60 at1~60 kg / m forged alloy steel profile rail manufacturing method and profile rail

Abstract

The application discloses a manufacturing method of 60AT1-60kg / m forged alloy steel special-shaped rail and the special-shaped rail, and the method comprises the following steps: heating, heating to 600-650 DEG C at a first heating speed, and then keeping the temperature for a first time, and then heating to 900-920 DEG C at a second heating speed, and then keeping the temperature for a second time; cooling, cooling to below 800 DEG C at a first air blowing pressure and a first cooling speed, then cooling to 250-300 DEG C at a second air blowing pressure and a second cooling speed, and then cooling to below 200 DEG C at a third air blowing pressure and a third cooling speed; tempering, heating to 200-240 DEG C in the first stage, keeping the temperature for a third time, heating to 260-280 DEG C in the second stage, keeping the temperature for a fourth time, and finally air cooling to room temperature. The heat-affected softening area width of the forged and pressed position of the special-shaped rail is small, and there are only 2-3 soft spots with a width of about 30 mm below the surface hardness of 380 HB.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of forged special-shaped rail, in particular, relates to a manufacturing method of 60AT1-60kg / m forged alloy steel special-shaped rail and the special-shaped rail. BACKGROUND

[0002] With the frequent railway transportation and the continuous growth of the volume, the stability and efficiency of the line operation are increasingly required, and thus the comprehensive mechanical properties of the rails used in the line are required to be higher. In order to meet the requirements of the line operation and use, the domestic major steel enterprises have developed high-strength and high-hardness bainite alloy rails which can be used for the processing and manufacturing of switches, so as to further enhance the wear resistance of the line switches and prolong the service life. The asymmetric section of the frog, the point rail and the special-shaped rail used for connecting different rail lines are the key components for guiding the conversion of the switch, and the local heel end of the special-shaped rail is formed by high-temperature hot forging into a standard rail which can be conveniently connected with the line. In this process, the comprehensive mechanical properties of the forged heel end are significantly decreased, and the width of the local heat-affected softening zone is large, especially for high-strength alloy steel. In order to restore the comprehensive mechanical properties of the alloy steel heel end, the forged heel end needs to be re-heat treated, but the heat treatment process is difficult, and there is no standard technical requirement for reference in the industry. The restoration and improvement of the comprehensive mechanical properties of the heel end have been a problem in the manufacturing of the product, mainly manifested as the unobvious improvement of the comprehensive mechanical properties, the wide control index of the softening zone, and the local low-collapsed saddle-shaped wear which is not conducive to the prolongation and stability improvement of the service life of the special-shaped rail.

[0003] At present, in order to restore the comprehensive mechanical properties of the alloy steel special-shaped rail, the forged rail can be air-cooled or tempered after forging. Patent CN104087852A discloses a high-strength bainite rail and a production method thereof. The method is to accelerate the cooling of the rail head when the rail is cooled to 450-500 DEG C by using the residual heat of the rail rolling, and then air-cool to room temperature when the temperature is reduced to 220-300 DEG C, so as to obtain a production method of bainite alloy rail with good wear resistance. However, the online heat treatment method used in the heat treatment of the patent is rough, the detailed cooling parameters of the rail at each position are not specified, and the method for restoring and controlling the soft zone after the loss of the hot die forging performance of the heel end is not disclosed, which cannot meet the manufacturing needs of the forged heel end of the special-shaped rail. In addition, patent CN114015945A discloses a bainite rail with uniform hardness gradient and a production method thereof. The bainite rail with uniform hardness gradient is manufactured by smelting, casting, rolling, online heat treatment, processing and tempering heat treatment. The patent also does not disclose the method for restoring and controlling the soft zone after the loss of the hot die forging performance of the heel end, which cannot meet the manufacturing needs of the forged heel end of the special-shaped rail. SUMMARY

[0004] The application provides a manufacturing method of 60AT1-60kg / m forged and pressed alloy steel special-shaped rail and the special-shaped rail, and aims at solving the technical problem of how to recover the performance and control the soft area after the hot die forging performance of the rail heel end is lost.

