夏比摆锤冲击国标与美标两种试验方法对冲击试验结果的影响

Difference of the Impact Test Result Obtained by Charpy Pendulum Impact Carried by Methods of the National Standard and American Standard

本文主要分析夏比摆锤冲击试验国标和美标的异同,采用了系列冲击法研究了两项标准对冲击性能的影响,结果表明:当冲击吸收功较低时,按照GB/T229—2007和ASTM E23—07a标准试验得出的结果相近;当冲击吸收功较高时,按照ASTM E23—07a标准试验得出的结果比GB/T229—2007的结果高,导致这一结果主要是由于摆锤打击刀刃半径的不同,打击刀刃和冲击试样接触面积小,冲击试样产生的塑性变形小,侧向膨胀值低,冲击吸收功相应的也低,反之,冲击试样产生的塑性变形大,侧向膨胀值高,冲击吸收功相应的也高;国标和美标夏比V型冲击试样的公称尺寸相同,主要区别为机加工偏差的不同,且美标要求较高。

The difference between the national standard and American standard of charpy pendulum impact test has been investigated. Testing results indicate that the similar results can be obtained by the two methods when the impact absorbing energy is low. However,the impact properties obtained by ASTM E23-07a are higher than that of GB /T 229-2007 in case of high impact absorbing energy. This is mainly caused by difference in impact blade radius. A small plastic deformation will be occur when the contact area between impact blade and impact testing specimen is small,leading to a lower expansion and impact absorbing energy. Conversely,a big plastic deformation will be occur in case of big contact area between impact blade and impact testing specimen,causing a higher expansion and impact absorbing energy. The two methods of national standard and American standard have the same nominal size for specimen but quite different in machining deviation. Compared with national standard,the machining deviation requirement of American standard is stricter.