温度对U-2.5%Nb合金力学性能的影响

研究了U-2.5%Nb合金在-100～700℃温度范围内的力学性能。结果表明,合金的抗拉伸强度随试验温度上升呈下降趋势,其塑性在600℃以下温度并非单调变化,而是在500℃附近延伸率和断面收缩率分别出现极小值,合金拉伸断口与室温(20℃)相比具有明显的沿晶断裂特征。试验温度高于600℃后,合金塑性明显升高。热处理后的该合金加热至500℃经保温并冷至室温后,合金的冲击韧性有所降低。在-100℃～室温的温度范围,合金的冲击韧性随试验温度的降低而下降,并在-30～-10℃的温度范围发生韧脆转变。当温度低于-30℃后冲击韧性下降趋势明显减缓,合金冲击断裂面颗粒高低不平,具有准解理断裂特征。

Effects of Temperature on the Mechanical Properties of U-2.5%Nb Alloys

The mechanics properties of U-2.5%Nb alloy from-100 to 700 ℃ were studied.The results show that alloy tensile strength decreases with the temperature increasing,The plasticity isn’t monotone change below 600 ℃,and the elongation ratio and the area reduction ratio obtain the minimums value near 500 ℃.The tensile fracture morphology along grain boundary rupture presents obviously contrast room temperature,and the plasticity increases obviously beyond 600 ℃.Upon heating up to 500 ℃,for 1 h and then cooling to room temperature(20 ℃),the impact toughness of the alloy decreases in contrast to no heating up.In the range of-100 ℃～room temperature,the impact toughness of the alloy decreases with the temperature decreasing,the ductile-brittle transition temperatures of U-2.5%Nb alloy is in the range of-30～-10 ℃,the trend mentioned above becomes weak below-30 ℃.The fracture plane is irregular after the impact test,which has a rupture characteristic of quasi-cleavage.