Heat treatment method for reducing air gouging cracking risk of pearlite wear-resistant lining plate and optimizing comprehensive performance

Abstract

The invention discloses a heat treatment method for reducing the air gouging cracking risk of a pearlite wear-resistant lining plate and optimizing the comprehensive performance. The heat treatment method comprises the following steps: normalizing at high temperature: thermally preheating to 250-300 DEG C, and preserving heat for 2-3 hours; heating to 600-650 DEG C, and preserving heat for 3-4 hours; heating to Acm + (100-150) DEG C, and preserving heat; spheroidizing annealing is conducted, air cooling is conducted to 450-500 DEG C, heat preservation is conducted for 2-3 h, heating is conducted to Ac1 + (10-20) DEG C, heat preservation is conducted, slow cooling is conducted to Ar1-(10-20) DEG C, and heat preservation is conducted for 2-3 h; trimming and planing the root of the riser, air-cooling to 300-350 DEG C, preserving heat, trimming and planing the root of the riser in a heat preservation stage, returning to a furnace, preserving heat after trimming and planing, slowly cooling to be less than or equal to 150 DEG C along with the furnace, discharging and cooling to room temperature; performance heat treatment comprises a sub-temperature normalizing stage and a tempering stage, in the sub-temperature normalizing stage, preheating is conducted to 250-300 DEG C, heat preservation is conducted for 2-3 h, heating is conducted to 600-650 DEG C, heat preservation is conducted for 3-4 h, heating is conducted to Ac1 + (30-50) DEG C, in the tempering stage, preheating is conducted to 200 DEG C, heat preservation is conducted for 2 h, heating is conducted to 500-550 DEG C, heat preservation is conducted for 6 h, slow cooling is conducted to the temperature smaller than or equal to 200 DEG C, and discharging and air cooling are conducted. The cracking risk of the pearlite wear-resistant lining plate in the air gouging process is reduced, and the wear resistance, strength and fracture toughness of the pearlite wear-resistant lining plate are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of heat treatment of steel materials, and more specifically relates to a heat treatment method for reducing the risk of air gouging cracking of a pearlite wear-resistant liner and optimizing comprehensive performance. Background Art

[0002] Pearlite wear-resistant linings have been widely used in mining machinery due to their high hardness, good toughness and impact fatigue resistance, and have become an indispensable and important component in mining equipment. For example, pearlite wear-resistant linings can be used as linings for mining crushers, semi-autogenous mills, ball mills and other equipment to improve the wear resistance and service life of the equipment; in material conveying systems, pearlite wear-resistant linings can withstand the impact and wear of high-drop hoppers and protect system equipment from damage.

[0003] In the prior art, pearlite wear-resistant liners are mostly cast. To ensure the installation and use of the liners, the root of the riser after the pearlite wear-resistant liners touch the riser needs to be processed by arc gouging to remove excess material, burrs or uneven surfaces. However, cracks often occur during the gouging process. The reason for the cracking is that the pearlite wear-resistant liners are heated during the gouging process, the molten metal is blown away by the high-speed airflow, the adjacent matrix undergoes austenite structure transformation, and cools to martensite, forming microcracks. In addition, the casting cools unevenly and residual stress causes the cracks to expand.

[0004] The production process of pearlite wear-resistant liner casting after sanding: bumping the riser - normalizing - repairing and planing - tempering - finishing - flaw detection - rework - normalizing - inspection. In order to avoid the problem of cracking by air planing, it is usually normalized and air-cooled to 500℃ and then put into the furnace for insulation. Air planing is carried out at 500℃. After air planing, it is promptly put into the furnace for insulation. After the production batch is polished, the furnace is cooled to room temperature. However, due to the high temperature of the workpiece, the operator cannot stay close for a long time, and intermittent work is often used, which is inefficient. In addition, the performance heat treatment heating temperature is set above the complete austenitization temperature. After normalizing, the pearlite wear-resistant liner has a higher hardness, but poorer toughness.

