不同热成形工艺下TA32钛合金的流变性能及组织演变

Study on Rheological Properties and Microstructure Evolution of TA32 Titanium Alloy under Different Thermoforming Processes

摘要:

针对随炉成形及到温成形2种主要的热成形工艺,通过高温拉伸试验,从TA32钛合金热成形流变性能及组织演变的角度出发,首先研究温度、变形速率、应变量等共性因素的影响,再对比分析2种热成形工艺下不同升温速率和冷却方式等特性因素的影响。设计两因素两水平工艺试验,分析不同高温润滑剂及热成形条件下TA32钛合金的氧化行为。结果表明:温度为800℃、应变速率为0.001 s~(-1)、保温时间为30 min、应变量为0.45～0.6,且选用到温热成形(升温速率为800℃/5 min,空冷)时,TA32钛合金的变形抗力较低,塑性较好,晶粒较为均匀,β相等轴晶粒较多,综合成形性能较好;到温成形条件下,选用立方氮化硼(CBN)作为高温润滑剂时,成形件的氧化程度最低。综合考虑,TA32钛合金板材最优高温成形方案为到温成形工艺并采用CBN作为高温润滑剂。

关键词:TA32钛合金;组织演变;到温成形;随炉成形;高温润滑剂

Abstract:

In order to study the two main thermoforming processes of thermoforming with furnace and temperaturereached thermoforming,through the analysis of thermoforming rheological properties and microstructure evolution of TA32 titanium alloy,the effects of common influence factors such as temperature,deformation rate and strain were studied firstly,and then the effects of heating rates and cooling methods under two thermoforming processes were compared.The oxidation behavior of TA32 titanium alloy under different high temperature lubricants and thermoforming conditions was also researched by two-factor two-level orthogonal test.The best formability and properties of TA32titanium alloy present during temperature-reached thermoforming with these process parameters:the temperature 800℃,strain rate 0.001 s~(-1),holding time 30 min,strain between 0.45 and 0.6,heating rate 800℃/5 min and air-cooling.Under this condition,TA32 titanium alloy has better plasticity,lower deformation resistance,uniform grains,and the moreβequiaxed grains.The lowest oxidation degree is found that the sample with the lubricant of cubic boron nitride(CBN)during the temperature-reached thermoforming.Finally,the temperature-reached thermoforming with the lubricant of CBN is the best process for TA32 titanium alloy sheets thermoforming.

Key words:TA32 titanium alloy;microstructure evolution;temperature-reached thermoforming;thermoforming with furnace;high temperature lubricants