There are two popular types of raw material for making pellet die.
One type is 20CrMnTi (alloy steel), which is mainly used for making ring die for wood.
The other type is 4Cr13 (stainless steel), which is more suitable for making pellet die for animal feed. 
4Cr13 steel is a martensitic stainless steel, the steel has good machinability, after heat treatment (quenching and tempering), it has excellent corrosion resistance, polishing performance, high strength and wear resistance , suitable for manufacturing molds under the action of high load. Here below is the details about the raw material 4Cr13.
●Chemical composition:
Carbon C: 0.36～0.45
Silicon Si: ≤0.60
Manganese Mn: ≤0.80
Sulfur S: ≤0.030
Phosphorus P: ≤0.035
Chromium Cr: 12.00～14.00
Nickel Ni: allowed to contain ≤0.60
●Mechanical properties
Mechanical properties: Hardness: Annealed, ≤201HB, indentation diameter 3.9～4.3mm; Quenching, ≥50HRC
Heat treatment specification and metallographic structure:
1) Annealing, slow cooling at 800～900℃ or fast cooling at about 750℃;
2) Quenching, oil cooling at 1050～1100℃
3) Tempering, 200 ~ 300 ℃ rapid cooling.
Metallographic structure: The structure is characterized by martensitic type.
