温度对V-5Cr-5Ti合金拉伸性能及组织结构的影响

对真空自耗重熔制备的V-5Cr-5Ti合金进行了室温到1150℃温度范围的拉伸性能测试,获得了不同温度下的拉伸应力应变曲线,用SEM和光学显微镜对断口形貌和金相组织进行了观察,分析了温度对断口形貌和组织的影响。结果表明:V-5Cr-5Ti合金的屈服强度和极限强度总体上随温度升高而降低,但在300℃到700℃之间出现应变失效效应,断裂伸长率随温度升高而降低,断面收缩率随温度升高先增大再而降低,在400℃时断面收缩率最大;温度较低时塑性变形以滑移为主,温度较高时以晶界开裂为主,并伴随有晶界熔化的现象,高温断口表现为韧性断裂为主,具有韧性与脆性共存的现象。

Influences of Temperature on the Tensile Properties and Microstructure of V-5Cr-5Ti Alloy

Tensile properties of the V-5Cr-5Ti alloy fabricated by the vacuum consumable arc remelting(VAR) method are tested at 18℃ to 1150℃,and the tensile stress-strain curves are obtained at different temperatures.The fracture surfaces and microstructures are observed using scanning electron microscopy(SEM) and optical microscopy,and the effects of temperature on them are obtained in this paper.Results show that the yield and ultimate strength of the V-5Cr-5Ti alloy generally decreases with increasing temperature,but strain aging appears between 300℃ and 700℃.The percentage of elongation at break decreases with increasing temperature.But the percentage reduction of area at break firstly increases and then decreases with increasing temperature,and the maximum reduction appears at 400℃.The plastic deformation is dominated by dislocation slip at low temperature;at high temperature,it is dominated by grain boundary cracking,accompanied with grain boundary melting.The fractographs of the V-5Cr-5Ti alloy show that at high temperature ductile fracture and brittle fracture coexist,but ductile fracture plays the dominating role to break.