440C Stainless Steel Strip / 440C Stainless Steel Coil 0.3 - 6.0mm
SS440C 2B NO.1 Surface
Stainless steels are high-alloy steels which have high corrosion
resistance compared to other steels due to the presence of large
amounts of chromium. Based on their crystalline structure, they are
divided into three types such as ferritic, austenitic, and
martensitic steels. Another group of stainless steels are
precipitation-hardened steels. They are a combination of
martensitic and austenitic steels.
Grade 440C stainless steel is a high carbon martensitic stainless
steel. It has high strength, moderate corrosion resistance, and
good hardness and wear resistance. Grade 440C is capable of
attaining, after heat treatment, the highest strength, hardness and
wear resistance of all the stainless alloys. Its very high carbon
content is responsible for these characteristics, which make 440C
particularly suited to such applications as ball bearings and valve
parts.
APPLICATIONS
Typical applications include:
- Rolling element bearings
- Valve seats
- High quality knife blades
- Surgical instruments
- Chisels
SPECIFICATIONS
UNS: ASTM/ASTE S44000
DIN: 1.4125
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.
WELDING
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.
MACHINING
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.
Compostion
| Grade | | C | Mn | Si | P | S | Cr | Mo | Ni | N |
|---|
| 440C | min.
max. | 0.95
1.20 | -
1 | -
1 | -
0.04 | -
0.030 | 16.00
18.00 | -
0.75 | - | - |
Mechanical Properties
| Tempering Temperature (°C) | Tensile Strength (MPa) | Yield Strength 0.2% Proof (MPa) | Elongation (% in 50mm) | Hardness Rockwell (HR C) | Impact Charpy V (J) |
|---|
| Annealed* | 758 | 448 | 14 | 269HB max# | - |
| 204 | 2030 | 1900 | 4 | 59 | 9 |
| 260 | 1960 | 1830 | 4 | 57 | 9 |
| 316 | 1860 | 1740 | 4 | 56 | 9 |
| 371 | 1790 | 1660 | 4 | 56 | 9 |
Physical Properties
| Grade | Density (kg/m3) | Elastic Modulus (GPa) | Mean Coefficient of Thermal Expansion (mm/m/°C) | Thermal Conductivity(W/m.K) | Specific Heat
0-100°C (J/kg.K) | Electrical Resistivity (nW.m) |
|---|
| | | 0-100°C | 0-200°C | 0-600°C | at 100°C | at 500°C | | |
| 440 C | 7650 | 200 | 10.1 | 10.3 | 11.7 | 24.2 | - | 460 | 600 |
Possible Alternative Grades
| Grade | Why it might be chosen instead of 440C |
|---|
| 440A/B | Slightly softer and more corrosion resistant grade needed |
| 440F | High machinability required, with same hardness and hardenability
as 440C |
| 420 | Lower strength and hardness needed than any of the 440 grades |
| 416 | Higher machinability required, and the much lower hardness and
strength is still adequate |