[0005] According to one aspect of the application, a manufacturing method of 60AT1-60kg / m forged and pressed alloy steel special-shaped rail is provided, which comprises the following steps:

[0006] (1) heating: the full-section of the forged special-shaped rail heel end is heated, and the temperature is raised to 600-650 DEG C at a first temperature raising speed, and then the temperature is kept for a first time, and then the temperature is raised to 900-920 DEG C at a second temperature raising speed, and then the temperature is kept for a second time;

[0007] (2) cooling: the forged special-shaped rail heel end after the heating is cooled, and the temperature is cooled to 600-800 DEG C at a first air blast pressure and a first cooling speed, and then the temperature is cooled to 250-300 DEG C at a second air blast pressure and a second cooling speed, and then the temperature is cooled to 200-250 DEG C at a third air blast pressure and a third cooling speed;

[0008] (3) tempering: the forged special-shaped rail heel end after the cooling is tempered, and the temperature is raised to 200-240 DEG C in the first stage, and then the temperature is kept for a third time, and then the temperature is raised to 260-280 DEG C in the second stage, and then the temperature is kept for a fourth time, and then the temperature is air cooled to room temperature.

[0009] Further, in the step (1), the temperature is raised to 600-650 DEG C at the first temperature raising speed within 300-600 DEG C, and the first temperature raising speed is greater than the second temperature raising speed.

[0010] Further, in the step (1), the first temperature raising speed is 2.5-3.5 DEG C / s, and the second temperature raising speed is 1.5-2.5 DEG C / s.

[0011] Further, in the step (1), the first time for keeping the temperature is 25-35 s, and the second time for keeping the temperature is 15-25 s.

[0012] Further, in the step (1), the first time for keeping the temperature is 30 s, and the second time for keeping the temperature is 20 s.

[0013] Further, in the step (2), the first air blast pressure is 0.02-0.05 Mpa, the second air blast pressure is 0.1-0.15 Mpa, and the third air blast pressure is 0.05 Mpa.

[0014] Further, in the step (2), the first cooling speed is 1-1.5 DEG C / s, the second cooling speed is 1.5-2.5 DEG C / s, and the third cooling speed is 1-1.2 DEG C / s.

[0015] Further, the third holding time in step (3) is 60-90 min, and the fourth holding time is 240-300 min.

[0016] Further, the first stage of tempering in step (3) is heated to 200 DEG C, and the second stage is heated to 280 DEG C.

[0017] According to another aspect of the present application, there is also provided a 60AT1-60kg / m forged alloy steel profile rail, which is prepared by the method for manufacturing the 60AT1-60kg / m forged alloy steel profile rail, and has a top surface hardness value less than HBW380, less than 3 soft spots, a soft zone hardness of 317-375 HB, and a width of not more than 30 mm.

[0018] The present application has the following beneficial effects:

[0019] The present application uses the heat treatment technology of re-controlling full-face induction heating + rapid and continuous compressed air cooling + long-time low-temperature tempering, which is beneficial to the performance loss recovery; in the heating process, the induction heating speed is fast, the heating temperature is high, and after appropriate holding, the uniformity of the temperature of each part of the local heating and the fineness of the organization transformation are improved, the temperature gradient per unit distance near the furnace mouth is increased, the excessive buffer zone of the furnace mouth temperature and the gap distance between the furnace mouth and the rail top are reduced, and the heat overflow is weakened. The continuous air cooling and low-temperature tempering in the cooling stage further reduce the proportion and area of the generation of austenite and ferrite softening organization, and expand the bainite strong and tough organization transformation zone, which is beneficial to the soft zone control. Through the above method, the performance loss of the forged profile rail heel end can be better recovered, and the heat-affected softening zone width after the local heat treatment of the forged profile rail heel end by the method of the present application is small, the soft spots with a surface hardness of less than 380 HB are only 2-3, and the width is only about 30 mm, which can meet the requirements of the current standard and reach the domestic leading control level (the soft spots with a surface hardness of less than 360 HB are generally controlled to be 3-5 in China), and the local wear is not easy to occur in the line use, which is beneficial to the extension of the service life.

