. The two ends of the blank are cut according to the length required by the process, and the water riser roll neck is pinched by KD to obtain the semi-finished blank roll;

[0063] Following the previous fire, KD stretching is continued to the final size of the large circle. At the same time, the holding time at the initial forging temperature is extended in this fire to achieve the effect of high-temperature diffusion homogenization, reduce the micro-segregation of elements between dendrites, and improve the forging performance.

[0064] S6 Sixth fire: After the semi-finished blank roll is heated and kept warm, the heating temperature is T start ± 10 ℃, and the holding time is 30 to 60 minutes per 100mm of the roll neck diameter size after heating. After coming out of the furnace, KD stretches the roll necks at both ends to the roll neck size of the blank figure, and rounds the finished blank roll;

[0065] The special feature of this firing is that after the billet is out of the furnace, the large circle is not allowed to deform again to avoid small deformations causing tensile stress on the core and cracks in the core. At the same time, the roller necks at both ends are pulled out of the finished product with KD anvils and hammers to ensure that the core is in a two-way or three-way compressive stress state to avoid cracks in the core.

[0066] Among them, Tstart is the initial forging temperature, which ranges from 1150 to 1200°C. The selection of the initial forging temperature is closely related to the material and is generally 100 to 150°C lower than the solidus temperature of the material.

[0067] Specifically, the forging method controls surface cracks while fully compacting the core defects of brittle and crack-prone materials, significantly improving the product qualification rate to more than 90%. The wear resistance and accident resistance of the forged semi-steel blanking roller produced by this method are significantly better than those of traditional blanking roller materials, and are more suitable for blanking rollers with deep hole grooves.

[0068] Specifically, the steel ingot is a cast steel ingot made of semi-steel material, and its composition is as follows by mass percentage: C 1.0-1.6%, Si 0.2-0.7%, Mn 0.4-1.0%, Cr 1.0-2.0%, Ni 0.1-1.0%, Mo 0.2-0.8%, P, S≤0.02%, and the rest are iron and other impurity elements; and Cu+Pb+Sb+As+Bi+Sn+Zn<0.2% among the impurity elements.

[0069] Specifically, the step heating curve in step S1 is:

[0070] Preheating stage: heat the steel ingot to Tpre and keep it warm, where Tpre is 750-850℃;

[0071] Homogenization diffusion stage: heat the steel ingot to Texpand ±10℃ and keep it warm, with a heating rate of ≤50℃ / h, where Texpand = Tstart +30℃;

[0072] Initial forging stage: slowly cool the steel ingot to Tstart ±10℃ and keep it warm, with a cooling rate of ≤50℃ / h.

[0073] Furthermore, the holding time in the preheating stage is h1, the holding time in the homogenization diffusion stage is h2, and the holding time in the initial forging stage is h3; h1, h2, and h3 are determined according to the diameter of the steel ingot, h1 is kept warm for 40 to 80 minutes per 100 mm, h2 is kept warm for 2 to 5 hours per 100 mm, and h3 is kept warm for 1 to 2 hours per 100 mm.

[0074] Function of the preheating stage: The temperature is set near the phase change temperature to uniform the internal and external temperature and structure, and prevent cracks on the surface and core of the ingot due to structural stress and temperature stress.

[0075] Homogenization diffusion stage: set a higher diffusion temperature to achieve better diffusion effect in a shorter time. High temperature diffusion improves element segregation.

[0076] Initial forging stage: In order to avoid excessive temperature rise in the core due to deformation heat effect, resulting in overheating and overburning, the temperature should be lowered to the appropriate initial forging temperature before forging, and then kept warm for a period of time before forging.

[0077] Specifically, the specific operation of pressing the jaws in step S1 is: pressing the jaws at the riser end of the ingot body 100mm, the jaw size is determined according to the inner diameter of the matching upsetting leak plate, and the bottom of the ingot and the jaws handle are gas-cut and discarded.

[0078] Specifically, the final forging temperature of each step is ≥850°C.

[0079] Specifically, the specific operations and parameters of step S2 are: the pressing amount ≥ 20% of the blank height, 90° flipping, and one pass of pressing with the staggered anvil.

[0080] Specifically, the specific operations and parameters of step S4 are: the pressing amount ≥ 20% of the blank height, 90° flipping, and odd-even anvil arrangement.

