440C(UNS S44004)
chemical composition
|
Carbon |
0.95 to 1.20 |
% |
Manganese (Maximum) |
1.00 |
% |
|
Phosphorus (Maximum) |
0.040 |
% |
Sulfur (Maximum) |
0.030 |
% |
|
Silicon (Maximum) |
1.00 |
% |
Chromium |
16.00 to 18.00 |
% |
|
Molybdenum (Maximum) |
0.75 |
% |
Iron |
Balance |
|
Product form:
Sheet
Plate
Bar
Pipe & Tube (welded & seamless)
Fittings (i.e. flanges, slip-ons, blinds, weld-necks, lapjoints, long welding necks, socket welds, elbows, tees, stub-ends, returns, caps, crosses, reducers, and pipe nipples)
General properties
JIS SUS440C is a high-carbon chromium steel designed to provide stainless properties with maximum hardness. It has been used primarily as a bearing steel, and is used in the hardened plus tempered condition. When heat-treated, Type 440C attains the highest hardness of any stainless stee (about Rockwell C 60).
Applications:
This stainless steel principally has been used in bearing assemblies, including bearing balls and races. In addition, it should be considered for cutlery, needle valves, ball check valves, valve seats, pump parts, ball studs, bushings, and wear-resistant textile components.
Decay resistance
440C resists corrosion in normal domestic environments and very mild industrial environments, including many petroleum products and organic materials.
This grade is used in the hardened plus tempered condition. Optimum corrosion resistance is obtained by hardening from 2000ºF (1093 centigrade degree) to ensure better carbide solution.
However, care should be taken to minimize time at 2000ºF (1093 centigrade degree) to avoid excessive grain coarsening. For best corrosion resistance, the tempering temperature should be below about 800ºF (427 centigrade degree).
For optimum corrosion resistance, surfaces must be free of scale, lubricants, foreign particles, and coatings applied for drawing and heading. After fabrication of parts, cleaning and/or passivation should be considered.
|
Notes
:The following 4-level rating scale is intended for comparative purposes only. Corrosion testing is recommended; factors which affect corrosion resistance include temperature, concentration, pH, impurities, aeration, velocity, crevices, deposits, metallurgical condition, stress, surface finish and dissimilar metal contact.
|
Nitric Acid |
Moderate |
Sulfuric Acid |
Restricted |
|
Phosphoric Acid |
Restricted |
Acetic Acid |
Restricted |
|
Sodium Hydroxide |
Moderate |
Salt Spray (NaCl) |
Restricted |
|
Humidity |
Good |
|
|
|
Physical Property
|
Specific Gravity |
|
-- |
7.62 |
|
|
Density |
|
-- |
0.2750 |
lb/in³ |
|
Mean Specific Heat |
|
32ºF, 212ºF |
0.1100 |
Btu/lb/ºF |
|
Mean Coefficient of Thermal Expansion |
|
32ºF, 212ºF |
5.60 |
x 10-6 in/in/ºF |
|
Thermal Conductivity |
|
212ºF |
168.0 |
BTU-in/hr/ft²/ºF |
|
Modulus of Elasticity (E) |
|
-- |
29.0 |
x 103 ksi |
|
Electrical Resistivity |
|
70.0ºF |
361.0 |
ohm-cir-mil/ft |
Heat Treatment
Annealing
For maximum softness, this steel should be heated uniformly to 1550/1600ºF (843/871ºC). Soak and cool very slowly in the furnace. Brinell hardness approximately 223. Intermediate or process annealing treatment-heat uniformly to 1350/1400ºF (732/760 centigrade degree). Air cool. Brinell hardness about 255.
Hardening
Heat to 1850/1950ºF (1010/1066 centigrade degree); soak; quench in warm oil or cool in air. Do not overheat. When overheated, full hardness cannot be obtained. See comments under corrosion resistance.
Tempering
Heat to 1850/1950ºF (1010/1066 centigrade degree); soak; quench in warm oil or cool in air. Do not overheat. When overheated, full hardness cannot be obtained. See comments under corrosion resistance.
Processing Form
Hot working
Heat to 1850/1950ºF (1010/1066 centigrade degree); soak; quench in warm oil or cool in air. Do not overheat. When overheated, full hardness cannot be obtained. See comments under corrosion resistance.
Cold working
If annealed for maximum softness, this steel can be moderately cold formed or headed.
Machinability
For most machining operations, this steel cuts best when in the dead soft annealed condition. Because of its high carbon content it machines somewhat like high-speed steel. Because chips are tough and stringy, chip curlers and breakers are important.
Grinding and polishing
In cutlery applications, grinding and polishing are very important. 440C works well in these operations but considerable care must be used not to overheat since both the hardness and corrosion resistance may be lowered.
Welding
Because of its high-hardness capability, this steel is seldom welded. However, if welding is necessary, the parts should be preheated and maintained at about 500ºF (260 centigrade degree), welded, and then immediately given a 6-8 hour anneal at 1350/1400ºF (732/760 centigrade degree) with a slow furnace cool. The parts should not be allowed to cool below 500ºF (260 centigrade degree) between welding and annealing. High welding heat inputs should be used. To obtain mechanical properties in the weld similar to those in the base metal, welding consumables of like composition should be considered. Otherwise, AWS E/ER309 might also be considered.
Standard:
|
AMS 5618 |
AMS 5630 |
|
AMS 5880 |
ASTM A276 |
|
ASTM A314 |
ASTM A473 |
|
ASTM A493 |
ASTM A580 |
|
ASTM A756 |
| |
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