激光快速修复Ti-6Al-4V合金的显微组织与力学性能

Microstructures and Mechanical Properties of Laser Rapid Repaired Ti-6Al-4V Alloy

针对Ti-6Al-4V合金在加工和服役过程中的损伤特点,对Ti-6Al-4V合金锻件的3种典型误加工缺陷——槽缺陷、面缺陷和体缺陷进行了激光快速修复研究。激光修复区与锻件基体形成致密冶金结合,Al、V合金元素由锻件基体到激光修复区均匀分布,无宏观偏析。激光修复区组织为粗大原始β晶粒内分布细长的α针及编织细密的α+β板条组织,呈现典型的魏氏结构,热影响区组织从锻件的等轴α+转变β组织逐步过渡到魏氏(α+β)组织。对预制有3种类型缺陷的激光修复试样进行室温静载拉伸试验和硬度测试,结果表明修复试样的拉伸性能达到锻件标准(HB5224-1982)。激光修复试样的硬度和强度高于锻件基体,而塑性则低于锻件基体。因此,激光修复区和锻件基体可看作是一种“强+弱”的组合,这与二者的显微组织是相对应的。

Laser rapid forming has been used to repair three kinds of mis-machining defects in Ti-6A1-4V alloy forgings： the milling groove, the milling surface and the milling rib, respectively. There is dense metallurgical bonding between laser repaired zone and forging matrix. The AI and V elements were uniformly distributed without fluctuation and segregation from the matrix to the laser-repaired zone. The laser-repaired zone exhibited the typical Widmanstaten microstructure consisting of prior huge columnar β grains, in which fine acicular a and α＋β basket weave were distributed. In the heat affected zone, the microstructure changed from equiaxed grains to Widmanstaten structure gradually. The results of hardness and room temperature tensile test show that the mechanical properties of repaired samples reached the forging standards of HB5224-1982, and hardness of laser-repaired zone is higher than that of the forging matrix, meanwhile, the plasticity is lower than that of the forging matrix. Therefore, the laser-repaired zone and the forging matrix can be treated as a combination of “strong ＋ weak”, corresponding to the different microstructures of laser-repaired zone and the forging matrix, respectively.