Effect of welding process on fatigue crack growth behaviour of ASTM 517 'F' grade steel weld metals

The fatigue crack growth behaviours of two weld metals deposited by shielde d metal are welding (SMAW) and flux cored are welding (FCAW) processes have been compared. Load carrying cruciform joints, with a lack of penetration (LOP) defect, were fabricated from high strength, quenched and tempered ste el of ASTM 517 'F' grade. Fatigue crack growth experiments were carried out in a vertical pulsator (Schenck 200 kN capacity) with a frequency of 30 Hz under constant amplitude loading (stress ratio R = 0). It was found that t he fatigue crack growth resistance of the weld metal deposited by the SMAW process is superior, compared to the weld metal deposited by the FCAW proce ss. The high heat input involved in the FCAW process probably contributes t o the changes in weld metal properties, which result in a change in fatigue crack growth behaviour.