[0081] Specifically, after the finished blanking roller is obtained in step S6, it is placed in air cooling to cool to 600±10°C and then put into the post-forging furnace in order to speed up the cooling speed, avoid the precipitation of network carbides or the precipitation temperature is too high, reduce the precipitation of network carbides, and thus avoid cracking caused by network carbides.

[0082] Specifically, the total forging ratio of the forging method is ≥3 to achieve the effect of fully compacting the core.

[0083] Specifically, this forging method controls surface cracks while achieving full compaction of the core defects of brittle and crack-prone materials, significantly improving the product qualification rate. The forged semi-steel blanking roll produced by this method has a uniform pearlite matrix and carbide structure from the surface to the inside, and the hardness difference within 200mm of the surface is ≤3HS, which is more suitable for blanking rolls with deep hole grooves.

[0084] The invention provides a forged semi-steel blanking roller with high wear resistance and high accident resistance. The blanking roller is made by the forging method, and its wear resistance and accident resistance are significantly better than those of traditional blanking roller materials.

[0085] Specifically, the microstructure of the forged semi-steel blanking roll is composed of a pearlite matrix and a large amount of free carbides. Because the free carbide content is 15-25% (high), the wear resistance is higher than that of ordinary forged steel and spheroidal cast iron rolls. In addition, after being processed by the forging method proposed by the present invention, the strength is significantly improved compared with the cast steel roll. In addition, due to the presence of free carbides, the high-temperature hardness of the semi-steel roll is higher than that of the cast steel roll, which prevents the matrix from producing plastic flow and reduces the wrinkles on the roll surface.

[0086] Furthermore, the hardness difference within 200mm on the surface of the forged semi-steel blanking roller is ≤3HS, which is particularly suitable for steel section rollers with deep hole grooves.

[0087] According to the standard requirements, the defect equivalent of the working layer is ≤Ф2, the defect equivalent of other areas is ≤Ф6, and the defect wave is ≤50%, which meets the flaw detection standards.

[0088] Example 1

[0089] The chemical composition of the selected material is C1.6%, Si 0.5%, Mn 0.6%, Cr 1.5%, Ni 0.5%, Mo0.5%, P, S 0.005%, and the remaining impurity elements Cu+Pb+Sb+As+Bi+Sn+Zn<0.2%. According to the blank size (below Figure 2 ) Select a suitable steel ingot. This embodiment adopts 66T steel ingot forging production, with a nozzle size of 1615mm, a riser size of 1838mm, and an average size of 1726.5mm.

[0090] First fire: After the ingot comes, press Figure 3 The curve is heated and kept warm before forging. After the steel ingot is taken out of the furnace, the edge is chamfered, and the roller body 100mm from the riser end of the steel ingot begins to press the jaws Φ800×1000, and the bottom of the ingot and the jaws are cut by gas to discard the material.

[0091] Second fire: heating furnace 1150±10℃, keeping warm for 15h, KD pre-drawing length to Φ1550mm, pressing amount is 20% of the billet height, 90° flipping, pressing one pass with staggered anvil, pre-drawing ratio is 1.24.

[0092] The third fire: heating furnace 1150±10℃, keeping warm for 40h, upsetting to H=1800mm, upsetting ratio is 1.9.

[0093] Fourth fire: heating furnace 1150±10℃, keeping temperature for 18h, KD drawing six times out of furnace Φ1450mm, reduction amount is 20% of the billet height, 90° turning, odd and even anvil arrangement, drawing ratio is 2.1.

[0094] The fifth fire: heating furnace 1150 ± 10 ℃, keep warm for 40h, KD out of the furnace stretched to Φ1330mm, press Figure 4 Cut the material and pinch out the roller necks at both ends to the required length to the required diameter of Φ900mm.

[0095] The sixth fire: heating furnace 1150 ± 10 ℃, keep warm for 6h, KD out of the furnace to lengthen the roller necks at both ends, round them to the diameter required by the rough drawing, and gas cut the excess waste at both ends to produce the finished product.

[0096] There are almost no cracks on the surface during the forging process, the production process goes smoothly, and the finished product is produced after six firings.

