时效对冷轧6201铝合金硬度及导电性能的影响

Effects of Aging on Hardness and Conductivity of Cold-rolled 6201 Aluminum Alloy

采用重力铸造方法制备了高Mg、Si含量的6201(Al-0.81Mg-0.79Si)合金。经550℃×1 h固溶处理、水淬、室温3道次82.6%压下量轧制后,在130℃合金再经不同时间(8~48 h)的时效处理,考察冷轧后低温时效对合金微观组织、硬度和导电性的影响。结果表明,固溶处理导致合金元素溶于基体产生晶格畸变,硬度明显增加、导电率急剧下降。轧制产生高密度位错和非平衡空位,诱导纳米析出相形成,硬度急剧增加、导电率稍有下降。130℃×8 h时效加速了高密度共格纳米析出相析出,达到峰值时效,合金硬度最大,导电性显著提高。24 h及更长时间时效,导致析出相偏聚,非共格析出相形成,产生过时效和析出饱和,合金硬度显著下降直至保持不变。随时效时间的延长,位错、空位等缺陷持续湮灭,合金的导电性持续增加。

6201 alloy(Al-0.81Mg-0.79Si)with high Mg and Si contents was prepared by gravity casting.After solution treatment at 550℃×1 h,water quenching and three-pass rolling with 82.6%reduction at room temperature,the alloy was aged at 130℃for different time(8-48 h).The effects of low temperature aging after cold rolled on the microstructure,hardness and conductivity of the alloy were investigated.The results show that,solution treatment results in alloy elements being dissolved in matrix and inducing lattice distortion.The hardness of the alloy obviously increases while the conductivity dramatically decreases.High density of dislocations and nonequilibrium vacancies produce during rolling,which induce the formation of nano precipitates.The hardness of the alloy increases sharply and the conductivity decreases slightly.Aging at 130℃for 8 h accelerates the precipitation of high density of coherent nano precipitates to reach the peak aging,the hardness of the alloy is the largest and the conductivity is improved significantly.24 h and longer aging results in over-aging and precipitation saturation as the precipitates are segregated and incoherent precipitates form,the hardness of the alloy decreases significantly until it remains constant.With the prolongation of the time,the defects such as dislocation and vacancy are annihilated continuously,and the conductivity of the alloy continues to increase.