面向薄壁件的激光熔覆修复工艺参数优化研究

目的减少薄壁零件激光熔覆修复时基板的变形量,提高成形质量。方法在前期单道单因素试验的基础上,通过三因素三水平正交试验在2mm厚的45钢上熔覆Fel合金粉末,分析了激光功率、扫描速度和送粉率对薄板变形行为的影响,并根据因素效应图分析基体变形量随各因素水平的变化,找出出现这种变化的原因。通过正交试验的极差分析提出了基体变形的公式,根据公式确定各因素对基体变形影响的主次关系,并根据变形结果,最终找到使基板变形最小的最优工艺参数。通过光学显微镜(OM)、扫描电子显微镜(SEM)和显微硬度计,研究最优工艺参数下熔覆层的显微组织和硬度,并对在最优工艺参数下熔覆的试件进行成形质量评价。结果影响基板变形的因素主次顺序依次为:激光功率、扫描速度和送粉率。基板变形量最小且冶金结合良好的最佳工艺参数为:激光功率600 W,扫描速度12 mm/s,送粉率1.2 r/min。此工艺下所得熔覆层的最高硬度达到348HV,约是基体硬度的1.6倍。结论该工艺参数可以有效减少基体的变形且激光熔覆成形质量良好,基体表面得到显著强化。

Optimization of Laser Cladding Repair Process Parameters for Thin-wall Parts

The work aims to reduce the deformation of the substrate during laser cladding repair of thin-wall parts, and im-prove the forming quality. On the basis of previous single channel and single factor test, Fe1 alloy powder was cladded on 2 mm thick 45 steel by three factors and three level orthogonal test, and the influences of laser power, scanning speed and powder feeding rate on the deformation behavior of sheet metal were analyzed. According to the factor effect diagram, the changes of the substrate deformation along with the factors level were also investigated and the corresponding reason was found out. The formula of the deformation of the substrate was put forward by the extreme analysis of the orthogonal test. According to the formula, the main and secondary relation of the influence on the substrate deformation caused by the factors was determined, and the optimum process parameters to minimize the substrate deformation were finally found out according to the deformation results. The microstructure and hardness of the cladding layer under the optimal process parameters were studied by optical mi?croscope (OM), scanning electron microscope (SEM) and microhardness tester, and the molding quality of the cladding layer under the optimal process parameters was evaluated. The factors affecting the substrate deformation were laser power, scanning speed and powder feeding rate in order. The optimal process parameters to minimize the substrate deformation and realize good metallurgical bonding were 600 W laser power, 12 mm/s scanning speed and 1.2 r/min powder feeding rate. The maximum hardness of the cladding layer under such process was 348HV (about 1.6 times of the substrate hardness). The process parameters can effectively reduce the substrate deformation, ensure the good laser cladding quality and strengthen the substrate surface significantly.