为了提高船用高负荷齿轮机械性能，对船用高负荷齿轮材料（42CrMoA）进行激光合金化强化处理，并对处理后的样件进行显微组织分析以及对HXD1000TMJC型数字式显微硬度计进行硬度检测，探究激光合金化处理参数，如粉层厚度、激光输出功率、扫描速度和离焦量以及合金粉末成分对性能的影响。结果表明：以42CrMoA材料为基体的齿轮，经过激光合金化强化处理后其强化层由合金化层和淬硬层组成，强化层总深度1.1 mm；随着合金粉层厚度的增加，淬硬层中马氏体质量分数减少，晶粒变得更加粗大；扫描速度的增加会导致强化层深度减小；离焦量减小会使光斑直径逐步缩小，强化层的宽度也随之显著缩小，合金粉末优化后，显微组织显著细化，硬质颗粒密度增大。

In order to improve the mechamical performance of marine highload gear，this paper studied laser alloying and strengthening treatment of marine highload gear material (42CrMoA)，and the treated samples were subjected to microstructure analysis and HXD1000TMJC digital microhardness testerfor hardness testing，to investigate the effects of laser alloying treatment parameters such as powder layer thickness，laser output power，scanning speed, defocusing amount and alloy powder composition on the performance. The results show that the reinforced layer of the gear with 42CrMoA material as the substrate consists of alloyed layer and hardened layer after laser alloying strengthening treatment，and the total depth of the reinforced layer is 1.1 mm; with the increase of the thickness of the alloy powder layer，the martensite mass fraction in the hardened layer decreases and the grains become more coarse; the increase of the scanning speed leads to the decrease of the depth of the reinforced layer; the decrease of the defocusing amount leads to the gradual reduction of the spot diameter，and the width of the reinforced layer also decreases significantly.After the alloy powder is modified,microstructure is refined prominently and hardened grain density increases.

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