[0005] Therefore, it is necessary to comprehensively consider factors such as material and process, and propose a new heat treatment process for pearlite wear-resistant liner to reduce the risk of cracking of pearlite wear-resistant liner during gouging, so as to achieve efficient and high-quality gouging operations, and at the same time improve the comprehensive performance of pearlite wear-resistant liner such as wear resistance, strength and toughness. Summary of the invention

[0006] In order to solve some or all of the technical problems existing in the above-mentioned prior art, the present invention provides a heat treatment method for reducing the cracking risk of pearlite wear-resistant liner gouging and optimizing the comprehensive performance, comprising the following steps:

[0007] (I) High temperature normalizing, the pearlite wear-resistant lining plate is subjected to high temperature normalizing treatment after sand removal and riser contact. The high temperature normalizing is carried out in a three-stage heating manner, including: the first stage heating, preheating the pearlite wear-resistant lining plate to 250-300°C, and keeping it warm for 2-3h; the second stage heating, heating the pearlite wear-resistant lining plate to 600-650°C, and keeping it warm for 3-4h; the third stage heating, heating the pearlite wear-resistant lining plate to Acm+(100-150)°C and then keeping it warm, and then taking it out of the furnace and air cooling it after the end of the insulation;

[0008] (ii) Spheroidizing annealing, spheroidizing annealing treatment is performed on the pearlite wear-resistant lining after high-temperature normalizing, including: the pearlite wear-resistant lining is normalized and air-cooled to 450-500°C, kept in the furnace for 2-3 hours, heated to Ac1+(10-20)°C and kept warm, and after the end of the heat preservation, slowly cooled to Ar1-(10-20)°C, kept warm for 2-3 hours, and then taken out of the furnace and air-cooled;

[0009] (III) The root of the riser is planed and annealed, and the pearlite wear-resistant lining is air-cooled to 300-350℃ and then put into the furnace for heat preservation. During the heat preservation stage, the root of the riser is planed while it is hot. After the root of the lining riser is planed, it is returned to the furnace for heat preservation, and then slowly cooled to ≤150℃ and cooled to room temperature, and then the subsequent finishing-defect detection-repair process is carried out;

[0010] (IV) Performance heat treatment: the pearlite wear-resistant lining is subjected to performance heat treatment after the riser root is planed, including sub-temperature normalizing stage and tempering stage. The sub-temperature normalizing stage includes: preheating the pearlite wear-resistant lining to 250-300°C and keeping it warm for 2-3 hours; heating the pearlite wear-resistant lining to 600-650°C and keeping it warm for 3-4 hours; heating the pearlite wear-resistant lining to Ac1+(30-50)°C and keeping it warm. After the insulation is completed, the pearlite wear-resistant lining is taken out of the furnace and air-cooled to ≤150°C. The tempering stage includes: preheating the pearlite wear-resistant lining to 200°C and keeping it warm for 2 hours; heating the pearlite wear-resistant lining to 500-550°C and keeping it warm for 6 hours; after the insulation is completed, the pearlite wear-resistant lining is slowly cooled to ≤200°C and taken out of the furnace and air-cooled.

[0011] Furthermore, in the above heat treatment method for reducing the risk of cracking of pearlite wear-resistant liner gouging and optimizing the overall performance:

[0012] In the second stage of heating in the high temperature normalizing step, the pearlite wear-resistant liner is heated to 600-650°C at a heating rate of ≤80°C / h;

[0013] In the spheroidizing annealing step, the pearlite wear-resistant lining is heated to Ac1+(10-20)°C at a heating rate of ≤100°C / h, and the pearlite wear-resistant lining is slowly cooled to Ar1-(10-20)°C at a cooling rate of ≤20°C / h;

[0014] In the step of planing the root of the riser, the pearlite wear-resistant liner is slowly cooled to ≤150°C at a cooling rate of ≤30°C / h along with the furnace;

[0015] In the performance heat treatment step, the pearlite wear-resistant lining plate is heated to 600-650°C at a heating rate of ≤80°C / h in the sub-temperature normalizing stage, and the pearlite wear-resistant lining plate is heated to 500-550°C at a heating rate of ≤80°C / h in the tempering stage, and the pearlite wear-resistant lining plate is slowly cooled to ≤200°C at a cooling rate of ≤30°C / h.

