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CN-119387772-B - Efficient welding method

CN119387772BCN 119387772 BCN119387772 BCN 119387772BCN-119387772-B

Abstract

The invention relates to a high-efficiency welding method, belongs to the technical field of welding processes, and solves the problems that the existing welding process is easy to generate defects such as hot cracks, air holes, coarse crystallization and the like when welding high-strength materials, and the strength and low-temperature toughness of weld metal are insufficient. The invention provides a high-efficiency welding method, which adopts a groove welding process, wherein the welding directions of adjacent welding layers are opposite, the welding directions of the same welding layer are the same, the welding method adopts a low-carbon low-alloy welding wire, and the high-efficiency welding method is suitable for welding P690QL2 steel by mass percent of each component in the welding wire, so that the mechanical property and the low-temperature toughness of a welding joint are obviously improved.

Inventors

  • ZUO YUE
  • AN TONGBANG
  • CAO ZHILONG
  • ZHU YANJIE
  • XU ZIXIN
  • XIAO HONGJUN
  • MA CHENGYONG

Assignees

  • 钢铁研究总院有限公司

Dates

Publication Date
20260508
Application Date
20241128

Claims (6)

  1. 1. A method for welding P690QL2 steel by MAG welding without post heat treatment after welding is characterized in that, The welding method adopts a groove welding process, the welding bead directions of adjacent welding layers are opposite, and the welding bead directions of the same welding layer are the same; the welding method adopts a low-carbon low-alloy welding wire, and the welding wire comprises the following components in percentage by mass ：C 0.051～0.056%、Si 0.30～0.50%、Mn 1.81～1.85%、Cr 0.26～0.28%、Ni 3.77～4.0%、Cu 0.008～0.0097%、Mo 0.007～0.01%、V 0.0005～0.001%、Ti 0.054～0.055%、Al 0.013～0.018%; The preparation method of the welding wire adopts ultra-pure smelting, forging, rolling, bright drawing and surface cleaning processes, and vacuum annealing is adopted after the preparation is finished; the welding method comprises the following specific steps: s1, forming a groove according to the material and specification of a piece to be welded; s2, performing layer-by-layer stacked welding by adopting active gas shielded welding, wherein after each layer of welding is finished, the welding direction is adjusted, the welding directions of adjacent welding layers are opposite, the welding directions of the same welding layer are the same, the volume proportion of shielding gas in MAG welding is 95% argon and 5% carbon dioxide, the temperature between channels in the welding process is controlled at 100-120 ℃, the specific technological parameters are that the welding current is 310-340A, the welding voltage is 31-33V, the welding speed is 40-44 cm/min, and the heat input is controlled at 14-16 KJ/cm; S3, after welding, performing postwelding treatment by adopting a heat preservation slow cooling mode, directly performing heat preservation after welding for 2-6 hours, and then performing air cooling; the microstructure of the weld metal formed by the welding method is ferrite and bainite, the ratio of the ferrite to the bainite is ferrite=0.80-0.85:0.15-0.20, and the grain size is 1.70-1.80 mu m.
  2. 2. The welding method according to claim 1, wherein the workpiece to be welded is subjected to preheating treatment at a preheating temperature of 100-120 ℃.
  3. 3. The welding method according to claim 1, wherein the flow rate of the shielding gas is controlled to be 18-22 l/min.
  4. 4. The welding method according to claim 1, wherein the specific process parameters in the step S2 are that the welding current is 325+/-5A, the welding voltage is 31-33V, the welding speed is 42cm/min, and the heat input is controlled to be 14-16 KJ/cm.
  5. 5. The welding method according to claim 1, wherein the weld metal microstructure formed by the welding method is ferrite and bainite, the ferrite=0.83:0.17, the ferrite is ferrite, the bainite is the bainite, and the grain size is 1.74 μm.
  6. 6. The welding method according to claim 1, wherein the yield strength of the welding joint formed by the welding method is equal to or more than 792MPa, the tensile strength is equal to or more than 894MPa, the elongation is equal to or more than 13.5%, the average absorption energy of the impact test at-60 ℃ is equal to or more than 130.4J, and the hardness of the joint is 315-367HV.

