Manufacturing method of long-roller-service supporting roller

Abstract

The invention discloses a manufacturing method of a long-service supporting roller, which belongs to the field of roller manufacturing, and comprises the following steps: smelting an alloy, and preparing steel raw materials, so that the steel comprises the following chemical components in percentage by weight: 0.55 to 0.75 percent of C, 0.10 to 0.40 percent of Si, 0.40 to 0.80 percent of Mn, 5.50 to 6.50 percent of Cr, 0.55 to 0.80 percent of Ni, 0.70 to 1.20 percent of Mo, 0.20 to 0.50 percent of V and less than or equal to 0.010 percent of P; s is less than or equal to 0.010%; and the balance of Fe and inevitable impurities. Preparing steel ingots from steel raw materials according to a smelting procedure production process; manufacturing the steel ingot into a roller blank according to a forging procedure production process; the roller blank is subjected to heat treatment according to preheating, induction type differential temperature heating, rapid cooling, high-temperature tempering and secondary tempering; and according to the drawing requirements of a finished product, the roller blank subjected to heat treatment is machined, and the long-roller-service forged steel supporting roller is obtained. The high-performance supporting roller can be manufactured and produced, and the problems of abrasion resistance and accident resistance of the supporting roller on a rolling line are effectively solved.

Description

Technical Field

[0001] The invention relates to the field of roll manufacturing, in particular to a method for manufacturing a long roll support roll. Background Art

[0002] With the rapid development of the steel industry, the material grades and performance of hot-rolled plates are constantly improving, and the proportion of high-grade or high-strength plates is constantly increasing, which leads to more and more serious uneven wear of the roll surface during the normal rolling of high-strength plates; on the other hand, improving production efficiency is one of the best means to reduce costs and improve efficiency. The rolling line urgently needs to reduce the batch of roll changes and maximize the service life of the rolls. Therefore, a new method for making long roll service support rolls is needed, which can effectively produce high-strength and wear-resistant long roll service support rolls, solve the wear resistance and accident resistance problems of large forged steel support rolls, thereby improving the precision of rolled materials and the production efficiency of rolling mills, and meeting the urgent needs of various rolling lines for long roll service support rolls. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a method for manufacturing a long roll support roller to manufacture high-performance support rollers, aiming to solve the problems of wear resistance and accident resistance of the support rollers on the rolling line.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is: a method for manufacturing a long roll support roll, comprising the following steps:

[0005] Step 1: Melt the alloy and prepare the steel raw materials so that the chemical composition and weight percentage of the steel are:

[0006] C 0.55%~0.75%, Si 0.10%~0.40%, Mn 0.40%~0.80%, Cr 5.50%~6.50%, Ni 0.55%~0.80%, Mo 0.70%~1.20%, V 0.20~0.50%, P≤0.010%; S≤0.010%; the rest is Fe and unavoidable impurities; steel raw materials are made into steel ingots according to the smelting process production process;

[0007] Step 2: Prepare a roll blank from the steel ingot according to the forging process production process;

[0008] Step 3: heat-treating the roll blank according to preheating, induction temperature differential heating, quenching cooling, high temperature tempering, rapid cooling out of the furnace, and secondary tempering;

[0009] Step 4: According to the requirements of the finished product drawing, the heat-treated roller blank is machined to obtain the long roll forged steel support roller.

[0010] The further improvement of the technical solution of the present invention is that the working layer of the long roll forged steel support roll is a tempered martensite structure, the surface hardness is ≥60HSD, and the matrix microhardness HV is ≥500.

[0011] The further improvement of the technical solution of the present invention is that the specific steps of the heat treatment method in step 3 are as follows:

[0012] Step 3.1: The roll blank is put into a box furnace and preheated to 400-450°C;

[0013] Step 3.2: The roller body enters the induction quenching equipment for induction heating, the austenitizing temperature is 970-1010℃, and the austenite is kept warm for 60-90min;

[0014] Step 3.3: Spray water to rapidly cool the roll blank for 180-240 minutes;

[0015] Step 3.4: Tempering treatment at 500-600℃ for 80-100h;

[0016] Step 3.5: After the first tempering, cool quickly to room temperature and then perform the second tempering.

[0017] A further improvement of the technical solution of the present invention is that cracking of the support roller is prevented by controlling the water spraying pressure.

[0018] A further improvement of the technical solution of the present invention is that the rapid cooling by water spraying is specifically to spray water evenly on the surface of the roller body at a pressure of 0.2 MPa.

