Micro-behaviour of fatigue crack growth in welding heat-affected zone

Direct observation was accomplished on the fatigue crack growth behaviour in 16MnR steel weld HAZ with SEM and the fatigue loading equipment. Based on the observed results, an intermittent-kinked-forked fatigue crack growth model was developed and a calculating formulation for fatigue crack growth was established. The formula incorperates local strecs intensity factor, mechanical, cyclic and fatigue properties as well as a damage length parameter. The predicted values of the model were compared with the experimental data and they are in a good agreement.