Metal Additive Manufacturing Conference 2018

Present research is focused on an advanced stainless tool steel used for molding of corrosive plastics manufactured by laser powder bed fusion. In comparison to other tool steels, this steel possesses superior corrosion resistance and, achieves high strength via nano-precipitations of an intermetallic phase. Deeper understanding of the precipitation process is, therefore, necessary to develop new heat treatment parameters to tailor properties and performance of the final product. The stainless tool steel grade used in this investigation was manufactured by laser powder bed fusion. As a reference, the same steel grade manufactured by conventional casting and forging was used. After manufacturing, an aging heat treatment at different temperatures and times was performed with or without HIP. Microstructure analysis and mechanical tests were performed after the aging. Mechanical tests were carried out to evaluate the influence of the heat treatments and HIP on strength characteristics. Microstructure of the steel was investigated by means of optical, and scanning electron microscopy. Intermetallic nano-precipitations were investigated by transmission electron microscopy. The influence of the manufacturing route, aging heat treatment conditions, and HIP on microstructure, grain size, size and distribution of precipitations, and mechanical properties was discussed. This investigation supports development of new heat treatment parameters to achieve desirable combination of properties and performance in advanced stainless tool steel.