高强度钛合金管材残余应力测试及对比分析

Test and Analysis of the Residual Stress in Ti-3Al-2.5V Tubes with Different Processes

摘要:

无缝TA18钛合金管材的制备通常要经历大变形量的冷轧工艺，不可避免地引入残余应力。本实验利用X射线残余应力测试技术，对不同工艺条件制备的TA18(Ti-3Al-2.5V)合金多种规格冷轧管材外表面的残余应力进行了测试，并对比了管材切向残余应力的差别，针对其差别讨论了可能产生的原因。结果表明，工艺不当会导致钛合金管材在切向呈现拉应力，而适宜的工艺则在钛合金管材的切向形成压应力。残余拉应力显著地降低材料的应力腐蚀抗力和疲劳抗力，而残余压应力却可以不同程度地提高材料的疲劳寿命。因此，对比实验数据可以得出，TA18管材需要稳定制备工艺，从而达到残余压应力的应力状态，才能拥有更好的服役性能。

Abstract:

The residual stress of Ti-3Al-2.5V tube, which was manufactured by different thermal-mechanical processes, has been investigated. XRD was applied to measure the residual stress based on the shift of the peak of diffraction profiles. The results show that the residual stress values of Ti-3Al-2.5V tube under the certain fabrication parameters are all positive, whereas the values after the process change are negative. It means that the former one is tensile stress, which is opposite to the latter’s compressive stress. There is an obvious difference in fabrication process between them. Because the compressive stress can benefit the fatigue life and stress corrosion resistance, the tensile stress should be avoided in tubing production.