第三代核电技术中, 堆内核心构件堆芯围筒的焊接制造技术是一个急需攻克的难题, 由于工件尺寸大, 尺寸精度要求高, 需探索采用万瓦级激光焊接一次成形技术, 此前这类产品的激光单道焊接在国内外尚无成功的案例。对万瓦级光纤激光深熔焊接厚板焊接缺陷的抑制方法进行了研究。结果表明, 离焦量是万瓦级光纤激光深熔焊接厚板过程中一个关键工艺参数。负离焦时, 匹配优化离焦量和焊接速度可以有效抑制缺陷获得成形良好的全熔透焊缝; 背保护气体不仅改善了焊缝下表面成形, 同时改善了焊缝上表面成形使整个焊缝截面呈“I”型; 侧吹气体射流辅助激光深熔焊接, 可以较好抑制钉子头焊缝和上表面飞溅的产生; 采用横焊焊接方位时, 可以有效抑制焊缝塌陷与底部驼峰的产生。成功实现了15 kW 光纤激光单面自熔焊接双面成形18 mm厚不锈钢, 并实际应用于焊接生产堆芯围筒。

In the third generation nuclear power technology, reactor core components of reactor core shroud tube welding manufacturing technology is an urgent problem to overcome. Due to the large size of the work piece and the high dimensional accuracy, need to explore the use of million kilowatt class laser welding forming technology, such products of laser single pass welding had no successful cases at home and abroad. The suppression procedures of the above-mentioned welding defects during laser deep penetration welding of thick plate with 10-kW level high power fiber laser are investigated. The results reveal that defocus is a key parameter in 10-kW level high power fiber laser welding of thick plates. At a negative defocus, the match optimization of defocus and welding speed could achieve full penetration joint with a good appearance without defects. The application of a bottom shielding gas improves the weld appearances at both the top and bottom surfaces, resulting in an I-shaped cross section. The gas jet assisted laser deep penetration welding could suppress the formation of nail-head-shaped weld and top spatter. When the transverse welding orientation is adopted, the collapse of the weld seam and the occurrence of the hump at the bottom can be effectively suppressed. The 18 mm thick stainless steel was successfully realized by 15 kW fiber laser with single-sided self-fusion welding double-sided formation, and practical application in welding the reactor core shroud.