[0097] After the blank roll is cooled to 600±10℃, it is placed in the post-forging furnace, and the hardness after spray quenching + tempering heat treatment is 46~50HSD. The yield strength at room temperature is 585MPa, the tensile strength is 1101MPa, the elongation is 5%, the cross-sectional shrinkage is 5%, and the impact performance is 7J. The hardness at 200mm from the surface is 45-48HSD, and the hardness drop is ≤3HSD.

[0098] At 500℃, the yield strength is 322MPa, the tensile strength is 549MPa, the elongation is 55%, the cross-sectional shrinkage is 22%, and the impact performance is 17J. The defect equivalent of the working layer is ≤Ф1, the defect equivalent of other areas is ≤Ф4, the bottom wave is 100%, and the defect wave is <10%, which meets the requirements of the flaw detection standard.

[0099] Example 2

[0100] The chemical composition of the selected material is C1.4%, Si 0.55%, Mn 0.55%, Cr 1.45%, Ni0.53%, Mo0.56%, P, S 0.004%, and the remaining impurity elements Cu+Pb+Sb+As+Bi+Sn+Zn<0.2%. According to the blank size Figure 5 Select a suitable steel ingot. This embodiment adopts 70T steel ingot forging production, with a nozzle size of 1668mm, a riser size of 1952mm, and an average size of 1810mm.

[0101] First fire: after the ingot arrives, follow the special curve Figure 6 Carry out heating and heat preservation before forging. Chamfer the steel ingot after it comes out of the furnace, start pressing the jaws Φ1000×1000 from 100mm at the riser end of the ingot, and gas cut the ingot bottom and the jaws to discard the material.

[0102] Second fire: heating furnace 1170±10℃, keeping warm for 18h, KD pre-drawing length to Φ1600mm, pressing amount is 20% of the billet height, 90° flipping, staggered anvil pressing one pass, pre-drawing ratio is 1.28.

[0103] The third fire: heating furnace 1170±10℃, keeping warm for 45h, upsetting to H=1800mm, upsetting ratio is 1.9.

[0104] Fourth fire: heating furnace 1170±10℃, keeping temperature for 18h, KD drawing out of furnace for six passes Φ1480mm, reduction amount is 20% of the billet height, 90° turning, odd and even anvil arrangement, drawing ratio is 2.3.

[0105] The fifth fire: heating furnace 1170 ± 10 ℃, keep warm for 45h, KD out of the furnace stretched to Φ1350mm, press Figure 7 Cut the material and pinch out the roller necks at both ends to the required diameter of Φ900mm.

[0106] The sixth fire: heating furnace 1170 ± 10 ℃, keep warm for 7.5h, KD out of the furnace to lengthen the roller necks at both ends, round them to the diameter required by the rough drawing, and gas cut the excess waste at both ends to produce the finished product.

[0107] There are almost no cracks on the surface during the forging process, the production process goes smoothly, and the finished product is produced after six firings.

[0108] After the blank roll is cooled to 600±10℃, it is placed in the post-forging furnace, and the hardness after spray quenching + tempering heat treatment is 45-48HSD. The yield strength at room temperature is 568MPa, the tensile strength is 1100MPa, the elongation is 6.5%, the cross-sectional shrinkage is 6%, and the impact performance is 7J. The hardness at 200mm from the surface is 43-46HSD, and the hardness drop is ≤3HSD.

[0109] At 500℃, the yield strength is 320MPa, the tensile strength is 545MPa, the elongation is 57%, the cross-sectional shrinkage is 23%, and the impact performance is 18J. The defect equivalent of the working layer is ≤Ф1~2, the defect equivalent of other areas is ≤Ф4~5, the bottom wave is 90~100%, and the defect wave is <30%, which meets the requirements of the flaw detection standard.

[0110] Example 3

[0111] The chemical composition of the selected material is C1.3%, Si 0.65%, Mn 0.58%, Cr 1.5%, Ni 0.55%, Mo0.56%, P, S 0.004%, and the remaining impurity elements Cu+Pb+Sb+As+Bi+Sn+Zn<0.2%. According to the blank size Figure 8 Select a suitable steel ingot. This embodiment adopts 74T steel ingot forging production, with a nozzle size of 1760mm, a riser size of 2058mm, and an average size of 1909mm.

[0112] First fire: after the ingot arrives, follow the special curve Fig. 9 Carry out heating and heat preservation before forging. Chamfer the steel ingot after it comes out of the furnace, start pressing the jaws Φ1000×1000 from 100mm at the riser end of the ingot, and gas cut the ingot bottom and the jaws to discard the material.

