Welded connection method for high manganese steel and steel rail

Abstract

The invention provides a welding connection method for high-manganese steel and a steel rail, which comprises the following steps that a transition piece and the steel rail are connected and fixed through flash welding to form a middle piece, and the transition piece is used for connecting a high-manganese steel piece to be welded and the steel rail; normalizing heat treatment is conducted on the middleware, and thermal aging treatment is conducted on the middleware subjected to normalizing heat treatment; and the transition piece and the high manganese steel piece to be welded are connected and fixed through flash welding, so that the high manganese steel piece to be welded and the steel rail are connected and fixed. According to the welding connection method for the high manganese steel and the steel rail, the performance of a final connecting piece product can be effectively improved, internal residual stress of the final connecting piece product is reduced, and the service life of the final connecting piece product is prolonged.

Description

Technical Field

[0001] The invention relates to the technical field of railway turnout manufacturing, in particular to a welding connection method for high manganese steel and a rail. Background Art

[0002] The railroad turnout's frog and other components are usually made of high manganese steel (referring to alloys with a manganese content of more than 10%), and the rails are usually made of carbon steel. The welding between the high manganese steel and the rails needs to be completed using an intermediate transition material. In the process of realizing the present invention, the inventor found that after the high manganese steel and the rails are welded together, cracks will appear in the weld area in about 2 to 5 years. After observation and research, it was found that the cracks are mostly concentrated on the transition material of the connecting medium, and most of the cracks are near the fusion line between the rails and the connecting medium. After analysis, the cause of the crack formation is an intergranular crack along the grain boundary, and the surrounding is accompanied by element segregation. In addition, the combined effect of stress makes stress corrosion cracking prone to occur in the welding medium. Since the high manganese steel flash welding joint is composed of three metals: rail, transition material, and high manganese steel, the three materials have different physical properties and different organizational states. Residual stress will inevitably exist during flash welding. At the same time, the upsetting force borne by the weld area during flash welding will produce mechanical stress. In addition, the temperature at the weld is high during flash welding, and the temperature far away from the weld is low. The temperature difference gradient is large, which will also produce temperature stress. The superposition of these unfavorable conditions will greatly affect the fatigue strength and life of the product, and may also increase the speed of product corrosion. Summary of the invention

[0003] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a welding connection method for high manganese steel and rails to improve the problem of fatigue cracks easily occurring at transition pieces due to material and stress reasons in the prior art.

[0004] To achieve the above object, the technical solution adopted by the present invention is:

[0005] A welding connection method for high manganese steel and rails, comprising the following steps:

[0006] The transition piece is connected and fixed to the steel rail by flash welding to form an intermediate piece, wherein the transition piece is used to connect the high manganese steel piece to be welded and the steel rail;

[0007] Performing normalizing heat treatment on the intermediate part, and performing thermal aging treatment on the intermediate part after the normalizing heat treatment;

[0008] The transition piece and the high manganese steel piece to be welded are connected and fixed by flash welding, so that the high manganese steel piece to be welded and the rail are connected and fixed.

[0009] Furthermore, the rail is made of carbon steel, and the transition piece is made of CrMnN i Mo series austenitic single-phase stainless steel.

[0010] Furthermore, the material of the transition piece is 1Cr 17 Mn 11 Mo2.

[0011] Furthermore, the temperature range of the normalizing heat treatment is 850° C. to 910° C., and the holding time is 1 minute to 3 minutes.

[0012] Furthermore, after the normalizing heat treatment, the intermediate piece is subjected to air cooling, and the air cooling time is 2 minutes to 4 minutes.

[0013] Furthermore, the heat preservation temperature of the thermal aging treatment is 350° C. to 500° C., and the heat preservation time is 3-5 hours.

[0014] Furthermore, the heating rate of the thermal aging treatment is 130°C / h to 170°C / h, and the cooling rate is 100°C to 140°C / h.

[0015] Furthermore, the intermediate piece is subjected to normalizing heat treatment by a normalizing coil.

[0016] Furthermore, before the normalizing heat treatment is performed on the intermediate piece, the excess weld metal of the transition piece is ground and polished.

[0017] Furthermore, after the intermediate piece is subjected to heat aging treatment, the intermediate piece is further ground and polished again.

