Bainite semi-steel roller and preparation process thereof
By adjusting the chemical composition and heat treatment process, the metallographic structure of bainite semi-steel rolling rolls is solved, and the problem of difficult control of matrix structure composition during the preparation process is achieved, and the high tensile strength, hardness and wear resistance of the rolls are achieved.
Patent Information
- Application Number
- CN202411893640.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-20
- Publication Date
- 2025-03-25
AI Technical Summary
During the preparation of bainite semi-steel rolls, it is difficult to control the structure of the matrix inside the roll, resulting in the inability to guarantee the tensile strength and hardness and cannot meet the needs of use.
By adjusting the chemical composition and heat treatment process, the ratio of bainite in the metallographic structure of the roll is controlled to ensure that the roll forms enough bainite during cooling to avoid the formation of pearlite and martensite. Specific steps include: high-temperature insulation for 10-12 hours, cooling to 300-500℃ for 2-10 hours, heating to 400-550℃ for 8-10 hours, and finally cooling the furnace below 200℃.
The bainite proportion in the roll has reached more than 50%, the tensile strength reaches more than 650MPa, and the hardness reaches more than 45HSD, which significantly improves the mechanical properties and wear resistance of the roll.
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Abstract
Description
Technical Field
[0001] The present application relates to the field of roll manufacturing, and in particular to a bainite semi-steel roll and a preparation process thereof. Background Art
[0002] Semi-steel rolls are a major type of rolls at present. Worldwide, the metallographic structure of semi-steel rolls is a combination of pearlite and carbide, accounting for more than 80%, so the performance of pearlite basically determines the performance of semi-steel rolls. However, the strength and hardness of pearlite are not satisfactory, so some researchers began to develop semi-steel rolls with a metallographic structure mainly composed of bainite matrix. Since bainite has higher strength and higher hardness than pearlite, semi-steel rolls with bainite as the main component have received widespread attention.
[0003] In the process of preparing bainitic semi-steel rolls, researchers analyzed the metallographic structure continuous cooling transformation curve and found that during the cooling process after complete austenitization, the transformation temperature of austenite to bainite is roughly in the range of 300-500°C. Once this range is exceeded, the proportion of bainite in the roll will be greatly reduced, which brings a more severe test to the preparation of the roll. However, because the roll is an item with a certain size in terms of volume and weight, it cannot be cooled quickly like small parts, and isothermal quenching cannot be achieved. Therefore, the matrix structure composition in the roll is difficult to control, making it impossible to guarantee the tensile strength and hardness of the semi-steel roll, and it is difficult to meet the use requirements. Summary of the invention
[0004] In order to solve the above technical problems, the present application provides a bainite semi-steel rolling roller and a preparation process thereof.
[0005] In the first aspect, the present application provides a preparation process for a bainitic semi-steel rolling mill, comprising the following steps: I. preparing a casting mold; II. smelting and casting: batching, smelting, tapping the smelted molten steel, pouring it into the casting mold obtained in step I, removing the sand and obtaining a semi-steel rolling mill alloy; III. heat treatment: keeping the semi-steel rolling mill alloy obtained in step II at 880-1100°C for 10-12h, cooling to 300-500°C, keeping it for 2-10h, then heating to 400-550°C, keeping it for 8-10h, and finally cooling to below 200°C to obtain a bainitic semi-steel rolling mill; IV. finishing: obtaining a bainitic semi-steel finished rolling mill roll.
[0006] Preferably, in step II, the composition of the alloy includes the following chemical components by weight percentage: C 1.3-2.1%; Si 0.2-1.0%; Mn 0.4-1.5%; Cr 0.5-3.0%; Ni 3.0-4.5%; Mo 0.5-1.2%; the remainder is Fe and other impurities.
[0007] Preferably, in step II, the composition of the alloy includes the following chemical components by weight percentage: C 1.4-2.0%; Si 0.2-0.8%; Mn 0.6-1.4%; Cr 0.7-2.5%; Ni 3.2-4.2%; Mo 0.6-1.0%; the remainder is Fe and other impurities.
[0008] Preferably, in step II, the composition of the alloy includes the following chemical components by weight percentage: C 1.5-1.8%; Si 0.3-0.6%; Mn 0.8-1.3%; Cr 0.8-2.0%; Ni 3.5-4.0%; Mo 0.5-0.8%; the remainder is Fe and other impurities.
