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CN-121988839-A - Stepped cooperative welding process for high-strength steel thick-wall member and welding member

CN121988839ACN 121988839 ACN121988839 ACN 121988839ACN-121988839-A

Abstract

The invention belongs to the technical field of special welding processes, and provides a stepped cooperative welding process for a high-strength steel thick-wall member and a welding member. The process constructs a stepped collaborative preheating temperature field, carries out differential temperature control on the root of a groove, the outer edges of a main body and a base metal, adopts argon tungsten-arc welding for root bottoming, then adopts manual arc welding for gradually increasing a transition layer of heat input layer by layer, immediately carries out intermediate annealing treatment after finishing the transition layer so as to remodel a stress field, adopts submerged arc automatic welding for multilayer filling, carries out a high-energy plasticizing welding bead in a specific filling stage, and finally carries out post-heating and stage cooling. According to the invention, through the accurate time sequence cooperation of heat input and heat history, the defect of an interlayer bonding region is effectively eliminated, the welding residual stress is greatly reduced, the primary qualification rate and the comprehensive mechanical property of the thick-wall joint are remarkably improved, and the welding method is particularly suitable for high-quality welding of thick-wall components with tensile strength more than 690 MPa.

Inventors

  • MA XIZHEN
  • LI YANHUI
  • DING SHAOMING
  • CHEN YIJUN
  • GAO QINGWEI
  • CHEN GUOXI
  • SHI YUNXIAO
  • XU SHILIN

Assignees

  • 河南省锅炉压力容器检验技术科学研究院
  • 西安交通大学

Dates

Publication Date
20260508
Application Date
20260408

Claims (10)

  1. 1. The step-type cooperative welding process for the high-strength steel thick-wall member is characterized by comprising the following steps of: S1, processing a double U-shaped composite groove on a thick-wall workpiece to be welded, and purifying the surface and two sides of the groove; S2, preheating a welding area, wherein the preheating temperature of the root area of the groove is T 1 , the preheating temperature of the main groove area is T 2 , the preheating temperature of the outer edge area of a base metal heat affected zone at two sides of a thick-wall workpiece is T 3 , and the preheating temperature of the outer edge area of the base metal heat affected zone is T 1 > T 2 > T 3 ; s3, performing root backing welding by adopting tungsten inert gas shielded welding to form a first layer of welding bead, and welding a transition layer by adopting manual arc welding; S4, carrying out heat treatment on the whole thick-wall workpiece, and cooling after the heat treatment is finished; s5, carrying out filling cover surface welding by adopting submerged arc automatic welding; and S6, carrying out post heat treatment on the whole thick-wall workpiece, and cooling in stages after the post heat treatment is finished, thus completing the stepped cooperative welding process.
  2. 2. The step-type collaborative welding process for a high-strength steel thick-wall member according to claim 1, wherein in the step S1, the tensile strength of a thick-wall workpiece to be welded is equal to or greater than 690MPa, and the wall thickness is 30-150 mm.
  3. 3. The stepped cooperative welding process for a thick-wall member of high-strength steel according to claim 2, wherein in the step S1, the double-U-shaped composite groove is formed by smoothly connecting a root narrow-gap U-shaped region and an upper wide-groove U-shaped region, the width of the root U-shaped region is 8-12 mm, and the opening angle of the upper U-shaped region is 15-20 °.
  4. 4. The stepped cooperative welding process for thick-walled components of high strength steel according to claim 1 wherein 150< t 1 ≤180℃,120＜T 2 ≤150℃,80≤T 3 +.110 ℃ in S2.
  5. 5. The stepped collaborative welding process for the high-strength steel thick-wall member according to claim 4, wherein in the step S3, the root backing welding performed by the tungsten inert gas shielded welding adopts a pulse wire feeding process, and the inert gas is helium-argon mixed gas, wherein the volume ratio of helium is 25-40%.
  6. 6. The step-type collaborative welding process for a high-strength steel thick-wall member according to any one of claims 1 to 5, wherein in the step S3, manual arc welding is performed by using a low-hydrogen type alkaline welding rod, the number of transition layers is not less than 2, and the welding heat input amount of the transition layers is gradually increased by 10 to 15%.
  7. 7. The step-type cooperative welding process for high-strength steel thick-wall components according to claim 6, wherein in the step S4, the heat treatment temperature is 580-620 ℃, the heat treatment time is determined according to the maximum wall thickness H (mm) of the thick-wall workpiece, and the calculation formula is that the heat preservation time (min) =1.5×h (mm); the cooling rate is 50-80 ℃ per hour, and the cooling is carried out to 120-150 ℃.
  8. 8. The stepped cooperative welding process for a high-strength thick-wall member according to claim 3,4, 5 or 7, wherein in S5, the welding current of the submerged arc automatic welding is 750 to 850a, the arc voltage is 38 to 42v, and the welding speed is 18 to 22cm/min.
  9. 9. The step-type collaborative welding process for a high-strength steel thick-wall member according to claim 8, wherein in S6, the post heat treatment is performed at 300-500 ℃ for 2-3 hours; The cooling stage is divided into two stages, wherein the cooling speed of the first stage is 50-100 ℃ per hour, the cooling is carried out until the cooling temperature reaches 240-260 ℃, and the second stage is naturally cooled to room temperature.
  10. 10. A welded component characterized in that it is manufactured by the stepped cooperative welding process for a high-strength steel thick-walled component according to any of claims 1 to 9.

