A welding electrode for repairing high manganese steel forks

Abstract

This invention provides a welding electrode for repairing high-manganese steel frog welding, comprising a core and a flux coating on the core surface. The flux, by weight percentage, comprises: marble 30-40%, fluorite 4-8%, silica fume 2-5%, metallic manganese 25-45%, rutile 3-8%, soda ash 0.5-1%, chromium powder 5-10%, molybdenum powder 2-5%, nickel powder 3-6%, graphite 1-3%, and calcined mica 1-3%. The core, by weight percentage, comprises: C≤0.10%, Mn: 0.40-0.65%, Si≤0.030%, S≤0.030%, P≤0.030%, Cr≤0.20%, Ni≤0.30%, and Cu≤0.20%. This invention achieves excellent comprehensive mechanical properties by adjusting the appropriate content of different alloying elements and ensures that the room temperature microstructure of the weld metal is austenitic.

Description

Technical Field

[0001] This invention belongs to the field of welding materials technology, and in particular relates to a welding electrode for repairing high manganese steel fork welds. Background Technology

[0002] With the rapid development of my country's railways, railway operating speeds are constantly increasing, and operating density is also constantly rising, placing increasingly higher demands on the quality of railway tracks. As a crucial structural component of the rails, the quality of frogs is a significant factor affecting railway development; therefore, even higher quality requirements are placed on frogs.

[0003] Railway frogs are mostly made of high-manganese steel. However, during service, these high-manganese steel frogs are prone to defects such as surface wear, cracks, spalling, collapse, and crushing, requiring welding repair. Therefore, quality requirements need to be placed on the welding materials, which must possess not only a certain degree of wear resistance, hardness, and crack resistance, but also high strength and toughness. However, in existing technologies, the tensile strength and elongation after fracture of welding electrodes used for frog repair are relatively low. Summary of the Invention

[0004] In view of this, the present invention aims to overcome the defects in the prior art and proposes a welding electrode and welding method for welding repair of high manganese steel turnouts.

[0005] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0006] In a first aspect, the present invention provides a welding electrode for welding repair of high manganese steel turnouts, wherein the welding electrode of the present invention comprises a welding core and a powder coating on the surface of the welding core;

[0007] The powder, by mass percentage, is composed of the following: marble 30-40%, fluorite 4-8%, silica powder 2-5%, metallic manganese 25-45%, rutile 3-8%, soda ash 0.5-1%, chromium powder 5-10%, molybdenum powder 2-5%, nickel powder 3-6%, graphite 1-3%, and calcined mica 1-3%.

[0008] The core material, by mass percentage, is composed of the following: C≤0.10%, Mn 0.40-0.65%, Si≤0.030%, S≤0.030%, P≤0.030%, Cr≤0.20%, Ni≤0.30%, Cu≤0.20%, with the balance being Fe.

[0009] The weld metal of the welding electrode used for welding repair of high manganese steel fork comprises the following components by weight percentage: C 0.15-0.35%, Mn 12.0-18.0%, Cr 3.0-5.0%, Ni 2.0-5.0%, Mo 1.0-2.0%, Si≤0.30%, S≤0.020%, P≤0.030%, with the balance being Fe and unavoidable impurities.

[0010] Among them, carbon (C) is a strong austenitizing element: C atoms exist as interstitial atoms in austenite, and are a stabilizing austenite element. They play a significant role in solid solution strengthening, enhancing the strength of the austenite matrix, improving the low-temperature deformation stability of the weld structure, and increasing the strength of the weld metal. Low C content will result in the weld hardness failing to meet the requirements, while excessively high C content can easily lead to weld embrittlement and cracking.

[0011] Manganese (Mn) is an austenitizing element that can form an infinite substitution solid solution in austenite, providing solid solution strengthening. When combined with other alloying elements such as carbon (C) and nickel (Ni), manganese can help maintain the stability of austenite up to room temperature. Excessive manganese content reduces tensile strength and yield strength, while insufficient manganese content fails to guarantee the retention of a fully austenitic structure at room temperature. Therefore, it is necessary to control the manganese content appropriately.

[0012] The addition of chromium (Cr) distorts the austenite lattice, resulting in solid solution strengthening. It also promotes the precipitation of carbides within the austenite matrix, leading to second-phase strengthening. Furthermore, the addition of Cr enhances the corrosion resistance of high-manganese steel.

[0013] Mo is an austenitizing element that helps improve the growth tendency of dendrites and significantly improves the morphology, quantity and distribution of carbides, making it easier to obtain a deeper hardening depth.

[0014] In high-manganese steel, silicon acts as a deoxidizer, playing a role in solid solution strengthening and improving yield strength. However, excessive silicon content can easily cause high-manganese steel to form coarse grains, which has an adverse effect on mechanical properties.

[0015] Preferably, the weld metal has a tensile strength ≥750MPa, elongation after fracture ≥40%, room temperature impact energy ≥70J, and Brinell hardness ≥200HBW.

[0016] Secondly, the present invention also provides a welding method for welding high manganese steel fork weld repair using the above-mentioned welding rod, including the following steps: 1) no preheating before welding, the interpass temperature is 90-100℃; 2) welding is performed using shielded metal arc welding, the welding current is 120A-160A, and the welding speed is 2.5-5.5mm / s.