[0018] According to the technical solution of the present invention, a welding connection method for high manganese steel and rails of the present invention reduces various residual stresses in the transition piece by normalizing heat treatment and heat aging treatment of the intermediate piece formed by the transition piece and the rail, thereby avoiding fatigue cracks in the transition piece or slowing down the speed at which fatigue cracks in the transition piece occur, thereby extending the service life of the high manganese steel flash welding joint. The method is simple, low-cost and has good economic prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is the stress distribution diagram of the rail side of the comparison group.

[0020] Figure 2 This is a stress distribution diagram of a set of rail sides in an experiment of Example 1 of the present invention.

[0021] Figure 3 This is a stress distribution diagram of the rail side of the second group of experiments in Example 2 of the present invention.

[0022] Figure 4This is a stress distribution diagram of the rail side of the third group of experiments in Example 3 of the present invention.

[0023] Figure 5 This is a stress distribution diagram of the rail side of the fourth group of experiments in Example 4 of the present invention.

[0024] Figure 6 This is the stress distribution diagram on the transition piece side of the comparison group.

[0025] Figure 7 This is a stress distribution diagram of a transition piece side in an experiment of Example 1 of the present invention.

[0026] Figure 8 This is a stress distribution diagram of the transition piece side of the second experimental group of embodiment 2 of the present invention.

[0027] Fig. 9 This is a stress distribution diagram of the transition piece side of the third group of experiments in Example 3 of the present invention.

[0028] Fig.10 This is a stress distribution diagram of the transition piece side of the fourth group of experiments in Example 4 of the present invention. DETAILED DESCRIPTION

[0029] In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present invention are given in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0031] A welding connection method for high manganese steel and rails in an embodiment of the present invention can be used for connecting frogs and rails, and can also be used for connecting other high manganese steel components and rails. Since rails are mostly made of carbon steel, the properties of which are quite different from those of high manganese steel, and the thermal expansion coefficients of the two materials are different, if high manganese steel and rails are directly welded and fixed, large internal stress will inevitably be generated, which will affect the welding performance at the welded joint and its service life. Therefore, a transition piece is required to connect and fix the two.

[0032] Specifically, a welding connection method for high manganese steel and rails according to an embodiment of the present invention comprises the following steps:

[0033] S1. Connect and fix the transition piece and the rail by flash welding to form an intermediate piece, which is used to connect the high manganese steel welded piece and the rail. After the intermediate piece is cooled to room temperature, the excess weld can be ground and polished to make its surface smooth.

[0034] Specifically, the embodiment of the present invention adopts CrMnNiMo series austenitic single-phase stainless steel as the material of the transition piece, specifically, for example, 1Cr 17 Mn 11 Mo2. This material is stainless steel with good corrosion resistance and is not prone to grain coarsening and carburization precipitation. At the same time, it also has some physical properties of high manganese steel, which can well realize the connection between high manganese steel and carbon steel rails, which is conducive to extending the service life of the connecting parts.

[0035] S2. Perform normalizing heat treatment on the intermediate piece. The temperature range of normalizing heat treatment is 850℃~910℃, and the holding time is 1 minute to 3 minutes. Specifically, for example, the intermediate piece can be subjected to normalizing heat treatment through a normalizing coil. After normalizing treatment, the intermediate piece is blow-cooled, and the blowing cooling time is 2 minutes to 4 minutes. Perform thermal aging treatment on the intermediate piece after blowing cooling. The holding temperature of thermal aging treatment is 350℃~500℃, and the holding time is 3 hours to 5 hours. The heating rate of thermal aging treatment is 130℃ / h~170℃ / h, and the cooling rate is 100℃ / h~140℃ / h. After the intermediate piece after thermal aging treatment is cooled to room temperature, it can be ground and polished again.

[0036] S3. Connect and fix the transition piece and the high manganese steel piece to be welded by flash welding, so that the high manganese steel piece to be welded and the rail are connected and fixed to form a final connector product.

[0037] Embodiment 1: A welding connection method for high manganese steel and rails in this embodiment comprises the following steps:

[0038] S11, the transition piece and the rail are connected and fixed by flash welding to form an intermediate piece, which is used to connect the high manganese steel welded piece and the rail. After the intermediate piece is welded and cooled to room temperature, the excess weld meat can be ground and polished to make its surface smooth. Specifically, the embodiment of the present invention uses 1Cr 17 Mn 11 Mo2 is used as the material for the transition piece.

