A welding process of Mn18Cr2 austenitic high manganese wear-resistant steel and 45 steel

Abstract

The application discloses a welding process of Mn18Cr2 austenitic high-manganese wear-resistant steel and 45 steel, which comprises the following steps: welding preparation, differential partition preheating only for the 45 steel at 150-200 DEG C, transition layer TIG welding (ER310 welding wire, interlayer temperature is less than or equal to 80 DEG C), filling and cover layer welding (ERMn18Cr2 solid welding wire, multi-layer and multi-pass, combined with segmented back welding and symmetrical welding, interlayer temperature is less than or equal to 80 DEG C), air cooling and hammering or shot peening strengthening after welding, so that the hardness of the welding seam reaches HRC45-HRC55, and visual inspection and penetration inspection are adopted to accept the welding seam. The process solves the problems of temperature control conflict, organization deterioration and crack sensitivity in the welding of dissimilar steels, improves the strength and toughness of the joint, simplifies the operation and controls the cost, and is suitable for repeated load working conditions of pressing and rolling dies and is convenient for large-scale popularization.

Description

Technical Field

[0001] This invention belongs to the field of welding technology, specifically relating to a welding process for Mn18Cr2 austenitic high-manganese wear-resistant steel and No. 45 steel, applicable to dissimilar metal welding of austenitic high-manganese wear-resistant steel and carbon structural steel. Background Technology

[0002] Currently, some rolling dies employ a dissimilar metal composite structure design. For example, the body is made of 45# steel, while the rolling contact surface uses Mn18Cr2 austenitic high-manganese wear-resistant steel. The two need to be reliably connected through welding to meet the requirements of the die under repeated load conditions. The problem is that although a basic welding process framework has been established, the fundamental differences in the physicochemical properties between Mn18Cr2 austenitic high-manganese wear-resistant steel and 45# steel mean that welding quality control still faces multiple technical bottlenecks, specifically as follows:

[0003] (1) The inherent conflict in temperature control requirements makes the technical contradictions difficult to reconcile. The welding characteristics of Mn18Cr2 steel require rapid cooling to suppress the precipitation of brittle carbides in the heat-affected zone of austenite and avoid a significant decrease in the toughness of the material; while 45 steel, due to its high carbon content, requires slow cooling measures after welding to reduce the tendency of martensitic hardening and prevent cold cracking. This temperature control conflict of "one end requires rapid cooling and the other end requires slow cooling" is difficult to coordinate and balance through conventional welding processes, becoming the primary bottleneck restricting the welding quality of the two dissimilar metals.

[0004] (2) The joint structure is severely deteriorated, and the mechanical properties are poorly matched. Under the action of welding thermal cycling, a complex transition layer is formed in the joint area, which leads to the deterioration of the structure of the heat-affected zone of both materials: the heat-affected zone of Mn18Cr2 steel is prone to grain coarsening, accompanied by carbide precipitation, which causes obvious embrittlement (manifested as a sharp increase in Brinell hardness and a decrease in impact toughness of more than 50%); the heat-affected zone of 45 steel is prone to the formation of hardened martensite structure, and the plasticity and impact resistance are significantly reduced. Ultimately, the key mechanical properties such as strength and toughness of the welded joint are far lower than the standard of the base material, making it difficult to meet the long-term use requirements of the mold under heavy load conditions.

[0005] (3) Extremely high sensitivity to cracks and significant difficulty in defect control. Two factors lead to frequent crack defects during welding, making control extremely difficult: On the one hand, the linear expansion coefficient of Mn18Cr2 steel is 1.6 times that of low carbon steel, while its thermal conductivity is only 1 / 6 of that of low carbon steel. When welded with No. 45 steel, it is prone to generate huge thermal stress. Combined with the influence of impurities such as S and P in the material, it is very easy to generate crystallization cracks and liquefaction cracks in key parts such as the weld center and fusion line; On the other hand, the high hardening tendency of No. 45 steel interacts with the welding residual stress, which easily induces cold cracks and delayed cracks. Existing measures such as hammering stress relief and hydrogen removal treatment can only partially alleviate the problem. The crack detection rate remains at a high level, which seriously affects the reliability of the welded joint.

