Semi-high-speed steel cold-rolled working roll and preparation method thereof

Abstract

The invention relates to a semi-high-speed cold-rolled working roll and a preparation method thereof, belongs to the technical field of machining, and at least aims to solve the problems that the hardness of a roll body of a semi-high-speed cold-rolled working roll prepared by an existing method is poor; the hardness uniformity is poor; and the grain size grade of the working roll is low. The invention relates to a semi-high-speed steel cold rolling working roll which comprises the following chemical components in percentage by weight: 0.65-1.00% of C; 0.70% to 1.10% of Si; 0.20% to 0.50% of Mn; 6.50 to 9.00 percent of Cr; 0.65 to 0.85 percent of Ni; 0.75% to 1.00% of V; 1.60% to 2.00% of Mo; 0.65 to 1.00% of W; less than or equal to 0.015% of S; p is less than or equal to 0.015; and the balance of Fe and inevitable impurities. The prepared working roll is high in hardness, good in uniformity and high in grain size grade.

Description

Technical Field

[0001] The present invention relates to the technical field of mechanical manufacturing, and in particular to a semi-high speed steel cold rolling work roll and a preparation method thereof. Background Art

[0002] With the continuous improvement of rolling technology and the requirements for the quality of rolled materials, it is required that the cold rolling roll has excellent wear resistance, roughness retention and accident resistance while being able to adapt to the working conditions of roll surface texturing and long-cycle rolling. The cold rolling work roll made of semi-high speed steel material contains strong carbide-forming elements such as Cr, Mo, and W, and the carbide types are mainly M7C3 type rich in Cr, M 23 C6 and MC type carbides rich in V. Its tempering resistance, strength and toughness, and wear resistance can be effectively improved compared with the currently commonly used cold rolling work roll made of Cr5 forged steel material.

[0003] The hardness of the roll body of the existing semi-high speed cold rolling work roll is mostly 80-90HSD. If the required hardness of the roll body > 90HSD, a cryogenic treatment process needs to be added during the heat treatment process, and the hardness uniformity of the roll body ≤ 1.5HSD. And according to the literature, the effect of cryogenic treatment on the hardness improvement of semi-high speed steel materials is unstable. Therefore, it is necessary to continuously improve and optimize the preparation method of the semi-high speed steel cold rolling work roll. Summary of the Invention

[0004] In view of the above analysis, the embodiments of the present invention aim to provide a semi-high speed steel cold rolling work roll and a preparation method thereof, at least to solve one of the problems of poor roll body hardness of the semi-high speed cold rolling work roll prepared by the existing method; poor hardness uniformity; and low grain size grade of the work roll.

[0005] The object of the present invention is mainly achieved by the following technical solutions:

[0006] The present invention provides a semi-high speed steel cold rolling work roll, and its chemical composition by weight percentage is: C 0.65-1.00%; Si 0.70-1.10%; Mn 0.20-0.50%; Cr 6.50-9.00%; Ni 0.65-0.85%; V 0.75-1.00%; Mo 1.60-2.00%; W 0.65-1.00%; S≤0.015%; P≤0.015; the rest is Fe and inevitable impurities.

[0007] Further, the sum of the weight percentages of the Cr element, Mo element, and W element satisfies: 9.50% ≤ Cr + Mo + W < 11.5%.

[0008] The present invention also provides a preparation method of a semi-high speed steel cold rolling work roll for preparing the above semi-high speed steel cold rolling work roll, including the following steps:

[0009] S1: Configure raw materials according to chemical components and obtain an electroslag remelted ingot through electroslag remelting smelting;

[0010] S2: Heat and forge the electroslag remelted ingot to make a first roll blank forging;

[0011] S3: Perform post-forging heat treatment on the first roll blank forging, and then cool it to room temperature to obtain a second roll blank forging;

[0012] S4: Rough machine the second roll blank forging and then perform ultrasonic flaw detection to obtain a third roll blank forging;

[0013] S5: Perform quenching and tempering heat treatment and semi-finishing machining on the third roll blank forging to obtain a fourth roll blank forging;

[0014] S6: Perform induction hardening, tempering and finish machining on the fourth roll blank forging to obtain the final working roll.

[0015] Further, the step S2 includes:

[0016] S21: Heat and hold the semi-high speed electroslag remelted ingot;

[0017] S22: In the first forging pass, with the nozzle side of the electroslag ingot as the reference, at a distance of 80 - 120 mm from the end face of the ingot body on the nozzle side, adopt the press clamp process with a clamp diameter of 350 - 450 mm to obtain a first forging blank;

[0018] S23: In the second forging pass, use a upsetting leaky plate and an upsetting cover plate to upset the first forging blank to obtain a second forging blank, and use a V-shaped cylindrical anvil to draw out the second forging blank from the end face of the ingot body on the nozzle side to the riser side in a cyclic order to obtain a third forging blank;

[0019] S24: In the third forging pass, use the upsetting leaky plate and the upsetting cover plate again to upset the third forging blank to obtain a fourth forging blank, and use a V-shaped cylindrical anvil to draw out the fourth forging blank from the end face of the ingot body on the nozzle side to the riser side in a cyclic order to obtain a fifth forging blank;

[0020] S25: In the fourth forging pass, use the upper and lower flat anvils or the upper flat anvil and the lower V-shaped anvil to draw out the fifth forging blank, cut the material, pre-forge the water riser roll neck, and draw out the roll body to obtain a sixth forging blank;

[0021] S26: In the fifth forging pass, according to the requirements of the forging size, adopt the reverse forming order, first form the roll neck, then form the roll body, draw out the roll body and the water riser roll neck of the sixth forging blank to the target size, and forge out the first roll blank forging.

[0022] Further, in step S3, the post-forging heat treatment process is as follows: heat the first roll blank forging to 820 - 850 °C, hold for 20 - 25 h, then cool in the furnace to 300 - 350 °C, and then heat up to 620 - 640 °C, hold for 80 - 100 h, and then cool in the furnace to room temperature.

[0023] Further, in step S5, the quenching and tempering heat treatment process is as follows: heat the third roll blank forging to 920 - 950 °C, hold for 15 - 20 h, then air-cool to 300 - 350 °C, and then heat up to 620 - 640 °C, hold for 25 - 40 h, and then cool in the furnace to room temperature.

[0024] Further, in step S6, the induction hardening process is as follows: use a dual-frequency induction device to heat the roll body part of the fourth roll blank forging from one end to the other end at a speed of 20 - 35 mm / min to 1030 - 1040 °C, and then perform continuous water cooling until room temperature.

[0025] Further, in step S6, the tempering temperature is 400 - 500 °C, the tempering time is 20 - 30 h, and the number of tempering times is 3 - 5 times.

