Schwingfestigkeit laserauftraggeschweißter legierter Stähle

Abstract

Laser cladding is an established, sustainable and value-adding process. So far, merely statically loaded parts profit from its application as its impact on part properties under cyclic loads was not investigated systematically, yet. It is shown that residual stresses are the driving factor determining fatigue strength. These can neither be manipulated by process parameters nor by thermal post-processing so as to influencing fatigue strength significantly positive. Either the material combination is to be chosen so that thermal expansion of the substrate material is higher than of the coating or mechanical post-processing, i.e. by deep rolling is to be applied. Compressive residual stresses are to be induced to the interface of substrate and coating as this area is most prone to failure. Within the representative example of laser cladding of high and low alloy steel with a cobalt-based alloy higher fatigue strength could be realised as for the latter in as-cast condition.