[0006] (4) Insufficient process stability limits large-scale promotion. Existing welding processes have stringent requirements for parameter accuracy. For example, interpass temperature fluctuations of only ±10℃ can cause welding defects. Moreover, the process effect is significantly affected by factors such as workpiece thickness and welding position, resulting in large performance dispersion of welded parts and poor consistency of weld surface quality in actual production.

[0007] In addition, although innovative technologies such as thermo-coupling can improve joint performance to some extent, they require specialized equipment such as zoned temperature control devices and synchronous forging mechanisms, which result in high investment costs and complex operating procedures. This makes it difficult to promote and apply these technologies in enterprises and conventional production scenarios, thus limiting the large-scale implementation of this type of dissimilar metal welding technology.

[0008] In summary, existing technologies are insufficient to achieve high-quality, low-cost welding of Mn18Cr2 austenitic high-manganese wear-resistant steel with No. 45 steel. There is an urgent need to design a dedicated welding process that balances economy, safety, and reliability to ensure that the welded joint can meet the requirements for repeated use and to solve the technical problems in actual production. Summary of the Invention

[0009] This invention provides a welding process for Mn18Cr2 austenitic high-manganese wear-resistant steel and No. 45 steel. It effectively solves practical production problems encountered in existing dissimilar metal welding processes, such as the inherent conflict between rapid and slow cooling temperature control, mismatched mechanical properties due to weld joint microstructure deterioration, high crack sensitivity and difficulty in defect control, insufficient stability of existing processes, and limitations on large-scale application. Through innovative welding processes and parameter optimization, reliable welding of the two dissimilar metals is achieved, significantly improving the strength, toughness, and other key mechanical properties of the weld joint, reducing the incidence of defects such as cracks, simplifying the operation process, controlling production costs, avoiding high investment in specialized equipment, and ensuring that the weld joint can meet the long-term use requirements under repeated load conditions of the rolling die. This promotes the large-scale implementation of this type of dissimilar metal welding technology in conventional production scenarios and enterprises.

[0010] The technical solution of this invention to solve the technical problem is as follows:

[0011] This invention provides a welding process for Mn18Cr2 austenitic high-manganese wear-resistant steel and No. 45 steel, used to weld the rolled contact surface of Mn18Cr2 austenitic high-manganese wear-resistant steel onto the No. 45 steel body. The welding process includes:

[0012] S1. Preparations before welding;

[0013] S1.1 Welding equipment and welding materials: A welding machine that can be used for both manual argon arc welding and shielded metal arc welding is adopted. The transition layer material is Φ2.4mm ER310 austenitic stainless steel welding wire, and the filler layer and cover layer material is Φ2.0mm or Φ2.4mm ERMn18Cr2 solid welding wire.

[0014] S1.2 Pre-treatment of weldments: The oil and moisture on the contact surfaces of the 45# steel body and the Mn18Cr2 austenitic high manganese wear-resistant steel are removed by flame baking, and then mechanically ground until the metal luster is exposed. Then, the contact surfaces of the 45# steel body and the Mn18Cr2 austenitic high manganese wear-resistant steel are machined to form bevels. The bevels are then joined to form the weld joint, ensuring that the bevel angle and gap meet the fusion requirements.

[0015] S1.3 Welding position and welding requirements: Horizontal rotary welding 1G, the weld overlay and the base material need to be fully fused, the weld is free of defects such as cracks, porosity, and lack of fusion, and the dimensions meet the design standards;

[0016] S1.4. Based on the welding equipment, the material of the workpiece, the welding materials, and the welding requirements, formulate the welding process parameters;

[0017] S2, Welding implementation;

[0018] S2.1 Differentiated zone preheating: Preheating is only applied to one side of the 45# steel body, and the preheating temperature is controlled at 150-200℃. No preheating treatment is applied to the Mn18Cr2 austenitic high manganese wear-resistant steel side.

[0019] S2.2, TIG welding of the filter layer: The transition layer is welded using a Φ2.4mm ER310 austenitic stainless steel welding wire on a dual-purpose welding machine for manual TIG welding and shielded metal arc welding. The welding parameters are controlled as follows: welding current 100~140A, arc voltage 10~14V, wire feed speed 1.0~1.5m / min, welding speed 8~12cm / min; the temperature is controlled throughout the welding process, and the interpass temperature does not exceed 80℃.