[0020] In addition to the objects, features, and advantages described above, the present application has other objects, features, and advantages. The present application will be further described below with reference to the drawings. BRIEF DESCRIPTION OF DRAWINGS

[0021] The accompanying drawings, which form a part of this application, are included to provide a further understanding of the application, and are incorporated in and constitute a part of this application. The embodiments illustrated in the drawings are provided to explain the present application and, do not limit the present application. In the drawings:

[0022] Figure 1 The figure is a schematic diagram of the heating and cooling equipment structure for the profile rail forged heel end.

[0023] Figure 2 Structure diagram of forging and pressing the heel end of the special-shaped rail;

[0024] Figure 3 Structure diagram of forging and pressing the heel end of the special-shaped rail.

[0025] In the figure: 1. Induction heating furnace; 2. Air cooling device; 3. Softening zone; 4. Forging and pressing the heel end of the special-shaped rail; 5. Rail head; 6. Rail waist; 7. Rail bottom. DETAILED DESCRIPTION

[0026] The embodiments of the present application will be described in detail below with reference to the accompanying drawings, but the present application can be implemented in various different ways as defined and covered by the following.

[0027] The embodiments of the first aspect of the present application provide a manufacturing method of 60AT1-60kg / m forged and pressed alloy steel special-shaped rail, comprising the following steps:

[0028] (1) Heating: full-section heating of the forged special-shaped rail heel end is performed by using a medium-frequency induction furnace, and after being heated to 650 DEG C at a first heating rate and being kept for a first time, the temperature is increased to 900-920 DEG C at a second heating rate and being kept for a second time; then the furnace is immediately taken out for air cooling;

[0029] (2) Cooling: the forged special-shaped rail heel end after heating is cooled, and after being cooled to 600-800 DEG C at a first air cooling pressure and a first cooling rate, the temperature is cooled to 250-300 DEG C at a second air cooling pressure and a second cooling rate, and then the temperature is cooled to 200-250 DEG C at a third air cooling pressure and a third cooling rate;

[0030] (3) Tempering: the forged special-shaped rail heel end after cooling is tempered, and in the first stage, the temperature is increased to 200-240 DEG C and kept for a third time; in the second stage, the temperature is increased to 260-280 DEG C and kept for a fourth time, and finally air-cooled to room temperature.

[0031] The present application adopts the heat treatment technical means of re-controlling full-section induction heating + rapid and continuous air cooling + long-time low-temperature tempering, which is beneficial to the recovery of the performance loss; in the heating process, the induction heating speed is fast, the heating temperature is high, and after being heated to the temperature, appropriate keeping can improve the uniformity of the temperature of each part of the local heating and the fine degree of the organization transformation, increase the temperature gradient per unit distance near the furnace mouth, reduce the excessive buffer zone of the furnace mouth temperature and the gap distance between the furnace mouth and the rail top, and weaken the heat overflow. In the cooling stage, the continuous air cooling and low-temperature tempering further reduce the proportion and area of the generation of austenite and ferrite softening organization, expand the transformation zone of the bainite strong and tough organization, and can be beneficial to the soft zone control. Through the above method, the lost performance of the forged and pressed special-shaped rail heel end can be better recovered, and the heat-affected softening zone can be reasonably controlled.

[0032] The present application combines the process of rapid intermittent continuous cooling after forging and low-temperature long-time staged tempering, by reasonably distributing and accurately controlling the cooling speed and time of different parts, to reduce the martensite, austenite and stress residue, avoid the precipitation of unfavorable organization, further improve the comprehensive mechanical properties of the profile rail heel end such as strength and hardness, reduce the width of the local heat-affected softening zone, improve the quality of the alloy steel profile rail heel end after forging, and prolong the reliability and service life of the profile rail.

