摘要:
针对激光熔覆过程中易出现的熔覆层开裂的问题,采用了单向送粉双向扫描激光熔覆工艺,较好地抑制了熔覆层的开裂.通过对激光熔覆过程温度场、应力场进行计算分析,发现采取单向送粉单向扫描工艺时,熔覆层顶部以及与基体接合处会出现明显的应力集中现象,且应力水平较大,而采取双向扫描工艺后,熔覆层内拉应力水平显著降低,且熔覆层顶部的应力集中现象基本消除.在进行以45钢为基体,熔覆Ni60合金粉末的激光熔覆试验中,应用该熔覆方法后,发现无论是单道熔覆还是多道搭接熔覆,皆可有效地避免熔覆层开裂.结果表明,该方法对于裂纹的抑制作用是有效且可行.
Abstract:
A new craft of laser cladding,unidirectional powder feeding and double scanning,was developed to solve the problem of cracking in the cladding coats.The temperature field and stress field of laser cladding were computed.The results indicate that the value of stress is very large and the stress concentration problem is serious at the top of cladding coat and the joint between coat and base material in the process of unidirectional scanning.After the second scanning,the value of stress can be decreased and the stress concentrated at the top of cladding coat can be eliminated.The results of laser cladding 45 steel with Ni60 alloy powder by the craft of unidirectional powder feeding and double scanning show that the cracking of the coats can be avoided both in single-pass cladding and multi-pass lap cladding by the craft,which is effective and feasible for controlling crack in laser cladding.
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