Designation by Standards
Chemical Composition (in weight %)
S7 is a general purpose air hardening tool steel having high impact and shock resistance. It has good resistance to softening at moderately high temperatures. This combination of properties makes it suitable for many hot-work and cold-work applications.
Chisels, rivet sets, punches, driver bolts. Hot punching and shearing.
Physical properties (avarage values) at ambient temperature
Density [g/cm3]: 7.86
Coefficient of Linear Thermal Expansion 10-6 oC-1
Heat to 810-850oC, cool slowly in furnace. This will produce a maximum Brinell hardness of 229.
To relieve machining stresses for greater accuracy in hardening - first rough machine, then anneal below the critical at 649/677oC a minimum of one hour at temperature and cool slowly, then finish machine.
Harden from a temperature of 930-960oC followed by air or oil quenching. Hardness after quenching is 59-61 HRC.
Tempering temperature: 150-400oC.
Tempering Temperature (oC) vs. Hardness (HRC)
Hot forming temperature: 1066-1121oC.
The machinability of S7 alloy may be rated at about 75/80 % of a 1 % carbon tool steel.
Corrosion resistance of this alloy is better than that of plain carbon steels. However it will rust unless given protective treatment.
All technical information is for reference only.