衬板叠轧Mg/Al复合板基体组织演变优化强塑性机制

Optimization mechanism of matrix microstructure evolution on strength-plasticity of Mg/Al composite plate during hard-plate accumulative roll bonding

Mg/Al复合板兼并了镁合金的轻质性及铝合金的可塑性、耐腐蚀等性能,显著增强了其综合性能,但制造周期长、工艺要求高等不足制约了异质复合板成形技术的快速发展。为此,本文提出一种衬板辅助叠轧成形新方法。研究结果表明:3ARB时Mg/Al复合板抗拉强度可达235 MPa,伸长率为14.7%,镁板中出现明显的韧窝,呈韧性断裂特征,综合性能为最佳。由于此时Mg板基面滑移与非基面滑移同时开动,促进了动态再结晶的生成,此时Mg板再结晶比例为77.21%。随着累积叠轧的进行,大角度晶界增加和晶粒细化明显,原始晶粒已经基本破碎细化成等轴晶,Mg、Al基体硬度波动逐渐减小,复合板内部结构逐渐趋于稳定。本研究可为高性能异质复合板成形制造提供了一种新思路。

Mg/Al composite plate combines the light weight of Mg alloy and the plasticity and corrosion resistance of Al alloy,which significantly enhances its comprehensive performance.However,the long manufacturing cycle and high process requirements limit the rapid development of heterogeneous composite plate forming technology.Therefore,a new method of ARB(accumulative roll bonding)forming with hard plates is proposed in this paper.The results show that the tensile strength of Mg/Al composite plate can reach 235 MPa and the elongation is 14.7%at 3ARB.There are obvious dimples in the magnesium plate,which are ductile fracture characteristics,and the overall performance is the highest.Since the basal slip and non-basal slip of the Mg plate start at the same time,which promotes the formation of dynamic recrystallization.At this time,the recrystallization ratio of the Mg plate is 77.21%.With the progress of ARB,the high angle grain boundary increases and the grain refinement is obvious.The original grains have been basically broken and refined into equiaxed grains.The hardness fluctuation of Mg and Al matrix decreases gradually,and the internal structure of the composite plate tends to be stable.This provides a new idea for forming and manufacturing high-performance heterogeneous composite plates.