[0009] By adopting the above technical scheme, the present application controls the chemical composition and heat treatment process, so that the final product can have a metallographic structure mainly composed of bainite, thereby improving the tensile strength and hardness of the rolling mill. The bainite structure has high strength and hardness, and these characteristics are achieved through a specific heat treatment process. During the heat treatment process, the rolls are first kept at 880-1100℃ for 10-12 hours. The purpose of this high temperature stage is to ensure that the organization is completely austenitized and obtain a uniform organizational structure so that the required bainite organization can be smoothly formed in the subsequent cooling process; then, the semi-steel rolls are cooled to 300-500℃ and kept in this temperature range for 2-10 hours. This is a key step. In this temperature range, austenite can be transformed into bainite. The formation of bainite requires a certain temperature range and time. Too high temperature will lead to the formation of pearlite, while too low temperature will promote the formation of martensite. By accurately controlling the cooling rate and holding time, these two unfavorable situations can be effectively avoided; then the semi-steel rolls are heated to 400-550℃ and kept for 8-10 hours. This process helps to further stabilize the bainite organization and eliminate possible residual stress; finally, by slowly cooling the furnace to below 200℃, the integrity and stability of the bainite organization can be ensured. The entire heat treatment process not only effectively promotes the formation of bainite, but also avoids the formation of martensite, thereby ensuring the high hardness and high strength of the roller.
[0010] Moreover, by adjusting the chemical composition ratio of the roller alloy, the present application can effectively control the proportion of bainite in the metallographic structure, thereby significantly improving the comprehensive performance of the semi-steel roller. Specifically, the proportion of each element in the present application can ensure that the roller forms sufficient bainite during the cooling process without excessively generating pearlite or martensite, which helps to refine the grains, improve the toughness of the material, enhance the hardenability and hardness of the material, and stabilize the bainite structure, significantly improve the strength and toughness of the material, so that it can still maintain good mechanical properties at high temperatures. The specific ratio of these chemical components can shift the pearlite part in the transformation curve to the right, so that the roller does not transform into pearlite before transforming from austenite to bainite, so that the final bainite semi-steel roller has a larger proportion of bainite, and therefore has a higher tensile strength and hardness.
[0011] In summary, through the above-mentioned specific heat treatment process, the cooling temperature of martensite can be successfully avoided. The precisely controlled chemical composition ratio in the rolling roller is combined to make the pearlite partially shift to the right in the transformation curve. In this way, a semi-steel rolling roller mainly composed of bainite is successfully prepared. Its tensile strength reaches more than 650MPa and its hardness reaches more than 45HSD, which is significantly better than the traditional semi-steel rolling roller. It has higher strength and hardness and can show excellent performance in practical applications.
[0012] Preferably, in step I, the casting mold includes an upper box, a middle box and a lower box arranged in sequence from top to bottom, wherein the upper box is cast by sand casting, and the middle box and the lower box are cast by metal mold sand casting.
[0013] By adopting the above technical scheme, the upper box in step I of the present application adopts sand casting, which can ensure the complex shape and dimensional accuracy of the upper part of the mold and meet the structural requirements of the semi-steel rolling mill; the middle box and the lower box adopt metal mold hanging sand casting, and utilize the high strength and stability of the metal mold to ensure the durability and rigidity of the mold at high temperature, prevent deformation and cracks, effectively reduce the defects such as pores and inclusions inside the casting, have good thermal conductivity, help control the cooling rate, and make it easier for the semi-steel rolling mill to form the required bainite structure during the cooling process, thereby improving the comprehensive performance of the material.
[0014] Preferably, in step II, the temperature when tapping the steel is 1450-1550°C, and the temperature when pouring into the mold is 1400-1500°C.
[0015] By adopting the above technical scheme, the present application controls the temperature during steel tapping to 1450-1550°C and the temperature during pouring into the mold to 1400-1500°C, which can ensure that the molten steel maintains good fluidity under high temperature conditions and avoid pouring difficulties and internal defects of the casting caused by too low temperature. Appropriate high-temperature pouring helps to promote the uniform distribution of alloy elements, improve the density and mechanical properties of the casting, thereby further improving the tensile strength and hardness of the bainitic semi-steel rolling mill.
[0016] In a second aspect, the present application provides a bainitic semi-steel rolling roller produced by the above-mentioned preparation process, wherein the bainitic semi-steel rolling roller has a bainite content ≥50%, a tensile strength ≥650MPa, and a hardness ≥45HSD.
