7059铝合金热处理工艺及力学性能研究

Study on Heat treatment Technology and Mechanical Properties of 7059 Aluminum Alloy

设置七水平三因素正交试验,以期获得较佳的7059铝合金热处理工艺,然后对比硬度、力学性能、显微组织,验证采用正交试验所获得的最终热处理工艺的优越性。通过正交试验以及对比力学性能及显微组织,得到470℃/3 h+120℃/12 h+165℃/10 h为较佳的热处理工艺。在此热处理工艺下可将抗拉强度从挤压态的505 MPa提升至761.7 MPa,虽然相较于挤压态的韧性有所降低,但此时仍有8.2%的断后伸长率和8%的断面收缩率,断裂方式也由挤压态的韧性断裂变为以韧性断裂为主的韧脆混合断裂。经过测试,采用最终热处理工艺布氏硬度达到193.5 HBW,高于正交试验中的各次结果。

In this paper, a three-factor orthogonal test is conducted to obtain a better heat treatment technology of 7059 aluminum alloy. Then, through the comparisons of hardness, of mechanical properties, and of microstructures, the researchers test the excellence of the final heat treatment obtained from the three-factor orthogonal test. Through the tests and comparisons, 470 ℃/3 h+120 ℃/12 h+165 ℃/10 h is proved to be the best heat treatment. In this heat treatment process, the tensile strength can be increased from the extrusion of 505MPa tothat of 761.667MPa. Although the toughness of extrusion decreases, the sample still has the elongation of 8.167% at break and 8% shrinkage rate.The fracture mode also changes from ductile fracture in the squeezed state to ductile- brittle mixed fracture dominated by ductile fracture. The brinell hardness of the final and best heat treatment reaches 193.5HBW, which is higher than those of all other results of the orthogonal test.