半固态5083铝合金的二次加热组织与触变轧制

Microstructure of Reheated Semi-Solid 5083 Aluminum Alloy and Thixo-Rolling

采用大挤压比热挤压预变形的SIMA法制备了5083铝合金半固态坯料,研究了在不同加热温度和保温时间条件下二次加热重熔组织的演变规律,以及不同工艺参数对一道次触变轧制后带材力学性能的影响。结果表明,在二次加热过程中,晶粒形状和液相率主要受加热温度影响,而受加热保温时间的影响不大。在一道次触变轧制中,当二次加热温度为600℃,轧制变形量为60%时,可以获得抗拉强度为260.93MPa,伸长率为26.81%的较好综合力学性能的带材。经40%变形量二次冷轧后,带材的抗拉强度提高了70MPa。结合拉伸断口的宏观和微观形貌分析,可知带材的断裂方式为微孔聚集型的韧性断裂。

Semi-solid 5083 aluminum alloy billets were prepared by SIMA by hot extrusion with high extrusion ratio pre-deformation,and the evolution of reheating microstructures at different reheating temperatures and holding time was observed.The effect of key processing parameters on the microstructures and mechanical properties of thixo-rolled materials after one-pass rolling were analyzed.The results show that grain shape and liquid fraction are mainly controlled by reheating temperature during the reheating process,while role of holding time can be ignored.The strip exhibits the acceptable mechanical properties with tensile strength of 260.93 MPa and elongation of 26.81% after one-pass thixo-rolling with reheating temperature of 600 ℃ and pre-deformation of 60%.After two-passes cold rolling with 40% deformation,the tensile strength of the strip is improved by 70MPa.The macro-and micro-observation of the tensile fracture surface reveal that the fracture mechanism of the rolled samples is characterized by ductile fracture with micro-pore accumulation.