(1. 中南大学 材料科学与工程学院,长沙 410083;
2. 中南大学 教育部有色金属材料科学与工程实验室,长沙 410083)
摘 要: 利用力学性能测量和透射电镜观察等手段对轨道交通车辆大型材用7005 铝合金热处理特性进行研究。结果表明:该合金在线挤压淬火后于105 ℃时效时,随着时效的进行,开始阶段硬度上升很快,时效8 h后,硬度(HB)达100 HB;时效50 h后,硬度(HB)可达125 HB以上;此后随着时效时间的延长硬度上升缓慢,时效200 h后,硬度仍未达到峰值;经(105 ℃,8 h)+(155 ℃,8 h)双级时效后,σb=395 MPa,σ0.2=330 MPa,δ=12%,硬度为117 HB。合金在较高温度(155 ℃和180 ℃)单级时效及双级时效时间过长,均引起析出相粒子明显长大、粗化,导致合金强度降低。
关键字: 7005铝合金;热处理特性;淬火;时效;力学性能
7005 Al alloy employed in railway trains
(1. School of Materials Science and Engineering, Central South University, Changsha 410083, China;
2. Key Laboratory of Nonferrous Metal Materials Science and Engineering, Ministry of Education,
Central South University, Changsha 410083, China)
Abstract:The heat treatment characteristic of the 7005 aluminum alloys was studied by mechanical properties measurement and TEM. The results show that, during the process of aging at 105 ℃ after on-line quenching, the hardness(HB) of alloy increases quickly at first and reach about 100 HB after aging for 8h and 125 HB after 50 h, then the hardness increases slowly with increasing aging time, and the hardness does not reach the peak value even the alloy is aged for 200 h. After aging at (105 ℃, 8 h)+(155 ℃, 8 h), the mechanical properties of 7005 aluminum alloy are σb=395 MPa, σ0.2=330 MPa, δ=12%, 117 HB. If the aging of alloy at high temperature (155 ℃, 180 ℃) or the two-stage aging is too long, the precipitated phases of the alloy will grow and coarsen, and then the alloy strength decreases.
Key words: 7005 Al alloy; heat treatment characteristic; quenching; aging; mechanical properties