Low Transformation Temperature Welding Consumables for Residual Stress Management : A Numerical Model for the Prediction of Phase Transformation Induced Compressive Residual Stresses
Low Transformation Temperature Welding Consumables for Residual Stress Management : A Numerical Model for the Prediction of Phase Transformation Induced Compressive Residual Stresses
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2014
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由于凝固的焊缝金属和周围母材之间的热应变，在结构钢焊接接头中观察到有害的拉伸残余应力。这些有害应力叠加在外部应力上，使焊接接头更容易出现疲劳失效。因此，压缩残余应力的存在，而不是典型的残余拉伸应力，提高了结构焊接接头的抗疲劳性。在这项研究工作中，使用 Sysweld 对采用开发的低转变温度焊丝 (LTTW) 的熔化极气体保护焊 (GMAW) 进行了数值分析。对结构钢板上的全方位角焊缝的模拟清楚地评估了不同实验开发的 LTTW 焊丝对残余应力产生和焊接变形控制的影响。铬当量较高的合金可以更好地控制面外畸变。它们对焊趾周围压缩残余应力产生的影响并不明显，值得进一步研究。模拟结果与实验确定的结果相当吻合。与其他焊缝相比，使用较高铬当量焊丝制成的焊缝在焊缝内部和周围表现出最大诱导残余压应力（约为 600 MPa），且横向变形值相对较低。 Sysweld 模拟的应力随时间演变图能够显示热收缩和相变引起的膨胀之间的相互作用，以及促进角焊缝中总体残余压应力所需的马氏体量。
Harmful tensile residual stresses are observed in structural steel weld joints as a result of the thermal strains between the solidified weld metal and surrounding base material. These harmful stresses, superimposed on external stresses, make the welded joints more prone to fatigue failures. Thus, the presence of compressive residual stresses, instead of the typical tensile residual stresses, improves the fatigue resistance of the structural welded joint. In this research work, numerical analysis of gas metal arc welding (GMAW) with developed low transformation temperature welding (LTTW) wires was performed using Sysweld. Simulation of all-around fillet welds on a structural steel plate clearly estimated the effects of the different experimentally developed LTTW wires on residual stress generation and welding distortion control. Alloys with higher chromium equivalent promoted greater control on out-of-plane distortion. Their effect on compressive residual stress generation around the weld toes was not as evident and deserves further investigation. Simulation results agreed reasonably well with the experimentally determined results. The weld made using the higher chromium equivalent welding wire showed the maximum induced compressive residual stress in and around the weld joint (at the order of 600 MPa) with relatively low transverse distortion values compared to the other welds. Stress evolution with time plots from Sysweld simulation were able to show the interaction between thermal contraction and phase transformationinduced expansion, and also the amount of martensite required to promote overall residual compressive stresses in the fillet weld joint.