Introduction
DIN 1.2738 steel is one kind of plastic mold steel especially for big steel mold parts, it is equivalent to AISI P20+Ni tool steel.
Smelting method : EAF+LF+VD+ESR
Main Characteristics : If futures excellent hardening penetration, good workability, polishing and photoengraving properties, This steel is used for plastic moulds of medium and big size. It can be subject to a nitriding treatment to improve its wear resistance.
Major Applications : Injections and thermoplastic extrusion moulds, rubber moulds, moulds carrier frames, container.
Chemical Composition : (%)
| C | Si | Mn | Cr |
|---|---|---|---|
| 0.35-0.45 | 0.20-0.40 | 1.30-1.60 | 1.80-2.10 |
| Mo | Ni | P | S |
|---|---|---|---|
| 0.15-0.25 | 0.90-1.20 | ≤0.030 | ≤0.030 |
Comparable Standards : (%)
| UNI | W.Nr | DIN |
|---|---|---|
| - | 1.2738 | 40Cr/MnNiMo8-6-4 |
| AFNOR | AISI/SAE | BS |
|---|---|---|
| ~40 CMND8 | ~P20 + Ni | ~P20 + Ni |
Critical Points :
| Ac 1 | 710°C |
|---|---|
| Ms | 290°C |
Supply Conditions : Hardened and Tempered Normal HP 280-320 & 380-400
Heat Treatments :
Annealing :
- Heat to 710-740℃, with hold at minimum rate for 3 hours.
- Slow furnace cooling to 600℃.
Stress relieving :
- To be carried out after machining and before the final heat treatment
- Heating to 530-580℃ for 2 hours.
Hardening :
- Preheating to 500-550℃
- Austenitizing at 840-880℃
- Oil or thermal bath cooling at 200-230℃, then oil cooling according to the steel shape size
- Quenched hardness 52-54 HRC
Tempering :
- To be carried out after the hardening and when the steel is at 60-80℃, at 500-600℃ according to the required hardness and with permanance for atleast 2 Hr.
- Cooling in air