[0016] Furthermore, in the above-mentioned heat treatment method for reducing the risk of cracking of pearlite wear-resistant lining due to air planing and optimizing the comprehensive performance, in the step of planing the root of the riser, a part of the pearlite wear-resistant lining is first lifted out of the furnace and planed while hot, and then returned to the furnace in time after the planing is completed, and then another part of the pearlite wear-resistant lining is planed, and after all the pearlite wear-resistant liners loaded in the furnace are planed, they are put into the furnace for insulation for 1 hour, and then slowly cooled to below 150°C and taken out of the furnace to cool to room temperature.

[0017] As a specific implementation, in the above heat treatment method for reducing the risk of cracking of pearlite wear-resistant liner gouging and optimizing comprehensive performance, the pearlite wear-resistant liner is a pearlite wear-resistant liner made of 80Cr2Mo and having an equivalent cross-sectional thickness of 300 mm, and:

[0018] In the high-temperature normalizing step, the pearlite wear-resistant lining is preheated to 250°C in the first stage of heating and kept warm for 2 hours; the pearlite wear-resistant lining is heated to 600-650°C at a heating rate of ≤80°C / h in the second stage of heating and kept warm for 3 hours; the pearlite wear-resistant lining is heated to 960-980°C in the third stage of heating and kept warm for 8 hours, and then taken out of the furnace for air cooling after the end of the heat preservation;

[0019] In the spheroidizing annealing step, the pearlite wear-resistant lining is normalized and air-cooled to 450-500°C after being put into the furnace for 2 hours of heat preservation, and then heated to 810-820°C at a heating rate of ≤100°C / h, and then slowly cooled to 670-680°C at a cooling rate of ≤20°C / h after being kept for 8 hours, and then taken out of the furnace for air cooling;

[0020] In the step of repairing and planing the root of the riser, the pearlite wear-resistant lining is spheroidized annealed and air-cooled to 300°C before being put into the furnace for heat preservation. During the 300°C heat preservation stage, a part of the pearlite wear-resistant lining is first lifted out of the furnace for hot planing, and returned to the furnace in time after the planing is completed, and then another part of the pearlite wear-resistant lining is planed. After all the pearlite wear-resistant linings loaded in the furnace are planed, they are put into the furnace for heat preservation for 1h, and then slowly cooled to below 150°C at a cooling rate of ≤30°C / h, taken out of the furnace and cooled to room temperature, and the finishing-flaw detection-repair process is carried out;

[0021] In the performance heat treatment step, the sub-temperature normalizing stage includes: preheating the pearlite wear-resistant lining to 300°C and keeping it warm for 2 hours; heating the pearlite wear-resistant lining to 600-650°C at a heating rate of ≤80°C / h and keeping it warm for 3 hours; heating the pearlite wear-resistant lining to 830-850°C and keeping it warm for 6 hours, and after the insulation is completed, it is taken out of the furnace and air-cooled to below 150°C. The tempering stage includes: preheating the pearlite wear-resistant lining to 200°C and keeping it warm for 2 hours; heating the pearlite wear-resistant lining to 500-520°C at a heating rate of ≤80°C / h and keeping it warm for 6 hours; after the insulation is completed, the pearlite wear-resistant lining is slowly cooled to below 200°C at a cooling rate of ≤30°C / h and taken out of the furnace and air-cooled.

[0022] Furthermore, in the above-mentioned heat treatment method for reducing the risk of cracking of the pearlite wear-resistant liner due to air planing and optimizing the comprehensive performance, the hardness of the pearlite wear-resistant liner treated by the heat treatment method is HBW 340-370, the yield strength is 702Mpa, the tensile strength is 1197Mpa, and the impact toughness at 0°C is 16J, 20J, and 22J.

