基于分区表征的异质金属搅拌摩擦焊接残余变形数值模拟

Numerical simulation on residual distortion of dissimilar metals during friction stir welding based on subregion characterization

为了研究焊缝材料屈服强度变化与焊接残余变形之间的关联机制,提出了基于力学性能分区表征的异质金属搅拌摩擦焊接残余变形计算方法。通过搅拌摩擦焊接实验研究了搅拌头转动方向对搅拌摩擦焊接搅拌区的力学性能曲线影响,并以实验测定的材料本构关系定义搅拌区材料的屈服强度,通过分区表征不同的屈服强度,建立了搅拌摩擦焊接的顺序热力耦合模型,结合分区表征模型研究了搅拌区屈服强度变化对异质金属搅拌摩擦焊接残余变形的影响。结果表明,前进侧材料为2024-T3,后退侧材料为6061-T6时,搅拌区屈服强度为171 MPa、抗拉强度为194 MPa,前进侧和后退侧材料互换,搅拌区屈服强度为166 MPa、抗拉强度为186 MPa。前进侧材料和后退侧材料互换后屈服强度和抗拉强度产生差异的原因是前进侧和后退侧材料的流动行为差异。以实测的力学性能曲线为依据,建立了搅拌摩擦焊接异质合金的顺序热力耦合模型,前进侧材料为2024-T3,后退侧材料为6061-T6时,搅拌摩擦焊接构件最大残余变形为1.2 mm,前进侧材料为6061-T6,后退侧材料为2024-T3时,搅拌摩擦焊接构件最大残余变形为1.3 mm。随着搅拌区材料屈服强度提升,搅拌区弯曲刚度增加,导致残余变形减小。

To study the correlation mechanism between the changes of yield strengths of weld materials and welding residual distortion,the calculation method of residual distortion of dissimilar metals during friction stir welding based on machanical property subregion characterization was proposed.The influence of the rotation direction of the stirring tool on the mechanical property curves of the stirring zone in friction stir welding was studied through friction stir welding experiments.The yield strength of the stirring zone material was defined based on the experimentally measured material constitutive relationship.Different yield strengths were characterized by subregions.The sequential thermo-mechanical coupled model of friction stir welding was established.The influence of yield strength changes in the stirring zone on the residual distortion of dissimilar metals during friction stir welding was studied.The results show that when the advancing side material is 2024-T3 and the retreating side material is 6061-T6,the yield strength of the stirring zone is 171 MPa and the tensile strength is 194 MPa.When the materials at advancing and retreating sides are exchanged,the yield strength of the stirring zone is 166 MPa and the tensile strength is 186 MPa.The reason for the difference in yield strength and tensile strength caused by the exchange of materials on the advancing and retreating sides is the different flow behaviors at advancing and retreating sides.According to the measured mechanical property curves,the sequential thermo-mechanical coupled model for friction stir welding of dissimilar metals was established.When the advancing side material is 2024-T3 and the retreating side material is 6061-T6,the maximum residual distortion of the friction stir welding component is 1.2 mm.When the advancing side material is 6061-T6 and the retreating side material is 2024-T3,the maximum residual distortion of the friction stir welding component is 1.3 mm.With the increase of yield strength of the stirring zone material,the bending stiffness of the stirring zone increases,leading to the decrease of residual distortion.