组织不均匀性对TA15钛合金电子束焊焊接接头热影响区应变集中的影响

Effects of microstructure inhomogeneity on strain concentration of heat affected zone of TA15 titanium alloy electron beam weld joint

关键词:  钛合金  电子束焊  热影响区  组织不均匀性

Key words:  titanium alloy  electron beam welding  heat affected zone  inhomogeneity of microstructure

摘要:

通过对TA15钛合金电子束焊焊接接头热影响区进行纳米压痕试验和小试样拉伸试验，结合基于组织的有限元模拟，研究了热影响区中α相和α'相不均匀性对热影响区应变集中的影响. 结果表明，α'相的屈服强度和加工硬化系数均高于α相，α'相是热影响区中较“硬”的组织，α相是热影响区中较“软”的组织，两种组织具有不同的力学性能，因此热影响区组织具有不均匀性. 组织不均匀性导致其细观应力应变分布不均匀，α'相承受较高的应力而α相有较大的应变，从而引起局部塑性变形的不协调，最终形成沿α相的塑性应变集中带.

Abstract:

The effects of inhomogeneity of α phase and α' phase on strain concentration of heat affected zone of TA15 titanium alloy electron beam weld joint were investigated through instrumented nano-indentation test and tensile test of small specimens combined with the microstructure-based finite element method. The results showed that the yield strength and the hardening exponent of α' phase were higher than α phase. The α' phase was the "harder" microstructure, while the phase is the "softer" microstructure. Two phases had different mechanical properties, so the microstructures of heat affected zone were inhomogeneous. The inhomogeneity of microstructure resulted in the inhomogeneity of stress and strain. The α' phase had higher stress while the α phase had higher strain, which caused the incongruity of plastic deformation and eventually led to the plastic strain concentration bands along α phase.