Abstract: Hydrogen damage in iron or 99.99% purity has been investigated by Doppler broadening measurement.Experimental results show that when the iron is charged with hydrogen in 0.5mol/L H_2SO_4 solution,the critical current density to cause hydrogen damage is 20mA/cm~2.While a little As_2O_3,saying 250mg/L,added to H_2SO_4 solution,even rather small current density.≤0.2mA/cm~2,would cause hydrogen damage.With the help ofi slow tensile test,it revealed that the hydrogen damage occurred in the specimen may be influential to the subsequent process of deformation and fracture.

Key words: hydrogen damage, critical current density, positron annihilation technique, hydrogen-induced defect