材料期刊网

对T616时效处理的6061铝合金的拉伸性能、晶间腐蚀性能和电导率进行了测试,并采用OM和TEM对其组织进行了观察.结果表明,6061铝合金经180℃×8 h T6峰值时效后,虽然强度较高,但有严重晶间腐蚀倾向;T616预时效时间对拉伸性能影响不大,但中断时效温度和时间对其影响显著.由于较高的中断时效温度和较长的中断时间能获得高密度的晶内析出相和呈球状不连续分布的晶界析出相,因此,T616时效处理后的6061铝合金不仅能保持较高强度,同时还能显著提高晶间腐蚀抗力.经180℃×2 h+150℃×2160 h+180℃×8 h T616时效,合金抗拉强度和屈服强度分别为348.5和326.9 MPa,相对于T6状态,仅分别下降了2.1%和1.4%,腐蚀类型由T6状态的晶间腐蚀转变为均匀腐蚀,腐蚀深度约为30μm.

It is important to achieve a good combinization of high tensile properties and high intergranular corrosion resistance for 6000 series alloys in wider applications. In this paper, the effect of T616 temper on tensile and intergranular corrosion properties of 6061 aluminum alloy was investigated by tensile test, intergranular corrosion test, OM and TEM. The experimental results show that after T6 temper the ultimate strength and yield strength of 6061 alloy are 356.0 and 331.6 MPa respectively,but it has a serious tendency to intergranular corrosion sensitivity. It is found that pre-ageing time of T616 temper has no remarked effect on tensile properties of the alloy, but interrupted temperature and interrupted time have obvious effects on its tensile and intergranular corrosion properties. After T616 treatment, the tensile strength of 6061 aluminium alloy reaches its peak strength firstly and then decreases to a small value with the increase of interrupted time after pre-ageing at interrupted temperature of 150 ℃, and the corrosion mode also changes from intergranular to uniform corrosion. Higher interrupted temperature and longer interrupted time are beneficial to achieve a good combinization of tensile properties and intergranular corrosion resistance, which results from the high density of precipitates inside grains and discontinuously distributed precipitates on grain boundaries. After an optimum T616 treatment of 180 ℃×2 h+150 ℃×2160 h+180 ℃×8 h, the ultimate strength and yield strengthare 348.5 and 326.9 MPa respectively, close to those after T6 temper. The corrosion mode is changed from the intergranular corrosion of 6061 Al alloy after T6 temper to a uniform etching with the etching depth about 30 μm.