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.
Highlights
Increasing the strength of an automobile frame enables a reduction in weight and an increase in passenger protection
Post-heat treatment alters the microstructures of the deposited layer that are produced via the direct energy deposition (DED) process, and it changes its mechanical properties
Wang et al [8] compared the abrasive wear behavior of a variety of tool steel coatings (CPM 9V, CPM 10, and CPM 15V) in the laser cladding process. They reported that when large amounts of residual austenite exist in the deposited layer, the mechanical properties can be improved via transformation into martensite, which is promoted by the post-heat treatment
Summary
Increasing the strength of an automobile frame enables a reduction in weight and an increase in passenger protection. Post-heat treatment alters the microstructures of the deposited layer that are produced via the direct energy deposition (DED) process, and it changes its mechanical properties. Wang et al [8] compared the abrasive wear behavior of a variety of tool steel coatings (CPM 9V, CPM 10, and CPM 15V) in the laser cladding process They reported that when large amounts of residual austenite exist in the deposited layer, the mechanical properties can be improved via transformation into martensite, which is promoted by the post-heat treatment. Most of the abovementioned studies used laser cladding and they aimed to improve the mechanical properties (e.g., hardness, wear resistance, fatigue life) through the post-heat-treatment process.
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