Experimental investigations of processing the high carbon cold-work tool steel 1.2358 by laser metal deposition for the additive manufacturing of cold forging tools

Abstract

In the field of tool making, Laser Beam Melting of metals has been already used to fabricate injection moulds with complex inner cooling channels made out of the low-carbon maraging tool steel X3NiCoMoTi18-9-5 (1.2709). Furthermore, laser metal deposition (LMD) is an established technology for the repair of worn-out tools and the deposition of wear resistance coatings based on metal matrix composites. However, at the moment, the processing of high-carbon tool steels for the additive manufacturing of complete cold forging tools has only been investigated to a limited extent. Within the scope of the presented research, the processing of the high-carbon cold-work tool steel 60CrMoV18-5 (1.2358) by LMD is analyzed in detail. In this context, geometrically simple cuboidal structures are directly generated on dissimilar substrate plates made out of the hot-work tool steel X37CrMoV5-1(1.2343) via the application of various process parameter combinations. The manufactured cuboidal structures are metallographically prepared and subsequently analyzed with respect to substrate bonding, relative density, defect formation, microstructure, chemical composition, and microhardness. In this context, the influence of the particle size distribution of the used tool steel powder on the LMD process itself and the resulting relative density are extensively researched. For this purpose, high-speed camera measurements of the powder particle stream were conducted in order to determine both the powder particle stream diameter and the lateral powder particle distribution with regard to the distance z from the powder nozzle. Furthermore, the influence of an additional substrate preheating (maximum preheating temperature of 400 °C) on the resulting microstructure and hardness of the additively generated samples is the subject of the presented investigations.

Additive Manufacturing of a Cold‐Work Tool Steel using Electron Beam Melting

“…Another positive side effect is the possibility of reducing post‐processing costs and lead‐time in the fabrication of the tools. Reports from both SLM and EBM‐processed maraging and tool steels can be found in the literature . Mainly hot‐work tool steels have been attempted by EBM .…”

“…Mainly hot‐work tool steels have been attempted by EBM . In the field of high‐carbon cold‐work tool steels, only a few contributions are available . One reason for this could be that such alloys are hard to process in AM due to high susceptibility to cracking during melting and solidification, especially for laser application.…”

The Hardness of Additively Manufactured Alloys

“…Due to the high costs of AM compared to conventional casting and forging processes, the use of plain carbon and low alloy steels have not found significant usage for AM applications outside of a few studies [82,83]. Many of the steels used in AM have been tools steels [84][85][86][87][88][89][90], studied for specialized repair applications in which high strength and wear resistance is crucial.…”

“…Typical microstructures of tool steels processed by AM include a martensitic matrix with some carbide precipitation and retained austenite [85,90]. After deposition of tool steels, heat treatment is desirable to increase ductility and toughness.…”

Investigation on Alloying Element Distribution in Cr8Mo2SiV Cold‐Work Die Steel Ingot during Homogenization

“…Cr8Mo2SiV steel belongs to the high‐carbon and high‐alloy cold‐working die steel, also known as ledeburite steel . It is mainly used to manufacture all kinds of molds for pressing metal materials at room temperature, including cold stamping die and cold heading die, embossing mold, punching die, drawing die, and so on . It is worth noting that the redistributive behavior of the solute atoms in the solidification process resulted in the uneven distribution of the alloying elements in the cast microstructure.…”