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以混合的Ti、V、Cr元素粉末为原料,采用CO_2激光器激光熔覆沉积Ti-20V-15Cr阻燃钛合金,并针对合金沉积层的显微组织、冶金质量以及显微硬度展开研究。结果表明,采用CO_2激光器制备的Ti-20V-15Cr阻燃钛合金,沉积试样成分分布均匀、组织致密、未出现裂纹、熔合不良等缺陷;沉积试样整体由单相!晶粒组成,但原始!晶粒形态对激光熔覆沉积工艺下的熔池凝固条件变化极为敏感;沉积试样底部、中部和顶部区域沿沉积层生长方向依次出现三种形态的晶粒生长:柱状晶、类等轴晶和等轴晶。基于合金凝固柱状晶/等轴晶转变模型以及激光熔覆沉积过程试样底部、中部和顶部熔池凝固条件分析,揭示了激光熔覆沉积Ti-20V-15Cr合金的凝固组织形成机理,采用显微硬度计对沉积试样各区域显微硬度进行测试。测试结果表明,沉积试样各区域硬度分布均匀,未出现明显波动,平均显微硬度约为372HV。
The mixed Ti, V and Cr powders were used as raw materials, and the Ti-20V-15Cr flame-retardant titanium alloy was deposited by CO 2 laser cladding. The microstructure, metallurgical quality and microhardness of the deposited alloy were studied. The results show that Ti-20V-15Cr flame-retardant titanium alloy prepared by CO 2 laser has the advantages of uniform distribution, compact structure and no defects such as cracks and poor fusion. The deposited sample is composed of single phase grains, The morphology of the original grains is very sensitive to the changes of the solidification conditions of the molten pool under the laser cladding deposition process. There are three kinds of grain growth in the bottom, middle and top of the deposited samples along the growth direction of the deposited layer: columnar crystal, Axial and equiaxed crystals. The solidification microstructure of Ti-20V-15Cr alloy deposited by laser cladding was revealed based on the solidification columnar / equiaxed transformation model and the analysis of the solidification conditions in the bottom, middle and top of the laser cladding deposition process. Microhardness tester for each area of the deposited samples were tested for microhardness. The test results show that the hardness distribution of the deposited samples in each region is uniform, no obvious fluctuations, the average microhardness of about 372HV.