钛合金激光快速成形过程中缺陷形成机理研究

Research on Forming Mechanism of Defects in Laser Rapid Formed Titanium Alloy

采用微观测试分析方法,研究了钛合金激光快速成形过程中缺陷的形成机理。结果发现,成形件内部存在两种类型的缺陷,即气孔和熔合不良。气孔形貌呈球形,在成形件内部的分布具有随机性,气孔是否形成取决于粉末材料的特性,主要是指粉末的松装密度,氧含量对气孔的形成没有影响。熔合不良缺陷形貌一般呈不规则状,主要分布在各熔覆层的层间和道间,熔合不良缺陷是否产生取决于成形特征参量是否匹配,其中最显著的影响因素是能量密度、多道间搭接率以及Z轴单层行程?Z。

The defects forming mechanism in the Laser Rapid Forming （LRF） process of titanium and titanium alloy was studied through microscopic analysis methods. The results showed that there were two kinds of defects, porosity and ill bonding in the laser multi-layer cladding. For the LRF titanium and titanium alloy, the porosity was spherical and randomly distributed in samples due to the low loose density of the powders, and the oxygen content wasn＇t the factor to influence the porosity rate. The ill bonding tended to be irregular shape and generally occurred between the layers and the line boundaries. The laser energy density, overlap and Z-increment △Z were main process characteristic parameters to influence the ill bonding.