时效时间对AA6014铝合金板材力学性能及晶间腐蚀性能的影响

Effect of aging time on mechanical properties and intergranular corrosion resistance of AA6014 aluminum alloy sheet

采用显微硬度仪、拉伸试验和晶间腐蚀浸泡试验等研究了185℃时效时间对6014-T4P铝合金板材硬度、力学性能和晶间腐蚀敏感性的影响,采用透射电镜观察了合金晶内和晶界析出相形貌,以阐明晶间腐蚀机理。结果表明:随着时效时间的增加,合金的硬度及抗拉强度呈先升高后保持稳定最终有所下降的变化规律,断后伸长率逐渐下降。合金的晶间腐蚀敏感性呈先升高后降低的趋势,在时效时间为500 min时电位最负、晶间腐蚀敏感性最高。随着时效时间的延长,合金的腐蚀类型由最初的点蚀转变为连续晶间腐蚀最终变为局部斑状腐蚀,这与晶界析出相的形貌及无沉淀析出带(PFZ)的宽度紧密相关。

Effect of aging at 185℃for different time on hardness,mechanical properties and intergranular corrosion sensitivity of 6014-T4P aluminum alloy sheet was studied by means of microhardness tester,tensile test and intergranular corrosion immersion test.The morphology of precipitated phases in the alloy grain and at the grain boundary was observed by transmission electron microscopy to clarify the mechanism of intergranular corrosion.The results show that with the increase of aging time,the hardness and tensile strength of the alloy first increase,then remain stable and finally decrease,and the elongation gradually decreases.The sensitivity of intergranular corrosion of the alloy increases first and then decreases with the increase of aging time,when the aging time is 500 min,the potential of the alloy is the most negative and the intergranular corrosion sensitivity is the highest.With the increase of aging time,the corrosion type of the alloy changes from initial pitting corrosion to continuous intergranular corrosion and finally to local pitting corrosion,which is closely related to the morphology of precipitated phase at grain boundary and the width of precipitate-free zone(PFZ).