## 2 Research Method  
### Research on Metal Powder for AM  
This study considered the alloy components of commercial mold steels and the associated hardness values after heat treatment to determine two types of metal powders that were expected to be usable in functional parts of the shearing steel. The two selected metal powders are functional metal powder alloy materials that can achieve a high hardness of 57-60 HRC using AM and without heat treatment. Additionally, they are specialized for metal AM without the need for forging materials and are manufactured as spherical particles, with an average particle size of 100 \(\upmu\)m, using gas atomization. Next, the mechanical properties of these two types of metal powders and of one type of matrix tool steel forging material, which is presently the most suitable among known forging materials for shear steel because of its excellent mechanical properties, were studied. Table 2 lists the main alloy components of the two metal powder materials and of the matrix tool steel forging material used in this study. To simplify this text, the matrix tool steel forging material and the two metal powder materials will be henceforth referred to as Forging_C, AM_A, and AM_B, respectively. Forging_C is a Cr-Mo-V-based alloy tool steel material, with its main features being a uniform microstructure and excellent wear resistance and compressive strength. It is also presently the most suitable material for use in shear steel [17]. Table 3 lists the main mechanical properties of Forging_C.  
\begin{table}
\begin{tabular}{c c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Steel Grade**} & \multirow{2}{*}{\begin{tabular}{c} **AISI or** \\ **JIS** \\ \end{tabular} } & \multicolumn{8}{c}{**Chemical Composition (wt/\%)**} & \multicolumn{8}{c}{**Heat Treatment and**} \\  & & **C** & **Si** & **Mn** & **Cr** & **Mo** & **W** & **V** & **Co** & **Q.T. [FOOTNOTE:]Footnote [ENDFOOTNOTE]** & **HRC** \\ \hline \multirow{2}{*}{\begin{tabular}{c} Flame-hardened \\ steel \\ \end{tabular} } & 23F85 & 0.70–0.72 & 0.86–1.00 & 0.02–0.78 & 0.17–1.01 & 0.08–0.16 & & 0.07–0.19 & Air & 56–60 & \\ \cline{2-11}  & & KFH-1 & 0.75–0.80 & 0.95–1.05 & 0.70–0.80 & 1.00–1.10 & 0.20–0.25 & & 0.03–0.05 & Air & 56–60 & \\ \hline \multirow{4}{*}{\begin{tabular}{c} Carbon \\ steel \\ \end{tabular} } & Carbon & \multirow{4}{*}{W1-10} & \multirow{4}{*}{1.05} & \multirow{4}{*}{0.20} & \multirow{4}{*}{0.30} & \multirow{4}{*}{0.35} & \multirow{4}{*}{0.35} & \multirow{4}{*}{0.35} & \multirow{4}{*}{0.35} & \multirow{4}{*}{0.35} & \multirow{4}{*}{0.35} & \multirow{4}{*}{0.35} \\  & & & & & & & & & & \\ \cline{2-11}  & SKS93 & 1.05 & & 0.95 & 0.40 & & & Oil & 57–63 & \\ \cline{2-11}  & SKS3 & 0.95 & & 1.05 & 0.75 & - & 0.75 & & Oil & 57–60 & \\ \cline{2-11}  & \multirow{2}{*}{\begin{tabular}{c} Closed \\ steel \\ \end{tabular} } & D2 & 1.50 & & & 12.0 & 1.00 & & 0.35 & Air & 57–63 & \\ \cline{2-11}  & & 8\% Cr & & & & & & & & & \\ \cline{2-11}  & & 1.00 & 1.00 & 0.40 & 8.00 & 2.00 & & 0.30 & Air & 57–63 & K340 \\ \hline \multirow{2}{*}{\begin{tabular}{c} High-speed tool \\ steel \\ \end{tabular} } & M2 & 0.85 & & & 4.15 & 5.00 & 6.30 & 1.90 & & Oil & 58–64 & \\ \cline{2-11}  & SKH40 & 1.30 & & & 4.15 & 5.00 & 6.20 & 3.00 & 8.40 & Oil & 64–67 & S590 \\ \hline \multirow{2}{*}{\
\begin{tabular}{c} Matrix tool steel \\ \end{tabular} } & YXR 3 & 0.60 & 1.50 & 0.40 & 4.30 & 2.90 & & 1.80 & Oil & 58–61 &
\begin{tabular}{c} CALDIE, \\ W360 \\ \end{tabular} \\ \hline \hline \end{tabular}
\end{table}
Table 1: Commercial tool steels used in mold manufacturing.