室温多向模锻道次对Al-5Mg-0.3Mn合金组织与性能的影响

Influence of multi-directional die forging passes on microstructure and properties for Al-5Mg-0.3Mn alloy at room temperature

为了提高Al-5Mg-0.3Mn合金的力学性能,在室温条件下分别对合金铸锭进行3道次(等效应变∑ε_((3 pass))=2.34)、6道次(等效应变∑ε_((6 pass))=4.68)和9道次(等效应变∑ε_((9 pass))=7.02)的多向模锻变形,达到了显著的细晶强化和形变强化效果。通过对Al-5Mg-0.3Mn合金锻件进行显微组织观察和力学性能测试,结果表明:多向模锻能够显著细化合金晶粒并提高合金力学性能。在低等效应变条件下,基体位错快速增殖并产生形变强化,使合金的力学性能显著提高;随着等效应变的增大,位错向晶界转变,使晶粒显著细化,位错被消耗,形变强化减弱,使合金的力学性能出现小幅度降低。当等效应变为4.68时,Al-5Mg-0.3Mn合金获得最优力学性能,屈服强度和抗拉强度分别提高至458和565 MPa。

In order to improve the mechanical properties of Al-5 Mg-0.3 Mn alloy,the alloy ingot was subjected to the muli-directional die forging deformation with three passes(∑ε_((3pass))=2.34),six passes(∑ε_((6 pass))=4.68)and nine passes(∑ε_((9 pass))=7.02)at room temperature to achieve significant fine grain strengthening and deformation strengthening effects.The results of microstructure observation and mechanical properties testing for Al-5 Mg-0.3 Mn alloy forgings show that the multi-directional die forging can significantly refine alloy grain and improve the mechanical properties of alloy.Under the condition of low equivalent strain,matrix dislocations multiply rapidly and produce deformation strengthening,which greatly improves the mechanical properties of alloy.With the increasing of equivalent strain,the transformation of dislocations to grain boundaries makes the grains be refined remarkably,and the dislocations are consumed.However,the deformation strengthening is weaken,and the mechanical properties of alloy are slightly reduced.When the equivalent strain becomes 4.68,the Al-5 Mg-0.3 Mn alloy obtains the optimal mechanical properties,and the yield strength and tensile strength increase to 458 and 565 MPa,respectively.