[0026] Further, in step S21, the heating temperature is 1180 - 1200 °C, and the holding time T satisfies: D / 100 ≤ T ≤ D / 75, where D is the diameter of the ingot in mm; T is the holding time in h.

[0027] Further, in step S23, the ratio of the height of the first forging blank to the height of the second forging blank H1 / H2 ≥ 1.5, where H1 is the height of the first forging blank, H2 is the height of the second forging blank, in mm.

[0028] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0029] 1. Through reasonable composition design and optimization of forging, heat treatment and other process parameters, the hardness of the roll body of the work roll can reach 93 - 98 HSD, without the need for cryogenic treatment, avoiding the instability of the work roll performance affected by cryogenic treatment.

[0030] 2. Through reasonable composition design and optimization of forging, heat treatment and other process parameters, the grain size grade of the work roll matrix reaches 8 - 9 levels, the carbides are finer and more dispersed, the hardness uniformity of the work roll can be better, the hardness of the roll body of the prepared work roll reaches 93 - 98 HSD, and the hardness uniformity of the roll body ≤ 1 HSD.

[0031] 3. By optimizing the alloy composition and reasonable thermal process parameters, the hardness uniformity of the roll body of the work roll can reach ≤ 1 HSD, and the service performance such as accident resistance is better.

[0032] 4. The preparation method of the present invention uses a V-shaped cylindrical anvil during forging, which increases the metal deformation amount in the contact area between the forging blank and the anvil surface, makes the surface deformation of the forging blank more uniform, and at the same time can reduce the deformation tensile stress on the surface of the billet at the lap joint of the front and rear anvils and the surface of the billet in contact with the anvil surface during the drawing process, reduce the surface damage of the billet, and make the forging blank not easily produce surface cracks.

[0033] 5. The preparation method of the present invention, during forging, strictly controls the height and diameter of the forging blank in each heating stage of the forging process, and at the same time adopts a drawing method of "decreasing reduction amount in sequence" matching the V-shaped cylindrical anvil. As the temperature of the forging blank decreases from high to low, the deformation amount decreases by 4%-6% between every two passes. The large initial deformation amount promotes the refinement of coarse carbides, and the small later deformation amount reduces the surface tensile stress to avoid cracks, which can reduce the number of cleaning and repairing heating stages, improve the forging efficiency and material utilization rate; at the same time, this drawing method can also reduce the axial tensile stress of the forging blank and effectively control the generation of surface cracks on the forging blank.

[0034] 6. The preparation method of the present invention adopts the "reverse forming" method in the finished product stage during the forging process, conforms to the change of the temperature field of the forging blank, first forms the roll neck with a faster cooling rate, and then forms the roll body with a slower cooling rate, which can prevent the end of the roll neck from cracking, thereby reducing the number of finished product heating stages and improving the material utilization rate and production efficiency.

[0035] In the present invention, the above technical solutions can also be combined with each other to achieve more preferred combination schemes. Other features and advantages of the present invention will be described in the subsequent specification, and some advantages can be made obvious from the specification, or understood by implementing the present invention. The objectives and other advantages of the present invention can be achieved and obtained through the content specifically pointed out in the specification and the drawings. Brief Description of the Drawings

[0036] The drawings are only for the purpose of showing specific embodiments and are not considered as limitations to the present invention. Throughout the drawings, the same reference signs represent the same components.

[0037] Figure 1 It is the as-cast metallographic photo of the semi-high speed steel electroslag ingot in Example 1 of the present invention;

[0038] Figure 2 It is the microstructural photo of the semi-high speed steel cold rolling work roll in Example 1 of the present invention;

[0039] Figure 3 It is the grain size photo of the semi-high speed steel cold rolling work roll in Example 1 of the present invention;

[0040] Figure 4 It is the physical drawing of the fifth forging blank in Example 1 of the present invention;

[0041] Figure 5This is the physical drawing of the fifth forging blank in Comparative Example 2 of the present invention. Specific Embodiments

[0042] The preferred embodiments of the present invention will be specifically described below with reference to the accompanying drawings. The accompanying drawings form a part of this application and are used together with the embodiments of the present invention to explain the principles of the present invention, and are not used to limit the scope of the present invention.

[0043] The present invention provides a semi-high-speed steel cold rolling work roll, and its chemical composition is as follows by weight percentage: C 0.65 - 1.00%; Si 0.70 - 1.10%; Mn 0.20 - 0.50%; Cr 6.50 - 9.00%; Ni 0.65 - 0.85%; V 0.75 - 1.00%; Mo 1.60 - 2.00%; W 0.65 - 1.00%; S ≤ 0.015%; P ≤ 0.015; the balance is Fe and unavoidable impurities;

[0044] The reasons for limiting the slab composition of the semi-high-speed steel cold rolling work roll and its preparation method in the present invention are described below. Only % is used to represent the mass percentage in the composition.

[0045] C: It can enhance the hardenability of high-speed steel to obtain high-carbon martensite, thereby improving the hardness of the steel. In addition, C can form alloy carbides M6C (such as Fe4W2C, Fe4Mo2C) and M 23 C6 (carbide of Cr and C) with W, Mo, Cr and other alloying elements. The former precipitates during tempering to improve the hardness and red hardness of high-speed steel, and the latter dissolves in the matrix to increase the austenite alloy degree and further enhance the matrix hardness. If the C content is too high, large-sized carbides will be formed in the semi-high-speed steel, resulting in deteriorated toughness; if the C content is insufficient, the hardness of the high-speed steel will be reduced. The present invention controls the C content within 0.65 - 1.00%.

[0046] Si: It can improve the quenching and tempering hardness of the steel, and an appropriate content of Si can also improve the toughness and flexural strength of the steel. The present invention controls the Si content within 0.70 - 1.10%.

[0047] Mn: It increases the hardenability content of the steel, and the general content does not exceed 2%. The present invention controls the Mn content within 0.20 - 0.50%.

[0048] Cr: The Cr element can enhance the hardenability of the steel. As the addition amount of Cr increases, the precipitation amount of M 23 C6-type carbides increases, and the hardness increases accordingly. The present invention controls the C content within 6.50 - 9.00%.

[0049] Ni: Nickel can improve the strength of steel, increase the fatigue resistance of steel and reduce the sensitivity of steel to notches, but excessive nickel will increase residual austenite and reduce hardness. In the present invention, the Ni content is controlled at 0.65-0.85%.

[0050] V: V generates MC carbide with C at high temperature. MC carbide dissolves or partially dissolves in the matrix during quenching, and then precipitates as fine VC during tempering to enhance the thermal stability and secondary hardness of the steel. In the present invention, the V content is controlled at 0.75-1.00%.

[0051] Mo: mainly forms metastable M2C eutectic carbide, which can be decomposed into MC and M6C carbide (such as Fe4Mo2C) during subsequent heat treatment. The present invention controls the Mo content to 1.60-2.00%.

