Ti6242钛合金电子束冷床熔炼(EB)技术

Melting technology of electron beam cold hearth melting of Ti6242 titanium alloy

利用3 150 kW型电子束冷床熔炼(EB)炉制备Ti6242钛合金大规格扁锭,采用Langmuir定律建立了Ti6242钛合金EB熔炼过程熔体中各元素饱和蒸气压及挥发规律的数学模型,分析了熔炼工艺参数与铸锭化学成分均匀性之间的关系。结果表明:Ti6242钛合金EB炉熔炼过程中Al、Sn元素挥发严重,实际挥发率分别为12.27%和7.86%,与挥发模型吻合度较高(理论挥发率分别为11.68%和9.825%)。3 150 kW型电子束冷床熔炼(EB)炉的最佳熔炼速度为1.28×10^(-4) m/s(即700 kg/h),在此工艺下铸锭化学成分均匀性良好,完全符合国标GB/T 3620.1—2007的要求。Ti6242钛合金EB铸锭的低倍组织为等轴晶组织,明显不同于VAR铸锭。利用EB炉一次熔炼制备的Ti6242钛合金扁锭可用于直接轧制成形Ti6242钛合金板材,圆锭可用于制备高品质、大规格棒材,实现钛合金的低成本、短流程制备。

The large specification flat ingots of Ti6242 titanium alloy were prepared by using 3150 kW electron beam cold hearth melting(EB)furnace.The mathematical model of saturated vapor pressure and volatilization law of various elements in EB melting process of Ti6242 titanium alloy was established by using Langmuir law.The relationship between the smelting process parameters and the homogeneity of the chemical composition of ingot was analyzed.The results showed that Al and Sn elements of Ti6242 titanium alloy volatilized seriously in EB furnace melting,and the actual volatilization rate was 12.27%and 7.86%respectively,which was in good agreement with the volatilization model(theoretical volatilization rate was 11.68%and 9.825%respectively).The optimum melting speed of the 3150 kW electron beam cooling hearth melting(EB)furnace was 1.28×10-4 m/s(700 kg/h).Under this process condition,the chemical composition of the ingot had good uniformity and fully met the requirements of GB/T 3620.1-2007.The macrostructure of Ti6242 titanium alloy was equiaxed grain structure,which is obviously different from VAR ingot.The flat ingot of Ti6242 titanium alloy prepared by EB furnace single smelting can be used for direct rolling to sheet,and the round ingot can be used to prepare high quality and large size bar,realizing the low cost and short process of titanium alloy preparation.