摘  要：激光增材制造技术是现代机械制造的重要组成部分，激光增材制造时，确认快速成形的围观组织形貌和激光工艺参数的选择和是保证快速成形产品质量的关键所在。因此，研究激光增材制造的工艺参数及组织性能分析具有非常长远的意义。

本研究首先通过单层单道激光熔覆实验研究了激光功率、激光扫描速度和送粉速度对熔敷层的宏观形貌，显微组织的影响并优化工艺参数。随后利用优化后的工艺参数进行多层多道制造，对试样凝固组织和性能进行了分析并研究了固溶热处理对材料的影响。主要结论如下：

（1）在激光功率，送粉速度和激光扫描速度三种工艺参数中，激光功率对单层单道熔覆层的形貌影响最小，送粉速度的影响最大，激光扫描速度次之。

（2）单层单道熔覆层的显微组织主要由发达树枝状晶、细小树枝状晶和等轴晶组成。

（3）激光轨迹采用单向平行扫描所获得的316L显微组织由发达树枝状晶与等轴晶和细密树枝晶两种显微组织交替分布。

（4）单向平行扫描获得的产品具有各向异性，垂直于激光扫描方向的综合拉伸力学性能优于平行方向；固溶热处理可可以改变增材制造试样的显微组织形态，破坏原本的树枝晶和等轴晶，使其抗拉强度稍有降低，但是试样的断后伸长率显著提高。

关键词：激光增材制造技术；显微组织；拉伸力学性能；热处理

Abstract：Laser material manufacturing technology is an important part of modern machinery manufacturing, laser material manufacturing, to confirm the rapid formation of the aerial surface morphology and laser technology parameters of choice and to ensure the quality of rapid prototyping products is the key. Therefore, it is of great significance to study the process parameters and microstructural performance of laser reinforcements.

In this study, the effects of laser power, laser scanning speed and powder feeding rate on the macroscopic morphology and microstructure of the deposited layer were studied by single-layer single-channel laser cladding. The multi-layer multi-channel manufacturing was carried out by using the optimized process parameters. The solidification structure and properties of the samples were analyzed and the effect of solution heat treatment on the materials was studied. The main conclusions are as follows:

   (1) In laser power, powder feeding speed and laser scanning speed, the laser power has the least effect on the morphology of single-layer cladding cladding, the maximum effect of powder feeding speed and laser scanning speed is the second.

   (2) The microstructures of monolayer single-channel cladding are mainly composed of developed dendrites, fine dendrites and equiaxed grains.

   (3) Laser trajectories The 316L microstructures obtained by unidirectional parallel scanning were alternately distributed by the developed dendrites and equiaxed and fine dendrites.

   (4) Unidirectional parallel scanning of the product has anisotropy, perpendicular to the laser scanning direction of the comprehensive tensile mechanical performance is better than the parallel direction; solution heat treatment can change the weight of the sample manufacturing microstructure, Of the dendrites and equiaxed crystals, so that the tensile strength slightly reduced, but the specimen after the elongation was significantly improved.

Key words: laser reinforcements manufacturing technology; microstructure; tensile mechanical properties; heat treatment

目  录

第一章 绪 论 1

1.1  现代机械制造技术 1

1.1.1  减材制造技术 1

1.1.2  等材制造技术 2

1.1.3  增材制造技术 2

1.2  激光熔覆技术 4

1.2.1  激光熔覆技术概述 4

1.2.2  激光熔覆技术的特点 6