从失效案例探讨钢制紧固件的氢脆问题

Hydrogen Brittleness Fracture of Steel Fasteners

讨论了影响钢制紧固件氢脆敏感性的主要因素。分析认为,设计上要充分考虑材料强度对氢脆敏感性的影响,尽量降低其强度水平;要采用合适的热处理工艺,以减少晶界脆化元素,抑制薄膜状碳化物的形成,从而获得氢脆敏感性小的显微组织;在加工及装配过程中,应尽可能避免在零件表面产生机械损伤;要采用低氢脆电镀工艺,必要时采用无氢脆的达克罗等涂覆方法;电镀后要采用合理的除氢工艺,进行严格除氢处理;对于重复使用件,在酸洗去除镀层后要先进行除氢处理,然后电镀,再除氢。

The major influencing factors of the sensitivity of steel fasteners to hydrogen brittleness were discussed,and some suggestions were offered as follows.In design,the sensitivity of material strength to hydrogen brittleness should be taken into consideration and lower strength materials should be adopted.Proper heat treatment should be adopted to reduce the distribution of grain-boundary weakening elements along the grain boundaries,change the shape of carbides along the grain boundaries,and restrain the forming of thin-film carbides.During processing and assembly,surface mechanical damage of parts should be avoided.Electric plating processes with less hydrogen brittleness possibility should be used.And some coating technologies with no hydrogen brittleness such as dacromet should be adopted.After electric plating,appropriate dehydrogenation processes should be used.As for repetitive-use parts,the following process procedure should be adopted： pickling（deplating）→dehydrogenation→electric plating→dehydrogenation.