[0023] The heat treatment method of the present invention for reducing the cracking risk of pearlite wear-resistant liner gouging and optimizing comprehensive performance has the following advantages and beneficial effects:

[0024] The present invention adopts a heat treatment process of high-temperature normalizing + spheroidizing annealing + sub-temperature normalizing + tempering after the riser is touched, so that the cast grains of the pearlite wear-resistant liner are refined, the composition and structure are homogenized, and the carbides in the liner are spheroidized to obtain spherical or granular carbides uniformly dispersed on the ferrite, thereby reducing the overheating sensitivity of the adjacent matrix structure when heating during the air gouging process, having better plasticity and toughness, and reducing the cracking risk of the pearlite wear-resistant liner during the air gouging process. The treated pearlite wear-resistant liner has a microstructure of fine austenite grains and undissolved carbides, and the undissolved carbides are uniformly distributed on the matrix in the form of fine spheres, which significantly improves the wear resistance, strength and fracture toughness of the pearlite wear-resistant liner. In addition, since the temperature of the workpiece during the riser root gouging operation is lower than that of the prior art, it is ensured that the workers performing the riser root gouging operation are convenient to operate, thereby improving the gouging efficiency and realizing efficient and high-quality gouging operations. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. 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. In the drawings:

[0026] Figure 1It is a schematic diagram of the process sequence of the heat treatment method of the present invention for reducing the risk of cracking of the pearlite wear-resistant liner due to air gouging and optimizing the comprehensive performance;

[0027] Figure 2 It is a schematic diagram of the process timing of a heat treatment method for reducing the risk of cracking due to air planing of a pearlite wear-resistant liner and optimizing the comprehensive performance according to an embodiment of the present invention. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the specific embodiments of the present invention and the corresponding drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0029] like Figure 1 As shown, the heat treatment method provided by the present invention for reducing the cracking risk of pearlite wear-resistant liner gouging and optimizing the comprehensive performance comprises the following steps:

[0030] (a) High temperature normalizing, pearlite wear-resistant lining plate sand cleaning and riser after high temperature normalizing treatment, the purpose is to refine the pearlite wear-resistant lining plate casting overheated coarse grains, eliminate network carbides, make the composition and organization more uniform, for the subsequent spheroidizing annealing to lay a good organizational foundation, and high temperature normalizing can also eliminate the casting process and left in the refined pearlite wear-resistant lining plate internal stress. High temperature normalizing is carried out in a three-stage heating manner, including: in the first stage, the pearlite wear-resistant lining is preheated to 250-300°C and kept warm for 2-3h; in the second stage, the pearlite wear-resistant lining is heated to 600-650°C at a heating rate of ≤80°C / h and kept warm for 3-4h; in the third stage, the pearlite wear-resistant lining is heated to 100-150°C above the Acm temperature (i.e., heated to Acm+(100-150)°C) according to the power of the heat treatment heating furnace and then kept warm. The specific holding time is determined according to the actual furnace load, and after the holding is completed, it is taken out of the furnace and air-cooled.

[0031] (ii) Spheroidizing annealing: the pearlite wear-resistant lining after high temperature normalizing is subjected to spheroidizing annealing treatment, the purpose of which is to spheroidize the lamellar pearlite structure of the pearlite wear-resistant lining into granular pearlite, thereby reducing the pearlite phase boundary area, enhancing the stability of the pearlite, and at the same time making the organization uniform, improving the plasticity and toughness of the matrix. Spheroidizing annealing includes: the pearlite wear-resistant lining is air-cooled to 450-500°C after normalizing, and after being kept in the furnace for 2-3 hours, it is heated to 10-20°C above the Ac1 temperature (i.e., heated to Ac1+(10-20)°C) at a heating rate of ≤100°C / h and then kept warm. The specific holding time is determined according to the actual furnace loading. After the holding is completed, it is slowly cooled to 10-20°C below the Ar1 temperature (i.e., cooled to Ar1-(10-20)°C) at a cooling rate of ≤20°C / h, kept warm for 2-3 hours for holding transformation, and then taken out of the furnace and air-cooled. In the process of spheroidizing annealing, isothermal spheroidizing annealing is used to shorten the spheroidizing annealing cycle and improve production efficiency.