[0052] W: W can react with Fe and C to generate a certain amount of insoluble M6C type primary carbides, making the quenching temperature of the steel close to the melting point and increasing the supersaturation of the matrix after quenching. During the tempering process, W participates in the formation of a large number of nano-scale secondary carbides (such as Fe4W2C), producing a secondary hardening effect. However, as the W content increases, coarse-sized, network-distributed eutectic carbides are precipitated during the solidification of high-W steel, which is detrimental to the plasticity of the steel. The present invention controls the W content to 0.65-1.00%.

[0053] P and S: are harmful elements and should be strictly controlled. Considering the manufacturing cost and process, the present invention controls the content of P and S to ≤0.015%.

[0054] Preferably, 9.50%≤Cr+Mo+W<11.5%, so as to ensure that a certain content of carbides is formed with C and the hardness of the working roll is ≥92HSD.

[0055] Preferably, a semi-high speed steel cold rolling work roll, the chemical composition of which is calculated by weight percentage: C 0.80-1.00%; Si 0.80-1.10%; Mn 0.35-0.50%; Cr 7.8-9.00%; Ni 0.78-0.85%; V 0.82-1.00%; Mo 1.73-2.00%; W 0.81-1.00%; S≤0.015%; P≤0.015; the rest is Fe and unavoidable impurities. Preferably, 10.34%≤Cr+Mo+W<11.5%.

[0056] Preferably, a semi-high speed steel cold rolling work roll has the following chemical composition by weight percentage: C 0.65 - 0.80%; Si 0.70 - 0.80%; Mn 0.20 - 0.35%; Cr 6.50 - 8.7%; Ni 0.65 - 0.78%; V 0.75 - 0.82%; Mo 1.60 - 1.80%; W 0.65 - 0.90%; S ≤ 0.015%; P ≤ 0.015; the balance being Fe and unavoidable impurities; preferably, 10.34% ≤ Cr + Mo + W < 11.5%.

[0057] The present invention also provides a method for preparing the above-mentioned semi-high speed steel cold rolling work roll, which includes the following steps:

[0058] S1: Configure raw materials according to chemical components and obtain an electroslag remelting ingot through electroslag remelting smelting;

[0059] S2: Heat and forge the electroslag remelting ingot to make a first roll blank forging;

[0060] S3: Perform post-forging heat treatment on the first roll blank forging, and then cool it to room temperature to obtain a second roll blank forging;

[0061] S4: After rough machining the second roll blank forging, perform ultrasonic flaw detection to obtain a third roll blank forging;

[0062] S5: Perform quenching and tempering heat treatment and semi-finishing machining on the third roll blank forging to obtain a fourth roll blank forging;

[0063] S6: Perform induction hardening, tempering and finishing machining on the fourth roll blank forging to obtain the final work roll.

[0064] Specifically, in step S2, heating and forging the electroslag remelting ingot to make a first roll blank forging includes the following steps:

[0065] S21: Heat and hold the semi-high speed electroslag remelting ingot;

[0066] Specifically, the heating temperature is 1180 - 1200 °C, and the holding time T satisfies: D / 100 ≤ T ≤ D / 75, where D is the diameter of the ingot in mm; T is the holding time in h; exemplarily, the heating temperatures are 1182 °C, 1184 °C, 1185 °C, 1186 °C, 1188 °C, 1190 °C, 1192 °C, 1194 °C, 1195 °C, 1196 °C, 1198 °C.

[0067] S22: In the first forging pass, taking the nozzle side of the electroslag ingot as a reference, at a distance of 80 - 120 mm from the end face of the ingot body on the nozzle side, adopt the press clamp process with a clamp diameter of 350 - 450 mm to obtain a first forging blank;

[0068] Specifically, the diameter of the tongs is determined based on the diameter of the upsetting die hole at the production site, as well as the weight and diameter of the forging billet. In practical applications, the empirical formula for the diameter of the tongs is generally: tongs diameter = die hole diameter + correction factor × billet diameter. Among them, the correction factor is usually adjusted according to actual production experience and material properties and can be determined by conventional methods. The height of the first forging billet is set as H1 and the diameter is set as Φ1;

[0069] Exemplarily, with the nozzle side of the electroslag ingot as the reference, the distances from the end face of the ingot body on the nozzle side using the pressing tong process are 82mm, 84mm, 85mm, 86mm, 88mm, 90mm, 92mm, 94mm, 95mm, 96mm, 98mm, 100mm, 102mm, 104mm, 106mm, 108mm, 110mm, 112mm, 114mm, 115mm, 116mm, 118mm.

[0070] The tongs diameters are 355mm, 360mm, 365mm, 370mm, 375mm, 380mm, 385mm, 390mm, 395mm, 400mmm, 405mm, 410mm, 415mm, 420mm, 425mm, 430mm, 435mm, 440mm, 445mm.

[0071] S23: In the second heat treatment, use the upsetting die and the upsetting cover plate to upset the first forging billet to obtain the second forging billet. Then, use the V-shaped cylindrical anvil to draw out the second forging billet from the end face of the ingot body on the nozzle side to the riser side in a cyclic order to obtain the third forging billet;

[0072] Specifically, the height of the second forging billet is set as H2 and the diameter is set as Φ2; the height of the third forging billet is set as H3 and the diameter is set as Φ3. The ratio of the height of the first forging billet to the height of the second forging billet H1 / H2 ≥ 1.5, which can ensure that after using the V-shaped cylindrical anvil to draw out the second forging billet from the end face of the ingot body on the nozzle side to the riser side in a cyclic order, the diameter reduction ratio of the third forging billet and the second forging billet satisfies (Φ2 / Φ3) 2 ≥ 2; at the same time, it can ensure that the eutectic carbide is broken;

[0073] The cyclic order drawing process includes: using the V-shaped cylindrical anvil to draw out the second forging billet from the end face of the ingot body on the nozzle side to the riser side. After pressing one pass, flip it 90°, then press the next pass from the end face of the ingot body on the nozzle side to the riser side, and flip it 90°. Repeat this process for multiple passes of drawing to obtain the third forging billet, ensuring that the diameter reduction ratio of the third forging billet and the second forging billet (Φ2 / Φ3) 2 ≥ 2;

[0074] Among them, the anvil angle θ of the V-shaped cylindrical anvil is 100°-140°, and the anvil width ratio is 0.6-0.8, which can ensure a large deformation amount on the surface and core of the forging blank; the number of passes for sequential circular drawing is 8-10. Among them, the deformation amount in the first pass and the second pass is 23%-27%, and then between every two passes, the deformation amount decreases by 4%-6%; that is, if the deformation amount in the first pass and the second pass is 23%-27%, then the deformation amount in the third pass and the fourth pass is 17-23%, and so on; the overlap amount between the two anvils before and after each pass is 100-200 mm.