[0020] S2.3 Welding of Filler and Cover Layers: After the filter layer is inspected and found to be defect-free, the filler and cover layers are welded using a dual-purpose manual argon arc welding and shielded metal arc welding machine with Φ2.0mm or Φ2.4mm ERMn18Cr2 solid welding wire. During filling, a multi-layer, multi-pass welding process is adopted, with a weld overlap ratio of 30-50%. After each layer is welded, the weld slag is cleaned and defects are checked, and the interpass temperature is continuously controlled to not exceed 80℃. The welding method adopts a combination of segmented back-welding and symmetrical welding. The cover layer is ensured to be fully formed and smoothly transitioned to the base material.

[0021] S2.4 Post-weld treatment and flaw detection: After welding, the weld should be immediately air-cooled to room temperature. Light hammering or shot peening should be applied to strengthen the weld so that the weld hardness reaches HRC45-55. The finished product is inspected by a combination of visual inspection and penetrant testing. Magnetic particle testing is abandoned. After passing the inspection, the product is put into use.

[0022] Furthermore, the welding equipment is a Panasonic YC-400TX4 dual-purpose welding machine for both manual argon arc welding and shielded metal arc welding.

[0023] Furthermore, during the pretreatment, the oil and moisture are baked off using an oxy-acetylene flame, and then mechanically polished with sandpaper or a grinding wheel until a metallic luster is exposed.

[0024] Furthermore, during the differentiated zone preheating, only one side of the 45# steel body is preheated with an oxy-acetylene flame.

[0025] Compared with existing technologies, the welding process of Mn18Cr2 austenitic high-manganese wear-resistant steel and No. 45 steel described in this invention has the following beneficial effects:

[0026] (1) Significantly reduce production costs: This welding process uses domestic ER310 and ERMn18Cr2 welding wires, which can reduce material costs by more than 40%, eliminate welding defect rate and reduce rework losses. Combined with efficient welding parameter design (welding speed 8-12cm / min), production efficiency can be increased by about 50%, and the welding time per unit product can be shortened by 30%.

[0027] (2) Extend the service life of equipment: The excellent wear resistance and crack resistance of the weld seam extend the maintenance cycle of the welded components by 2-3 times, reduce the number of downtime maintenance and reduce maintenance costs.

[0028] (3) Promote technological autonomy and industrial upgrading: This welding process breaks through the technical barriers of welding dissimilar metals such as high manganese steel and medium carbon steel, fills the technological gap in related fields in China, and its innovative processes such as differentiated preheating and transition layer can provide reference for welding similar dissimilar steels. Attached Figure Description

[0029] Figure 1This is a schematic diagram of welding Mn18Cr2 austenitic high manganese wear-resistant steel to No. 45 steel according to this application;

[0030] In the figure: 1. The body of No. 45 steel; 2. The weld joint; 3. The rolled contact surface of Mn18Cr2 austenitic high manganese wear-resistant steel. Detailed Implementation

[0031] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Unless otherwise defined, the technical or scientific terms used herein should have the ordinary meaning understood by those skilled in the art to which this disclosure pertains. The terms "upper," "lower," "left," "right," "front," and "back" used in the present patent application specification and claims are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship also changes accordingly. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Any aspects not detailed in this invention are well-known to those skilled in the art.

[0032] Example 1

[0033] like Figure 1 As shown, this invention provides a welding process for Mn18Cr2 austenitic high-manganese wear-resistant steel and No. 45 steel, used to weld the rolled contact surface 3 of Mn18Cr2 austenitic high-manganese wear-resistant steel onto the No. 45 steel body 1. The welding process includes:

[0034] S1. Preparations before welding;

[0035] S1.1 Welding equipment and welding materials: Panasonic YC-400TX4 dual-purpose welding machine for manual TIG welding and shielded metal arc welding is used. The transition layer material is Φ2.4mm ER310 austenitic stainless steel welding wire. The high chromium and nickel content of this welding wire can effectively buffer the dilution of dissimilar base metal alloy elements and inhibit embrittlement caused by carbon migration. The filler layer and cover layer materials are Φ2.0mm or Φ2.4mm ERMn18Cr2 solid welding wire.