Description

Efficient welding method Technical Field The invention relates to the technical field of welding processes, in particular to a high-efficiency welding method. Background With the worldwide increasing demand for liquefied carbon dioxide storage and transportation, low temperature, high pressure storage tanks are becoming critical devices. However, most of the liquefied carbon dioxide tank materials currently used are steel materials having relatively low yield strength, such as 07MnNiMoVDR (yield strength 490 MPa) and 15MnNbR (yield strength 370 MPa). Although the materials can meet the requirements of common low-temperature storage tanks, the materials often have defects such as limited strength and unsatisfactory impact resistance under the high-pressure and low-temperature limit working conditions such as liquefied carbon dioxide storage tanks, so that the bearing capacity and the safety of the storage tanks are difficult to reach the optimal state. To achieve a higher storage capacity of the tank per unit volume, the choice of materials with higher strength levels is a necessary trend. The 690 MPa-grade high-strength low-temperature steel P690QL2 has excellent low-temperature toughness and high-strength performance, and is one of ideal materials for manufacturing liquefied carbon dioxide storage tanks. The P690QL2 steel can effectively reduce the wall thickness of the storage tank and lighten the structure weight, thereby improving the storage efficiency and the economic benefit of the storage tank on the premise of not increasing the cost. Furthermore, the use of such high strength materials allows for a higher safety margin for the tank when faced with high pressure conditions. However, the technical challenges of P690QL2 steel in welding processes are significant. Because of the high strength of the material, defects such as hot cracks, air holes, coarse crystallization and the like are easy to generate in the welding process, and the defects can influence the toughness and mechanical properties of the welded joint, in particular the impact resistance under the low-temperature environment. The weld metal formed by the prior art has poor low-temperature toughness and impact resistance, and is difficult to meet the special requirements of a liquefied carbon dioxide storage tank. Disclosure of Invention In view of the above analysis, the present invention aims to provide a high-efficiency welding method, which is used for solving at least one of the problems that the existing welding process is easy to generate defects such as hot cracks, air holes, coarse crystallization and the like when the material is high-strength (especially P690QL2 steel), and the low-temperature toughness and impact resistance of weld metal are poor. The invention provides a high-efficiency welding method, which adopts a groove welding process, wherein the welding directions of adjacent welding layers are opposite, and the welding directions of the same welding layer are the same; the welding method adopts a novel low-carbon low-alloy welding wire, and the welding wire comprises the following components in percentage by mass ：C 0.04～0.08％、Si 0.30～0.50％、Mn 1.6～2.0％、Cr 0.15～0.35％、Ni 3.5～4.0％、Cu 0.008～0.01％、Mo 0.007～0.01％、V 0.0005～0.001％、Ti 0.02～0.07％、Al 0.0.01～0.018％. The welding method comprises the following steps: s1, forming a groove according to the material and specification of a piece to be welded; s2, performing layer-by-layer stacked welding by adopting active gas shielded welding of a consumable electrode, namely MAG welding, wherein after each layer of welding is finished, the welding directions are adjusted, the welding directions of adjacent welding layers are opposite, and the welding directions of the same welding layer are the same; And S3, after welding, performing postweld treatment. Specifically, the pre-heating treatment is carried out before the welding of the to-be-welded piece, the pre-heating temperature is 100-120 ℃, and the inter-channel temperature in the welding process is controlled to be 100-120 ℃. Specifically, the composition of the shielding gas for MAG welding in step S2 is 95% argon+5% carbon dioxide (volume ratio). Specifically, the flow rate of the shielding gas is controlled to be 18-22L/min. Specifically, the specific process parameters of the step S2 are that the welding current is 310-340A, the welding voltage is 31-33V, the welding speed is 40-44 cm/min, and the heat input is controlled to be 14-16 KJ/cm. Specifically, a heat-preservation slow cooling mode is adopted for carrying out postweld treatment. In particular, the welding method is suitable for welding P690QL2 steel. Specifically, the weld metal microstructure formed by the welding method is ferrite and bainite, the ferrite=0.80-0.85:0.15-0.20, and the grain size is 1.70-1.80 μm. Furthermore, the yield strength of the welding joint formed by the welding method is more than or equal to 792MPa, the tensile strength is more than or equ