双相2OCr钢冲击载荷应变速率敏感性研究

THE STRAIN RATE SENSITIVITY OF DUAL PHASE 20Cr UNDER IMPACT LOAD

利用分离式霍普金斯杆技术,在旋转盘击拉伸试验机上测试了双相20Cr钢冲击拉伸应力一应变曲线,研究了应变速率及组织对动态力学性能的影响.结果表明,双相20Cr钢是一种应变速率敏感材料,在相当高应变速率下仍可保持高的初始加工硬化率并具有较大的应变速率敏感系数,正是这种特性维持了双相20Cr钢在冲击戴荷作用下的高强度、塑性水平.马氏体相的加入使体铁素体晶粒明显细化,马氏体对强度的贡献主要通过增加强化相比例和使其体铁素体相强化而获得.

Split hopkinson bar recovery experimental techniques are used to investigate the stress-strain curves of dual phase 20Cr under impact tensile·load on a rotating circular plate impact tensile machine. The effect of strain rate and structure on the dynamic properties is discussed. The results indicate that dual phase 20Cr is one of mterials sensitive to strain rates. It exhibites a rapid rate of initial working hardening and excellent indexes of strain rate sen-sitivity even at quite high strain rates. It is these characters that maintain the strength and plasiticity of dual phase 20Cr on a high grade under impact load. The grain size of ferrite is obversely refined by martensite. With the additions of martensite, the proportion of reinforcement phase inceases, ferrite is hard- ened, thus the strength scrambles.