[0019] A further improvement of the technical solution of the present invention is that: in the chemical composition of the steel raw material, the weight percentage content of C, Mo and Ni alloy elements is controlled, the weight percentage content of Mo element is not lower than that of C element, and the weight percentage content of Ni element is not lower than that of C element.

[0020] Due to the adoption of the above technical solution, the technical progress achieved by the present invention is as follows: by optimizing the proportion of alloy elements of the support roller, the content of major alloy elements such as C, Cr, Mo, and V is optimized, the size and quantity of carbides in the organization are increased, and the wear resistance and roller shape retention ability of the support roller are improved. By reducing the C content, the homogenization degree of the steel ingot of the material is improved, and the processability of production is improved. By increasing the content of Mo and V elements, the secondary hardening characteristics and high temperature stability of the material are improved, thereby obtaining a higher tempering temperature, more carbides, and lower residual stress. Alloy elements Cr and Mo can improve the heat strength and hardenability of steel, and alloy element Ni can significantly improve the strength of steel without reducing its toughness. Every 1% increase in Ni can increase the strength of steel by about 30MPa. By increasing the content of Mo and V elements, the secondary hardening characteristics and high temperature stability of the material are improved, thereby obtaining a higher tempering temperature, more carbides, and lower residual stress, which can effectively improve the strength and stress crack resistance of the roll. By developing and designing a rapid cooling process after a tempering, a large number of nano-scale carbide particles are precipitated in the tempering structure through rapid cooling, which plays the effect of strengthening and toughening with nano-particles, not only improving the strength and hardness of the matrix, but also improving the wear resistance of the matrix. By adopting a secondary tempering treatment, the tempering temperature is increased and the tempering time is shortened during the secondary tempering process, which effectively reduces the precipitation of M7C3 and M23C6 carbides, and increases the precipitation of M2C and M3C high-hardness carbides, thereby enhancing the wear resistance of the support roller matrix. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative work.

[0022] Figure 1 It is a schematic flow chart of the production method of the present invention. DETAILED DESCRIPTION

[0023] The present invention is further described in detail below in conjunction with embodiments:

[0024] like Figure 1 As shown, a method for manufacturing a long roll support roll is suitable for rolling lines with short roll replacement cycles due to poor roll shape retention or severe uneven wear, and is also suitable for general rolling line support roll manufacturing, which specifically includes the following steps:

[0025] Step 1: Melt the alloy and prepare the steel raw materials. In view of the serious component segregation and poor solidification quality in the existing steel ingot smelting and casting, optimize the material design, improve the solidification quality, reduce the component segregation, optimize the content of major alloying elements such as C, Cr, Mo, and V, increase the size and number of carbides in the organization, improve the wear resistance and roll shape retention of the roll, optimize and increase the Ni element content, strictly limit the upper limit of P and S content, improve the strength and toughness of the material, and thus improve the accident resistance of the roll. Make the chemical composition and weight percentage of the steel:

[0026] C 0.55%~0.75%, Si 0.10%~0.40%, Mn 0.40%~0.80%, Cr 5.50%~6.50%, Ni 0.55%~0.80%, Mo 0.70%~1.20%, V 0.20~0.50%, P≤0.010%; S≤0.010%; the rest are Fe and inevitable impurities; the steel raw material is made into steel ingot according to the smelting process production process; the weight percentage content of C, Mo and Ni alloy elements is focused on controlling, so that the weight percentage content of Mo element is not lower than that of C element, and the weight percentage content of Ni element is not lower than that of C element.

[0027] Step 2: Prepare a roll blank from the steel ingot according to the forging process production process;

[0028] Step 3: heat treat the roll blank in the following steps: preheating, induction temperature differential heating, quenching cooling, high temperature tempering, rapid cooling out of the furnace, and secondary tempering; specifically:

[0029] Step 3.1: The roll blank is put into a box furnace and preheated to 400-450°C;

[0030] Step 3.2: The roller body enters the induction quenching equipment for induction heating, the austenitizing temperature is 970-1010℃, and the austenite is kept warm for 60-90min;

[0031] Step 3.3: Rapidly cool the roll blank by spraying water for 180-240 minutes; a large number of nano-scale carbide particles are precipitated in the tempered structure, which has the effect of strengthening and toughening the nano-particles, and prevents the support roll from cracking by controlling the water spray pressure. Rapid cooling by spraying water is specifically to use 0.15-0.25MPa pressure to spray water evenly on the surface of the roll body.

