冷轧压下量对时效6156铝合金组织与性能的影响

The Effect of Cold-rolling Thickness Reduction on Mechanical Properties and Microstructures of 6156 Al alloy

摘要:

采用拉伸试验、金相观察、X射线衍射、扫描电镜及透射电镜等,研究了180 ℃/1 h欠时效+50~80%压下量冷轧+100 ℃/48 h再时效的6156铝合金组织和力学性能。拉伸测试表明,合金抗拉强度、屈服强度和断裂延伸率分别为515~564 MPa、472~551 MPa和5.7~11.1%,获得高强度和良好塑性。微观分析表明,合金强度源于形变强化和析出强化共同作用,并随压下量增加而增大；合金塑性改善源于位错密度下降和析出强化增强；拉伸断口上沿晶与穿晶断裂并存,增大压下量,韧窝变浅、数量增加。

Abstract:

The mechanical properties and microsctructures of the 6156 Al alloy subjected to a thermomechanical treatment consisting of under-ageing at 180 ℃ for 1 h, cold-rolling at room temperature with the thickness reductions of 50~80% and re-ageing at 100 ℃ for 48 h were investigated by optical microscopy, tensile test, X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The tensile test indicates that the alloy can achieve high strength and relatively good ductility simultaneously and the ultimate strength, yield strength and elongation to failure are 515~564 MPa, 472~551 MPa and 5.7~11.1%, respectively. The microsctrucural observations show that the high strength results from the combination of deformation and precipitation strengthening and increases with increasing the thickness reductions. The improved ductility is attributed to both the decreased dislocation density and increased precipitation strengthening. The fractographies of the alloy consist of intergranular and dimple-induced transgranular fracture and the dimples have shallow depths and increased number with increasing the thickness reductions.