[0033] In the present embodiment, step (1) uses a medium-frequency induction furnace to conduct full-face induction heating on the forged profile rail heel end, which not only reduces the temperature stress during the heating process, but also reduces the temperature non-uniformity in the length and height directions of the profile rail, ensuring that the temperature difference is not greater than 50°C, thereby preparing for cooling. During the heating process, the heating speed is slightly faster at low temperatures and slightly slower at high temperatures, which is balanced before and after, and in addition to the stepwise insulation at different temperatures, it is more conducive to the diffusion of heat and internal atomic vibration, reducing the temperature difference of different parts and the thermal expansion and contraction of each part being consistent, thereby facilitating the reduction of temperature stress and temperature non-uniformity.

[0034] In step (1), the heating speed before the temperature rises to 600-650°C is greater than the heating speed after 600-650°C. Preferably, in the present embodiment, 650°C is used as the dividing point, which has the effect of not producing phase change and reducing organizational stress. The principle is that phase change is a change from one organizational structure to another, and the volume, atomic structure arrangement and distribution of the two organizational structures are different, which will cause different degrees of distortion in the metal lattice, leading to different degrees of expansion, shrinkage and other physical property changes, which will produce extrusion, expansion and other effects on the surrounding metal. These microscopic extrusion and expansion distortions gradually accumulate to a certain extent and evolve into a larger stress field, thereby affecting the deformation of the metal. The larger the stress field, the stronger the stress. If no phase change occurs, there is no obvious organizational change, i.e., no obvious increase in organizational stress. At the same time, 650°C can produce microscopic recovery and recrystallization, further reducing organizational stress.

[0035] In step (2), the compressed air cooling is adopted in stages, different cooling air pressures are set for different areas of the forged and pressed end of the profiled rail, which can not only avoid the formation of martensite due to the rapid surface cooling at high temperature and reduce thermal stress, but also generate bainite at medium and low temperatures, reduce the microstructure stress, stabilize austenite at low temperature and improve the comprehensive mechanical properties. The principle is that at high temperature (900-920℃ after discharge), the cooling speed is slightly low, which can inhibit the diffusion of local metal carbon and alloy elements to inhibit the rapid cooling of local metal to the martensite phase change area to generate more martensite, the strength and hardness will be too high, and the toughness will be reduced. The appropriate rapid cooling at medium and low temperature (below 600-800℃) is to inhibit the decomposition of part of austenite into pearlite and other soft phases due to the further inhibition of carbon element and alloy element diffusion at high temperature. Further reducing the cooling speed at low temperature (250-300℃) can not only reduce the temperature stress, but also reduce the possibility of austenite to martensite transformation by increasing the probability of element diffusion.

[0036] In step (3), low-temperature staged tempering is adopted, the end of the profiled rail is put into the heating furnace and heated to 200-240℃, and then held for 60-90min, and then heated to 260-280℃ again, and held for 240-300min, and then discharged and air-cooled to room temperature. Different low-temperature tempering temperatures and holding times are set to further strengthen the matrix by gradually increasing the temperature in stages at different temperatures, which is more conducive to the recovery of micro defects of the metal material, a small amount of carbide is partially precipitated, the comprehensive mechanical properties such as hardness, strength, plasticity and toughness are further improved after tempering, and the recovery temperature is more uniform and complete, which is more conducive to the recovery of the material to the original high-strength wear-resistant and high-toughness characteristics.

[0037] In the embodiment of the present application, in step (1), the temperature is raised to 600-650℃ at a first temperature raising speed in the range of 300-600℃, and the first temperature raising speed is greater than the second temperature raising speed. Preferably, the first temperature raising speed in step (1) is 2.5-3.5℃ / s, and the second temperature raising speed is 1.5-2.5℃ / s. Setting the temperature raising speed in the above range can not only ensure the efficiency of the temperature raising speed, but also appropriately alleviate the organization and thermal stress and inhibit the growth of the organization before phase change to prepare for phase change.

