搅拌针对搅拌摩擦焊接搅拌区晶粒影响研究

采用完全热力耦合模型,通过跟踪物质点的真实应变分量计算Zener-Hollomon参数,并由此计算搅拌区内的焊后晶粒尺寸。结果表明:热力影响区和搅拌区边界可以通过材料流动的不同行为进行界定;搅拌区随搅拌针直径的增加而增加,同时热力影响区变窄;在搅拌区域内,应变率对最终晶粒尺寸有明显影响;靠近搅拌针的材料,在快速绕针流动与旋推的作用下,经历了较大的应变率,最终得到较为细小的材料晶粒。

Grain sizes in stirring zone of friction stir welding with different pins

Fully coupled thermo-mechanical model was used to calculate the Zener-Hollomon parameter based on the obtainedtrue strain components of the traced particles. The grain sizes in the stirring zone were then computed. Results indicate that theboundaries of the stirring zone and the thermo-mechanical affected zone can be determined by the different material flows. Thesize of the stirring zone increases with the increase of the pin diameter and the size of the thermo-mechanical affected zonedecreases simultaneously. The material near the welding pin rotates and flows rapidly around the pin,thus higher strain rates canbe obtained in this region and lead to smaller final grain size.