摘要
应用分离式Hopkinson压杆(SHPB)装置对0Cr17Mn5Ni4Mo3Al不锈钢圆柱试件进行动态冲击实验。当用300 mm子弹、以50 m/s的速度加载,真应变达到45%时,不锈钢发生以轴线为对称轴的圆锥型破坏。但是用100 mm的子弹以同样的速度进行多次加载,真应变达到80%时,试件仍保持完好。说明试件的破坏与绝热条件有关。对处于破坏临界状态的试件进行金相观察发现:在横截面上,一个圆环形区域内的晶粒被拉长错位;而通过轴线的纵剖面内则有一个与轴线呈45°、宽度约10μm的狭长矩形区域内的晶粒被拉伸成"Z"字形,形成绝热剪切带,晶粒变形从端面到中心逐渐减弱。当高速变形继续进行时,该区域的温度会继续升高,试件将发生绝热剪切破坏。
Cylindrical specimens made of 0Cr17Mn5Ni4Mo3Al stainless steel were impacted on Split Hopkinson Pressure Bar （SHPB） device. When the speed of 300 mm long bullet is 50 m/s and the true strain has reached 45%, the specimens present axisymmetric circular cone damage whose symmetric axis coincides with the shaft line. But the specimens, which are impacted many times and the total strain has reached 80%, are undamaged using 100 mm long bullet with the same speed. So the specimen＇s failure is associated with the adiabatic condition. Observation of the specimen in a critical damage state under metallographic microscope reveals following phenomenon, crystal grains have a little offset in circular area at the specimen end face and the crystal grains are elongated and transformed into a ＂Z＂ shape in a slender zone of 10μm width and the angle between the zone and the axial line is about 45°at the longitudinal section. It is concluded that this most acute plastic deformation localization zone is adiabatic shear band. The temperature in this zone will rise continually and the specimen will present adiabatic shear failure when high-speed deforming goes on.
出处
《实验力学》
CSCD
北大核心
2008年第4期339-344,共6页
Journal of Experimental Mechanics