[0038] In the embodiment of the present application, the first holding time in step (1) is 25-35 s, and the second holding time is 20-30 s. Further preferably, the first holding time in step (1) is 30 s, and the second holding time is 20 s. After the temperature is raised to 650 DEG C and held for 30 s, the temperature is raised to 920 DEG C and held for 20 s, and then the furnace is discharged for air blast cooling. This has the effect of homogenizing the temperature and preparing for the structure transformation. If the holding time is less than the above range, the homogenization effect is not obvious. If the holding time is greater than the above range, the structure will gradually coarsen, and the heat-affected zone will gradually widen.

[0039] In the embodiment of the present application, the first blast pressure in step (2) is 0.02-0.05 MPa, the second blast pressure is 0.1-0.15 MPa, and the third blast pressure is 0.05 MPa. The first cooling rate in step (2) is 1-1.5 DEG C / s, the second cooling rate is 1.5-2.5 DEG C / s, and the third cooling rate is 1-1.2 DEG C / s. The blast pressure and the cooling rate in the cooling process are set to the above values to achieve a balance among the strength, hardness, and toughness of the forged special-shaped rail. If the values are higher than the above protective range, the mechanical properties such as hardness and strength are too high, the plasticity and toughness are low, and the comprehensive mechanical properties are deteriorated. If the values are lower than the above protective range, the equipment is damaged, the mechanical properties such as hardness and strength are low, the plasticity and toughness are high, and the comprehensive mechanical properties are also deteriorated.

[0040] In the embodiment of the present application, the third holding time in step (3) is 60-90 min, and the fourth holding time is 240-300 min. In step (3), the first stage of tempering is raised to 200 DEG C, and the second stage is raised to 280 DEG C. Different low-temperature tempering temperatures and holding times are set mainly to gradually raise the temperature in steps at different temperatures, which is more conducive to the recovery of the micro defects of the metal material.

[0041] In the embodiment of the present application, the forged special-shaped rail heel end is heated in an induction heating furnace, as shown in FIGS. 1-3. Figure 1 and Figure 2 As shown in FIGS. 1-3, the forged special-shaped rail heel end 4 is conveyed into the furnace cavity of the induction heating furnace 1 by a mechanism, stopped after a certain distance, connected to the power supply to start heating, raised to a preset temperature, held, and then withdrawn from the furnace cavity of the induction heating furnace 1 to stop. At this time, the air blast cooling device 2 located near the furnace opening and above starts to spray compressed gas downward to continuously cool the locally heated part of the rail in a full-coverage manner. After the cooling temperature is reached, the air blast is stopped and the cooling continues to room temperature. The rail is then reloaded into a box-type resistance furnace for tempering treatment and then air-cooled after being discharged from the furnace. The softening zone 3 is located near the furnace opening of the induction heating furnace 1 and is formed by the local heating of the medium-high temperature induction heating furnace. The forged special-shaped rail heel end has a rail head 5, a rail waist 6, and a rail bottom 7.

