Designation by Standards
Chemical Composition (in weight %)
This alloy is one of the hot work, tungsten containing tool steels. The tungsten content is beneficial for hot strength at red heat, although toughness is somewhat reduced.
Used for hot working dies and tooling such as die casting, extrusion and hot forming of parts. Pressure die casting tools, moulds for Cu and Cu-alloys. This grade is not used for water cooled tools.
Physical properties (avarage values) at ambient temperature
Modulus of elasticity [103 x N/mm2]: 190-210
Density [g/cm3]: 7.80
Thermal conductivity [W/m.K]: 27.0
Electric resistivity [Ohm mm2/m]: 0.52
Specific heat capacity[J/g.K]: 0.46
Coefficient of Linear Thermal Expansion 10-6 oC-1
Heat to 780-810oC, cool slowly. This will produce a maximum Brinell hardness of 240.
Stress relieving to remove machining stresses should be carried out by heating to 650oC, holding for one hour at heat, followed by air cooling. This operation is performed to reduce distortion during heat treatment.
Harden from a temperature of 1080-1160oC followed by air, oil or warm bath quenching. Hardness after quenching is 47-53 HRC.
Tempering temperature: See the table bellow.
Tempering Temperature (oC) vs. Hardness (HRC)
Hot forming temperature: 1150-926oC.
The tungsten content makes H21 somewhat difficult to machine. As compared to the W group of water hardening low alloy steels rated at 100% for machinability the H21 would rate 55%.
This is a steel alloy and does not have corrosion resistance. It will rust unless given protective treatment.
This alloy may be welded. Consult the supplier for details.
All technical information is for reference only.