马氏体/贝氏体异种耐热钢接头焊接应力数值模拟

Simulation of welding stress of dissimilar welded joint between martensitic and bainitic heat-resistant steel

采用热弹塑性有限元方法对马氏体耐热钢9Cr1MoVNbN(T91)与低合金贝氏体耐热钢12Cr2MoWVTiB(G102)异种钢接头的温度场、应力场进行了数值模拟;并比较了接头在不同焊接线能量条件下的温度场、应力场。模拟计算结果表明,由于异种钢接头热物理性能的差异,其焊接温度场和应力应变场均不对称。由于T91的导热系数小于G102,加热过程中,G102侧的升温速度较快。而在冷却过程中,T91侧的温度梯度较G102侧小,而热影响区更宽。焊后T91钢一侧的应力梯度小于G102,但高应力区域比G102一侧宽。通过对模拟结果的比较分析,从降低焊接残余应力的角度出发,采用小线能量可减少接头中的拉伸残余应力。

The welding temperature and stress field have been simulated dynamically with thermal elasto-plastical finite element analysis method for dissimilar welded joints between martensitic（9Cr1 MoVNbN） and bainitic heat-resistant steel（12Cr2MoWVTiB）, and compared with different welding inputs.The results of numerical simulation shows that the welding temperature and stress field are asymmetrical in the direction of perpendicular to heat resource moving, due to the differences of thermal physical properties of dissimilar metal welding joint.The stress gradient in the side of T91 steel is less than that of G102 steel.However,the region of high stress in the side of T91 steel is larger than that of G102.Through the comparison of the results of numerical simulation,the tensile welding residual stress can be reduced with low welding heat input.