[0017] Compared with the prior art, the present invention has the following advantages:

[0018] (1) The welding electrode for repairing high-manganese steel turnouts described in this invention has reduced C and Mn content in its deposited metal, while adding elements such as Cr, Mo, and Ni. Since the effects of alloying elements on the mechanical properties of materials are significantly interactive, this invention achieves excellent comprehensive mechanical properties by adjusting the appropriate content of different alloying elements, and ensures that the room temperature microstructure of the electrode deposited metal is austenitic.

[0019] (2) The high manganese steel forging welding electrode of the present invention has the interaction and influence of various alloying elements in the weld metal, which ensures high hardness and excellent comprehensive mechanical properties, with tensile strength ≥750MPa, elongation after fracture ≥40%, room temperature impact energy ≥70J, and Brinell hardness ≥200HBW. Detailed Implementation

[0020] Unless otherwise defined, the technical terms used in the following embodiments have the same meaning as commonly understood by those skilled in the art to which this invention pertains. Unless otherwise specified, the experimental reagents used in the following embodiments are conventional biochemical reagents; and the experimental methods described are conventional methods.

[0021] The invention will be described in detail below with reference to specific embodiments.

[0022] Example 1

[0023] A welding electrode for repairing high manganese steel turnouts includes a core and a coating of flux powder on the surface of the core.

[0024] The powder, by weight percentage, is composed of the following: marble 35%, fluorite 6.5%, silica fume 2%, metallic manganese 32%, rutile 5%, soda ash 0.8%, chromium powder 8%, molybdenum powder 3%, nickel powder 4.5%, graphite 1.2%, and calcined mica 2%.

[0025] The core material, by mass percentage, is composed of the following: C 0.075%, Mn 0.48%, Si 0.025%, S 0.005%, P 0.012%, Cr 0.035%, Ni 0.023%, Cu 0.018%, with the balance being Fe.

[0026] Welding method: Welding current 150A, interpass temperature 90-100℃, welding speed 2.8mm / s.

[0027] The weld metal of the electrode, by mass percentage, is composed of the following: C 0.17%, Mn 13.21%, Cr 4.82%, Ni 4.43%, Mo 1.73%, Si 0.12%, S 0.005%, P 0.015%, with the remainder being Fe and unavoidable impurities.

[0028] Mechanical properties of the deposited metal: tensile strength 795MPa, elongation after fracture 40%, room temperature impact energy 82J, hardness 216HBW.

[0029] Example 2

[0030] A welding electrode for repairing high manganese steel turnouts includes a core and a coating of flux powder on the surface of the core.

[0031] The powder, by weight percentage, is composed of the following: marble 30%, fluorite 5%, silica fume 2%, metallic manganese 43%, rutile 3%, soda ash 1%, chromium powder 6.5%, molybdenum powder 2%, nickel powder 3%, graphite 3%, and calcined mica 1.5%.

[0032] The core material, by mass percentage, is composed of the following: C 0.075%, Mn 0.48%, Si 0.025%, S 0.005%, P 0.012%, Cr 0.035%, Ni 0.023%, Cu 0.018%, with the balance being Fe.

[0033] Welding method: Welding current 140A, interpass temperature 90-100℃, welding speed 3.8mm / s.

[0034] The composition of the electrode deposited metal by mass percentage is as follows: C 0.32%, Mn 17.26%, Cr 3.75%, Ni 2.78%, Mo 1.23%, Si 0.12%, S 0.005%, P 0.014%, with the remainder being Fe and unavoidable impurities.

[0035] Mechanical properties of the deposited metal: tensile strength 819 MPa, elongation after fracture 43.5%, room temperature impact energy 90 J, hardness 224 HBW.

[0036] Example 3

[0037] A welding electrode for repairing high manganese steel turnouts includes a core and a coating of flux powder on the surface of the core.

[0038] The powder, by weight percentage, is composed of the following: marble 32%, fluorite 4%, silica fume 2%, metallic manganese 38%, rutile 6%, soda ash 0.5%; chromium powder 7%, molybdenum powder 2.5%, nickel powder 3.5%, graphite 2.5%, and calcined mica 2%.

[0039] The core material, by mass percentage, is composed of the following: C 0.075%, Mn 0.48%, Si 0.025%, S 0.005%, P 0.012%, Cr 0.035%, Ni 0.023%, Cu 0.018%, with the balance being Fe.

[0040] Welding method: Welding current 160A, interpass temperature 90-100℃, welding speed 3.8mm / s.

[0041] The weld metal of the electrode, by mass percentage, is composed of the following: C 0.24%, Mn 15.93%, Cr 4.18%, Ni 3.11%, Mo 1.47%, Si 0.14%, S 0.004%, P 0.015%, with the remainder being Fe and unavoidable impurities.

[0042] Mechanical properties of the deposited metal: tensile strength 806 MPa, elongation after fracture 42%, room temperature impact energy 85 J, hardness 229 HBW.