Description

Stepped cooperative welding process for high-strength steel thick-wall member and welding member Technical Field The invention relates to the technical field of special welding processes, in particular to a stepped cooperative welding process for a high-strength steel thick-wall member and a welding member. Background The high-strength steel thick-wall member (the wall thickness is generally larger than 30 mm) is widely applied to core bearing parts of key equipment such as a nuclear power pressure vessel, a large-scale chemical reactor, heavy engineering machinery, an ocean platform and the like. The weld quality of such components is directly related to the structural integrity, safety service life and reliability of the overall equipment. Thus, its welding process has been a core technical challenge in modern high-end equipment manufacturing. Conventional thick-walled member welding typically employs a single or sequential combination of welding methods. The combined application of tungsten inert Gas (GTAW), manual arc welding (SMAW) and submerged arc automatic welding (SAW) is common, the general mode is that the GTAW is adopted for root priming to ensure the initial quality, the SMAW is utilized for flexibly welding part of the transition layer, and finally the SAW with high heat input is adopted for completing most filling and capping so as to improve the efficiency. However, with increasing levels of material strength and increasingly complex component designs, the conventional combination process described above exposes a number of inherent problems in application that are difficult to overcome, particularly: 1. The welding preheating mode is extensive, and the thermal stress field is difficult to accurately control. The prior art generally employs uniform preheating throughout or simple localized heating. This extensive preheating approach does not allow for accurate management of the differential heat requirements of the different areas of the thick-walled groove. The insufficient heat of the root area is easy to cause poor fusion or air holes of a GTAW backing weld bead, while the too high temperature of the outer edge of a heat affected zone of a base material can unnecessarily enlarge a softening zone, and the huge restraint stress generated by subsequent welding is concentrated in a narrower transition area, so that the risk of cold cracks generated in the root and the heat affected zone is greatly increased. 2. The switching time sequence of various welding methods is not matched with the stress evolution, and an interlayer defect sensitive area is easy to form. The three methods of GTAW, SMAW and SAW differ significantly in heat input, penetration and cooling characteristics. When the conventional process is switched, only accessibility and efficiency are often considered, and active regulation and control on the accumulation and release rules of welding stress are lacked. Particularly, when the SAW welding with high heat input is directly transferred after the SMAW transition layer is completed, the higher local residual stress formed by the SMAW welding bead is extremely easy to induce defects such as reheat cracks, unfused or micro segregation and the like at the physical interface (namely an interlayer bonding area) of the welding seam of two methods under the superposition effect of the high heat input of the subsequent welding bead of the SAW, and the area becomes a weak link recognized by a thick-wall welding joint. 3. Stress regulation during welding is passive and hysteresis. The prior art control of weld stress relies primarily on post-weld heat treatment (PWHT). However, in a continuous welding process for several tens or even up to hundred hours, internal stresses continue to accumulate and are extremely unevenly distributed, and the postweld heat treatment can eliminate most of the residual stresses, but has limited ability to "repair" damage to microscopic cracks, lattice distortions, and the like that have been generated during the welding process. Throughout the welding cycle, there is a lack of active, staged stress "break" and "remodelling" mechanisms. 4. The performance of conventional combinatorial processes is not maximized. The current process combinations are more simple "relay" and fail to fully exploit the inherent synergistic potential of the three approaches. For example, SAW processes are often considered as pure "fill tools" whose high heat input characteristics are not intentionally used to "heat process" the soldered areas to improve tissue performance. In summary, in the prior art, the welding process of thick-wall parts based on GTAW, SMAW and SAW has a systematic disadvantage in terms of thermal field precise management, multi-method coordinated stress timing control, active process intervention and the like, although the efficiency and quality are improved compared with those of a single method. The welding joint, in particular to a high-strength steel thic