Micro cold forming tools from hypereutectoid 8%Cr-steels by spray forming and selective laser melting

Abstract

Abstract In cold forming several options exist to meet the requirements of producing specific products, e. g. tool shape and lubrication. In the field of micro cold working such measures are not available. When geometrical tool dimensions become smaller the microstructure of the tool materials can interfere with tool making and the forming process, respectively. Aim of this work was to produce hypereutectoid Cr-steels by spray forming and selective laser melting to provide adapted tool materials. Spray forming is regarded as a fast primary forming process with subsequent hot working steps. Selective laser melting is a rapid tooling process for producing near net shape products from powder. Both techniques are known to deliver fine and homogeneous microstructure due to rapid solidification. Powder from spray forming overspray was used as feedstock for selective laser melting. Results are shown from alloy variations in vanadium, niobium and carbon of the steel X110CrMoV8-2 and their effect on microstructure, mechanical properties and friction coefficient of the materials using the strip-pulling test after hardening and tempering. The generated materials with hardness up to 63 HRC are micro-machinable to micro swaging tools with working diameter of less than 1 mm.