[0039] S12. Perform normalizing heat treatment on the middleware through the normalizing coil. The temperature range of normalizing heat treatment is 855℃~875℃, and the holding time is 2 minutes. After normalizing treatment, place the middleware in the wind box for air cooling. After blowing for 2 minutes, place the middleware in the thermal aging furnace for thermal aging treatment. The holding temperature of thermal aging treatment is 340℃~360℃, and the holding time is 4 hours. The heating rate of thermal aging treatment is 130℃ / h, and the cooling rate is 100℃ / h. After the middleware after thermal aging treatment cools to room temperature, it can be ground and polished again.

[0040] S13, connecting and fixing the transition piece and the high manganese steel piece to be welded by flash welding, so that the high manganese steel piece to be welded and the rail are connected and fixed to form a final connecting piece product.

[0041] Example 2: A welding connection method for high manganese steel and rails in this example is similar to the method in Example 1, and the same parts are not repeated here. The difference is:

[0042] S22. Perform normalizing heat treatment on the middleware through the normalizing coil. The temperature range of normalizing heat treatment is 865℃~885℃, and the holding time is 2 minutes. After normalizing treatment, place the middleware in the wind box for air cooling. After blowing for 2 minutes, place the middleware in the thermal aging furnace for thermal aging treatment. The holding temperature of thermal aging treatment is 390℃~410℃, and the holding time is 4 hours. The heating rate of thermal aging treatment is 150℃ / h, and the cooling rate is 120℃ / h. After the middleware after thermal aging treatment cools to room temperature, it can be ground and polished again.

[0043] Embodiment 3: A welding connection method for high manganese steel and rails in this embodiment is similar to the method in Embodiment 1, and the same parts are not repeated here, except that:

[0044] S32. Perform normalizing heat treatment on the middleware through the normalizing coil. The temperature range of normalizing heat treatment is 860℃~880℃, and the holding time is 3 minutes. After normalizing treatment, place the middleware in the wind box for blowing cooling. After blowing for 2 minutes, place the middleware in the thermal aging furnace for thermal aging treatment. The holding temperature of thermal aging treatment is 440℃~460℃, and the holding time is 4 hours. The heating rate of thermal aging treatment is 140℃ / h, and the cooling rate is 110℃ / h. After the middleware after thermal aging treatment cools to room temperature, it can be ground and polished again.

[0045] Example 4: A welding connection method for high manganese steel and rails in this example is similar to the method in Example 1, and the same parts are not repeated here. The difference is:

[0046] S32. Perform normalizing heat treatment on the middleware through the normalizing coil. The temperature range of normalizing heat treatment is 880℃~900℃, and the holding time is 2 minutes. After normalizing treatment, place the middleware in the wind box for air cooling. After blowing for 4 minutes, place the middleware in the thermal aging furnace for thermal aging treatment. The holding temperature of thermal aging treatment is 480℃~500℃, and the holding time is 4 hours. The heating rate of thermal aging treatment is 170℃ / h, and the cooling rate is 140℃ / h. After the middleware after thermal aging treatment cools to room temperature, it can be ground and polished again.

[0047] In order to prove that the welding connection method for high manganese steel and rails in the embodiment of the present invention is truly effective in reducing the stress at the transition piece and improving the mechanical properties at the transition piece, the following test experiments are conducted:

[0048] Experiment 1: Test whether heat treatment has the effect of reducing stress on the final connection product formed by the transition piece and the rail. The specific steps are as follows:

[0049] (1) Grouping the connector products that have been flash welded (including only step S1 and step S3) and the connector products that have been subjected to the heat treatment process of the embodiment of the present invention;

[0050] (2) The connector products that were not subjected to the heat treatment process of the present invention (including only step S1 and step S3 of the welding connection method of the present invention) were marked as the control group, and the connector products formed in Examples 1 to 4 were marked as Experimental Group 1, Experimental Group 2, Experimental Group 3, and Experimental Group 4;

[0051] (3) The connector products of the control group, experimental group 1, experimental group 2, experimental group 3, and experimental group 4 were respectively measured at the same position on the transition piece side and the rail side by using the hole drilling method. The residual stress of the part was calculated based on the elastic theory. The specific data are as follows: Figures 1 to 10 As shown in the figure, the horizontal axis represents different sampling points of a test piece, and the vertical axis represents the stress value corresponding to each point. 1#, 2#, 3#, 4#, 5# and 6# represent a test piece respectively.

