次生片层α相宽度对双态组织TC4钛合金动态压缩性能及其绝热剪切敏感性的影响规律

Effects of the width of secondary α phase on Dynamic Mechanical Properties and Sensitivity of Adiabatic Shear Banding in bimodal microstructures of TC4 alloy

摘要:

本文研究了冷却速率对双态组织TC4钛合金中次生片层α相宽度的影响,并利用分离式霍普金森压杆,进一步研究了次生片层α相宽度对双态组织TC4钛合金动态压缩性能及其绝热剪切敏感性的影响。结果表明：随着冷却速率的降低,次生片层α相宽度随之增宽；在动态压缩实验条件下,双态组织TC4钛合金的动态抗压强度随着次生片层α相宽度的增宽,呈现出逐渐降低的规律,而塑性应变则随着次生片层α相宽度的增宽,呈现出逐渐增加的规律；在强迫剪切实验条件下,双态组织TC4钛合金的绝热剪切敏感性随着次生片层α相宽度的增宽,呈现出逐渐降低的规律,且各双态组织TC4钛合金均随着撞击杆初速的提高,其绝热剪切敏感性增加。结合转变β区体积分数和次生片层α相宽度对双态组织TC4钛合金动态压缩性能及其绝热剪切敏感性的影响规律,可知：采用980℃/1h/AC+550℃/4h/AC固溶时效处理,所获得的双态组织TC4钛合金,其转变β区体积分数为80.7%,次生片层α相宽度为1.74μm,具有较好的高强度-低绝热剪切敏感性匹配,综合性能最优。

Abstract:

In this paper, the dynamic mechanical properties and sensitivity of adiabatic shear banding of TC4 alloy having bimodal microstructures were invesgated using Split Hopkinson Bar.The bimodal microstructures with different width of secondary α phase (α_s) were obtained via different heat treatment. The results showed that the width of α_s increased with the decreasing of cooling rate. Under dynamic compression experiments, the dynamic strength decreased as the width of α_s increased; while the dynamic strain exhibited an opposite trend. Under forced shearing experiments, the sensitivity of adiabatic shear banding decreased as the width of α_s increased. Besides, the sensitivity of adiabatic shear banding increased for the same microstructure with the increasing of impact velocity. Combined with the effects of volumn fraction of transformed β and width of α_s on dynamic mechanical properties and sensitivity of adiabatic shear banding of TC4 alloy, the bimodal microstructure obtained by the heat treatment,980℃/1h/A+550℃/4h/A, had good high strength and low sensitivity of adiabatic shear banding matching. The optimal bimodal microstructure had a volumn fraction of transformed β matrix of 80.7% and the width of α_s plates was 1.74 μm.