基于模拟分析7050铝合金单峰时效处理的微观组织和性能研究

Study on microstructure and properties of single peak aging treatment for 7050 aluminum alloy based on simulation analysis

采用JMatPro软件对7050铝合金的时效过程进行模拟计算,获得时效过程中各强化相析出开始时间、析出顺序和析出量数据,得到在100℃~140℃温度范围内时效处理时合金强度遵循先上升后下降的趋势。基于此温度范围内进行单峰时效热处理实验验证,利用室温拉伸、TEM和SEM研究合金组织对强度的影响。结果显示:合金强度变化规律与模拟分析结果一致。当时效温度为120℃时,合金可获得最高强度(抗拉强度597 MPa,屈服强度554 MPa)。随着时效温度的升高,合金晶内析出相密度增大,并发生一定程度粗化;晶界析出相变化趋势为连续线状→更加密集、连续链状→明显变粗、间断链状;合金的断裂形式从固溶态的穿晶韧性断裂为主转变为沿晶脆性断裂为主。

The aging process of 7050 aluminum alloy was simulated by the software JMatPro,and the precipitation start time,precipitation sequence and precipitation amount of each strengthening phase in the aging process were obtained.It was obtained that the alloy strength first increased and then decreased when aged at 100 ℃-140 ℃.Based on this,the single peak aging treatment test was carried out at 100 ℃-140 ℃.The effects of microstructure on the strength of the alloy were studied by room temperature tensile,TEM and SEM.The results show that the change law of alloy strength is consistent with the simulation analysis results.When the aging temperature is 120 ℃,the alloy can obtain the highest strength(tensile strength 597 MPa,yield strength 554 MPa).With the increase of the aging temperature,the density of precipitates in the alloy increases and coarsens to a certain extent;the change trend of precipitates at grain boundaries is slightly coarse and continuous line→more dense and continuous chain→obviously coarsened and discontinuous chain;and the fracture mode of the alloy changes from transgranular ductile fracture in solid solution state to intergranular brittle fracture.