搅拌摩擦加工道次及主轴转向对再生铝合金组织和性能的影响

Effects of friction stir processing passes and spindle rotation direction on microstructure and properties of recycled aluminum alloy

通过改变加工道次及主轴转向,研究了搅拌摩擦加工工艺对Al-7Si-0.9Fe-0.3Mg铝合金组织和力学性能的影响。结果表明:随着加工道次的增加,搅拌摩擦加工区的宽度和面积均逐渐增大,改变主轴转向后,加工区的宽度较主轴转向改变前低,但提高了加工区组织的均匀性和对称性。热机械影响区的宽度也随着加工道次的增加而增大,而改变主轴转向后,前进侧热机械影响区的宽度较主轴转向改变前低,返回侧与中心区的界限清晰,第二相分布的取向明显降低,改善了颗粒尺寸和分布均匀性。加工核心区的第二相颗粒尺寸随加工道次的增加而逐渐减小,圆整度逐渐提高,3道次时富铁相和共晶硅的平均长度分别为3.65和2.91μm,较单道次分别降低14.1%和38.6%。改变主轴转向后,第二相的细化和圆整化效果稍有降低。加工道次的增加对加工核心区的抗拉强度影响不显著,但伸长率显著提高,而改变主轴转向对合金抗拉强度和伸长率的影响均不明显。

The effects of friction stir processing technology on the microstructure and mechanical properties of Al-7 Si-0.9 Fe-0.3 Mg aluminum alloy were studied by changing the processing pass and spindle rotation direction.The results show that with the increase of processing pass,the width and area of the friction stir processing zone gradually increase.After changing the spindle rotation direction,the width of the processing zone is lower than that before the spindle rotation direction is changed,but the uniformity and symmetry of microstructure in processing zone are improved.The width of the thermo-mechanical affected zone increases with the increase of processing pass.After changing the spindle rotation direction,the width of the thermo-mechanical affected zone on the advanced side is lower than that before the spindle rotation direction is changed.The boundary between the return side and the center zone is clear,and the orientation of the second phase is significantly reduced,which improves the particle size and distribution uniformity.The second phase particle size in the processing center zone gradually decreases with the increase of processing pass,and the roundness gradually increases.The average length of the iron-rich phase and eutectic silicon under three processing passes is 3.65 and 2.91μm respectively,which is reduced by 14.1%and 38.6%compared with single pass respectively.After changing the spindle rotation direction,the effects of refinement and roundness of the second phase are slightly reduced.The increase of the processing pass has no significant effect on the tensile strength of the processing center zone,but the elongation increases significantly,while the effect of changing the spindle rotation direction on the tensile strength and elongation of the alloy is not significant.