[0052] Depend on Figures 1 to 10 It can be seen that the residual stress peak values ​​of the three test pieces of the connecting product in the comparison group at different positions are relatively large, and the fluctuation of the stress value line is relatively obvious; the residual stress peak values ​​of each test piece of the connecting product of Examples 1 to 4 after heat treatment are significantly reduced, the fluctuation of the stress value line is relatively gentle, and the overall distribution of residual stress is relatively even.

[0053] Experiment 2: Test whether the performance of the final connection product formed by heat treatment between the transition piece and the rail is improved compared with the existing products on the transition piece side and the rail side. The specific steps are as follows:

[0054] (1) The connector products of the control group, experimental group 1, experimental group 2, experimental group 3 and experimental group 4 were processed into test pieces for tensile, impact, hardness and metallographic tests according to the same requirements, and their performance was tested. The specific recorded data are shown in the following table:

[0055] Table 1

[0056]

[0057] Table 2

[0058]

[0059]

[0060] It can be seen from Tables 1 and 2 above that the tensile, impact, hardness and other properties of the test pieces after the heat treatment process of the embodiment of the present invention are significantly improved, and the microstructure detection results are all pearlite plus a small amount of ferrite.

[0061] The above two experiments prove that the welding connection method for high manganese steel and rails in the embodiment of the present invention improves the organizational properties and enhances the product quality. It has a positive effect on improving the organizational properties, reducing the stress peak of the welded joint, stabilizing the stress of the welded joint, and improving the stress distribution, and largely solves the cracking problem in the medium area (transition piece area).

[0062] The welding connection method for high manganese steel and rails provided in the embodiment of the present invention has a simple process method and low production cost, and can effectively improve product quality, reduce the stress peak at the product connection joint, improve the organizational properties, and solve the problem of cracking in the transition piece area. It has good economic benefits and can effectively ensure the long-term stable operation of railway facilities.

[0063] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0064] The above embodiments only express the preferred implementation modes of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for those of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A welding connection method for high manganese steel and rails, characterized in that: The following steps are involved: The transition piece is connected and fixed to the steel rail by flash welding to form an intermediate piece, wherein the transition piece is used to connect the high manganese steel piece to be welded and the steel rail; Performing normalizing heat treatment on the intermediate part, and performing thermal aging treatment on the intermediate part after the normalizing heat treatment; The transition piece and the high manganese steel piece to be welded are connected and fixed by flash welding, so that the high manganese steel piece to be welded and the rail are connected and fixed.

2. The welding connection method for high manganese steel and rail according to claim 1, characterized in that: The rail is made of carbon steel, and the transition piece is made of CrMnNiMo austenitic single-phase stainless steel.

3. The welding connection method for high manganese steel and rail according to claim 2, characterized in that: The material of the transition piece is 1Cr 17 Mn5Ni 11 Mo2.

4. The welding connection method for high manganese steel and rail according to claim 1, characterized in that: The temperature range of the normalizing heat treatment is 850° C. to 910° C., and the holding time is 1 to 3 minutes.

5. The welding connection method for high manganese steel and rail according to claim 4, characterized in that: After the normalizing heat treatment, the intermediate piece is further subjected to air cooling, and the air cooling time is 2 minutes to 4 minutes.

6. The welding connection method for high manganese steel and rail according to claim 1, characterized in that: The heat preservation temperature of the heat aging treatment is 350° C. to 500° C., and the heat preservation time is 3 to 5 hours.

7. The welding connection method for high manganese steel and rail according to claim 6, characterized in that: The heating rate of the thermal aging treatment is 130°C / h to 170°C / h, and the cooling rate is 100°C / h to 140°C / h.

8. The welding connection method for high manganese steel and rail according to claim 1, characterized in that: The intermediate piece is subjected to normalizing heat treatment by a normalizing coil.

9. The welding connection method for high manganese steel and rail according to claim 1, characterized in that: Before the intermediate piece is subjected to normalizing heat treatment, the method also includes grinding and polishing the excess weld metal of the transition piece.

10. The welding connection method for high manganese steel and rail according to claim 1, characterized in that: After the intermediate piece is subjected to heat aging treatment, the intermediate piece is further ground and polished again.

Images