V-5Cr-5Ti合金准静态和高应变率拉伸力学行为

Quasi-static and high strain rate tensile mechanical behavior of V-5Cr-5Ti alloy

研究了电弧熔炼V-5Cr-5Ti合金在应变率为3.3×10-5～1.2×102/s范围内的拉伸性能,获得了应变率敏感系数。结果表明,在室温下低应变率下V-5Cr-5Ti合金的屈服应力和极限抗拉强度随应变率增加而增大,延脆转变应变率大约在101～102/s之间,从准静态到动态应变率范围应变率敏感系数较大;经光学显微镜、TEM、XRD和EDS分析表明,电弧熔炼V-5Cr-5Ti合金平均晶粒尺寸为200μm左右的等轴晶,且晶粒大小不均匀,应变率对晶粒尺寸没有明显影响;低应变率时,断裂表面为微孔洞聚集和穿晶断裂的混合模式,高应变率时为脆性断裂;V-5Cr-5Ti合金为板条马氏体组织,在晶界处有第二相析出物Ti(O、C、N)存在。

In this work the static and dynamic tensile properties of vanadium V-5Cr-5Ti alloy were investigated at strain rates ranged from 3. 3×10-5 to 1. 2×102/s, coefficient of strain rate sensitivity was obtained. The material microstructures were analyzed using optical microscope, SEM, TEM, XRD and EDS. Results show that the yield strength a increases with strain rate. The brittle-ductile transition strain-rate is about 101 to 102/s, from the quasi-static to dynamic strain rates higher strain rate sensitivity coefficient. At room temperature the tensile fracture at a low strain rate occurs via mixed modes of microvoid aggregating and transgranular cracking;at high strain rate the fracture occurs via a brittle mode. The analysis by TEM, XRD and EDX shows the existence of lath martensite, and on there exits precipitate phase of Ti（O, C, N） in grain boundaries.