|Chemical Element||% Present|
0.95 - 1.20
16.00 - 18.00
0.00 - 1.00
0.00 - 1.00
0.00 - 0.04
0.00 - 0.03
0.40 - 0.80
Bar Up To 100mm Dia or Thickness
Elongation A50 mm
General Physical Properties
10.1 x 10-6/K
Modulus of Elasticity
0.6 x 10-6 Ω .m
- Rolling element bearings
- Valve seats
- High quality knife blades
- Surgical instruments
- Excellent hardness
- High wear resistance
- Good mechanical strength
- Good fatigue resistance
- Moderate corrosion resistance
If welding is necessary pre-heat at 250°C and follow welding with a full anneal. Grade 420 filler will give a high hardness weld (although not as high as the 440C), but 309 or 310 will produce soft welds with higher ductility.
In the annealed condition this grade is relatively easily machined; approximately the same as for high speed steel. Chips are tough and stringy so chip breakers are important. If these grades are hardened machining becomes more difficult and probably impossible.
Good resistance to the atmosphere, fresh water, foods, alkalies and mild acids. Best resistance in the hardened and tempered and passivated condition. A smooth polished surface also assists.
The corrosion resistance of grade 440C approximates that of grade 304 in many environments.
- 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.
Not recommended for use in temperatures above the relevant empering temperature, because of reduction in mechanical properties by over-tempering.