[0113] Second fire: heating furnace 1180±10℃, keeping warm for 19h, KD pre-drawing length to Φ1650mm, pressing amount is 20% of the billet height, 90° flipping, staggered anvil pressing one pass, pre-drawing ratio is 1.3.

[0114] The third fire: heating furnace 1180±10℃, keeping warm for 45h, upsetting to H=1850mm, upsetting ratio is 1.85.

[0115] Fourth fire: heating furnace 1180±10℃, keeping temperature for 18h, KD drawing out of furnace for six passes Φ1500mm, reduction amount is 20% of the billet height, 90° turning, odd and even anvil arrangement, drawing ratio is 2.4.

[0116] The fifth fire: heating furnace 1180 ± 10 ℃, keep warm for 45h, KD out of the furnace stretched to Φ1370mm, press Fig.10 Cut the material and pinch out the roller necks at both ends to the required diameter of Φ900mm.

[0117] The sixth fire: heating furnace 1180 ± 10 ℃, keep warm for 9h, KD out of the furnace to lengthen the roller necks at both ends, round them to the diameter required by the rough drawing, and gas cut the excess waste at both ends to produce the finished product.

[0118] There are almost no cracks on the surface during the forging process, the production process goes smoothly, and the finished product is produced after six firings.

[0119] After the blank roll is cooled to 600±10℃, it is placed in the forging furnace, and the hardness after quenching and tempering heat treatment is 43~47HSD. The yield strength at room temperature is 547MPa, the tensile strength is 1044MPa, the elongation is 9%, the cross-sectional shrinkage is 10%, and the impact performance is 8J. The hardness at 200mm from the surface is 41-45HSD, and the hardness drop is ≤3HSD.

[0120] At 500℃, the yield strength is 335MPa, the tensile strength is 540MPa, the elongation is 57%, the cross-sectional shrinkage is 23%, and the impact performance is 18J. The defect equivalent of the working layer is ≤Ф2, the defect equivalent of other areas is ≤Ф5, the bottom wave is >80%, and the defect wave is <30%, which meets the requirements of the flaw detection standard.

[0121] Comparative Example 1

[0122] The chemical composition of the selected material is C1.6%, Si 0.5%, Mn 0.6%, Cr 1.5%, Ni 0.5%, Mo0.5%, P, S 0.005%, and the remaining impurity elements Cu+Pb+Sb+As+Bi+Sn+Zn<0.2%. According to the blank size (same as Example 1), a suitable steel ingot is selected. This comparative example adopts 66T steel ingot forging production, the nozzle size is 1615mm, the riser size is 1838mm, and the average size is 1726.5mm.

[0123] First firing: After the ingot arrives, pre-forging heating and heat preservation are performed according to the special curve (same as in Example 1). The edges are chamfered after leaving the furnace, the riser end of the ingot is pressed with a jaw of Φ800×1000, and the bottom of the ingot and the handle of the jaw are gas-cut and discarded.

[0124] Second firing: heating furnace 1180±10℃, keeping warm for 40h, upsetting to H=1800mm, upsetting ratio is 1.53.

[0125] The third fire: heating furnace 1180±10℃, keeping warm for 18h, KD drawing six times out of the furnace Φ1450mm, the reduction is 20% of the billet height, 90° turning, odd and even anvils, and the drawing ratio is 2.1.

[0126] Fourth fire: heating furnace 1180±10℃, keeping warm for 10h, taking out of furnace, stretching roller body to Φ1370mm with upper flat and lower V anvil, and pinching roller necks at both ends to Φ900mm.

[0127] The fifth fire: heating furnace 1180±10℃, keep warm for 8h, take out of the furnace, stretch the roller necks at both ends to the diameter required by the rough drawing, and gas cut the excess material at both ends to produce the finished product.

[0128] There are slight cracks on the surface during the forging process, the production process is smooth, and the finished product is produced in five firings. The ultrasonic test of the roller body shows no bottom wave, and the defect wave is greater than 50%, which does not meet the requirements of the flaw detection standard.