[0042] During heating, the heating speed is controlled to be not greater than 2.5-3.5 ℃ / s within 600-650 ℃ to reduce stress, and then the temperature is increased to 900-920 ℃ after holding for about 30 s, at this time, the heating speed is controlled to be about 1.5-2.5 ℃ / s, and holding for 20 s, then the furnace is discharged to perform air cooling, so as to ensure that the structure transformation is sufficient and the temperature in longitudinal and transverse directions is more uniform, and the temperature difference is not greater than 50 ℃, to prepare for cooling. After heating, the profiled rail is withdrawn from the furnace, the compressed air of the air blower is opened to cool the forged head of the profiled rail, and different cooling air pressures are set in different areas of the forged head of the profiled rail during the cooling process, the air pressure of the forming section is about 0.02 MPa, the air pressure of the transition section to the original material heat affected zone section is about 0.05 MPa, and the cooling speed is controlled to be 1-1.5 ℃ / s, so as to avoid a large amount of martensite on the surface and reduce local thermal stress of the surface layer, when the temperature is cooled to 600-800 ℃, the air pressure of the forming section is adjusted to be about 0.1 MPa, the air pressure of the transition section to the original material heat affected zone section is about 0.15 MPa, and the cooling speed is controlled to be 1.5-2.5 ℃ / s, so as to quickly reduce the temperature of the rail head, refine the grains and promote the profiled rail to reach the bainite structure phase change temperature, so as to effectively control the overall cooling of the profiled rail, easily obtain good strength, hardness and reduce the width of the softening zone, when the residual temperature is lower than about 300 ℃, the air pressure is set to be 0.05 MPa before and after, and the cooling speed is controlled to be 0.8-1.2 ℃ / s, and the air cooling is stopped when the temperature is cooled to about 200 ℃, and then the temperature is cooled to room temperature, the process method not only can generate more bainite structure at low temperature, but also can obtain a small amount of martensite structure. After the cooling of the forged head of the profiled rail is completed and the temperature is cooled to room temperature, the profiled rail is placed in a resistance furnace to perform segmented low-temperature tempering, the temperature is increased to 200 ℃ in the tempering furnace, holding for 60-90 min, then the temperature is increased to 280 ℃, holding for 240-300 min, and then the profiled rail is discharged and air cooled to room temperature, and in this way, the residual stress can be gradually eliminated in stages, the excessive precipitation of carbides can be controlled, and the material brittleness can be reduced.

[0043] According to still another aspect of the present application, a 60AT1-60 kg / m forged alloy steel profiled rail is also provided, which is prepared by using the manufacturing method of the 60AT1-60 kg / m forged alloy steel profiled rail, the hardness value of the top surface of the forged alloy steel profiled rail is less than HBW380, the number of soft spots is less than 3, the hardness of the soft zone is between 317-375 HB, and the width is not greater than 30 mm.

[0044] The hardness value of the longitudinal rail head top surface of the alloy steel profile rail heel end after forging is less than HBW380, the number of soft spots (the interval between measuring points is 10 mm) is about 2-3, the hardness of the soft area is between 317-375 HB, the width is not more than 30 mm, the surface hardness except the soft area is between 407-468 HB, the impact absorption energy is not less than 120 J, the tensile strength is in the range of 1343-1477.5 MPa, and the elongation after fracture is between 12.5-14.3%, so that the material performance after forging is effectively restored and improved.

[0045] The following examples more specifically describe the disclosure of the present application, which are only for illustrative purposes.

[0046] Example 1

[0047] The present example provides a manufacturing method of 60AT1-60kg / m forged alloy steel profile rail, comprising the following steps:

[0048] (1) Heating: the full-section of the forged profile rail heel end is heated by using a medium-frequency induction furnace, the temperature is raised to 650℃ at a rate of 2.5℃ / s and then kept for 30s, and then the temperature is raised to 900℃ at a rate of 1.5℃ / s and then kept for 20s, and then the forged profile rail heel end is taken out of the furnace for air cooling;

[0049] (2) Cooling: the forged profile rail heel end after heating is cooled, the temperature is cooled to 800℃ at a rate of 0.02MPa and 1.0℃ / s, then the temperature is cooled to 280℃ at a rate of 0.1MPa and 1.5℃ / s, and then the temperature is cooled to below 200℃ at a rate of 0.05MPa and 1.1℃ / s;

[0050] (3) Tempering: the forged profile rail heel end after cooling is tempered, the temperature is raised to 200℃ in the first stage and kept for 60min, the temperature is raised to 280℃ in the second stage and kept for 240min, and then air cooling is performed to room temperature.

