Additive Manufacturing of Tool Steels

Abstract

The public funded project “AddSteel” aims to develop functionally adapted steel materials for additive manufacturing (AM). Based on the AM process laser powder bed fusion (LPBF), the holistic process chain, including alloy design, powder atomization, AM, and postheat treatment, is considered to achieve this objective. Tool steels are usually characterized by higher carbon content and limited weldability, leading to limited processability for LPBF. To extend these limitations, different approaches for tool steels are investigated: for high-carbon tool steels, the effects of lower martensite start temperature are investigated using the alloy 1.2842 as an example. A low martensite start temperature seems to be advantageous for crack-free processing with LPBF. In order to avoid a high hardness level after rapid cooling, the use of a hot work steel with a carbon content of 0.2 wt% is investigated. Due to the chemical composition of the material, a moderate preheating temperature <300 °C is required. In addition, very high scanning speeds are possible with an improved shielding gas flow. Finally, the experience along the process chain with the standard steels is used for a modification of the alloy 1.2344. The effects of this modification on AM and heat treatment are investigated.