BS4659 BA2 is a cold work, air hardening tool steel, which offers high surface hardness in hardening, good wear resistance, great through hardenability. A2 tool steel is also characterised by its high dimensional stability after hardening and tempering, high compression resistance and good resistance to tempering.
Chemical Analysis - A2 Tool Steel
| C. | Mn. | Cr. | Si | V. | |
| Min.% | 0.95 | 0.45 | 4.75 | 0.2 | 0.4 |
| Max.% | 1.05 | 0.75 | 5.50 | 0.4 | 0.4 |
Forging:
Heat slowly and uniformly to 700°C. Forge within a range of 1050/1100°C, reheating if necessary. Cool ver y slowly (preferably in a furnace) to avoid setting up stresses.
Annealing:
Heat uniformly to 850°C, equalise, then furnace cool. (Hardness about 215 Brinell). Fully machined tools should be packed during annealing.
Stress Relieving:
If machining operations have been heavy or if the tool has an unbalanced section, remove stresses before hardening by heating up to 675°C, equalise, then cool in furnace to 500°C before slowly cooling in air.
Hardening:
Pre heat to 600/700°C and thoroughly soak. Continue heating to the final hardening temperature of 950/980°C. Allow sufficient time for the component to be heated through. Quench in oil or cool in air.
Martempering:
Martempering is an alternative hardening procedure which may be used when suitable salt bath equipment is available.
Tempering:
Heat uniformly and thoroughly at the selected tempering temperatures and hold for at least one hour per inch of total thickness.