超临界水冷堆包壳材料用C-276合金的热拉伸行为研究

Study on hot tensile behavior of C-276 alloy for cladding material in supercritical water-cooled reactor

采用G1eeble-3500热模拟试验机,利用金相显微镜、扫描电子显微镜等手段,研究了不同温度对C-276合金热拉伸行为的影响。结果表明:该合金在1050~1250℃具有良好的塑性,断面收缩率均大于70%,且在1200℃时最大;在950-1250℃热拉伸试样断口处均有颈缩现象,为沿原始晶界开裂,且韧窝随温度的上升而增多、变深,塑性越来越好,当温度超过1200℃时断口韧窝数量开始缓慢减少,塑性缓慢下降;随着温度的上升,合金的动态再结晶百分比增大,且再结晶晶粒开始缓慢增粗,在1150-1250℃时发生完全动态再结晶。对于C-276合金,当应变速率为1s^-1时,最佳的热加工温度范围为1150~1250℃。

Influence of different temperatures on the hot tensile behavior of C -276 alloy was studied by using Gleeble -3500 thermal simulation testing machine,metallographic microscope and scanning electron microscope.The results show that the alloy has a good plasticity in the range of 1050-1250℃,the reduction of area is above 70%,and reaches the maximum at 1200℃.The obvious necking occurs at the tensile fracture,where is the original grain boundary fracture in the range of 950-1250℃.With the temperature rising,the dimple become deeper and the dimple number increases,which means the plasticity becomes better and better.When the temperature exceeds 1200℃,the fracture dimples and the plasticity begins to decrease slowly.The dynamic recrystallization percentage of the alloy increases with the increase of the temperature,and the recrystallized grains begin to grow slowly,and the full dynamic recrystallization occurs in the range of 1150-1250℃.Thus,it can be concluded that for C -276alloy,the optimal heat deformation temperature range is 1150-1250℃ at the strain rate of 1 s^-1.