(1. 中南大学 材料科学与工程学院，长沙 410083；2. 三一重工股份有限公司 泵送研究院，长沙 410100)
摘 要: 测定2A14合金连续冷却转变动力学曲线(CCT图)，并对该曲线进行应用研究。通过DSC分析和SEM组织观察确定2A14合金合理的固溶温度，采用动态电阻法测得固溶后合金连续冷却过程的电阻—温度曲线，根据曲线斜率变化判断相变信息，绘制2A14合金的CCT图，利用透射电镜(TEM)观察连续冷却过程中合金的组织转变。结果表明：2A14合金适宜的固溶温度为505 ℃；随着冷却速度的增加，相变开始温度先降低，在达到某冷却速度时骤升，然后持续增加；相变主要集中在140~380 ℃的温度区间发生，抑制相变发生的临界冷却速度稍大于38.5 ℃/s；在实验范围内，20 mm厚的2A14合金板适宜采用60 ℃或100 ℃水淬，参考所测CCT图制定分级淬火工艺，可以在最大限度减小淬火应力的同时，抑制第二相的析出。
关键字: 2A14合金；连续冷却转变动力学曲线(CCT图)；原位电阻；相变；冷却速度
2A14 aluminum alloy and its application
（1. School of Materials Science and Engineering, Central South University, Changsha 410083, China;
2. Institute of Pumping, SANY Heavy Industry Co., Ltd., Changsha 410100, China）
Abstract:The continuous cooling transformation (CCT) curve of 2A14 aluminum alloy and its application were studied. The solutionizing temperature was ascertained by DSC analysis and SEM observation. Electrical resistance—temperature curves of 2A14 alloy in the continuous cooling processes after solid solution treatment were obtained by in-situ resistance measurement. Messages of the phase transformation were judged by analyzing the slope change of the obtained curves. The CCT diagram for Al-Cu-Mg alloy was plotted. The microstructure evolution during the cooling was examined by TEM observation. The results show that the appropriate solid solution temperature is 505 ℃. The phase transformation starting temperature decreases with the increase of cooling rates when the cooling rate is slow, but when the cooling rate is a little higher the phase transformation starting temperature increases suddenly. The phase transformation mainly takes place between 140 and 380 ℃. The critical cooling rate for preventing the phase transformation is above 38.5 ℃/s. It is better for 2A14 plates with the thickness of 20 mm to quench by 60 ℃ or 100 ℃ water. Interrupted quenching process can be established according to the tested CCT diagram to decrease quenching stress utmost and inhibit the precipitation of the secondary phases at the same time.
Key words: 2A14 alloy; continuous cooling transformation (CCT) curve; in-situ electrical resistance; phase transformation; cooling rate