[0075] Exemplarily, the anvil angle θ of the V-shaped cylindrical anvil is 105°, 110°, 115°, 120°, 125°, 130°, 135°.

[0076] S24: In the third heat treatment, use the upsetting leak plate and the upsetting cover plate to upset the third forging blank again to obtain the fourth forging blank, and use the V-shaped cylindrical anvil to draw the fourth forging blank from the nozzle side ingot body end face to the riser side in a sequential circular manner to obtain the fifth forging blank;

[0077] Specifically, the height of the fourth forging blank is set as H4 and the diameter is set as Φ4; the height of the fifth forging blank is set as H5 and the diameter is set as Φ5. The ratio of the height of the third forging blank to the height of the fourth forging blank H3 / H4≥1.5, which can ensure that after drawing the fourth forging blank from the nozzle side ingot body end face to the riser side in a sequential circular manner using the V-shaped cylindrical anvil, the diameter forging ratio of the fifth forging blank and the fourth forging blank satisfies (Φ4 / Φ5) 2 ≥2; at the same time, it can ensure that the eutectic carbide is broken;

[0078] The sequential circular drawing process includes: using the V-shaped cylindrical anvil to draw the fourth forging blank from the nozzle side ingot body end face to the riser side. After pressing one pass, turn it 90°, and then press the next pass from the nozzle side ingot body end face to the riser side, and turn it 90°. Repeat this process to complete multiple passes of drawing until the third forging blank is obtained, and the diameter forging ratio of the third forging blank and the second forging blank (Φ4 / Φ5) 2 ≥1.5;

[0079] Among them, the anvil angle θ of the V-shaped cylindrical anvil is 100°-140°, and the anvil width ratio is 0.6-0.8, which can ensure a large deformation amount on the surface and core of the forging blank; the number of passes for sequential circular drawing is 8-10. Among them, the deformation amount in the first pass and the second pass is 23%-27%, and then between every two passes, the deformation amount decreases by 4%-6%; that is, if the deformation amount in the first pass and the second pass is 23%-27%, then the deformation amount in the third pass and the fourth pass is 17-23%, and so on; the overlap amount between the two anvils before and after each pass is 100-200 mm.

[0080] S25: In the fourth heating, the fifth forging blank is drawn out using upper and lower flat anvils or an upper flat anvil and a lower V-shaped anvil, cut to length, the riser neck of the water head is pre-forged, and the roll body is drawn out to obtain the sixth forging blank;

[0081] Among them, the roll body diameter of the sixth forging blank is Φ 6-1 , and the roll neck diameter of the sixth forging blank is set to Φ 6-2 ;

[0082] Specifically, the ratio of the roll body diameters of the fifth forging blank and the sixth forging blank (Φ5 / Φ 6-1 ) 2 ≥1.3, which can ensure that the grains of the forging blank after subsequent drawing are not coarsened and the precipitated secondary carbides do not show a network distribution.

[0083] S26: In the fifth heating, according to the forging size requirements, in the reverse forming order, first form the roll neck, then form the roll body, and draw out the roll body and the riser neck of the water head of the sixth forging blank to the target size to forge the first roll blank forging.

[0084] Specifically, according to the forging size requirements, that is, according to the design size requirements of the first roll blank forging to be forged; reverse forming means first forming the roll neck with a faster cooling rate and then forming the roll body with a slower cooling rate. This is because due to the end effect, the cooling rate at the roll neck ends on both sides of the forging blank is fast, and cracks are likely to occur. Therefore, first form the roll neck. The ratio of the roll body diameters of the sixth forging blank and the first roll blank forging satisfies (Φ 6-1 / Φ 0-1 ) 2 ≥1.3, and the ratio of the roll neck diameters of the sixth forging blank and the first roll blank forging satisfies (Φ 6-2 / Φ 0-2 ) 2 ≥1.3, which can ensure that the grains of the forged first roll blank forging are not coarsened and the precipitated secondary carbides do not show a network distribution, and at the same time ensure that the sixth forging blank can complete the final forming of the first roll blank forging in this heating. Among them, Φ 0-2 is the roll neck diameter of the first roll blank forging (i.e., the target design value of the work roll neck), and Φ 0-1 is the roll body diameter of the first roll blank forging (i.e., the target design value of the work roll body).

[0085] Specifically, in step S3, the first roll blank forging is subjected to post-forging heat treatment and then cooled to room temperature to obtain the second roll blank forging; among them, the post-forging heat treatment process is: heating the first roll blank forging to 820 - 850 °C, holding for 20 - 25 h, then cooling in the furnace to 300 - 350 °C, and then heating up to 620 - 640 °C, holding for 80 - 100 h, and then cooling in the furnace to room temperature. Through the post-forging heat treatment, the internal stress of the workpiece can be eliminated, the grain size can be refined, and the carbides can be spheroidized.

[0086] Specifically, in step S4, after rough machining the second roll blank forging, ultrasonic flaw detection is performed to obtain the third roll blank forging. The rough machining mainly removes the scale and decarburized layer on the surface of the forging blank, so that the surface roughness reaches ≤ Ra3.2 to meet the requirements of ultrasonic flaw detection for the surface roughness of the workpiece. Through ultrasonic flaw detection, it is determined whether the internal quality of the workpiece meets the quality requirements of relevant manufacturing standards. If not, this workpiece is scrapped and needs to be remelted and forged again; if it meets the requirements, subsequent operations are carried out.

[0087] Specifically, in step S5, the third roll blank forging is subjected to quenching and tempering heat treatment and semi-finishing machining to obtain the fourth roll blank forging. The quenching and tempering heat treatment process is as follows: The third roll blank forging is heated to 920 - 950 °C, held for 15 - 20 h and then air-cooled to 300 - 350 °C, and then heated up to 620 - 640 °C, held for 25 - 40 h and then furnace-cooled to room temperature. The semi-finishing machining is to remove the surface oxide layer of the roll body part of the roll blank forging.

[0088] Specifically, in step S6, the fourth roll blank forging is subjected to induction hardening, tempering and finishing machining to obtain the final working roll. The induction hardening process is as follows: Using a dual-frequency induction device, the roll body part of the fourth roll blank forging is heated segment by segment from one end to the other end at a speed of 20 - 35 mm / min to 1030 - 1040 °C and then continuously water-cooled until room temperature; then immediately put into the furnace and heated to 400 - 500 °C for tempering, the tempering time is 20 - 30 h, and tempering is carried out 3 - 5 times successively, which can timely eliminate the internal stress of quenching, avoid the generation of microcracks, and achieve secondary hardening, while improving hardness, strength and toughness.

