非真空激光定向凝固参数对DZ22合金熔覆层组织的影响

Effect of Non-vacuum Laser Directional Solidification Parameters on Cladding Layer of DZ22 Alloy

为改善DZ22合金的定向凝固熔覆层组织,实现定向凝固基材的大面积修复,本工作采用固定变量法,通过改变相应的激光工艺参数,研究激光工艺参数对DZ22合金定向凝固熔覆层组织的影响。结果表明,随着电流和脉宽的增大,熔覆层一次枝晶间距变大,二次枝晶逐渐变多且不断长大,等轴晶区域也增多,转向枝晶区高度增大;随着频率的增大,熔覆层上层等轴晶区域先增多后减少,一次枝晶干逐渐变细;而扫描速度和一次枝晶尺度呈负相关,随着扫描速度的变大,一次枝晶间距逐渐减小,转向枝晶区高度也降低,高扫描速度不利于形成柱状晶组织。

In order to improve the microstructure of laser directional solidification cladding for DZ22,realize large area repairing for directional solidification base materials,fixed variable method was adopted in this work,with which the influence of laser process parameters on the microstructure of directionally solidification alloy DZ22 was studied by changing the laser process parameters.The results showed that the primary dendrites spa-cing and the height of the steering dendrites zone became larger,the number of the secondary dendrites and the volume was bigger,and the zone of isoaxial crystal was increased with the increase of current and pulse width;The zone of isoaxial crystal in the laser cladding upper layer was enlarged first and then reduced,and the primary dendrites were tapering with the increase of frequency;Scanning velocity was negatively correlated with the primary dendrites scale,and the primary dendrites spacing and the height of the steering dendrites zone became smaller with the increase of scanning velocity,besides,high scanning speed was not conducive to the formation of columnar structure.