退火温度对6201铝合金硬度的影响

Effect of different annealing temperatures on hardness of 6201 aluminum alloy

对加工硬化态直径为9.5 mm的6201铝合金进行了1 h不同温度的退火处理。通过硬度分析、宏微观组织分析以及DSC分析等方法探讨了加工硬化、时效强化以及固溶强化机制在6201铝合金不同温度退火过程中的作用。研究结果表明：退火温度在100~200℃变化时,时效强化作用大于回复软化作用,6201铝合金的维氏硬度随温度升高而升高,在200℃达到最大值为112.4 HV0.2;退火温度在200~350℃变化时,在过时效软化及回复再结晶软化作用下,6201铝合金的维氏硬度随温度升高而降低,350℃达到最低值为40.8 HV0.2;退火温度在350~500℃变化时Mg2Si开始向铝基体回溶,在固溶强化主导作用下,合金的硬度值随退火温度的升高再次持续增加,在500℃时增至77.0 HV0.2。

A work hardening state 6021 aluminum alloy with the diameter of 9. 5 mm was heat treated at different temperatures for 1 h. The function of the different strengthening mechanisms（work hardening,aging hardening and solid solution hardening） on the 6201 aluminum alloy during heat treatment was investigated by hardness test,macro and micro structure and DSC analysis. The results show that the effect of aging hardening is larger than that of recovery softening in the 6201 aluminum alloy during the annealing temperature increasing form100 ℃ to 200 ℃. The hardness of the alloy continuously increases from 93. 2 HV0. 2 to 112. 4 HV0. 2 with the annealing temperature increasing from 100 ℃ to 200 ℃. Under the combined action of the overaging softening and recovery recrystallization softening,the hardness of the alloy continuously decreases with the annealing temperature increasing from 200 ℃ to 350 ℃,and the hardness value reaches 40. 8 HV0. 2 as the annealing temperature increasing to 350 ℃. Solid solution strengthening is dominant with the Mg2 Si phases redissolving to matrix as the annealing temperature higher than 350 ℃. The hardness increases again with the annealing temperature increasing from 350 ℃ to 500 ℃,and the hardness of the alloy annealed at 500 ℃ is about 77. 0 HV0. 2.