Influence of a Pronounced Pre-Deformation on the Attachment of Melt Droplets and the Fatigue Behavior of Laser-Cut AISI 304

Laser cutting is a suitable manufacturing method for generating complex geometries for sheet metal components. However, their cyclic load capacity is reduced compared to, for example, milled components. This is due to the influence of the laser-cut edge, whose characteristic features act as crack initiation sites, especially resolidified material in the form of burr and melt droplets. Since sheet metal components are often formed into their final geometry after cutting, another important factor influencing fatigue behavior is the effect of the forming process on the laser-cut edge. In particular, the effect of high degrees of deformation has not yet been researched in detail. Accordingly, sheets of AISI 304 were processed by laser cutting and pre-deformed. In the process, alpha'-martensite content was set to be comparable despite different degrees of deformation. It was found that deformation to high elongations caused a large part of the melt adhesions to fall off, but those still attaching were partially detached and thus formed an initial notch for crack initiation. This significantly lowered the fatigue strength.

Automated summary

Laser cutting is a suitable method for manufacturing complex geometries in sheet metal components, but it reduces the cyclic load capacity compared to milled components. The laser-cut edge, with its characteristic features of burr and melt droplets, acts as crack initiation sites, affecting fatigue strength. Forming processes after cutting also influence the fatigue behavior, particularly the effect of high degrees of deformation. Research on this is still lacking. The pre-deformation of AISI 304 sheets showed that high elongation caused detachment of most melt adhesions, but those still attaching formed initial notches for crack initiation, significantly lowering fatigue strength.