[0032] Step 3.4: Tempering treatment at 500-600℃ for 80-100h;

[0033] Step 3.5: After the first tempering, the steel is quickly cooled to room temperature and then subjected to secondary tempering at 500-600℃ and 80-100h. The secondary tempering can effectively improve the precipitation of high-hardness carbides of M2C and M3C types and enhance the wear resistance of the support roller matrix. Finally, the working layer of the support roller long roll forged steel support roller obtains a full martensitic structure, which reduces the hardness drop in the working layer, improves the stability and wear resistance of the structure, and the surface hardness is ≥60HSD, and the matrix microhardness HV ≥500.

[0034] Step 4: According to the requirements of the finished product drawing, the tempered roller blank is machined to ensure the dimensional tolerance and shape and position tolerance of each part, and finally the long roll forged steel support roller is obtained.

[0035] According to the above steps, support rollers are manufactured and produced respectively, wherein only the chemical composition and weight percentage of the alloy raw material and the relevant parameters in the heat treatment process of step 3 are changed, and the support rollers in embodiments 1 to 4 are obtained respectively.

[0036] Table 1 Comparison table of main chemical components and weight percentage of support rollers in Examples 1 to 4

[0037]

[0038] Table 2 Heat treatment process parameters of support rollers in Examples 1 to 4

[0039]

[0040] According to the parameters shown in Table 1 and Table 2, the support rollers of Examples 1 to 4 were manufactured according to the manufacturing method of the long roll support roller, and samples of the support rollers of Examples 1 to 4 were taken for laboratory wear detection. The test results are shown in Table 3 below. The performance was compared with the conventional support roller control example, where the conventional support roller was used as a control example, and the raw material chemical composition and weight percentage were: C0.5%, Si 0.41%, Mn 0.65%, Cr 5%, Ni 0.45%, Mo 0.5%, V 0.12%, P0.005%; S≤0.004%; furnace cooling was selected during quenching cooling.

[0041] Table 3 Wear resistance test results

[0042] Example Hardness HRC Microhardness HV Relative wear resistance 1 47.2 520 3.1 2 47.6 520 3.2 3 50.7 550 3.6 4 52.1 585 4.0 Comparative Example 48.5 475 1.85

[0043] The embodiments described above are merely descriptions of preferred implementation modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for manufacturing a long roll support roll, characterized in that: The steps include: Step 1: Melt the alloy and prepare the steel raw materials so that the chemical composition and weight percentage of the steel are: C 0.55%~0.75%, Si 0.10%~0.40%, Mn 0.40%~0.80%, Cr 5.50%~6.50%, Ni0.55%~0.80%, Mo 0.70%~1.20%, V 0.20~0.50%, P≤0.010%; S≤0.010%; the rest is Fe and inevitable impurities; the steel raw materials are made into steel ingots according to the smelting process production process; Step 2: Prepare a roll blank from the steel ingot according to the forging process production process; Step 3: heat-treating the roll blank according to preheating, induction temperature differential heating, quenching cooling, high temperature tempering, rapid cooling out of the furnace, and secondary tempering; Step 4: According to the requirements of the finished product drawing, the heat-treated roller blank is machined to obtain the long roll forged steel support roller.

2. The method for manufacturing a long roll support roll according to claim 1, characterized in that: The working layer of the long roll forged steel support roll is tempered martensite structure, the surface hardness is ≥60HSD, and the matrix microhardness is HV≥500.

3. The method for manufacturing a long roll support roll according to claim 1, characterized in that: The specific steps of step 3 heat treatment are as follows: Step 3.1: The roll blank is put into a box furnace and preheated to 400-450°C; Step 3.2: The roller body enters the induction quenching equipment for induction heating, the austenitizing temperature is 970-1010℃, and the austenite is kept warm for 60-90min; Step 3.3: Spray water to rapidly cool the roll blank for 180-240 minutes; Step 3.4: Tempering treatment at 500-600°C and heat preservation for 80-100h; Step 3.5: After the first tempering, the steel is taken out of the furnace and quickly cooled to room temperature, and then a second tempering is carried out at 500-600℃ and kept warm for 80-100h.

4. The method for manufacturing a long roll support roll according to claim 3, characterized in that: Prevent the support roller from cracking by controlling the water spray pressure.

5. The method for manufacturing a long roll support roll according to claim 4, characterized in that: The water spray rapid cooling specifically involves spraying water evenly on the roller surface at a pressure of 0.15-0.25MPa.

6. The method for manufacturing a long roll support roll according to claim 1, characterized in that: In the chemical composition of steel raw materials, the weight percentage content of C, Mo and Ni alloy elements is controlled, the weight percentage content of Mo element is not lower than that of C element, and the weight percentage content of Ni element is not lower than that of C element.

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