[0129] Comparative Example 2

[0130] The chemical composition of the selected material is C1.6%, Si 0.5%, Mn 0.6%, Cr 1.5%, Ni 0.5%, Mo0.5%, P, S 0.005%, and the remaining impurity elements Cu+Pb+Sb+As+Bi+Sn+Zn<0.2%. According to the blank size (same as Example 1), a suitable steel ingot is selected. This comparative example adopts 66T steel ingot forging production, the nozzle size is 1615mm, the riser size is 1838mm, and the average size is 1726.5mm.

[0131] First fire: heating furnace 1150±10℃, chamfering out of furnace, pressing jaws Φ800×1000 at the riser end of ingot, gas cutting ingot bottom and jaws to discard.

[0132] Second firing: heating furnace 1150±10℃, keeping warm for 40h, upsetting to H=1800mm, upsetting ratio is 1.53.

[0133] The third fire: heating furnace 1150±10℃, keeping warm for 18h, KD drawing six times out of the furnace Φ1450mm, the reduction is 20% of the billet height, 90° turning, odd and even anvils, and the drawing ratio is 2.1.

[0134] Fourth fire: heating furnace 1150±10℃, keeping warm for 10h, taking out of furnace, stretching roller body to Φ1370mm with upper flat and lower V anvil, pinching roller necks at both ends to Φ1000mm.

[0135] The fifth fire: heating furnace 1150±10℃, keep warm for 10h, take out of the furnace, stretch the roller necks at both ends to the diameter required by the rough drawing, and gas cut the excess material at both ends to produce the finished product.

[0136] There are slight cracks on the surface during the forging process, the production process is smooth, and the finished product is produced in five firings. The ultrasonic detection of cracks in the roller body is large, the bottom wave attenuation is less than 10%, and the defect wave is 70-80%, which does not meet the requirements of the flaw detection standard.

[0137] Microcracks were generated on the surface of both Comparative Examples 1 and 2 during the forging process. This was because the pre-drawing process was not performed and the surface cast structure was not broken, resulting in surface cracks during large deformation upsetting.

[0138] The ultrasonic inspection of comparative example 1 showed that the heart had no bottom. This was because comparative example 1 did not perform the pre-drawing process, the high-temperature diffusion effect was poor, and the initial forging temperature was set too high, resulting in overburning of the heart and enlargement of the heart defects.

[0139] Comparative Example 2 ultrasonic inspection showed cracks in the heart, large bottom wave attenuation, and high defect wave. This was because the special curve and pre-extraction process were not implemented in Comparative Example 2, resulting in large stress in the heart, poor diffusion effect, and insufficient compaction of the heart defect.

[0140] There are differences in performance between the various embodiments, and the flaw detection quality of embodiment 1 is the best because the segregation of the steel ingot is well controlled and the core defects are fully compacted;

[0141] The flaw detection quality of Example 3 is slightly worse than that of Example 1 because the tonnage of the steel ingot used is larger, the original segregation of the steel ingot is more serious, the initial forging temperature control requirements are more stringent, and higher requirements are placed on the high-temperature diffusion temperature and time.

[0142] In summary, the semi-steel blanking roll forged by the present invention has a hardness of 35-60 HSD, a room temperature yield strength of 480-800 MPa, a tensile strength of 800-1300 MPa, an elongation of ≥6.5%, a cross-sectional shrinkage of ≥6%, and an impact resistance of ≥7J;

[0143] Yield strength ≥320MPa at 500℃, tensile strength ≥540MPa, elongation ≥57%, section shrinkage ≥23%, impact resistance ≥18J;

[0144] The defect equivalent of the working layer is ≤Ф2, the defect equivalent of other areas is ≤Ф5, the bottom wave is >50%, the defect wave is <50%, which meets the requirements of the flaw detection standard; the hardness difference within 200mm of the surface is ≤3HS.

