核电321不锈钢旋转电弧窄间隙GTAW工艺

采用旋转电弧窄间隙钨极氩弧焊(NG-GTAW)新工艺对核电321不锈钢进行窄间隙焊接试验，根据工业生产实际对321不锈钢的施焊要求，将热输入严格控制在10 kJ/cm以下，并得到侧壁熔合良好、无明显缺陷的焊接接头。对旋转电弧NG-GTAW工艺过程温度场和应力场分布展开研究，发现在填充焊过程中，近焊缝区域最高温度可达600 ℃，此时奥氏体不锈钢处在敏化温度区间，在此温度长时间停留可能导致不锈钢耐蚀性能下降。在垂直于焊缝方向，近焊缝区域呈现拉应力，应力值略高于材料的屈服强度，随着与焊缝距离的增加，应力值逐渐降低，在一定位置处，拉应力转变为压应力。沿焊缝方向上，板材中间区域应力值较高，两端应力较低。创新点： 采用旋转电弧NG-GTAW新工艺，能够在满足焊接热输入要求的同时，提高焊接效率，减少填充量，为核级不锈钢焊接提供了一种高效率、高质量的焊接新方法。

Investigation on rotating arc narrow groove GTAW process of 321 stainless steel for nuclear plants

Narrow gap welding experiments were carried out on 321 stainless steel for nuclear plants by the novel rotating arc NG-GTAW process. According to the actual welding requirements of 321 stainless steel, the heat input was strictly controlled below 10 kJ/cm, and welded joint with good sidewalls fusion and no obvious defects was obtained. The temperature field and residual stress field distribution of the rotating arc NG-GTAW process were studied, and it was found that during the filling welding process, the highest temperature near the weld reached 600 ℃, at this time, the austenitic stainless steel was in the sensitization temperature range, staying at this temperature for a long time might cause the corrosion resistance of stainless steel to decrease. In the direction perpendicular to the weld, the area near the weld appeared tensile stress, and the stress value was slightly higher than the yield strength of the material. As the distance from the weld increased, the stress value gradually decreased. At a certain location, the tensile stress transformed into a compressive stress. In the direction parallel to the weld, the stress value was higher in the middle area of the plate, and which was lower at both ends.Highlights: The novel rotating arc NG-GTAW process could not only meet the welding heat input requirements, but also improve welding efficiency and reduce the amount of filling, which provided a high-efficiency and high-quality welding method for nuclear-grade stainless steel welding.