[0032] (III) Riser root planing, pearlite wear-resistant lining plate spheroidizing annealing out of the furnace air cooling to 300 ~ 350 ℃ and then into the furnace for heat preservation, during this heat preservation stage, the riser root planing operation is carried out while hot, the lining plate riser root planing is completed and promptly returned to the furnace for heat preservation, and then slowly cooled to ≤150 ℃ with the furnace at a cooling rate of ≤30 ℃ / h, and then cooled to room temperature, and then the subsequent finishing-flaw detection-repair process is carried out. For the case of a large amount of furnace loading, first hang a part of the pearlite wear-resistant lining plate out of the furnace for planing while hot, and return to the furnace in time after the planing is completed, and then plan another part of the pearlite wear-resistant lining plate, and after all the pearlite wear-resistant lining plates loaded in the furnace are planed, they are put into the furnace for heat preservation for 1 hour, and then slowly cooled to below 150 ℃ and cooled to room temperature.

[0033] (IV) Performance heat treatment: the pearlite wear-resistant lining is subjected to performance heat treatment after the riser root is planed, including sub-temperature normalizing stage and tempering stage. The sub-temperature normalizing stage includes: preheating the pearlite wear-resistant lining to 250-300°C and keeping it warm for 2-3h; heating the pearlite wear-resistant lining to 600-650°C at a heating rate of ≤80°C / h and keeping it warm for 3-4h; heating the pearlite wear-resistant lining to 30-50°C above the Ac1 temperature (i.e., heating to Ac1+(30-50)°C) according to the power of the heat treatment heating furnace and then keeping it warm. The specific holding time is determined according to the actual furnace loading. The holding temperature can transform most of the matrix structure of the pearlite wear-resistant lining into austenite with fine grains. In addition, a part of the undissolved particulate carbide is retained. After the holding is completed, it is taken out of the furnace and air-cooled to ≤150°C to obtain pearlite and uniformly distributed spherical carbides. This structure not only has high strength and hardness, but also has good toughness. The tempering stage includes: preheating the pearlite wear-resistant lining to 200℃ and keeping it warm for 2h; heating the pearlite wear-resistant lining to 500-550℃ at a heating rate of ≤80℃ / h and keeping it warm for 6h; after the insulation, slowly cooling the pearlite wear-resistant lining to ≤200℃ at a cooling rate of ≤30℃ / h and air cooling it out of the furnace. The residual stress of the pearlite wear-resistant lining is reduced through tempering treatment.

[0034] As described above, the heat treatment method of the present invention for reducing the cracking risk of the pearlite wear-resistant liner due to air planing and optimizing the comprehensive performance adopts a heat treatment process of high-temperature normalizing + spheroidizing annealing + sub-temperature normalizing + tempering after the riser is touched. The cast grains of the pearlite wear-resistant liner are refined and the composition and structure are uniformed by high-temperature normalizing, and then spheroidizing annealing is performed to spheroidize the carbides in the liner to obtain spherical or granular carbides uniformly dispersed on the ferrite, thereby improving the cutting performance. In addition, compared with the lamellar pearlite after normalizing, the overheating sensitivity of the adjacent matrix structure during the air planing process is reduced by spheroidizing annealing. The principle is that the lamellar pearlite has many phase interfaces and a large phase interface area, a high nucleation rate during austenitization, and a faster austenite formation rate, so that the austenite can be formed in a short time. It is formed within a certain period of time. After the austenite is formed, it enters the growth stage too early, so the final austenite grains are coarse. Through spheroidizing annealing, the granular pearlite is heated and austenite is formed uniformly, which reduces the internal stress caused by uneven organization. At the same time, the spheroidized organization after spheroidizing annealing has better plasticity and toughness than the lamellar organization, making it less likely for the material to crack under external force. Therefore, the spheroidizing annealing heat treatment not only reduces the cracking risk of the pearlite wear-resistant liner during the gouging process, but also after spheroidizing annealing, the subsequent normalizing treatment adopts sub-temperature heating, and the heating state is fine austenite grains and undissolved carbides. After normalizing, the undissolved carbides are evenly distributed on the matrix in the form of small spheres, which helps to improve the wear resistance, strength and fracture toughness of the pearlite wear-resistant liner after heat treatment.

