EFFECT OF HYDROGEN ON FRACTURE OF U-NOTCHED BEND SPECIMENS OF SPHEROIDIZED AISI-1095 STEEL

The effect of hydrogen on fracture was studied in U-notch bend specimens of 1095 steel with three different notch acuities. The hydrogen was introduced by cathodic charging through the notch surfaces. Both precharging and dynamic charging effects on void initiation and growth, crack initiation and fracture were investigated. In prechargea specimens voids were initiated at lower strains and the void population increased more rapidly than in the uncharged case. The role of hydrogen is to promote plastic instability along characteristic slip lines and therefore accelerate void formation. In the dynamically charged specimens, cracks initiated at lower strains than for the other cases and propagated rapidly without accompanying void formation. The results are compared to those for the uncharged case and to previous theoretical and experimental results. © 1979 American Society for Metals and the Metallurgical Society of AIME.