燃料包壳用FeCrAl合金变形行为与热加工图研究

Hot Deformation Behavior and Processing Maps of FeCrAl Alloy for Nuclear Fuel Cladding

摘要:

本文通过热模拟压缩试验研究了燃料包壳用FeCrAl合金在形变温度为800~1000 ℃、应变速率为0.001~1 s-1工艺条件下的热变形行为，采用Arrhenius双曲线正弦函数模型建立了FeCrAl高温变形本构方程，结合动态材料模型绘制了FeCrAl在应变量为0.05~0.8的热加工图。结果显示，FeCrAl流变应力随着变形温度的升高而降低、随着应变速率的升高而增大，变形温度与应变速率均会影响其组织演化。根据热加工图，FeCrAl流变失稳区随着应变量的增加先扩展后趋于稳定，其最佳热加工工艺参数确定为:1）应变量为0.1时，应变速率< 0.008 s-1、变形温度为880~1000 ℃；2）应变量≥ 0.3时，应变速率< 0.027 s-1、变形温度> 950 ℃。

Abstract:

Hot working of FeCrAl alloy for nuclear fuel cladding was investigated by thermal simulation compression experiment under deformation temperature of 800~1000 ℃ and strain rate of 0.001~1 s-1. The constitutive equation of the hot deformation behavior of FeCrAl alloy was established through Arrhenius hyperbolic sine function. Based on the dynamic material model, the processing map of FeCrAl alloy was derived for strain of 0.05~0.8. Results show that the flow stress of FeCrAl alloy decreases with the increase of deformation temperature and increases with the increase of strain rate. Both the deformation temperature and strain rate will affect the microstructure evolution. According to the processing map, the instability zone of flow behavior of FeCrAl alloy expands and then stabilizes with the increase of strain, and the optimal hot processing safety areas of the alloy are determined as follows: 1) the strain rate < 0.008 s-1 and the deformation temperature 880~1000 °C (when the strain is approximately 0.1); 2) the strain rate < 0.027 s-1 and the deformation temperature > 950 °C (when the strain is ≥ 0.3).