固溶升温速率对Al-10.78Zn-2.78Mg-2.59Cu铝合金组织与性能的影响

Effect of Heating Rate for Solid Solution on Microstructure and Properties of Al-10.78Zn-2.78Mg-2.59Cu Aluminum Alloy

分别以3.6,180℃·h-1的升温速率将Al-10.78Zn-2.78Mg-2.59Cu铝合金升温至470℃进行固溶处理以及后续时效处理,研究了升温速率对试验合金显微组织和性能的影响。结果表明:较高升温速率下试验合金的平均晶粒尺寸和晶界平均取向角比较低升温速率下的大,小角度晶界占比更小,力学性能更低,导电性能更高;两种升温速率下试验合金的拉伸断口均存在明显韧窝,断裂方式均为穿晶断裂;升温速率对耐腐蚀性能影响不明显,晶间腐蚀深度均在30~100μm之间,晶间腐蚀等级为3级,剥落腐蚀等级为PC级;对试验合金屈服强度贡献最大的是固溶和时效沉淀析出强化,慢速升温能够有效提高试验合金的屈服强度。

Al-10.78 Zn-2.78 Mg-2.59 Cu aluminum alloy was heated to 470 ℃ at the heating rates of 3.6 ℃·h^-1 and 180℃·h-1,respectively,then treated by solid solution,and aged subsequently.The effects of heating rate on the microstructure and properties of tested alloy were studied.The results show that the average grain size and the average orientation angle of grain boundaries in tested alloy at the relatively high heating rate was higher,the fraction of low angle grain boundaries was smaller,the mechanical properties were lower and the conductivity was higher than those at the relatively low heating rate.Dimples existed obviously on the tensile fracture of tested alloy at the two heating rates,and the fracture modes were both transgranular.The effect of heating rate on corrosion resistance was little;the intergranular corrosion depth was between 30μm and 100μm,the intergranular corrosion grade was 3,and the peeling corrosion grade was PC.The solid solution and aging precipitation strengthening made the most important contribution to yield strength of the tested alloy.Heating up slowly can improve yield strength of the tested alloy effectively.