9Ni钢焊接产生白点的原因及影响分析

Cause and influence analysis of white spots produced by welding of 9Ni steel

由于06Ni9DR钢在-196℃下仍具有优异的低温韧性,在乙烯和LNG行业得到了大量应用。针对某工程中06Ni9DR钢焊接后射线检测底片上出现无规律白点的问题,经检查首先排除钢材和焊材的质量问题,然后通过对焊接试验试板产生白点处进行能谱分析和机械性能试验,判断为焊条中含有的钨在焊接时熔化不充分,形成夹钨或钨的化合物,造成射线检测时显现在底片中出现白点。由于白点呈小尺寸点状弥散,不影响焊缝质量评级和各项机械性能。

06Ni9DR(9Ni steel)is widely used in ethylene and LNG industry for its excellent low-temperature resistance at-196℃.For white spots on the post-weld plate of 9Ni steel in the radiographic test,the quality problems of steel and welding material are first excluded after inspection.Then,energy spectrum analysis and mechanical property tests are conducted on the plate where the white spots are located.It is found that tungsten inclusion or tungsten compounds caused by the unmelted tungsten in welding rod lead to white spots appearing on the plate in the radiographic test.However,the quality and mechanical properties of weld lines are uninfluenced by such dot-like dispersed white spots.