[0089] In the forging process of the present invention, a V-shaped cylindrical anvil is adopted, which increases the metal deformation amount in the contact area between the forging blank and the anvil surface, makes the surface deformation of the forging blank more uniform, and at the same time can reduce the deformation tensile stress on the surface of the billet at the lap joint of the front and rear anvils and the billet in contact with the anvil surface during the drawing process, reduce the surface damage of the billet, and make the forging blank not easy to produce surface cracks. At the same time, in the present invention, by strictly controlling the height and diameter of the forging blank in each heating stage during the forging process, and at the same time adopting a "decreasing reduction amount in sequence" drawing method matching the V-shaped cylindrical anvil, as the temperature of the forging blank decreases from high to low, the deformation amount decreases by 4% - 6% between every two passes. The large initial deformation amount promotes the refinement of coarse carbides, and the small later deformation amount reduces the surface tensile stress to avoid cracks, which can reduce the number of cleaning heating stages and improve the forging efficiency and material utilization rate; at the same time, this drawing method can also reduce the axial tensile stress of the forging blank and effectively control the generation of surface cracks of the forging blank; in the finished product stage of the present invention, the "reverse forming" method is adopted, which conforms to the change of the temperature field of the forging blank, first forms the roll neck with a faster cooling rate, and then forms the roll body with a slower cooling rate, which can prevent the roll neck end from cracking, thereby reducing the number of finished product heating stages and improving the material utilization rate and production efficiency.

[0090] The present invention achieves a working roll body hardness of 93-98HSD and a roll body hardness uniformity of ≤1HSD through reasonable component design and optimized design of process parameters such as forging and heat treatment. The matrix grain size grade of the working roll reaches grade 8-9 and the carbide distribution is relatively uniform.

[0091] Example 1

[0092] The present embodiment provides a semi-high speed steel cold rolling work roll, the chemical composition of which is calculated by weight percentage: C 0.90%; Si 0.95%; Mn 0.40%; Cr 8.70%; Ni 0.85%; V 0.85%; Mo 1.80%; W 0.90%; S and P ≤ 0.015; the rest is Fe and unavoidable impurities;

[0093] The preparation method comprises the following steps:

[0094] S1: raw materials are prepared according to chemical composition, and electroslag remelting is performed to obtain electroslag remelting ingots;

[0095] The diameter of the electroslag remelting steel ingot is Φ770mm and the height is 1800mm. In this embodiment, it is intended to be forged into a target roll body diameter of Φ 0-1 500mm, roll neck Φ 0-2 The working roll is 390mm.

[0096] S2: heating and forging the electroslag remelting steel ingot into a first roll blank forging;

[0097] The specific step S2 includes:

[0098] S21: heating and keeping the semi-high-speed electroslag remelting steel ingot warm;

[0099] Specifically, the heating temperature is 1180°C and the holding time is 10h;

[0100] S22: First fire, taking the nozzle side of the electroslag ingot as the reference, at a distance of 100 mm from the end face of the ingot body on the nozzle side, a clamping process is adopted with a jaw diameter of Φ400 mm to obtain the first forging blank;

[0101] Among them, the height of the first forging blank is H1=1700mm, and the diameter is Φ1=800mm;

[0102] S23: second fire, using an upsetting drain plate and an upsetting cover plate to upset the first forging blank to obtain a second forging blank, and using a V-shaped cylindrical anvil to pull the second forging blank from the ingot body end surface on the nozzle side to the riser side in a cyclic sequence to obtain a third forging blank;

[0103] Among them, the height of the second forging blank is H2=800mm, the diameter is Φ2=1100mm, the height of the third forging blank is H3=1720mm, the diameter is Φ3=750mm;

[0104] The ratio of the height of the first forging blank to the height of the second forging blank is H1 / H2 = 1700 mm / 800 mm = 2.125, meeting the requirement of H1 / H2 ≥ 1.5;

[0105] The diameter forging ratio of the third forging blank and the second forging blank satisfies (Φ2 / Φ3) 2 =(1100 mm / 750 mm) 2 = 2.156, meeting the requirement of (Φ2 / Φ3) 2 ≥ 2;

[0106] The cyclic cogging process includes: using an 800-mm-wide upper and lower V-shaped cylindrical anvil to cog the second forging blank sequentially from the nozzle side ingot body end face to the riser side. After finishing one pass, it is flipped 90°, and then pressed for the next pass from the nozzle side ingot body end face to the riser side. After cyclic flipping of 90° is completed, multiple passes of cogging are completed to obtain the third forging blank;

[0107] Among them, the anvil angle θ of the V-shaped cylindrical anvil is 120°, and the anvil width ratio is 0.6 - 0.8;

[0108] The number of passes of the cyclic sequential cogging is 8 passes. Among them, the deformation amounts of the first and second passes are 25%, the deformation amounts of the third and fourth passes are 20%, the deformation amounts of the fifth and sixth passes are 15%, and the deformation amounts of the seventh and eighth passes are 10%. The deformation amount decreases by 5% between every two passes, and the lap amount between the two anvils before and after each pass is 100 - 200 mm;

[0109] S24: In the third heat treatment, the third forging blank is cogged again using a cogging leak plate and a cogging cover plate to obtain the fourth forging blank, and the fourth forging blank is cogged sequentially from the nozzle side ingot body end face to the riser side using a V-shaped cylindrical anvil to obtain the fifth forging blank;

[0110] Among them, the height of the fourth forging blank is H4 = 750 mm, the diameter is Φ4 = 1120 mm, the height of the fifth forging blank is H5 = 2095 mm, and the diameter is Φ5 = 670 mm;

[0111] The ratio of the height of the third forging blank to the height of the fourth forging blank is H3 / H4 = 1720 mm / 750 mm = 2.29, meeting the requirement of H3 / H4 ≥ 1.5;

[0112] The diameter forging ratio of the fifth forging blank and the fourth forging blank satisfies (Φ4 / Φ5) 2 =(1120 mm / 670 mm) 2 = 2.79, meeting the requirement of (Φ4 / Φ5) 2 ≥ 2;

[0113] The cyclic drawing-out process includes: using an 800-mm-wide upper and lower V-shaped cylindrical anvil to draw out the second forging blank sequentially from the nozzle side ingot body end face to the riser side. After one pass is completed, it is flipped by 90°, and then pressed for the next pass from the nozzle side ingot body end face to the riser side. After cyclic flipping by 90° is completed, multiple passes of drawing-out are completed cyclically to obtain the third forging blank;

[0114] Among them, the anvil angle θ of the V-shaped cylindrical anvil is 120°, and the anvil width ratio is 0.6 - 0.8;

