热处理对800 MPa级钛合金对接焊平板残余应力影响的数值模拟

钛合金具有高强耐蚀、易焊等优质性能,广泛用于潜艇、深潜器等潜水器的受力构件及耐压耐蚀壳体。在焊接过程中,会不可避免的产生焊接残余应力,较大的焊接残余应力会影响焊接结构的安全性能,而焊后热处理能够有效减少焊接残余应力。本文首先采用数值模拟的方法对TC4对接焊平板热处理前后的残余应力进行计算,通过与试验结果进行对比研究,验证有限元数值模拟的合理性;然后采用该数值模拟方法研究Ti80对接焊平板多层多道焊的整个焊接过程以及焊后热处理方法。结果表明,焊后Ti80对接焊平板表面具有较大横向和纵向残余拉应力,通过热处理工艺后,残余拉应力得到明显降低。因此,通过焊后热处理方法可以在很大程度上降低对焊接结构力学性能可能产生的不利影响的残余拉应力。

Numerical simulation of the influence of heat treatment on the residual stress of Ti80 flat butt welding joint

Titanium alloy with high performance such as high strength corrosion resistance and easy welding.It is widely used in force components,pressure and corrosion resistant shells of submarines,deep submersibles and other submersibles.During the welding process,residual stress would inevitably occur,and the safety property of the welding structure would be effected by larger welding residual stress,and the welding residual stress could be effectively reduced by post weld heat treatment(PWHT).In this paper,the residual stress of the TC4 flat butt welding joint before and after PWHT is firstly simulated.Through a comparative study with test results,the rationality of the finite element numerical simulation is verified.Then,this numerical simulation method is used to study the entire welding process and PWHT of Ti80 flat butt joint with multi-layer welding.The results show that there are large transverse and longitudinal residual tensile stress in the surface of Ti80 flat butt welding joint,and the residual tensile stress is obviously reduced after PWHT.Therefore,the residual tensile stress which could affect the mechanical properties of welding structure is reduced to a great extent by PWHT.