Heat Treatment
Annealing - Full anneal - 850-900°C, slow furnace cool to about 600°C and then air cool. Sub-critical Annealing - 735-785°C and slow furnace cool.
Hardening - Heat to 1010-1065°C, followed by quenching in warm oil or air. Oil quenching is necessary for heavy sections. Immediately temper at 150-370°C to obtain a wide variety of hardness values and mechanical properties as indicated in the accompanying table.
Tempering in the range 425-565°C is to be avoided because of reduced impact resistance and corrosion resistance. Tempering in the range 590-675°C results in lower hardness (the product become machinable) and high impact resistance.