双相不锈钢大熔深TIG焊接头疲劳裂纹扩展数值模拟

Numerical simulation of fatigue crack propagation in duplex stainless steel deep-penetration TIG weld joint

基于扩展有限元法,对不同保护气体条件的双相不锈钢焊接接头疲劳裂纹扩展行为进行了数值模拟研究。结合疲劳试验,对比了焊接接头疲劳寿命及破坏发生位置,探究了焊接接头中裂纹尖端应力场演变规律、裂纹扩展路径及速率。结果表明,大熔深TIG焊接头疲劳寿命优于传统TIG焊接头,模拟所得寿命与试验值基本吻合。TIG焊接头中裂纹在厚度方向贯穿后,扩展速率迅速增加,快速到达失稳阶段,发生疲劳破坏;大熔深TIG焊接头中裂纹在厚度方向穿透前、后的扩展速率均较传统TIG焊慢,故其抗疲劳性能较好。

On the basis of the extended finite element method,the numerical simulations of the fatigue crack propagation behavior in the duplex stainless steel deep-penetration weld joints under different shielding gas conditions are carried out.The fatigue crack propagation life and the location of failure are compared with those of the experimental results.The evolution rules of the crack-tip stress field,the crack propagation path and rate in the weld joints are investigated in detail.The results indicated that,the fatigue performance of the deep-penetration TIG weld joint is superior to that of the traditional TIG weld joint,and the simulated fatigue life is in good agreement with the experimental one.After the penetration in the thickness,there is a sharp increase in the propagation rate and shortly reached an unstable state,resulting in fatigue failure.The fatigue crack propagation rates of the deep-penetration TIG weld joint is slower than those of the traditional TIG welding,both in the stages before and after the penetration in the thickness,making a better fatigue performance of the deep-penetration TIG weld joints.