[0017] Preferably, the tensile strength of the bainite semi-steel rolling roller is 690 MPa and the hardness is 70 HSD.
[0018] By adopting the above technical scheme, in the bainite semi-steel roller of the present application, the proportion of bainite reaches more than 50%, so that the roller has higher strength and hardness. Compared with the traditional pearlite semi-steel roller, the tensile strength of the bainite semi-steel roller is increased by more than 20%, not less than 650MPa, and the hardness is not less than 45HSD, which significantly improves the mechanical properties of the roller; Due to the combined effect of bainite and other matrix structures, the wear resistance of the bainite semi-steel roller is significantly improved, and compared with the pearlite semi-steel roller with the same carbon content, the wear resistance is improved by more than 50%; The design of the heat treatment process ensures that the roller avoids the formation of pearlite and martensite during the cooling process, thereby realizing a matrix structure dominated by bainite, further ensuring the excellent performance of the roller; In general, the precise control of the chemical composition and the reasonable control of the heat treatment parameters of the present application make the bainite semi-steel roller not only excel in strength and hardness, but also show excellent performance in practical applications, meeting the needs under high load conditions.
[0019] In summary, this application has the following beneficial technical effects: 1. The present application successfully avoids the cooling temperature of martensite by adjusting the chemical composition and heat treatment process, and integrates the precisely controlled chemical composition ratio in the roll, so that the pearlite part in the transformation curve is shifted to the right, thereby successfully preparing a semi-steel roll mainly composed of bainite, so that the proportion of bainite reaches more than 50%, significantly improving the tensile strength and hardness of the roll, the tensile strength reaches more than 650MPa, and the hardness reaches more than 45HSD. Compared with the traditional pearlite matrix roll, the tensile strength is increased by more than 20%; 2. The semi-steel roll with bainite matrix has higher wear resistance. Compared with the pearlite semi-steel roll with the same carbon content, the wear resistance is significantly improved, thereby extending the service life of the roll and reducing maintenance costs; 3. The design of the heat treatment process avoids the formation of pearlite and martensite, ensuring that the roller can stably transform into a bainite-based matrix structure during the cooling process, solving the problem of unstable composition caused by uneven internal temperature during isothermal quenching, so that large-volume and heavy semi-steel rollers can also obtain ideal bainite structure. BRIEF DESCRIPTION OF THE DRAWINGS
[0020] Figure 1 This is a schematic diagram of the surface structure metallographic structure of the bainite semi-steel rolling roller of the present application. DETAILED DESCRIPTION
[0021] The present application is further described in detail with reference to the embodiments and comparative examples.
[0022] Example 1 A preparation process of a bainite semi-steel roller comprises the following steps: I. Preparing the casting mold: A casting mold structure of an upper box, a middle box and a lower box arranged in sequence from top to bottom is adopted. The upper box is cast by sand mold, and the middle box and the lower box are cast by metal mold hanging sand. After the upper box, the middle box and the lower box are assembled in sequence, the casting mold is obtained and waits for casting; II. Melting and casting: According to the following chemical composition: C 1.3-2.1%, Si 0.2-1.0%, Mn 0.4-1.5%, Cr 0.5-3.0%, Ni 3.0-4.5%, Mo 0.5-1.2%, the balance is Fe and other impurities, the ingredients are prepared, melted, and tapped at a temperature of 1450°C, and poured into the mold obtained in step I at a temperature of 1400°C, and the sand is removed to obtain a semi-steel roll; III. Heat treatment: the semi-steel roll obtained in step II is placed in a heating furnace, kept at 1100°C for 10 hours, then cooled to a temperature between 300 and 500°C by air cooling, kept at that temperature for 2 hours, placed in the heating furnace again, heated to 550°C, kept at that temperature for 8 hours, and finally cooled to below 200°C by furnace cooling to obtain a bainite semi-steel roll; IV. Finishing: The rough roll obtained in step III is subjected to surface treatment and size trimming by grinding to ensure its surface quality and dimensional accuracy, thereby obtaining a bainite semi-steel finished roll.
