Experimental study on axial closed die rolling thermo-mechanical treatment of 6061 aluminum alloy

6061铝合金轴向辗压形变热处理试验研究

¹ School of Materials Science and Engineering, Northwestern Polytechnical University, Xi'an 710072, China
² Chongqing Innovation Center, Northwestern Polytechnical University, Chongqing 401135, China
³ Technical Center, Fushun Special Steel Co., Ltd., Fushun 113001, China

Received: 9 April 2024

Abstract

The microstructure and mechanical properties of 6061 aluminum alloy were studied by using the aging treatment of 540 ℃/3 h solid solution+60% reduction axial closed die rolling+180 ℃/1.5-8 h. Comparison was made with the aging treatment of 60% reduction rolling+540 ℃/3 h solid solution+180 ℃/8 h. The results show that after axial closed die rolling thermo-mechanical treatment, the dislocation density of the aluminum alloy increases, the PFZ width decreases, and the spheroidized β″ phase appears. The aluminum alloy obtains good comprehensive mechanical properties at the aging time of 2.5 h, the yield strength of 333 MPa and the tensile strength of 359 MPa. As the aging time gets longer, little change took place in the grain size of the aluminum alloy, the granular Mg₂Si precipitates in the grain decrease, and a small amount of coarse granular Mg₂Si precipitates appear at the grain boundary. The dimple at the tensile fracture gradually changes from large and deep to small and shallow, and the ductility of the aluminum alloy decreases with the aging time.

摘要

以540 ℃/3 h固溶+60%压下量轴向辗压+180 ℃/1.5~8 h时效的6061铝合金为研究对象, 通过与60%压下量镦粗+540 ℃/3h固溶+180 ℃/8 h时效处理对比, 研究了合金的组织和力学性能。结果表明: 进行轴向辗压形变热处理后, 合金内的位错密度增大, 无沉淀析出带(PFZ)宽度有所减小, 出现球化β″相; 合金在时效时间2.5 h时获得较好的综合力学性能, 屈服强度为333 MPa, 抗拉强度为359 MPa。随着时效时间延长, 合金的晶粒尺寸变化不大, 晶粒内部的颗粒状Mg₂Si析出相有所减少, 晶界上出现少量粗大的颗粒状Mg₂Si析出相; 拉伸断口处韧窝由大而深逐渐转变为小且浅, 合金的塑性随着时效时间的增加呈下降趋势。