Influence of the metallurgy on fatigue crack propagation in welded high strength steel joints

A literature study of high strength steels, fatigue and fatigue assessment of welds has beenconducted and is briefly presented in this paper together with experiments on fatigue crackgrowth rates of laser welded high strength steel. It is well-known that the fatigue life ofwelded joints is heavily dependent upon the surface geometry and welding defects because ofcrack initiation from the high stress concentrations associated with these types of weldingflaws. However, the crack propagation through different weld zones of laser-welded highstrength steels and the corresponding impact from the metallurgy is not fully understood.The experiments comprise three-point bending fatigue tests on laser-welded highstrength steel with machined surfaces. Measurement of the fatigue crack propagation ratetransverse the weld and hence through the different metallurgy and hardness of the heataffected zone and of the weld can contain information on the impact of the metallurgy on thecrack propagation speed. The influence of different high strength steel grades and of differentwelding parameters on the crack propagation and fatigue life is discussedGodkänd; 2013; 20131210 (andbra