温度对U-2.5%Nb合金力学性能的影响

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

摘要:

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

Abstract:

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.