W.NR. 1.2738

Main characteristics and applications

Pre-hardened plastic mould steel with excellent hardening penetration, good machinability, polishing and texturing properties.
This steel is used for plastic moulds of medium and big size. It can be subject to a nitriding or PVD treatment to improve its wear resistance.
Main applications: thermoplastic injections and extrusion moulds, rubber moulds, large moulds, frames, containers.

Comparable standards


Chemical composition (typical; in weight %)

CSiMnP (max)S (max)CrMoNi

Critical points

Ac1 720 °C

Ac3 800 °C

Ms 290 °C

Production technology

EAF – LF – VD - Forging – Heat treatment QT

US specification

In according to standard EN10228-3 Class 4 and standard SEP 1921 Class E/e

Delivery condition

WW.NR. 1.2738 is delivered in quenched and tempered condition, with hardness range 300 - 340 HB (32 - 37 HRC).

Physical properties (reference values)

Thermal expansion coefficient (10-6/K)12.012.412.914.1
Thermal conductivity (W/mk)33.133.534.532.6
Young modulus (Kn/mm2)212205200175

Heat treatment

AnnealingHeat to 680 - 700 °CMin. H.T. for 2 minute /mmAir or furnaceIn order to obtain hardness lower than 250 HB ( 24 HRC) to improve machinability
Stress relievingHeat to 560 - 600 °C (max 30 °C below tempering temperature)Min. H.T. for 2 minute /mmAir or furnaceTo be carried out after machining, is recommended to eliminate the residual stresses induced by mechanical working
HardeningHeat to 860-880°CMin. H.T. for 1 minute /mmPolymer-
TemperingHeat to 550 – 620°CMin. H.T. for 3 minute /mmAir or furnaceTo be carried out after hardening. 2nd Tempering must be performed to max 30°C below tempering temperature

C.C.T. curve


Tempering curve


Tool and Die Steel Includes Cold Work Steel, Hot Work Steel, Plastic Mould Steel, High Speed Steel. These tool materials adhere to great quality demands of steel like temper, strength, toughness, resistance to tempering, hardening capacity, dimensional stability etc. The range of Tool Steel in our store includes products from renowned manufacturers.