TC16钛合金冷镦变形特征的研究

A Study on The Deformation Features of TC16 Alloy Treated by Cold Upset Process

摘要:

采用快速顶锻试验机研究退火态TC16钛合金冷镦变形行为,利用显微硬度计、透射电镜及XRD技术分析TC16钛合金冷镦变形后的组织性能变化。结果表明,退火态TC16钛合金具有良好塑性变形能力,实现无裂纹1/8锻压比冷镦变形。冷镦样品不均匀变形明显,形成一字双叉剪切带,硬度值在剪切带区域最大。锻压比小于1/4时以位错强化为主,大于1/4时以细晶强化为主。锻压比为1/4时冷镦样品硬度梯度最大,力学性能不稳定,锻压比大于1/4后,力学性能逐渐趋于稳定。

关键词:TC16钛合金,冷镦,剪切带,强化机理

Abstract:

TC16 titanium alloy samples with a cold upset treatment carried on a fast upsetting testing machine were prepared. The properties and deformation structure of samples were analyzed by micro-hardness tester, TEM and XRD. The results demonstrated that the deformation was mainly because of the dislocation sliding, and the structure and properties of the deformation samples presented a certain extent of inhomogeneity. When the forging ratio was 1/6, the hardness was 300 HV which was stabilized. The hardness had increased 20% compared to the original sample. The original equiaxed crystals in the central part of the shearing band were stretched gradually with the increase of the deformation. Grain crack and refinement occurred when the grain width was less than 100 nm, which was the main reason of the stable hardness. Cracks were not observed in the central part of the sample under a larger deformation, due to the good plasticity of TC16 alloy. However, XRD showed that the martensite phase transformation had taken place during the process of the deformation.

Key words:TC16; cold upset; shear band; strengthening mechanism