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采用高功率激光对材料为304LN的AP1000核电站控制棒驱动机构(CRDM)Canopy焊缝模拟体进行堆焊维修,焊丝采用镍基Inconel 690合金,并研究堆焊工艺、堆焊层成形特点及显微组织。结果表明:通过焊丝伸入熔池,以熔体热传导的方式进行熔化,可以更好地保持熔池的稳定性,并获得表面成形优异的焊道;焊道搭接率为42%时,堆焊层非常平整,余高顶部和搭接部之间高度差仅在100～135滋m之间;熔池边界处未混合区铁素体富集,与奥氏体的Inconel 690堆焊层形成晶格差异,会导致平直的Ⅱ-型边界出现;堆焊21道次才能对整个密封环进行双层覆盖,两道交替堆焊可保证密封环不出现下塌现象。
High-power laser was used to perform overlay repairing on Canopy weld simulator of CR1000 with 304LN material. The welding wire adopts Inconel 690 alloy with nickel base and studied the surfacing technology, the forming characteristics of overlay and its microstructure organization. The results show that: the penetration of the welding wire into the molten pool and the melt conduction through the melt can better maintain the stability of the molten pool and obtain the weld bead with excellent surface forming. When the weld bead overlap rate is 42% The weld layer is very smooth, the height difference between the top and the lap of the remaining height is only between 100 and 135 μm; the ferrite is not enriched in the unmixed zone at the weld pool boundary, forming with the Inconel 690 surfacing layer of the austenite Lattice difference, will lead to the appearance of straight Ⅱ-type boundaries; surfacing 21 times in order to double the entire seal ring coverage, two alternately surfacing to ensure that the seal ring does not appear collapse phenomenon.