[0023] Example 2 A preparation process of a bainite semi-steel roller comprises the following steps: I. Preparing the casting mold: A casting mold structure of an upper box, a middle box and a lower box arranged in sequence from top to bottom is adopted. The upper box is cast by sand mold, and the middle box and the lower box are cast by metal mold hanging sand. After the upper box, the middle box and the lower box are assembled in sequence, the casting mold is obtained and waits for casting; II. Melting and casting: According to the following chemical composition: C 1.3-2.1%, Si 0.2-1.0%, Mn 0.4-1.5%, Cr 0.5-3.0%, Ni 3.0-4.5%, Mo 0.5-1.2%, the balance is Fe and other impurities, the ingredients are prepared, melted, and tapped at a temperature of 1550°C, and poured into the mold obtained in step I at a temperature of 1500°C, and the sand is removed to obtain a semi-steel roll; III. Heat treatment: the semi-steel roll obtained in step II is placed in a heating furnace, kept at 880°C for 12 hours, then cooled to a temperature between 300 and 500°C by air cooling, kept at that temperature for 10 hours, placed in the heating furnace again, heated to 500°C, kept at that temperature for 10 hours, and finally cooled to below 200°C by furnace cooling to obtain a bainite semi-steel roll; IV. Finishing: The rough roll obtained in step III is subjected to surface treatment and size trimming by grinding to ensure its surface quality and dimensional accuracy, thereby obtaining a bainite semi-steel finished roll.
[0024] Example 3 A preparation process of a bainitic semi-steel rolling roll, which is different from that in Example 1, in step II, the ingredients are prepared and smelted according to the following chemical composition: C1.4-1.8%, Si 0.2-0.6%, Mn 0.6-1.0%, Cr 0.7-2.0%, Ni 3.2-4.0%, Mo 0.6-0.9%, and the balance is Fe and other impurities, and the rest is the same as in Example 1.
[0025] Example 4 A preparation process of a bainitic semi-steel rolling roll, which is different from that in Example 1 in that, in step II, the ingredients are prepared and smelted according to the following chemical composition: C1.7-2.0%, Si 0.6-0.8%, Mn 1.0-1.4%, Cr 1.0-2.5%, Ni 3.3.5-4.2%, Mo 0.7-1.0%, and the balance is Fe and other impurities, and the rest is the same as in Example 1.
[0026] Example 5 A preparation process of a bainitic semi-steel rolling roll, which is different from Example 3 in that, in step II, the ingredients are prepared and smelted according to the following chemical composition: C1.5-1.8%, Si 0.3-0.6%, Mn 0.8-1.3%, Cr 0.8-2.0%, Ni 3.5-4.0%, Mo 0.5-0.8%, and the balance is Fe and other impurities, and the rest is the same as Example 3.
[0027] Comparative Example 1 The following steps are involved: I. Preparing the casting mold: A casting mold structure of an upper box, a middle box and a lower box arranged in sequence from top to bottom is adopted. The upper box is cast by sand mold, and the middle box and the lower box are cast by metal mold hanging sand. After the upper box, the middle box and the lower box are assembled in sequence, the casting mold is obtained and waits for casting; II. Melting and casting: According to the following chemical composition: C 2.2-2.6%, Si 1.2-1.5%, Mn 1.8-2.0%, Cr 3.5-4.0%, Ni 2.0-2.5%, Mo 1.5-1.8%, the balance is Fe and other impurities, the ingredients are prepared, melted, and tapped at a temperature of 1450°C, and poured into the mold obtained in step I at a temperature of 1400°C, and the sand is removed to obtain a semi-steel roll; III. Heat treatment: the semi-steel roll obtained in step II is placed in a heating furnace, kept at 1100°C for 10 hours, then cooled to a temperature between 300 and 500°C by air cooling, kept at that temperature for 2 hours, placed in the heating furnace again, heated to 450°C, kept at that temperature for 8 hours, and finally cooled to below 200°C by furnace cooling to obtain a bainite semi-steel roll; IV. Finishing: The rough roll obtained in step III is subjected to surface treatment and size trimming by grinding to ensure its surface quality and dimensional accuracy, thereby obtaining a bainite semi-steel finished roll.