[0051] Example 2

[0052] The present example provides a manufacturing method of 60AT1-60kg / m forged alloy steel profile rail, comprising the following steps:

[0053] (1) Heating: the full-section of the forged profile rail heel end is heated by using a medium-frequency induction furnace, the temperature is raised to 650℃ at a rate of 3.1℃ / s and then kept for 30s, and then the temperature is raised to 900℃ at a rate of 2.2℃ / s and then kept for 20s, and then the forged profile rail heel end is taken out of the furnace for air cooling;

[0054] (2) Cooling: the forged profile rail heel end after heating is cooled, the temperature is cooled to 800℃ at a rate of 0.03MPa and 1.2℃ / s, then the temperature is cooled to 300℃ at a rate of 0.15MPa and 2.5℃ / s, and then the temperature is cooled to below 200℃ at a rate of 0.05MPa and 1.0℃ / s;

[0055] (3) tempering: tempering the forged profiled rail heel end after cooling, the first stage is to heat to 200℃ and keep for 60min; the second stage is to heat to 280℃ and keep for 240min, and finally air cooling to room temperature.

[0056] Example 3

[0057] The present example provides a manufacturing method of 60AT1-60kg / m forged alloy steel profiled rail, comprising the following steps:

[0058] (1) heating: full-section heating of the forged profiled rail heel end is performed by using a medium-frequency induction furnace, heating to 650℃ at a rate of 3.5℃ / s and keeping for 30s, then heating to 900℃ at a rate of 2.5℃ / s and keeping for 20s, and then immediately taken out for air cooling;

[0059] (2) cooling: cooling of the forged profiled rail heel end after heating is performed at 0.05MPa, 1.5℃ / s to 800℃, then at 0.13MPa, 2.2℃ / s to 250℃, and then at 0.05MPa, 1.2℃ / s to below 200℃;

[0060] (3) tempering: tempering of the forged profiled rail heel end after cooling, the first stage is to heat to 200℃ and keep for 60min; the second stage is to heat to 280℃ and keep for 240min, and finally air cooling to room temperature.

[0061] Comparative Example 1

[0062] The present comparative example is basically the same as Example 1, except that:

[0063] the heating process is to heat to 950℃ at a rate of 3.8℃ / s; the cooling process is to cool to 200-250℃ at a rate of 3.6℃ / s; and the tempering process is to heat to 330℃ first, and then to 360℃.

[0064] Comparative Example 2

[0065] The present comparative example is basically the same as Example 1, except that:

[0066] the heating process is to heat to 930℃ at a rate of 2.4℃ / s; the cooling process is to cool to 260-300℃ at a rate of 3.3℃ / s; and the tempering process is to heat to 300℃ first, and then to 330℃.

[0067] Comparative Example 3

[0068] The present comparative example is basically the same as Example 1, except that:

[0069] Heating process to 890℃ at 2.8℃ / s, cooling process to 280-350℃ at 3.8℃ / s, tempering process to 280℃ first, then to 300℃.

[0070] The control parameters in examples 1-3 and comparative examples 1-3 are shown in Table 1.

[0071] Table 1 is the control parameters in examples 1-3 and comparative examples 1-3

[0072]

[0073] According to the technical requirements of TB / T2344.3 "Steel Rail Part 3: Special-shaped Steel Rail" and GB228.1, GB230.1, GB231.1 standards, the tensile strength of the forged and pressed part of the special-shaped rail heel end prepared in examples 1-3 and comparative examples 1-3 is detected, and the detection results are shown in Table 2.

[0074] Table 2 is the performance detection results of the forged and pressed part of the special-shaped rail heel end prepared in examples 1-3 and comparative examples 1-3

[0075]

[0076]

[0077] By comparing examples 1-3 and comparative examples 1-3, it can be seen that the examples 1-3 of the present application have certain influence on the final performance of the special-shaped rail under different heat treatment conditions. The hardness value of the longitudinal rail head surface of the alloy steel special-shaped rail heel end after forging is less than HBW380, and the number of soft spots is about 2-3 (the distance between measuring points is 10mm, as shown in Figure 3 The hardness of the soft zone is between 317 and 375 HB, the width is not more than 30mm, the surface hardness except the soft zone is between 407 and 468 HB, the impact energy is not less than 120J, the tensile strength is in the range of 1352-1477.5MPa, the elongation after fracture is between 12.5 and 14.3%, the tensile strength and impact performance are sampled at the rail head position, the material performance after forging is effectively restored and improved, and the comprehensive mechanical properties are significantly improved.

