Ф200mm TiAl合金VAR铸锭热变形行为研究

Study on Hot Deformation Behavior of Ф200 mm TiAl Alloy VAR Ingot

采用Gleeble-1500热模拟试验机研究了应变速率为10^-3～1s^-1、变形温度为1000-1200℃条件下，200mm直径TiAl合金VAR铸锭的热变形行为。结果表明，TLAl合金为负温度敏感和正应变速率敏感材料。当变形温度较低、应变速率较高时，变形过程中易产生绝热剪切带，导致不均匀塑性变形。TiAl合金VAR铸锭热变形过程中，再结晶首先在柱状晶晶界发生，随变形量的增加而增加，再结晶逐渐向晶内扩展，直至发生完全再结晶。

The hot deformation behavior of Ф200mm TiAI ahoy VAR ingot was studied by using Gleeble-1500 thermal simulation testing machine under the deformation temperature of 1000-1200℃ and strain rates of 10^-3-1s^-1. The results show that TiAl alloy exhibits negative temperature sensitivity and positive strain rate sensitivity. When the deformation temperature is lower and strain rate is higher, the adiabatic shear band is easily produced in deformation process to cause non-uniform plastic deformation. In the hot deformation process of TiAl alloy VAR ingot, recrystallization occurs at first in the columnar grain boundaries, and it increases with the increase of deformation, Recrystallization gradually spreads to the grain until the occurrence of complete recrystallization.