[0035] The following is a detailed description of the heat treatment method of the present invention for reducing the risk of cracking due to air gouging of pearlite wear-resistant liner and optimizing the comprehensive performance in combination with specific embodiments. The following embodiment is applied to a pearlite wear-resistant liner made of 80Cr2Mo and with an equivalent cross-sectional thickness of 300mm, which can effectively prevent cracking due to air gouging of pearlite wear-resistant liner and improve the wear resistance of the pearlite wear-resistant liner. Figure 2 As shown, the specific implementation process of the heat treatment method provided by the embodiment of the present invention is as follows:

[0036] (I) High temperature normalizing, including: the first stage heating, preheating the pearlite wear-resistant lining to 250 ° C, keeping warm for 2 hours; the second stage heating, heating the pearlite wear-resistant lining to 600 ~ 650 ° C, keeping warm for 3 hours; the third stage heating, heating the pearlite wear-resistant lining to 960 ~ 980 ° C, keeping warm for 8 hours, and then taking out of the furnace and air cooling after the end of the insulation.

[0037] (ii) Spheroidizing annealing, including: normalizing the pearlite wear-resistant lining plate and air cooling it to 450-500°C after it is put into the furnace and kept warm for 2 hours, then heated to 810-820°C, kept warm for 8 hours, then slowly cooled to 670-680°C, kept warm for 2 hours for insulation transformation, and then taken out of the furnace and air cooled.

[0038] (III) Repair and planing of the riser root, the pearlite wear-resistant lining is spheroidized annealed and air-cooled to 300℃ before being put into the furnace for insulation. During the 300℃ insulation stage, a part of the pearlite wear-resistant lining is first lifted out of the furnace for hot planing. After the planing is completed, it is returned to the furnace in time, and then another part of the pearlite wear-resistant lining is planed. After all the pearlite wear-resistant linings loaded in the furnace are planed, they are put into the furnace for insulation for 1h, and then slowly cooled to below 150℃ and taken out of the furnace to cool to room temperature for finishing-flaw detection-repair process.

[0039] (IV) Performance heat treatment, including sub-temperature normalizing stage and tempering stage. In the sub-temperature normalizing stage, preheat the pearlite wear-resistant lining to 300℃ and keep it warm for 2h; heat the pearlite wear-resistant lining to 600-650℃ and keep it warm for 3h; heat the pearlite wear-resistant lining to 830-850℃ and keep it warm for 6h. After the insulation is completed, take it out of the furnace and air cool it to below 150℃. In the tempering stage, preheat the pearlite wear-resistant lining to 200℃ and keep it warm for 2h; heat the pearlite wear-resistant lining to 500-520℃ and keep it warm for 6h; after the insulation is completed, slowly cool the pearlite wear-resistant lining to below 200℃ and take it out of the furnace and air cool it.

[0040] According to the embodiment of the present invention, 24 pearlite wear-resistant lining plates with a material of 80Cr2Mo and an equivalent cross-sectional thickness of 300mm were produced in three batches. According to the actual production situation, the riser root planing operation is convenient for workers to operate, and the planing efficiency is significantly improved. After inspection, only 2 pieces were cracked, and the crack depth was 2-3mm, and the cracks could also be removed by subsequent grinding. The performance test measured data are: hardness HBW 340-370, which is basically unchanged compared with the prior art process, the yield strength is increased from 610Mpa of the prior art process to 702Mpa, the tensile strength is increased from 1092Mpa of the prior art process to 1197Mpa, and the impact toughness at 0°C is increased from 3J, 3J, and 4J of the prior art process to 16J, 20J, and 22J; the metallographic test measured results are: the matrix structure of the pearlite wear-resistant lining plate has a higher grain size grade, the undissolved cementite is dispersed in granular form, and no carbide is precipitated along the crystal.