[0036] S1.2 Pre-treatment of weldment: The weldment consists of a 45 steel body 1, a weld joint 2, and a rolled contact surface 3 of Mn18Cr2 austenitic high manganese wear-resistant steel. The oil and moisture in the areas to be welded on the 45 steel body 1 and the rolled contact surface 3 of Mn18Cr2 austenitic high manganese wear-resistant steel are baked off by an oxy-acetylene flame. Then, the areas to be welded are mechanically ground with sandpaper or a grinding wheel until the metal luster is exposed to remove the oxide layer and rust, ensuring the cleanliness of the welding interface. Then, the areas to be welded on the 45 steel body 1 and the rolled contact surface 3 of Mn18Cr2 austenitic high manganese wear-resistant steel are machined to form bevels. The bevels are then joined to form the weld joint 2, ensuring that the bevel angle and gap meet the fusion requirements.

[0037] S1.3 Welding position and welding requirements: Horizontal rotary welding 1G, the weld overlay and the base material need to be fully fused, the weld is free of defects such as cracks, porosity, and lack of fusion, and the dimensions meet the design standards;

[0038] S1.4. Based on the welding equipment, the material of the workpiece, the welding materials, and the welding requirements, formulate the welding process parameters;

[0039] TIG welding process parameters

[0040] Welding current (A) Welding voltage (V) Wire feeding speed (m / min) Welding speed (cm / min) Interlayer temperature (°C) Single layer thickness (mm) 100-140 (DCEN) 10-14 1.0-1.5 8-12 ≤80 (forced cooling) 1.5-2.5

[0041] S1.5 Auxiliary equipment: Equipped with an oxy-acetylene flame heating device (for cleaning and preheating), angle grinder, file, hammer, flat chisel, welding mask, template, thermometer, magnifying glass and insulation cotton;

[0042] S2, Welding implementation;

[0043] S2.1 Differentiated zone preheating: Only one side of the 45# steel body is preheated, and the preheating temperature is controlled at 150-200℃ to match the cold crack prevention requirements of medium carbon steel. The Mn18Cr2 austenitic high manganese wear-resistant steel is not preheated on one side, as its solution-treated welding performance is excellent, and overheating is avoided to avoid affecting wear resistance.

[0044] S2.2, TIG welding of the filter layer: The transition layer is welded using a YC-400TX4 dual-purpose manual TIG welding and shielded metal arc welding machine with Φ2.4mm ER310 austenitic stainless steel welding wire. This transition layer blocks the carbon migration path and avoids the formation of a hard and brittle structure in the fusion zone. The welding parameters are controlled as follows: welding current 100~140A, arc voltage 10~14V, wire feed speed 1.0~1.5m / min, welding speed 8~12cm / min. Forced cooling measures are used throughout the welding process to ensure the stability of the structure, such as air cooling or other cooling methods. The temperature is monitored in real time by a thermometer, and the interpass temperature does not exceed 80℃.

[0045] S2.3 Welding of Filler and Cover Layers: After the filter layer is inspected and found to be defect-free, the filler and cover layers are welded using a YC-400TX4 manual TIG welding and shielded metal arc welding machine with Φ2.0mm or Φ2.4mm ERMn18Cr2 solid welding wire. During filling, a multi-layer, multi-pass welding process is adopted, with a weld overlap ratio of 30-50%. After each layer is welded, the weld slag is cleaned and defects are checked, and the interpass temperature is continuously controlled to not exceed 80℃. The welding method adopts a combination of segmented back welding and symmetrical welding to reduce residual stress concentration. The cover layer is ensured to be fully formed and smoothly transitioned to the base material.

[0046] S2.4 Post-weld treatment and flaw detection: After welding, immediately air-cool to room temperature, and perform light hammering or shot peening to strengthen the weld, so that the weld hardness reaches HRC45~55, matching the wear resistance requirements of Mn18Cr2 steel; the finished product is inspected for quality by a combination of visual inspection and penetrant testing, and magnetic particle testing is abandoned (because Mn18Cr2 steel is non-magnetic, magnetic particle testing is prohibited). After passing the inspection, it is put into use.

