Effect of Post-Heat Treatment on the AISI M4 Layer Deposited by Directed Energy Deposition

Abstract

Currently, high-speed steel (HSS) powders are deposited locally on a metal surface through direct energy deposition (DED) onto hardface tool steel. Although the HSS powder enhances the hardness and the abrasion resistance of a metal surface, it makes the tool steel brittle because of its high carbon content. In addition, the steel is likely to break when subjected to a high load over time. This study focused on improving the steel toughness by applying a post-heat treatment. To fabricate a uniformly deposited layer through DED, M4 powder was deposited onto a pre-heated substrate (AISI D2). In addition, four post-heat-treated specimens were prepared, and their mechanical properties were compared. The Charpy impact and hardness tests were conducted to evaluate the durability required for the D2 die. The deposited M4 powder possessed a high hardness but a relatively low impact toughness. During laser melting, a stable bond formed between M4 and D2 without any cracks or delamination. The hardness of the initial M4 deposited layer was 63 HRC, which changed to 54–63 HRC depending on the effect of the post-heat treatment. Moreover, the post-heat-treatment process improves the impact toughness of the M4 deposited layer by changing its microstructure.

Experimental Investigations in the Processing of AISI H11 Powder Blends Enriched with Tungsten Carbide Nanoparticles for the Additive Manufacturing of Tailored Hot Working Tools in the Directed Energy Deposition (DED-LB/M)—Impact of Tungsten Carbide Nanoparticles on Microstructural and Mechanical Characteristics

“…In contrast, it seems that only a small proportion of the dissolved tungsten is re-excreted as interdendritic WC or W2C precipitates (special carbides). This conclusion is also in good agreement with the findings of the According to [27,30,31], the solubility of WC in iron/steel is high. Tungsten Carbide begins to dissolve at temperatures below the solidus temperature of steels.…”

“…According to [27,30,31], the solubility of WC in iron/steel is high. Tungsten Carbide begins to dissolve at temperatures below the solidus temperature of steels.…”

“…The processing of high carbon tool steels in the DED-LB/M process is limited to a few basic investigations [23][24][25][26][27][28]. The evaluation of microstructural and mechanical characteristics of DED-LB/M specimens and coatings made out of the high-speed steel 1.3343 (AISI M2, or AISI M4) was the object of a few scientific investigations carried out in [25][26][27][28].…”

“…The processing of high carbon tool steels in the DED-LB/M process is limited to a few basic investigations [23][24][25][26][27][28]. The evaluation of microstructural and mechanical characteristics of DED-LB/M specimens and coatings made out of the high-speed steel 1.3343 (AISI M2, or AISI M4) was the object of a few scientific investigations carried out in [25][26][27][28]. In the scope of these investigations, the produced tool steel specimens showed promising mechanical properties after carrying out an appropriate thermal post processing similar to industrial application.…”

Properties of Tool Steels Printed by Directed Energy Deposition Process on S45C Base Metal

“…In addition, research is underway on tool steels that are not frequently used because of their high melting point or high thermal stress [ 11 ]. Various studies are being conducted to determine the optimal process parameters for lamination of tool steels [ 12 ], find hybrid manufacturing techniques with multiple additive processes [ 13 ], and develop post-treatment techniques involving heat treatment [ 14 ]. When molding metals through additive manufacturing, molds for hot stamping with conformal cooling channels [ 15 ] are considered highly advantageous [ 16 , 17 ].…”