6082铝合金的TTT曲线及其研究

TTT curves of 6082 aluminum alloy and its application

为研究6082铝合金的淬火敏感性,采用分级淬火的方法测定了6082铝合金的时间-温度-转化率(TTT)曲线,利用XRD、TEM并结合Avrami方程研究了6082合金在等温过程中的组织变化.结果表明:6082铝合金TTT曲线的鼻尖温度约为350℃,淬火敏感温度区间为300～420℃;6082铝合金过饱和固溶体在350℃等温时快速分解,初期形成大量杆状的β'相,随着时间的延长,晶内析出粗大的β相;合金在高温区域(≥420℃)和低温区域(≤300℃)时,淬火敏感性较低;鼻尖温度下的高相变驱动力和较快的扩散速率是Mg2Si相析出和长大的主要原因.在实际在线淬火过程中,建议在淬火敏感温度区间加快淬火冷却速率抑制平衡相的析出,在高温区域和低温区域可适当降低冷却速率减小热应力的影响.

To study the quench sensitivity of 6082 alloy,the time-temperature-transformation（TTT）curves of 6082 aluminum alloy were determined by an interrupted quench method,and the structure transformation during isothermal treatment was studied by XRD、TEM and Avrami equation.The results show that the nose temperature of TTT curves of 6082 alloy is 350℃and the quench sensitive temperature range is 300～420℃. The supersaturated solid solution of 6082 alloy decomposites quickly at 350℃.At the beginning plenty of Mg2 Si particles（β＇phase）were precipitated,and with the holding time prolonged,more and more thick Mg2 Si particles（βphase）were precipitated in the grain.The quench sensitivity is low both in high temperature zone（420℃）and low temperature zone（300℃）.Severe phase transformation driving force and high diffusion rate of solute atoms are the primary precipitating reasons of Mg2 Si particles.In the actual online hardening process,speeding up the cooling rate in the quench sensitive sector to reduce the precipitation of equilibrium phase is meaningful,and at higher or lower temperature,decreasing the cooling rate is helpful to relieve the effect of thermal load.