Claims

1. A welding process for Mn18Cr2 austenitic high-manganese wear-resistant steel and No. 45 steel, used for welding the rolled contact surface (3) of Mn18Cr2 austenitic high-manganese wear-resistant steel onto the No. 45 steel body (1), characterized in that, The welding process includes: S1. Preparations before welding; S1.1 Welding equipment and welding materials: A welding machine that can be used for both manual argon arc welding and shielded metal arc welding is adopted. The transition layer material is Φ2.4mm ER310 austenitic stainless steel welding wire, and the filler layer and cover layer material is Φ2.0mm or Φ2.4mm ERMn18Cr2 solid welding wire. S1.2, Pre-treatment of weldment: The oil and water in the contact area (3) of the 45 steel body (1) and the Mn18Cr2 austenitic high manganese wear-resistant steel are removed by flame baking, and then mechanically ground until the metal luster is exposed. Then, the bevels are machined in the contact area (3) of the 45 steel body (1) and the Mn18Cr2 austenitic high manganese wear-resistant steel. The bevels are then joined to form the weld joint (2), ensuring that the bevel angle and gap meet the fusion requirements. S1.3 Welding position and welding requirements: Horizontal rotary welding 1G, the weld overlay and the base material need to be fully fused, the weld is free of defects such as cracks, porosity, and lack of fusion, and the dimensions meet the design standards; S1.

4. Based on the welding equipment, the material of the workpiece, the welding materials, and the welding requirements, formulate the welding process parameters; S2, Welding implementation; S2.1 Differentiated zone preheating: Only one side of the 45 steel body (1) is preheated, and the preheating temperature is controlled at 150-200℃. No preheating treatment is applied to the Mn18Cr2 austenitic high manganese wear-resistant steel side. S2.2, TIG welding of the filter layer: The transition layer is welded using a Φ2.4mm ER310 austenitic stainless steel welding wire on a dual-purpose welding machine for manual TIG welding and shielded metal arc welding. The welding parameters are controlled as follows: welding current 100~140A, arc voltage 10~14V, wire feed speed 1.0~1.5m / min, welding speed 8~12cm / min; the temperature is controlled throughout the welding process, and the interpass temperature does not exceed 80℃. S2.3 Welding of Filler and Cover Layers: After the filter layer is inspected and found to be defect-free, the filler and cover layers are welded using a dual-purpose manual argon arc welding and shielded metal arc welding machine with Φ2.0mm or Φ2.4mm ERMn18Cr2 solid welding wire. During filling, a multi-layer, multi-pass welding process is adopted, with a weld overlap ratio of 30-50%. After each layer is welded, the weld slag is cleaned and defects are checked, and the interpass temperature is continuously controlled to not exceed 80℃. The welding method adopts a combination of segmented back-welding and symmetrical welding. The cover layer is ensured to be fully formed and smoothly transitioned to the base material. S2.4 Post-weld treatment and flaw detection: After welding, the weld should be immediately air-cooled to room temperature. Light hammering or shot peening should be applied to strengthen the weld so that the weld hardness reaches HRC45-55. The finished product is inspected by a combination of visual inspection and penetrant testing. Magnetic particle testing is abandoned. After passing the inspection, the product is put into use.

2. The welding process of Mn18Cr2 austenitic high-manganese wear-resistant steel and No. 45 steel according to claim 1, characterized in that, The welding equipment is a Panasonic YC-400TX4 dual-purpose welding machine for both manual argon arc welding and shielded metal arc welding.

3. The welding process of Mn18Cr2 austenitic high-manganese wear-resistant steel and No. 45 steel according to claim 1, characterized in that, During the pretreatment, oil and moisture are baked off with an oxy-acetylene flame, and then mechanically polished with sandpaper or a grinding wheel until a metallic luster is exposed.

4. The welding process of Mn18Cr2 austenitic high-manganese wear-resistant steel and No. 45 steel according to claim 1, characterized in that, During the differentiated zone preheating, only one side of the No. 45 steel body (1) is preheated with an oxy-acetylene flame.

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