[0145] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A forging method for a semi-steel blanking roll, characterized in that: The specific steps include: S1: The first fire: the steel ingot is quickly put into the furnace and heat treated according to the preset step-type heating curve. After the heat treatment is completed, the ingot is taken out of the furnace, the edges are chamfered, the jaws are pressed, and the bottom of the ingot and the jaws are gas-cut to discard the material. S2 second fire: After the steel ingot treated in S1 is heated and kept warm, the heating temperature is Tstart ± 10℃, and the holding time is 30 to 60 minutes per 100mm of the average water riser diameter of the steel ingot. After it is taken out of the furnace, the upper and lower V-shaped anvils are used to pre-draw it to the diameter required by the process at a pre-drawing ratio of 1.0 to 1.5; S3 third fire: After the steel ingot treated in S2 is heated and kept warm, the heating temperature is Tstart ± 10℃, and the holding time is 2 to 5 hours per 100mm of the pre-drawn diameter. After it is taken out of the furnace, it is upset to the height required by the process according to the upsetting ratio of 1.5 to 2.0; S4 fourth fire: After the steel ingot treated in S3 is heated and kept warm, the heating temperature is Tstart ± 10℃, and the holding time is 30 to 60 minutes per 100mm of height after upsetting. After it is taken out of the furnace, it is drawn to the diameter required by the process using upper and lower V-shaped anvils according to the KD drawing ratio of 1.5 to 2.5; S5 Fifth Fire: After the steel ingot treated in S4 is heated and kept warm, the heating temperature is Tstart ± 10℃, and the holding time is 2 to 5 hours for every 100mm of the drawing diameter. After it is taken out of the furnace, it is continued to be drawn by KD to the large circle diameter of the blank. The two ends of the blank are cut according to the length required by the process, and the water riser roll neck is pinched by KD to obtain the semi-finished blank roll; S6 Sixth fire: After the semi-finished blank roll is heated and kept warm, the heating temperature is T start ± 10 ℃, and the holding time is 30 to 60 minutes per 100mm of the roll neck diameter size after heating. After coming out of the furnace, KD stretches the roll necks at both ends to the roll neck size of the blank figure, and rounds the finished blank roll; Among them, Tstart is the starting forging temperature, ranging from 1100 to 1200℃.

2. The forging method according to claim 1, characterized in that: The steel ingot is a cast steel ingot made of semi-steel material, and its composition is as follows by mass percentage: C 1.0-1.6%, Si 0.2-0.7%, Mn 0.4-1.0%, Cr 1.0-2.0%, Ni0.1-1.0%, Mo 0.2-0.8%, P, S≤0.02%, and the rest are iron and other impurity elements; and among the impurity elements, Cu+Pb+Sb+As+Bi+Sn+Zn<0.2%.

3. The forging method according to claim 1, characterized in that: The step heating curve in step S1 is: Preheating stage: heat the steel ingot to Tpre and keep it warm, where Tpre is 750-850℃; Homogenization diffusion stage: heat the steel ingot to Texpand ±10℃ and keep it warm, with a heating rate of ≤50℃ / h, where Texpand = Tstart +30℃; Initial forging stage: slowly cool the steel ingot to Tstart ±10℃ and keep it warm, with a cooling rate of ≤50℃ / h.

4. The forging method according to claim 3, characterized in that: The holding time in the preheating stage is h1, the holding time in the homogenization diffusion stage is h2, and the holding time in the initial forging stage is h3; h1, h2, and h3 are determined according to the diameter of the steel ingot, h1 is 40 to 80 minutes per 100 mm, h2 is 2 to 5 hours per 100 mm, and h3 is 1 to 2 hours per 100 mm.

5. The forging method according to claim 1, characterized in that: The final forging temperature of each step is ≥850℃.

6. The forging method according to claim 1, characterized in that: The specific operation and parameters of step S2 are: the pressing amount is ≥ 20% of the blank height, 90° flipping, and one pass of pressing with staggered anvils.

7. The forging method according to claim 1, characterized in that: The specific operations and parameters of step S4 are: the pressing amount ≥ 20% of the blank height, 90° flipping, and odd-even anvil arrangement.

8. The forging method according to claim 1, characterized in that: After the finished blank roll is obtained in step S6, the blank roll is cooled to 600±10° C. and then placed in a post-forging furnace.

9. The forging method according to claim 1, characterized in that: The total forging ratio of the forging method is ≥3.

10. A forged semi-steel blanking roller with high wear resistance and high accident resistance, characterized in that: The blank opening roller is made by the forging method described in any one of claims 1 to 8. The hardness of the forged semi-steel blank opening roller is 35 to 60 HSD, the room temperature yield strength is 480 to 800 MPa, and the tensile strength is 800 to 1300 MPa; the hardness difference within 200 mm of the surface is ≤3HS, and it is suitable for opening deep hole grooves.

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