蠕变预加载Ti6321钛合金的动态力学性能和绝热剪切研究

Study on dynamic mechanical properties and adiabatic shear of Ti6321 titanium alloy under creep preloading

摘要:

蠕变加载对结构件的服役性能会产生一定的影响。本文对等轴、双态、魏氏组织Ti6321钛合金进行蠕变预加载,对蠕变后的材料进行动态压缩试验,应变率为3000s_-1^,研究经不同蠕变应力加载后的Ti6321钛合金动态力学行为。结果表明：蠕变后钛合金的动态力学性能均表现出屈服应力下降,抗压强度上升。随蠕变应力增加,三种组织钛合金在动态压缩后的冲击吸收功增大,绝热剪切敏感性降低。未蠕变的钛合金经动态压缩后均产生相变带,等轴组织和双态组织钛合金蠕变预加载再经动态压缩后未失效,仅产生形变带,魏氏组织产生相变带导致失效。蠕变推迟了等轴组织和双态组织钛合金的绝热剪切相变的发生。

关键词:Ti6321钛合金;蠕变;动态压缩;冲击吸收功;绝热剪切

Abstract:

Creep loading has a certain effect on the service performance of structural components. In this paper, the creep preloading on Ti6321 titanium alloy with equiaxed, bimodal and Widmanstatten microstructures were carried out. Dynamic compression tests of the material after creep investigated at a strain rate about 3000s-1. The dynamic behavior of Ti6321 titanium alloy after different creep stress loading was studied. The results show that the yield stress decreases and the compressive strength increases after creep preloading. With the increase of creep stress, the impact absorption energy of titanium alloy with three microstructures after dynamic compression increases and the adiabatic shear sensitivity decreases. Titanium alloys without creep have phase transition bands after dynamic compression, Titanium alloy with equiaxed microstructure and bimodal microstructure after dynamic compression after creep preloading do not fail, only produce deformation band. Titanium alloy with Widmanstatten microstructure fails due to phase transition bands. Adiabatic shear of equiaxed and bimodal microstructure are delayed by creep.

Key words:Ti6321 alloy; Creep; Dynamic compression; Shock absorption energy; Adiabatic shear