Views: 100 Author: EHI Technical Team Publish Time: 2026-08-27 Origin: Site
The mold steel is a type of steel specifically used to make various molds. Die casting molds, plastic molds, stamping molds, and hot forging molds all rely on mold steels. The mold steel is mainly divided into three categories according to its use: cold work mold steel, hot work mold steel, and plastic mold steel.
The cold work die steel is used to form metals at room temperature, and its main failure modes are wear, brittle fracture, and plastic deformation. The core requirements of cold work mold steels are high hardness and high wear resistance.
The plastic mold steel is used for molding plastic products and has high requirements for surface quality. The core requirements of plastic mold steels are good polishing performance, corrosion resistance, wear resistance, and dimensional stability.
The hot work mold steel works at high temperatures and is subjected to cold and hot cycles as well as molten metal erosion. The core requirements of hot work die steels are red hardness (maintaining hardness at high temperatures), high toughness, and resistance to thermal fatigue.
The cold work mold steel is used for forming molds at room temperature such as punching dies, stretching dies, and cold heading dies. The core contradiction of the cold work mold steel is that the higher the hardness, the more wear-resistant it is, but the poorer the toughness and the easier it is to crack. Cr12MoV、SKD11、DC53、D2，A2 ,etc belong to cold work steel.
Steel Grade | Hardness(HRC) | Wear Resistance | Toughness | Characteristic | Typical Application |
SKD11 | 58-62 | High | Low | SKD11 has high carbon and high chromium, strong hardenability, good dimensional stability. | SKD11 mold steel is used for cold work molds and precision punching molds |
DC53 | 62-63 | High | DC53 mold steel has twice the toughness compared to SKD11 | DC53 mold steel is an improved version of SKD11 mold steel, with outstanding toughness and less susceptibility to cracking | DC53 mold steel is used for precision stamping molds and cold forging molds |
D2 | 58-62 | Superior | Low | D2 mold steel has high compressive strength, with higher hardness than SKD11 mold steel but low toughness | D2 mold steel is used for cold heading dies and wire drawing dies |
A2 | 57-60 | Medium | Medium | The heat treatment deformation of the A2 mold steel is extremely small | A2 mold steel is used for precision stamping dies and parts with high requirements for dimensional stability |
The hot work die steel is used for die-casting molds, hot forging molds, hot extrusion molds, etc. The biggest enemy of hot work die steels is thermal fatigue - the mold repeatedly cycles between high temperature and cooling, and the surface is prone to cracking. Common hot work die steel grades include H11,H12,H13, 8407, 1.2714, 8418,etc. The most commonly steel used for die-casting molds are the H13 series.
Steel Grade | Hardness(HRC) | Heat Resistance Performance | Typical Application | |
H13/1.2344 | 44-48 | The working temperature of H13 hot work die steel can reach 540 ℃, and it can still maintain high red hardness in the range of 500-550 ℃ (reaching HRC 48-52 after tempering) | The H13 hot work die steel is used for aluminum/magnesium alloy die-casting, hot extrusion molds/PA-GF plastic molds | |
H11 | 42-46 | The heat resistance of H11 die steel is slightly lower than that of H13 die steel | The H11 hot work die steel can withstand strong impacts | |
The requirements for plastic mold steel are completely different from the hot work die steel and cold work die steel - Mechanical strength becomes secondary, surface finish, corrosion resistance and machinability take priority. Common plastic mold steels include P20, 718H, NAK80,S136,etc.
Steel Grade | Hardness(HRC) | Characteristic | Typical Application | |
P20 | 28-36 | P20 plastic mold steel is generally delivered in a pre hardened state, without heat treatment, and has extremely high cost-effectiveness | P20 plastic mold steel is used for ordinary household appliance shells and daily necessities molds | |
718/718H | 30-36 | 718/718H plastic mold steel is an improved version of P20 plastic mold steel (with added Ni), which has better strength and toughness | 718/718H plastic mold steel is used for household appliance shells, automotive interior parts, etc | |
NAK80 | 37-43 | NAK80 plastic mold steel is generally delivered in a pre hardened state, without heat treatment, and has a short processing cycle | NAK80 plastic mold steel is used for high gloss appearance parts, mirror appearance parts, etc | |
S136 | 48-52（after quenching） | S136 plastic mold steel combines corrosion resistance and high polishing performance, suitable for corrosive plastics | S136 plastic mold steel is used for optical lenses, transparent shells, medical molds, etc | |
There is no absolute best mold steel, only the most suitable one. Understand the working conditions, distinguish between cold‑work, hot‑work and plastic mold steels, balance wear resistance and toughness, and attach importance to smelting quality and heat treatment, so as to achieve stable mold service life.
Cold‑work mold steel works at room temperature, prioritizing hardness and wear resistance for stamping, blanking and cold heading. Hot‑work mold steel operates under high temperature, focusing on hot hardness, thermal fatigue resistance and toughness for die‑casting and hot forging.
H13 offers balanced hot hardness, thermal‑fatigue resistance and toughness. ESR‑refined H13 with higher purity further improves transverse toughness and extends die‑casting mold service life.
S136 is recommended. It features good corrosion resistance and high mirror polishing performance, ideal for corrosive plastics including PVC and flame‑retardant materials.