[0028] Comparative Example 2 The following steps are involved: I. Preparing the casting mold: A casting mold structure of an upper box, a middle box and a lower box arranged in sequence from top to bottom is adopted. The upper box is cast by sand mold, and the middle box and the lower box are cast by metal mold hanging sand. After the upper box, the middle box and the lower box are assembled in sequence, the casting mold is obtained and waits for casting; II. Melting and casting: According to the following chemical composition: C 2.2-2.6%, Si 0.1-0.15%, Mn 0.2-0.3%, Cr 0.2-0.4%, Ni 5.5-6.0%, Mo 0.2-0.4%, the balance is Fe and other impurities, the ingredients are prepared, melted, and tapped at a temperature of 1450°C, and poured into the mold obtained in step I at a temperature of 1400°C, and the sand is removed to obtain a semi-steel roll; III. Heat treatment: the semi-steel roll obtained in step II is placed in a heating furnace, kept at 1100°C for 10 hours, then cooled to a temperature between 300 and 500°C by air cooling, kept at that temperature for 2 hours, placed in the heating furnace again, heated to 500°C, kept at that temperature for 8 hours, and finally cooled to below 200°C by furnace cooling to obtain a bainite semi-steel roll; IV. Finishing: The rough roll obtained in step III is subjected to surface treatment and size trimming by grinding to ensure its surface quality and dimensional accuracy, thereby obtaining a bainite semi-steel finished roll.
[0029] Comparative Example 3 The following steps are involved: I. Preparing the casting mold: A casting mold structure of an upper box, a middle box and a lower box arranged in sequence from top to bottom is adopted. The upper box is cast by sand mold, and the middle box and the lower box are cast by metal mold hanging sand. After the upper box, the middle box and the lower box are assembled in sequence, the casting mold is obtained and waits for casting; II. Melting and casting: According to the following chemical composition: C 1.0-1.2%, Si 0.1-0.2%, Mn 1.6-1.8%, Cr 0.2-0.5%, Ni 4.6-5.0%, Mo 0.3-0.4%, the balance is Fe and other impurities, the ingredients are prepared, melted, and tapped at a temperature of 1450°C, and poured into the mold obtained in step I at a temperature of 1400°C, and the sand is removed to obtain a semi-steel roll; III. Heat treatment: the semi-steel roll obtained in step II is placed in a heating furnace, kept at 1100°C for 10 hours, then cooled to a temperature between 200 and 400°C by air cooling, kept at that temperature for 2 hours, placed in the heating furnace again, heated to 450°C, kept at that temperature for 8 hours, and finally cooled to below 200°C by furnace cooling to obtain a bainite semi-steel roll; IV. Finishing: The rough roll obtained in step III is subjected to surface treatment and size trimming by grinding to ensure its surface quality and dimensional accuracy, thereby obtaining a bainite semi-steel finished roll.
[0030] Performance Testing 1. The surface structure of the bainite semi-steel roll of Example 1 was subjected to metallographic analysis. The results are as follows: Figure 1 As shown, it is found that the bainite proportion of the bainite semi-steel roll of the present application is not less than 50%; 2. Referring to the national standard GB / T 228.1-2021 "Tensile test of metallic materials Part 1: Room temperature test method", the tensile strength of the bainitic semi-steel roller obtained in the embodiment and the comparative example was tested, and the results were recorded in Table 1; 3. Referring to the national standard GB / T 230.1-2018 "Metal Rockwell hardness test Part 1: Test method", the hardness of the bainitic semi-steel roller obtained in the embodiment and the comparative example was tested, and the results were recorded in Table 1.
[0031] Table 1 Performance test table Group Tensile strength / MPa Hardness / HSD Example 1 650 45 Example 2 655 48 Example 3 680 65 Example 4 675 63 Example 5 690 70 Comparative Example 1 530 35 Comparative Example 2 535 37 Comparative Example 3 570 42 Data Analysis: As can be seen from Table 1, the hardness of the bainite semi-steel roll obtained in the embodiment of the present application can reach 45-70HSD, which is increased by up to 35HSD compared with comparative examples 1-3. The tensile strength of the bainite semi-steel roll obtained in the embodiment can reach 650-690MPa, which is increased by 14-30% compared with comparative examples 1-3. It is proved that in the heat treatment process of the present application, the semi-steel roll is first kept at 880-1100°C for 10-12 hours. The purpose of this high temperature stage is to ensure that the organization is completely austenitized and obtain a uniform organizational structure so that the desired bainite organization can be smoothly formed in the subsequent cooling process; then, the semi-steel roll is cooled to 300-500°C. And keep it in this temperature range for 2-10 hours, which is a key step. In this temperature range, austenite can be transformed into bainite. The formation of bainite requires a certain temperature range and time. Too high temperature will lead to the formation of pearlite, while too low temperature will promote the formation of martensite. By accurately controlling the cooling rate and holding time, these two unfavorable situations can be effectively avoided. Next, the semi-steel roll is heated to 40-550℃ and kept for 8-10 hours. This process helps to further stabilize the bainite structure and eliminate possible residual stress. Finally, by slowly cooling the furnace to below 200℃, the integrity and stability of the bainite structure can be ensured. The entire heat treatment process not only effectively promotes the formation of bainite, but also avoids the formation of martensite, thereby ensuring the high hardness and high strength of the roll. At the same time, by adjusting the chemical composition ratio of the semi-steel roll, the proportion of bainite in the metallographic structure can be effectively controlled, thereby significantly improving the comprehensive performance of the semi-steel roll. Specifically, the proportion of each element in the present application can ensure that the roller forms sufficient bainite during the cooling process without excessively generating pearlite or martensite, which helps to refine the grains, improve the toughness of the material, enhance the hardenability and hardness of the material, and stabilize the bainite structure, significantly improve the strength and toughness of the material, so that it can still maintain good mechanical properties at high temperatures. The specific ratio of these chemical components can shift the pearlite part in the transformation curve to the right, so that the roller does not transform into pearlite before transforming from austenite to bainite, so that the final bainite semi-steel roller has a larger proportion of bainite, and therefore has a higher tensile strength and hardness.