[0043] Comparative Example 1

[0044] A welding electrode for repairing high manganese steel turnouts includes a core and a coating of flux powder on the surface of the core.

[0045] The powder, by weight percentage, is composed of the following: marble 28%, fluorite 3%, silica fume 3%, metallic manganese 36%, rutile 2%, soda ash 1%, chromium powder 12%, molybdenum powder 5.5%, nickel powder 3.8%, graphite 4.5%, and calcined mica 1.2%.

[0046] The core material, by mass percentage, is composed of the following: C 0.075%, Mn 0.48%, Si 0.025%, S 0.005%, P 0.012%, Cr 0.035%, Ni 0.023%, Cu 0.018%, with the balance being Fe.

[0047] Welding method: Welding current 160A, interpass temperature 90-100℃, welding speed 3.0mm / s.

[0048] The weld metal of the electrode, by mass percentage, is composed of the following: C 0.48%, Mn 15.42%, Cr 5.71%, Ni 3.29%, Mo 2.78%, Si 0.24%, S 0.005%, P 0.017%, with the remainder being Fe and unavoidable impurities.

[0049] Mechanical properties of the deposited metal: tensile strength 837MPa, elongation after fracture 30%, room temperature impact energy 60J, hardness 175HBW.

[0050] Comparative Example 2

[0051] A welding electrode for repairing high manganese steel turnouts includes a core and a coating of flux powder on the surface of the core.

[0052] The powder, by weight percentage, is composed of the following: marble 25%, fluorite 5%, silica powder 2%, metallic manganese 55%, rutile 3%, soda ash 1%, chromium powder 3%, molybdenum powder 1.5%, nickel powder 1.5%, and calcined mica 3%.

[0053] The core material, by mass percentage, is composed of the following: C 0.075%, Mn 0.48%, Si 0.025%, S 0.005%, P 0.012%, Cr 0.035%, Ni 0.023%, Cu 0.018%, with the balance being Fe.

[0054] Welding method: Welding current 160A, interpass temperature 90-100℃, welding speed 3.0mm / s.

[0055] The composition of the electrode deposited metal by mass percentage is as follows: C 0.066%, Mn 22.26%, Cr 1.30%, Ni 1.3%, Mo 0.75%, Si 0.32%, S 0.004%, P 0.015%, with the remainder being Fe and unavoidable impurities.

[0056] Mechanical properties of the deposited metal: tensile strength 694 MPa, elongation after fracture 20%, room temperature impact energy 77 J, hardness 168 HBW.

[0057] Table 1 shows a comparison of the mechanical properties of Examples 1-3 and Comparative Examples 1-2:

[0058] Table 1 Mechanical Properties

[0059] project Tensile strength (MPa) Elongation after fracture % Impact energy J Hardness HBW Example 1 795 40 82 216 Example 2 819 43.5 90 224 Example 3 806 42 85 229 Comparative Example 1 837 30 60 255 Comparative Example 2 694 20 77 168

[0060] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A welding electrode for repairing high-manganese steel frogs, characterized in that: This includes the core material and the flux coating on the surface of the core material; The powder, by weight percentage, is composed of the following: marble 30-40%, fluorite 4-8%, silica fume 2-5%, metallic manganese 25-45%, rutile 3-8%, soda ash 0.5-1%, chromium powder 5-10%, molybdenum powder 2-5%, nickel powder 3-6%, graphite 1-3%, and calcined mica 1-3%. The core material, by mass percentage, is composed of the following: C≤0.10%, Mn 0.40-0.65%, Si≤0.030%, S≤0.030%, P≤0.030%, Cr≤0.20%, Ni≤0.30%, Cu≤0.20%, with the balance being Fe.

2. The welding electrode for repairing high-manganese steel frog welding according to claim 1, characterized in that: The weld metal of the high-manganese steel fork welding repair electrode comprises the following components by weight percentage: C 0.15-0.35%, Mn 12.0-18.0%, Cr 3.0-5.0%, Ni 2.0-5.0%, Mo 1.0-2.0%, Si≤0.30%, S≤0.020%, P≤0.030%, with the balance being Fe and unavoidable impurities.

3. The welding electrode for repairing high-manganese steel frog welding according to claim 2, characterized in that: The tensile strength of the welded metal is ≥750MPa, the elongation after fracture is ≥40%, the room temperature impact energy is ≥70J, and the Brinell hardness is ≥200HBW.

4. The welding electrode for repairing high-manganese steel frog welding according to claim 1, characterized in that: The powder, by mass percentage, is composed of the following: 32-38% marble, 4-7% fluorite, 2-3% silica powder, 30-40% metallic manganese, 3-6% rutile, 0.5-1% soda ash, 6-8% chromium powder, 2-3% molybdenum powder, 3-4.5% nickel powder, 1-3% graphite, and 1-2% calcined mica.

5. A welding method using welding electrodes for welding repairs of high-manganese steel turnouts according to any one of claims 1-4, characterized in that: The steps include: 1) No preheating before welding, with an interpass temperature of 90-100℃; 2) Welding is performed using shielded metal arc welding with a welding current of 120A-160A and a welding speed of 2.5-5.5mm / s.