装甲钢温度-组织-应力耦合本构模型的建立及在焊接模拟中的应用

Establishment of Thermo-metallurgical-mechanical Coupling Constitutive Model for Armour Steel and Its Application in Welding Numerical Simulation

装甲钢焊接热循环过程中固态相变对焊接残余应力的演变及大小有着重要影响,而现有的有限元软件本构模型无法考虑固态相变的作用。在传热学、固态相变理论和连续介质力学的基础上,建立了温度-组织-应力耦合的本构模型,本构模型中综合考虑了固态相变引起的体积变化、力学性能变化和相变塑性对焊接残余应力的影响,采用ABAQUS子程序UMAT通过二次开发将该本构模型嵌入通用有限元软件中,对装甲钢平板对接焊进行研究,获得了装甲钢焊接热循环过程中温度、组织及残余应力变化规律。研究结果表明:装甲钢平板中断面表面宽度方向,在纵向残余应力表征上,耦合本构模型的模拟结果与X射线衍射测量结果具有较好的一致性,验证了耦合本构模型的正确性,并表明相变塑性对相变区的残余应力存在一定的松弛作用;对于装甲钢近缝区纵向残余应力大小:完全相变区<部分相变区<未发生相变区。

Solid-state phase transformation has significant effect on the evolution and magnitude of weld- ing residual stress for armour steel during welding thermal cycle, while the current constitutive model can not take solid-state phase transformation into account. Based on heat transfer theory, solid-state phase transformation theory and continuum mechanics, a thermo-metallurgieal-mechanieal coupling constitutive model in which the effects of volumetric change, yield strength change and transformation induced plastic- ity（TRIP） on residual stresses due to solid-state phase transformation on welding residual stress are con- sidered is established. The constitutive model is inserted into a general purpose implicit finite element program via user material subroutine UMAT. The change rules of temperature, mierostructure and residu- al stresses are obtained for a butt welding of armour steel plates. The research results show that longitudi- nal residual stresses obtained from the coupling constitutive model are in good agreement with experimen- tal results measured by X-ray diffraction perpendicular to weld centerline on the upper surface of the weldment. The correctness of developed computational method is confirmed, and TRIP has certain effects on the evolution of longitudinal residual stresses. For the magnitude of longitudinal residual stresses in the vicinity of weld zone, the fully-transformed region is less than partially-transformed region, and the par- tially-transformed region is less than untransformed region.