[0041] In summary, compared with the prior art, the heat treatment method of the present invention for reducing the cracking risk of pearlite wear-resistant liner gouging and optimizing the comprehensive performance has the following advantages and beneficial effects:

[0042] The present invention adopts a heat treatment process of high-temperature normalizing + spheroidizing annealing + sub-temperature normalizing + tempering after the riser is touched, so that the cast grains of the pearlite wear-resistant liner are refined, the composition and structure are homogenized, and the carbides in the liner are spheroidized to obtain spherical or granular carbides uniformly dispersed on the ferrite, thereby reducing the overheating sensitivity of the adjacent matrix structure when heating during the air gouging process, having better plasticity and toughness, and reducing the cracking risk of the pearlite wear-resistant liner during the air gouging process. The treated pearlite wear-resistant liner has a microstructure of fine austenite grains and undissolved carbides, and the undissolved carbides are uniformly distributed on the matrix in the form of fine spheres, which significantly improves the wear resistance, strength and fracture toughness of the pearlite wear-resistant liner. In addition, since the temperature of the workpiece during the riser root gouging operation is lower than that of the prior art, it is ensured that the workers performing the riser root gouging operation are convenient to operate, thereby improving the gouging efficiency and realizing efficient and high-quality gouging operations.

[0043] It should be noted that, in this article, in this article, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In addition, "front", "back", "left", "right", "upper" and "lower" in this article are all referenced to the placement state shown in the accompanying drawings.

[0044] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A heat treatment method for reducing the risk of cracking of pearlite wear-resistant liner gouging and optimizing comprehensive performance, characterized in that: The steps include: (I) High temperature normalizing, the pearlite wear-resistant lining plate is subjected to high temperature normalizing treatment after sand removal and riser contact. The high temperature normalizing is carried out in a three-stage heating manner, including: the first stage heating, preheating the pearlite wear-resistant lining plate to 250-300°C, and keeping it warm for 2-3h; the second stage heating, heating the pearlite wear-resistant lining plate to 600-650°C, and keeping it warm for 3-4h; the third stage heating, heating the pearlite wear-resistant lining plate to Acm+(100-150)°C and then keeping it warm, and then taking it out of the furnace and air cooling it after the end of the insulation; (ii) Spheroidizing annealing, spheroidizing annealing treatment is performed on the pearlite wear-resistant lining after high-temperature normalizing, including: the pearlite wear-resistant lining is normalized and air-cooled to 450-500°C, kept in the furnace for 2-3 hours, heated to Ac1+(10-20)°C and kept warm, and after the end of the heat preservation, slowly cooled to Ar1-(10-20)°C, kept warm for 2-3 hours, and then taken out of the furnace and air-cooled; (III) The root of the riser is planed and annealed, and the pearlite wear-resistant lining is air-cooled to 300-350℃ and then put into the furnace for heat preservation. During the heat preservation stage, the root of the riser is planed while it is hot. After the root of the lining riser is planed, it is returned to the furnace for heat preservation, and then slowly cooled to ≤150℃ and cooled to room temperature, and then the subsequent finishing-defect detection-repair process is carried out; (IV) Performance heat treatment: the pearlite wear-resistant lining is subjected to performance heat treatment after the riser root is planed, including sub-temperature normalizing stage and tempering stage. The sub-temperature normalizing stage includes: preheating the pearlite wear-resistant lining to 250-300°C and keeping it warm for 2-3 hours; heating the pearlite wear-resistant lining to 600-650°C and keeping it warm for 3-4 hours; heating the pearlite wear-resistant lining to Ac1+(30-50)°C and keeping it warm. After the insulation is completed, the pearlite wear-resistant lining is taken out of the furnace and air-cooled to ≤150°C. The tempering stage includes: preheating the pearlite wear-resistant lining to 200°C and keeping it warm for 2 hours; heating the pearlite wear-resistant lining to 500-550°C and keeping it warm for 6 hours; after the insulation is completed, the pearlite wear-resistant lining is slowly cooled to ≤200°C and taken out of the furnace and air-cooled.

2. The heat treatment method for reducing the risk of cracking of pearlite wear-resistant liner by gouging and optimizing comprehensive performance according to claim 1, characterized in that: In the second stage of heating in the high temperature normalizing step, the pearlite wear-resistant liner is heated to 600-650°C at a heating rate of ≤80°C / h; In the spheroidizing annealing step, the pearlite wear-resistant lining is heated to Ac1+(10-20)°C at a heating rate of ≤100°C / h, and the pearlite wear-resistant lining is slowly cooled to Ar1-(10-20)°C at a cooling rate of ≤20°C / h; In the step of planing the root of the riser, the pearlite wear-resistant liner is slowly cooled to ≤150°C at a cooling rate of ≤30°C / h along with the furnace; In the performance heat treatment step, the pearlite wear-resistant lining plate is heated to 600-650°C at a heating rate of ≤80°C / h in the sub-temperature normalizing stage, and the pearlite wear-resistant lining plate is heated to 500-550°C at a heating rate of ≤80°C / h in the tempering stage, and the pearlite wear-resistant lining plate is slowly cooled to ≤200°C at a cooling rate of ≤30°C / h.

