6061-T6铝合金力学性能试验研究

Experimental study on mechanical properties of 6061-T6 aluminum alloy

完善铝合金网壳耐火评价方法需要材性数据支撑,为此,对6061-T6铝材进行了常温及高温拉伸试验、高温蠕变试验研究,提出了高温材性(弹性模量、规定塑性延伸强度、抗拉强度)三段式折减系数模型、承载能力极限状态本构模型和蠕变第Ⅱ阶段速率模型。研究结果表明:板式节点的圆盘盖板与H形截面铝梁存在常温材料强度差异;当温度超过300℃时,6061-T6铝材屈强比接近于1.0;而在175℃以上时,需开始考虑热暴露时长增加对材料强度劣化的影响;断裂临界应力比随温度升高线性降低;当温度超过250℃时,热暴露时长对同应力比水平下蠕变断裂时间有显著影响。建议相关设计标准对高温材性试验的保温时间进行完善。

The refinement for fire resistance assessment method of aluminum alloy(Al-alloy)reticulated shell structure needs the support of material property data.The tensile tests of 6061-T6 Al-alloy at room temperature and high temperature and creep tests at high temperature were carried out.A three-part reduction factor model for high-temperature material properties(modulus of elasticity,specified plastic elongation strength,and tensile strength),a constitutive model for the limit state of load-bearing capacity,and a strain rate model of creep phase II were proposed.The results show that there is an ambient material strength difference between the disc plate and the H-section Al-alloy beam.Above 300℃,the ratio of yield strength to the ultimate strength of this grade aluminum is close to 1.0.Above 175℃,the effect of increased thermal exposure on the deterioration of material strength should be considered.The fracture critical stress ratio decreases linearly with the increasing temperature.Above 250℃,the duration of thermal exposure has a significant effect on the creep fracture time at the same stress ratio.It is recommended that additional requirements be given in relevant design standards on thermal exposure time(soaking time)for material testing at high temperatures.