多道搭接激光熔覆镍基合金中裂纹断口形貌研究Fractography Study on the Cracking Behavior of Laser-clad Multitrack Coatings
胡木林,谢长生,祝柏林,王爱华
摘要(Abstract)：
利用预置法激光重熔在铁基材料上获得了Ni基合金多道搭接的熔覆层。利用光学显微镜和扫描电镜对熔覆层组织、裂纹走向以及裂纹面进行分析。多道搭接时 ,Ni基合金熔覆层极易出现贯穿裂纹。裂纹的扩展呈周期性 ,裂纹面上高温热裂断口和冷脆断口交替出现。高温下的裂纹沿树枝晶界韧性稳态扩展 ,穿过树枝晶时有撕裂棱 ;失稳扩展沿裂纹面进行、断口呈放射状的脆性特征。数值分析表明 ,多道搭接时热应力在整个开裂过程中起重要作用。裂纹于夹杂附近在最大热应力作用下起裂 ,起裂方向垂直于扫描方向。随后裂纹在热应力、组织因素及已有裂纹综合作用下进一步扩展 ,方向发生偏离
关键词(KeyWords)： 激光熔覆;多道搭接;裂纹;断口;热应力
基金项目(Foundation): 华中理工大学激光国家重点实验室开放基金资助!(970 7B)
作者(Author): 胡木林,谢长生,祝柏林,王爱华
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