[0115] The number of passes for the cyclic sequential drawing-out is 8. Among them, the deformation amounts for the first and second passes are 25%, the deformation amounts for the third and fourth passes are 20%, the deformation amounts for the fifth and sixth passes are 15%, and the deformation amounts for the seventh and eighth passes are 10%. The deformation amount decreases by 5% between every two passes, and the lap amount between the two anvils before and after each pass is 100 - 200 mm;

[0116] S25: In the fourth heat treatment, use the upper and lower flat anvils or the upper flat anvil and the lower V-shaped anvil to draw out the fifth forging blank, cut the material, pre-forge the water riser neck of the roll, and draw out the roll body to obtain the sixth forging blank;

[0117] Among them, the roll body diameter of the sixth forging blank is Φ 6-1 = 580 mm, and the roll neck diameter of the sixth forging blank is set as Φ 6-2 = 450 mm;

[0118] The ratio of the roll body diameters of the fifth forging blank and the sixth forging blank (Φ5 / Φ 6-1 ) 2 =(670 mm / 580 mm) 2 = 1.32, meeting the requirement of (Φ5 / Φ 6-1 ) 2 ≥ 1.3;

[0119] S26: In the fifth heat treatment, according to the requirements of the forging dimensions, in the reverse forming order, first form the roll neck, and then form the roll body. Draw out the roll body and the water riser neck of the sixth forging blank to the target dimensions to forge the first roll blank forging.

[0120] Among them, the roll body diameter Φ 0-1 of the first roll blank forging is 500 mm, and the roll neck diameter Φ 0-2 of the first roll blank forging = 390 mm. The ratio of the roll body diameters of the sixth forging blank and the first roll blank forging meets the requirement of (Φ 6-1 / Φ 0-1 ) 2 =(580 mm / 500 mm) 2 = 1.34, meeting the requirement of (Φ 6-1 / Φ 0-1 ) 2 ≥ 1.3; The ratio of the roll neck diameters of the sixth forging blank and the first roll blank forging meets the requirement of (Φ6-2 / Φ 0-2 ) 2 =(450 mm / 390 mm) 2 = 1.32, meeting the requirement of (Φ 6-2 / Φ 0-2 ) 2 ≥ 1.3

[0121] S3: Subject the first roll blank forging to post - forging heat treatment, then cool it to room temperature to obtain the second roll blank forging;

[0122] The process of post - forging heat treatment is as follows: Heat the first roll blank forging to 850 °C, keep it at this temperature for 20 h, then cool it in the furnace to 300 °C, and then heat it up to 640 °C, keep it at this temperature for 100 h and then cool it to room temperature.

[0123] S4: Subject the second roll blank forging to rough machining and then ultrasonic flaw detection to obtain the third roll blank forging;

[0124] S5: Subject the third roll blank forging to quenching and tempering heat treatment and semi - finishing to obtain the fourth roll blank forging;

[0125] The process of quenching and tempering heat treatment is as follows: Heat the third roll blank forging to 950 °C, keep it at this temperature for 15 h and then air - cool it to 350 °C, then heat it up to 640 °C, keep it at this temperature for 30 h and then cool it in the furnace to room temperature. Semi - finishing is to remove the surface oxide layer of the roll body part of the roll blank forging.

[0126] S6: Subject the fourth roll blank forging to induction hardening, tempering and finish machining to obtain the final working roll.

[0127] Among them, the process of induction hardening is as follows: Use a dual - frequency induction device to heat the roll body part of the fourth roll blank forging from one end to the other end at a speed of 35 mm / min to 1040 °C and then conduct continuous water cooling until room temperature;

[0128] Immediately put it into the furnace and heat it to 470 °C for tempering, the tempering time is 30 h, and temper it 3 times successively.

[0129] The as - cast structure of the semi - high - speed steel electroslag ingot in this embodiment is as shown in Figure 1 The obtained microstructure of the working roll is as shown in Figure 2 The grain size photograph is as shown in Figure 3 As can be seen from Figure 3 the grain size grade of the working roll obtained in this embodiment is 8 - 9 levels and the carbide distribution is relatively uniform; the surface hardness is 96 - 98 HSD, and the hardness uniformity is ≤ 1 HSD.

[0130] The physical drawing of the fifth forging blank during the forging process in this embodiment is as shown in Figure 4 There are no cracks on the surface.

[0131] Example 2

[0132] This example provides a semi-high-speed steel cold rolling work roll, and its chemical composition is as follows by weight percentage: C 0.90%; Si 0.85%; Mn 0.38%; Cr 8.20%; Ni 0.80%; V 0.88%; Mo 1.78%; W 0.87%; S and P ≤ 0.015; the balance is Fe and unavoidable impurities;

[0133] This example prepares a work roll with the same specifications as in Example 1, and the preparation method includes the following steps:

[0134] S1: Configure raw materials according to chemical components, and obtain an electroslag remelted steel ingot through electroslag remelting and smelting;

[0135] S2: Heat and forge the electroslag remelted steel ingot to make a first roll blank forging;

[0136] Among them, in step S21: Heat the electroslag remelted steel ingot to 1190 °C, and the heat preservation time is 8 h; steps S22 - S26 are the same as in Example 1.

[0137] S3: Perform post-forging heat treatment on the first roll blank forging, and then cool it to room temperature to obtain a second roll blank forging;

[0138] The process of post-forging heat treatment is: Heat the first roll blank forging to 840 °C, after holding for 22 h, cool it in the furnace to 310 °C, then heat it up to 630 °C, hold for 85 h and then cool it to room temperature.

[0139] S4: Perform rough machining on the second roll blank forging and then perform ultrasonic flaw detection to obtain a third roll blank forging;

[0140] S5: Perform quenching and tempering heat treatment and semi-finishing machining on the third roll blank forging to obtain a fourth roll blank forging;

[0141] The process of quenching and tempering heat treatment is: Heat the third roll blank forging to 940 °C, after holding for 18 h, air-cool it to 330 °C, then heat it up to 630 °C, hold for 35 h and then cool it in the furnace to room temperature. Semi-finishing machining is to remove the surface oxide layer of the roll body part of the roll blank forging.

[0142] S6: Perform induction hardening, tempering and finishing machining on the fourth roll blank forging to obtain the final work roll.

[0143] Among them, the process of induction hardening is: Use a dual-frequency induction device to heat the roll body part of the fourth roll blank forging from one end to the other end at a speed of 30 mm / min to 1035 °C and then perform continuous water cooling until room temperature;

[0144] Immediately put it into the furnace and heat it to 480 °C for tempering, the tempering time is 28 h, and temper it 3 times successively.

[0145] The surface hardness of the work roll prepared in this embodiment is 94 - 96 HSD, and the hardness uniformity is ≤1 HSD. The grain size grade of the work roll prepared in this embodiment is 8 - 9 levels and the carbide distribution is relatively uniform.

