EFFECT OF ANODIC-DISSOLUTION AND HYDROGEN ABSORPTION ON PLASTIC ZONE AT FATIGUE-CRACK TIP IN STRUCTURAL-STEEL

The anodic dissolution and hydrogen absorption for A537 steel in 3.5% NaCl solution, as studied by speckle interferometry, occur simultaneou sly at the fatigue crack tip. However, the degree of anodic dissolutio n and hydrogen embrittlement vary with applied potential. The anodic d issolution of the steel increases the plastic zone size at the crack t ip, while the absorption of hydrogen into steel decreases the plastic zone size at the crack tip. In fact, the size of the plastic zone at t he crack tip is determined by the competition of the above two process es, i.e., the size of the plastic zone at the crack tip will decrease if hydrogen absorption plays a dominant role, and will increase if ano dic dissolution plays a dominant role.