Fatigue properties and damage mechanisms of components manufactured by laser additive welding of H13 on S355 steel

摘要： Laser additive manufacturing is an advanced, very perspective technology with potentially wide industrial applications, one of them being an improvement of durability of forms and dies. The aim is to improve surface properties like wear resistance using special layers of powder sintered or remelted by laser beam. Other possible applications are repairs of worn dies or shape changes. At present, dies are manufactured by machining with following bulk heat treatment, which is an expensive process. Another problem is to find suppliers with big size furnaces and limited capacity often results in long time dates and terms. Concerning repairs of dies, they are usually performed manually, using arc or plasma welding with numerous difficulties and disadvantages in comparison with promising and advanced laser overlaying. The paper contains results of a comprehensive evaluation of several types of hard overlayed powder of H13 tool steel on a S355 structural steel using laser beam. Properties like macro- and microstructure, mechanical properties like hardness and its course in the layers, high-cycle fatigue resistance in bending and fatigue damage mechanisms were investigated with the emphasis on fatigue crack initiation process evaluated using scanning electron microscopy. The results indicated that surface additive laser welded layers of a high quality can be reached. On the other hand, some drop of fatigue resistance and endurance limit was observed, affected by surface defects – small welding imperfections