[0146] Example 3

[0147] This embodiment provides a semi-high-speed steel cold rolling work roll, and its chemical composition by weight percentage is: C 0.80%; Si 0.80%; Mn 0.35%; Cr 7.8%; Ni 0.78%; V 0.82%; Mo 1.73%; W 0.81%; S and P ≤0.015; the rest are Fe and inevitable impurities;

[0148] This embodiment prepares a work roll with the same specifications as in Example 1, and the preparation method includes the following steps:

[0149] S1: Configure raw materials according to chemical components, and obtain an electroslag remelting steel ingot through electroslag remelting smelting;

[0150] S2: Heat and forge the electroslag remelting steel ingot into a first roll blank forging;

[0151] Among them, in step S21: Heat the electroslag remelting steel ingot to 1200 °C, and the holding time is 9 h; steps S22 - S26 are the same as in Example 1.

[0152] S3: Perform post-forging heat treatment on the first roll blank forging, and then cool it to room temperature to obtain a second roll blank forging;

[0153] The process of post-forging heat treatment is: Heat the first roll blank forging to 830 °C, after holding for 25 h, cool it in the furnace to 350 °C, then heat it up to 620 °C, hold for 90 h and then cool it to room temperature.

[0154] S4: After rough machining the second roll blank forging, perform ultrasonic flaw detection to obtain a third roll blank forging;

[0155] S5: Perform quenching and tempering heat treatment and semi-finishing on the third roll blank forging to obtain a fourth roll blank forging;

[0156] The process of quenching and tempering heat treatment is: Heat the third roll blank forging to 930 °C, after holding for 20 h, air-cool it to 340 °C, then heat it up to 635 °C, hold for 38 h and then cool it in the furnace to room temperature. Semi-finishing is to remove the surface oxide layer of the roll body part of the roll blank forging.

[0157] S6: Perform induction hardening, tempering and finishing on the fourth roll blank forging to obtain the final work roll.

[0158] Among them, the induction hardening process is as follows: using a dual-frequency induction device, the roll body part of the fourth roll blank forging is heated segment by segment from one end to the other end at a speed of 25 mm / min to 1040 °C, and then continuously water-cooled until room temperature;

[0159] Immediately put it into the furnace and heat it to 490 °C for tempering. The tempering time is 25 h, and it is tempered 3 times successively.

[0160] The surface hardness of the work roll prepared in this embodiment is 93 - 95 HSD, and the hardness uniformity is ≤ 1 HSD. The grain size grade of the work roll prepared in this embodiment is 8 - 9 levels, and the carbide distribution is relatively uniform.

[0161] Comparative Example 1

[0162] This comparative example provides a semi-high-speed steel cold rolling work roll, whose preparation method and process parameters are similar to those of Example 1, and a work roll with the same specifications as those of Example 1 is prepared;

[0163] The difference lies in that its chemical composition is by weight percentage: C 0.90%; Si 1.10%; Mn 0.40%; Cr 6.50%; Ni 1.0%; V 0.80%; Mo 1.80%; W 0.92%; S, P ≤ 0.015; the rest are Fe and unavoidable impurities;

[0164] The surface hardness of the semi-high-speed steel cold rolling work roll in this comparative example is 85 - 90 HSD, and the hardness uniformity is ≤ 1.5 HSD. The grain size grade of the work roll prepared in this comparative example is 7 - 8 levels.

[0165] Comparative Example 2

[0166] This comparative example provides a semi-high-speed steel cold rolling work roll, whose chemical composition is the same as that of Example 2 by weight percentage, and a work roll with the same specifications as those of Example 2 is prepared;

[0167] The preparation method is similar to that of Example 2, and the difference lies in that the induction hardening and tempering parameters of the fourth roll blank forging in step S6 are different.

[0168] Among them, the induction hardening process is as follows: using a dual-frequency induction device, the roll body part of the fourth roll blank forging is heated segment by segment from one end to the other end at a speed of 25 mm / min to 1080 °C, and then continuously water-cooled until room temperature;

[0169] Immediately put it into the furnace and heat it to 520 °C for tempering. The tempering time is 30 h, and it is tempered 3 times successively.

[0170] The surface hardness of the semi-high-speed steel cold rolling work roll in this comparative example is 83 - 87 HSD, and the hardness uniformity is ≤ 1.5 HSD. The grain size grade of the work roll prepared in this comparative example is 7 - 8 levels.

[0171] Comparative Example 3

[0172] This comparative example provides a semi-high speed steel cold rolling work roll, whose chemical composition is the same as that of Example 1, and a work roll with the same specifications as those of Example 1 is prepared;

[0173] The preparation steps include:

[0174] Smelting electroslag ingot blank - forging roll blank - post-forging heat treatment - surface quenching - final heat treatment;

[0175] Among them, smelting the electroslag ingot blank is the same as step S1 of Example 1 of the present invention; forging the roll blank is the same as step S2 of Example 1 of the present invention; post-forging heat treatment is the same as step S3 of Example 1 of the present invention; surface quenching is the same as step S6 of Example 1 of the present invention;

[0176] The final heat treatment includes: cryogenic treatment + low-temperature tempering.

[0177] Among them, in the process of cryogenic treatment, after surface quenching, the roll blank is cryogenically treated at a temperature of 130 ± 5 °C for 5 h;

[0178] Immediately, a low-temperature tempering treatment is carried out at a temperature of 120 ± 5 °C for 80 h.

[0179] The surface hardness of the semi-high speed steel cold rolling work roll in this comparative example is 95 - 98 HSD, and the hardness uniformity is ≤ 1.5 HSD. The grain size grade of the work roll prepared in this comparative example is 7 - 8 levels.

[0180] Comparative Example 4

[0181] This comparative example provides a semi-high speed steel cold rolling work roll, whose chemical composition is the same as that of Example 1, and a work roll with the same specifications as those of Example 1 is prepared, and the preparation method is similar. The difference lies in that: in steps S23 and S24, the deformation amount of multiple passes always remains unchanged at 20%.

[0182] The surface hardness of the semi-high speed steel cold rolling work roll in this comparative example is 93 - 95 HSD, and the hardness uniformity is ≤ 2 HSD. The grain size grade of the work roll prepared in this comparative example is 7 - 8 levels.

[0183] Comparative Example 5

[0184] This comparative example provides a semi-high speed steel cold rolling work roll, whose chemical composition is the same as that of Example 1, and a work roll with the same specifications as those of Example 1 is prepared, and the preparation method is similar. The difference lies in that: in step S26, according to the traditional forging sequence, the roll body is formed first, and then the two end roll necks are formed.

