Abstract
The influences of hydrogen on nano-indentation testing of IF and STPG370 steels before and after the hydrogen charging were investigated. The ”pop-in” behavior was observed in the nano-indentation force-penetration depth (F-h) curves. The force at pop-in (Fpop-in) was obtained in the uncharged specimens. But the behavior was not observed in the hydrogen charged specimens. It is cleared that hydrogen enhances initial plastic deformation in the nano scale regions. After 473K⁄1h heat treated with hydrogen charged the IF steel, however, hydrogen recharged the sample occurred pop-in. It is suggested that vacancy of hydrogen trap site became extinct by heat-treatment of473K.