[0078] Figure 3 In the present application, the hardness detection method of the forged and pressed surface of the special-shaped rail heel end is that the rail top is milled and polished to remove about 1mm at one end of the rail, and the surface Brinell hardness is detected at positions 10mm and 100mm and 10mm away from the end head, respectively. After 600mm away from the end head, the detection interval distance is 10mm, and the detection is continued to 1.5m position, and the heat affected softening zone is distributed at the position where the hardness value is lower than HB380 between 1m and 1.5m.

[0079] The above description is only the preferred embodiment of the present application, and is not intended to limit the present application. The present application can have various changes and modifications for those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method of manufacturing a 60A T1 - 60 kg / m forged alloy steel profiled rail, characterised by, The method comprises the following steps: (1) heating: the full section of the forged profile rail heel end is heated, and the temperature is raised to 600-650 DEG C at a first heating rate, and then the temperature is kept for a first time, and then the temperature is raised to 900-920 DEG C at a second heating rate, and then the temperature is kept for a second time; and the first heating rate is 2.5-3.5 DEG C / s, and the second heating rate is 1.5-2.5 DEG C / s; (2) cooling: the forged profile rail heel end after heating is cooled, and the temperature is cooled to 600-800 DEG C at a first air blowing pressure and a first cooling rate, and then the temperature is cooled to 250-300 DEG C at a second air blowing pressure and a second cooling rate, and then the temperature is cooled to 200-250 DEG C or below at a third air blowing pressure and a third cooling rate; and the first cooling rate is 1-1.5 DEG C / s, the second cooling rate is 1.5-2.5 DEG C / s, and the third cooling rate is 1-1.2 DEG C / s; (3) tempering: the forged profile rail heel end after cooling is tempered, and the temperature is raised to 200-240 DEG C in the first stage, and then kept for a third time, and then the temperature is raised to 260-280 DEG C in the second stage, and then kept for a fourth time, and then air cooled to room temperature.

2. The method of claim 1, wherein the 60AT1 ~ 60kg / m forged and pressed alloy steel profile rail is characterized by, In step (1), the first heating rate is greater than the second heating rate.

3. The manufacturing method of the 60AT1~60kg / m forged alloy steel special-shaped rail according to claim 1, characterized in that, In step (1), the first holding time is 25-35 s, and the second holding time is 15-25 s.

4. The method of claim 3, wherein the 60 AT1 - 60 kg / m forged alloy steel profile rail is manufactured by the steps of: In step (1), the first holding time is 30 s, and the second holding time is 20 s.

5. The manufacturing method of the 60AT1~60kg / m forged alloy steel special-shaped rail according to claim 1, characterized in that, In step (2), the first air blowing pressure is 0.02-0.05 MPa, the second air blowing pressure is 0.1-0.15 MPa, and the third air blowing pressure is 0.05 MPa.

6. The method of claim 1, wherein the 60AT1 ~ 60kg / m forged and pressed alloy steel profile rail is characterized by, In step (3), the third holding time is 60-90 min, and the fourth holding time is 240-300 min.

7. The manufacturing method of the 60AT1~60kg / m forged alloy steel special-shaped rail according to claim 1, characterized in that, In step (3), the first tempering stage is raised to 200 DEG C, and the second tempering stage is raised to 280 DEG C.

8. A 60 AT1 - 60 kg / m forged alloy steel special shaped rail, characterised in that, The forged profile rail is prepared by the method of any one of claims 1-7, wherein the top surface hardness value of the forged profile rail is less than HBW380, the number of soft spots is less than 3, the soft zone hardness is between 317-375 HB, and the width is not greater than 30 mm.

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