[0032] Overall, it is proved that the present application can successfully avoid the cooling temperature of martensite through a specific heat treatment process, and combines the precisely controlled chemical composition ratio in the semi-steel rolling roller to make the pearlite partially shift to the right in the transformation curve, thereby successfully preparing a semi-steel rolling roller mainly composed of bainite, which is significantly superior to traditional semi-steel rolling rollers, has higher strength and hardness, and can show excellent performance in practical applications.
[0033] The embodiments of this specific implementation method are all preferred embodiments of the present application, and are not intended to limit the protection scope of the present application. Therefore, all equivalent changes made based on the structure, shape, and principle of the present application should be included in the protection scope of the present application.
Claims
1. A process for preparing a bainite semi-steel roll, characterized in that: The following steps are involved: Prepare the casting mold; Melting and casting: batching, melting, tapping the molten steel, pouring it into the mold obtained in step I, removing the sand, and obtaining a semi-steel roll; Heat treatment: the semi-steel roll obtained in step II is kept at 880-1100°C for 10-12h, cooled to 300-500°C, kept for 2-10h, then heated to 400-550°C, kept for 8-10h, and finally cooled to below 200°C to obtain a bainite semi-steel roll; Finishing: Get bainitic semi-steel finished rolls.
2. The process for preparing a bainite semi-steel roll according to claim 1, characterized in that: In step II, the composition of the alloy includes the following chemical components by weight percentage: C1.3-2.1%； Si 0.2-1.0%; Mn 0.4-1.5%; Cr0.5-3.0%； Ni3.0-4.5%; Mo0.5-1.2%; The balance is Fe and other impurities.
3. The process for preparing a bainite semi-steel roll according to claim 2, characterized in that: In step II, the composition of the alloy includes the following chemical components by weight percentage: C1.4-2.0%； Si0.2-0.8%; Mn 0.6-1.4%; Cr0.7-2.5%； Ni3.2-4.2%; Mo0.6-1.0%; The balance is Fe and other impurities.
4. The process for preparing a bainite semi-steel roll according to claim 3, characterized in that: In step II, the composition of the alloy includes the following chemical components by weight percentage: C1.5-1.8%； Si0.3-0.6%; Mn 0.8-1.3%; Cr0.8-2.0%； Ni3.5-4.0%; Mo0.5-0.8%; The balance is Fe and other impurities.
5. The process for preparing a bainite semi-steel roll according to claim 1, characterized in that: In the step I, the casting mold includes an upper box, a middle box and a lower box arranged in sequence from top to bottom, wherein the upper box is cast by sand casting, and the middle box and the lower box are cast by metal mold hanging sand casting.
6. The process for preparing a bainite semi-steel roll according to claim 1, characterized in that: In step II, the temperature when tapping the steel is 1450-1550°C, and the temperature when pouring into the mold is 1400-1500°C.
7. A bainite semi-steel roller produced by the production process according to any one of claims 1 to 6, characterized in that: The bainite proportion of the bainite semi-steel rolling roller is ≥50%, the tensile strength is ≥650MPa, and the hardness is ≥45HSD.
8. The bainite semi-steel roller according to claim 7, characterized in that: The tensile strength of the bainite semi-steel roller is 690 MPa and the hardness is 70 HSD.