[0185] Figure 5This is a physical drawing of the fifth forging blank of this comparative example. It can be seen that there are many surface cracks. Therefore, during subsequent forging, due to the need to remove the crack damage, the number of forging heats needs to be increased. This comparative example requires a total of 9 forging heats to complete the forging, while only 5 forging heats are needed for production in Example 1; the material utilization rate of this comparative example is 65%, and the material utilization rate of Example 1 can be increased to 75%-80%. When forging semi-high-speed cold rolling work rolls using the method of the present invention, compared with the existing method, the surface of the forging blank is not prone to cracks, the number of production heats is small, and the material utilization rate is high.

[0186] The surface hardness of the semi-high-speed steel cold rolling work roll of this comparative example is 93-95 HSD, and the hardness uniformity is ≤2 HSD. The grain size grade of the work roll prepared in this comparative example is 7-8 levels.

[0187] Table 1 Chemical compositions of steel in examples and comparative examples (wt, %)

[0188]

[0189]

[0190] Table 2 Preparation processes and process parameters of examples and comparative examples

[0191]

[0192]

[0193] Analysis of the examples and comparative examples shows that in the chemical composition of Comparative Example 1, the content of Ni and the content of Cr+Mo+W do not meet the requirements of the present invention. The surface hardness, hardness uniformity, and grain size grade of the work roll prepared in Comparative Example 1 are all lower than those in Example 1; the chemical composition of Comparative Example 2 is the same as that of Example 2 in terms of weight percentage, but some process parameters in the preparation method do not meet the requirements of the present invention. The surface hardness, hardness uniformity, and grain size grade of the work roll prepared in Comparative Example 2 are all lower than those in Example 2; the chemical composition of Comparative Example 3 is the same as that of Example 1 in terms of weight percentage. When using the existing preparation method to prepare the work roll, although the hardness of the work roll is increased, the hardness uniformity and grain size grade are lower than those in Example 1. The chemical compositions of Comparative Example 4 and Comparative Example 5 are the same as that of Example 1 in terms of weight percentage. The forging steps in the preparation process are different from those in Example 1. The surface hardness, hardness uniformity, and grain size grade of the prepared work roll are all lower than those in Example 1. The hardness adaptability, uniformity, and grain size grade of the semi-high-speed steel work roll of the present invention are more excellent.

[0194] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered by the protection scope of the present invention.

Claims

1. A semi-high speed steel cold rolling work roll, characterized in that, The chemical composition by weight percentage is: C 0.65 - 1.00%; Si 0.70 - 1.10%; Mn 0.20 - 0.50%; Cr 6.50 - 9.00%; Ni 0.65 - 0.85%; V 0.75 - 1.00%; Mo 1.60 - 2.00%; W 0.65 - 1.00%; S ≤ 0.015%; P ≤ 0.015; The balance is Fe and unavoidable impurities.

2. The semi-high speed steel cold rolling work roll according to claim 1, characterized in that, The sum of the weight percentages of the Cr element, Mo element, and W element satisfies: 9.50% ≤ Cr + Mo + W < 11.5%.

3. A preparation method of a semi-high speed steel cold rolling work roll for preparing the semi-high speed steel cold rolling work roll according to claim 1 or 2, characterized in that, It includes the following steps: S1: Configure raw materials according to chemical components and obtain an electroslag remelting ingot through electroslag remelting smelting; S2: Heat and forge the electroslag remelting ingot to make a first roll blank forging; S3: Perform post-forging heat treatment on the first roll blank forging, and then cool it to room temperature to obtain a second roll blank forging; S4: After rough machining the second roll blank forging, perform ultrasonic flaw detection to obtain a third roll blank forging; S5: Perform quenching and tempering heat treatment and semi-finishing on the third roll blank forging to obtain a fourth roll blank forging; S6: Perform induction hardening, tempering, and finishing on the fourth roll blank forging to obtain the final working roll.

4. The preparation method according to claim 3, characterized in that, The said step S2 includes: S21: Heat and hold the semi-high-speed electroslag remelting ingot; S22: In the first heat, with the nozzle side of the electroslag ingot as the reference, at a position 80 - 120 mm from the end face of the ingot body on the nozzle side, adopt the press clamp process with a clamp mouth diameter of 350 - 450 mm to obtain a first forging blank; S23: In the second heat, use a upsetting leaky plate and a upsetting cover plate to upset the first forging blank to obtain a second forging blank, and use a V-shaped cylindrical anvil to draw out the second forging blank from the nozzle side end face of the ingot body to the riser side in a cyclic order to obtain a third forging blank; S24: In the third heat, use the upsetting leaky plate and the upsetting cover plate again to upset the third forging blank to obtain a fourth forging blank, and use a V-shaped cylindrical anvil to draw out the fourth forging blank from the nozzle side end face of the ingot body to the riser side in a cyclic order to obtain a fifth forging blank; S25: In the fourth heat, use upper and lower flat anvils or an upper flat anvil and a lower V-shaped anvil to draw out the fifth forging blank, cut the material, pre-forge the water riser roll neck, and draw out the roll body to obtain a sixth forging blank; S26: In the fifth heat, according to the forging size requirements, adopt the reverse forming order, first form the roll neck, then form the roll body, draw out the roll body and the water riser roll neck of the sixth forging blank to the target size, and forge out the first roll blank forging.

5. The preparation method according to claim 3, characterized in that, In step S3, the post-forging heat treatment process is: Heat the first roll blank forging to 820 - 850 °C, hold for 20 - 25 h, then cool in the furnace to 300 - 350 °C, then heat up to 620 - 640 °C, hold for 80 - 100 h, and then cool in the furnace to room temperature.

6. The preparation method according to claim 3, wherein In step S5, the quenching and tempering heat treatment process is: Heat the third roll blank forging to 920 - 950 °C, hold for 15 - 20 h, then air-cool to 300 - 350 °C, then heat up to 620 - 640 °C, hold for 25 - 40 h, and then cool in the furnace to room temperature.

7. The preparation method according to claim 3, characterized in that, In step S6, the induction hardening process is as follows: the roll body part of the fourth roll blank forging is heated section by section from one end to the other end at a speed of 20 - 35 mm / min to 1030 - 1040 °C by a dual-frequency induction device, and then continuously water-cooled until room temperature.

8. The preparation method according to claim 3, characterized in that, In step S6, the tempering temperature is 400 - 500 °C, the tempering time is 20 - 30 h, and the number of tempering times is 3 - 5 times.

9. The preparation method according to claim 4, characterized in that, In step S21, the heating temperature is 1180 - 1200 °C, and the holding time T satisfies: D / 100 ≤ T ≤ D / 75, where D is the diameter of the ingot in mm; T is the holding time in h.

10. The preparation method according to claim 9, wherein, In step S23, the ratio of the height of the first forging blank to the height of the second forging blank H1 / H2 ≥ 1.5, where H1 is the height of the first forging blank and H2 is the height of the second forging blank in mm.

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