高应变率下工业纯钛TA2变形与失效研究

利用Hopkinson杆,采用动态压缩实验研究帽形样品的工业纯钛在高应变率(10~3 s~(-1))下的变形与失效机制。从时间-剪应力曲线分析材料的剪切变化规律。结果表明:轧制变形后的试样,它的绝热剪切敏感性明显变强;而在轧制变形量相同的情况下,从材料厚度方向上取的试样,其绝热剪切敏感性比其它方向强。通过光学显微镜、扫描电镜和透射电镜分析其显微组织的变化规律。结果表明:试样的受剪部位均可观察到明显的绝热剪切带。绝热剪切带是材料宏观失效的先兆,带内晶粒细小,为等轴晶,发生了再结晶,带中的微裂纹、微空洞的形成最终导致材料失效。

Study on deformation and failure of TA2 under compressive load at high strain rate

Dynamic compressive mechanism of hat-shaped TA2 was investigated at high strain rate by Hopkinson bar.The time- shear stress curve evolution was analyzed.It was shown that adiabatic shear sensitivity of deformed materials(45% and 70%)was stronger than undeformed materials,and the samples from the thick direction were more sensitive.Microstructure evolution was investigated by means of optical microscope,scanning electron microscope(SEM)and transmission electric microscopy(TEM)- The shear bands were found in the shear zone of undeformed and deformed materials.Investigation indicated the damage frequently ocurred along shear band,grain sizes were very small in the shear bands.The final failure of TA2 was completed by connection of micro-crack and micro-cavity to one another through shear band.