3. The heat treatment method for reducing the risk of cracking of pearlite wear-resistant liner gouging and optimizing comprehensive performance according to claim 1 is characterized in that: In the step of planing the root of the riser, first lift a part of the pearlite wear-resistant lining out of the furnace and plan it while hot. After the planing is completed, return it to the furnace in time, and then plan another part of the pearlite wear-resistant lining. After all the pearlite wear-resistant linings loaded in the furnace are planed, put them into the furnace for insulation for 1 hour, and then slowly cool to below 150°C and take them out of the furnace to cool to room temperature.

4. According to the heat treatment method for reducing the cracking risk of air planing of pearlite wear-resistant liner and optimizing the comprehensive performance of claim 1, the pearlite wear-resistant liner is a pearlite wear-resistant liner made of 80Cr2Mo and with an equivalent cross-sectional thickness of 300 mm, characterized in that: In the high-temperature normalizing step, the pearlite wear-resistant lining is preheated to 250°C in the first stage of heating and kept warm for 2 hours; the pearlite wear-resistant lining is heated to 600-650°C at a heating rate of ≤80°C / h in the second stage of heating and kept warm for 3 hours; the pearlite wear-resistant lining is heated to 960-980°C in the third stage of heating and kept warm for 8 hours, and then taken out of the furnace for air cooling after the end of the heat preservation; In the spheroidizing annealing step, the pearlite wear-resistant lining is normalized and air-cooled to 450-500°C after being put into the furnace for 2 hours of heat preservation, and then heated to 810-820°C at a heating rate of ≤100°C / h, and then slowly cooled to 670-680°C at a cooling rate of ≤20°C / h after being kept for 8 hours, and then taken out of the furnace for air cooling; In the step of repairing and planing the root of the riser, the pearlite wear-resistant lining is spheroidized annealed and air-cooled to 300°C before being put into the furnace for heat preservation. During the 300°C heat preservation stage, a part of the pearlite wear-resistant lining is first lifted out of the furnace for hot planing, and returned to the furnace in time after the planing is completed, and then another part of the pearlite wear-resistant lining is planed. After all the pearlite wear-resistant linings loaded in the furnace are planed, they are put into the furnace for heat preservation for 1h, and then slowly cooled to below 150°C at a cooling rate of ≤30°C / h, taken out of the furnace and cooled to room temperature, and the finishing-flaw detection-repair process is carried out; In the performance heat treatment step, the sub-temperature normalizing stage includes: preheating the pearlite wear-resistant lining to 300°C and keeping it warm for 2 hours; heating the pearlite wear-resistant lining to 600-650°C at a heating rate of ≤80°C / h and keeping it warm for 3 hours; heating the pearlite wear-resistant lining to 830-850°C and keeping it warm for 6 hours, and after the insulation is completed, it is taken out of the furnace and air-cooled to below 150°C. The tempering stage includes: preheating the pearlite wear-resistant lining to 200°C and keeping it warm for 2 hours; heating the pearlite wear-resistant lining to 500-520°C at a heating rate of ≤80°C / h and keeping it warm for 6 hours; after the insulation is completed, the pearlite wear-resistant lining is slowly cooled to below 200°C at a cooling rate of ≤30°C / h and taken out of the furnace and air-cooled.

5. The heat treatment method for reducing the risk of cracking of pearlite wear-resistant liner due to gouging and optimizing comprehensive performance according to any one of claims 1 to 4, characterized in that: The pearlite wear-resistant lining plate treated by the heat treatment method has a hardness of HBW340-370, a yield strength of 702 MPa, a tensile strength of 1197 MPa, and an impact toughness of 16 J, 20 J, and 22 J at 0°C.

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