440C Martensitic Stainless Steel Bar

440C is a high carbon straight chromium high hardenability martensitic stainless steel, generally supplied in the annealed condition with a maximum Brinell hardness of 269 (Rc29) or annealed and cold drawn with a maximum Brinell hardness of 285 (Rc31).Characterised by good corrosion resistance in mild domestic and industrial environments, including fresh water, organic materials, mild acids, various petroleum products, coupled with extreme high strength, hardness and wear resistance when in the hardened and tempered condition. 440C due to its excellent hardenability is capable of being through hardened up to Rc60 depending upon carbon content and section size. Small sections can be air cooled and quite large sections oil quenched for maximum through hardness.Used for parts requiring a combination of excellent wear resistance, plus reasonable corrosion resistance. Typical applications are: Ball Bearings and Races, Bushings, Cutlery, Chisels, Knife Blades, Pump Parts, Surgical Instruments, Valve Seats etc.

Material magnetic in all conditions.


Colour Code Stocked Sizes
Dark Brown
(Bar end)

Stocked Sizes 45 mm to 160 mm diameter.
Bar Finish
Peeled Bar
Related Specifications
Australia AS 2837-1986 440C
Germany W.Nr 1.4125 X105CrMo17
Japan JIS G4303 SuS 440C
USA ASTM A276-98b 440C
SAE 51440C AISI 440C
UNS S44004
Chemical Composition
Min. % Max %
Carbon 0.95 1.20
Silicon 0 1.00
Manganese 0 1.00
*Nickel 0 1.00
Chromium 16.00 18.00
Molybdenum 0.00 0.75
Phosphorous 0 0.04
Sulphur 0 0.03
*Nickel addition optional.
Mechanical Property Requirements For Material in the Annealed Condition to 1) AS2837 - 1986 440C and 2) ASTM A276-98b 440C
Specification AS2837-1986 440C
Brinell Hardness 269 Max
Capable of attaining Rc59 minimum in 10mm test bar oil quenched from 1010oC - 1070oC.
Specifrication ASTM A276-98b 440C
Finish Hot Finished Cold Finished
Brinell Hardness 269 Max 285 Max
Capable of attaining Rc58 minimum in 9.50mm test bar air cooled 1020oC.
Typical Mechanical Properties At Room Temperature in the Annealed Condition (AS Supplied)
Tensile Strength Mpa 785
Yield Strength Mpa 420
Elongation in 50mm % 15
Impact Charpy J 6
Hardness HB 240
Rc 24
Typical Mechanical Properties At Room Temperature - Hardened By Oil Quench at 1030oC and Tempered as Indicated
Tempering Temperature oC 150 200 250 300 350 400
Tensile Strengt Mpa 2050 2020 1980 1890 1820 1780
Yield Strength Mpa 1930 1896 1845 1760 1675 1635
Elongation in 50mm % 4 4 4 4 4 4
Impact Charpy J 9 9 9 9 9 9
Hardness Rc 60 59 57 56 56 56
Section Size 25mm
High tensile strength, high yield strength and high hardness but low impact properties.
Elevated Temperature Properties
440C is not generally recommended for elevated temperature applications due to a reduction in corrosion resistance when tempered above 400oC
Low Temperature Properties
440C is also not recommended for use at sub-zero temperatures due to a further drop in impact properties.
Cold Bending
Moderate cold bending is possible when fully annealed to maximum softness.
Hot Bending
Not generally recommended due to the high hardenability - air hardening capabilities of this grade. If really necessary then work piece following operation should be cooled as slowly as possible either in a furnace or in warm dry lime or ashes to room temperature prior to annealing.
Corrosion Resistance
440C has a corrosion resistance somewhat similar to 410 grade, but lower than 431 grade, also lower than most of the 400 series ferritic stainless steels and all of the 300 series austenitic stainless steels.NB. It has optimum corrosion resistance in the hardened and tempered condition when tempered below 400oC. Hardening from 1090oC will ensure better carbide solution, and therefore better corrosion resistance, but minimum soaking time should be allowed at this temperature otherwise excessive grain growth can occur. Polishing will further develop its corrosion resistance. It is not recommended for use in the annealed condition.It is most important that oxygen is always allowed to circulate freely on all stainless steel surfaces to ensure that a chrome oxide film is always present to protect it. If this is not the case, rusting will occur as with other types of non stainless steels.

For optimum corrosion resistance surfaces must be free of scale and foreign particles.
Finished parts should be passivated.


Preheat to 760oC - 820oC, then heat slowly and uniformly to 1050oC - 1150oC, hold until temperature is uniform throughout the section and commence forging immediately.Do not overheat as this can cause a loss of toughness and ductility. Do not forge below 900oCFinished forgings should be cooled slowly in a furnace, warm dry lime or ashes to room temperature and annealed immediately.

NB. Air cooling after forging may cause cracking.


Heat Treatment
Sub-Critical Annealing
Heat uniformerly to 730oC - 770oC hold until temperature is uniform throughout the section.
*Soak as required. Cool in air.
Heat uniformerly to 840oC - 900oC, hold until temperature is uniform throughout the section.
*Soak as required. Cool in furnace.
Heat to 1010oC - 1070oC, hold until temperature is uniform throughout the section. *Soak as required. Quench in warm oil or air cool. Do not overheat. Temper immediately while still hand warm.NB. This grade can be hardened from 1090oC for optimum corrosion resistance but this will result in a lower hardness level obtained. 
Heat to 100oC - 400oC, as required, hold until temperature is uniform throughout the section. *Soak as required. Cool in air.Tempering within the range 100oC - 200oC will give optimum corrosion resistance and maximum hardness - up to Rc60 depending upon section size. NB. Tempering above 400oC is not recommended as it will result in a reduction in corrosion resistance and impact properties.*Heating temperatures, rate of heating, cooling and soaking times will vary due to factors such as work piece size/shape, also furnace type employed, quenching medium and work piece transfer facilities etc.

Please consult your heat treater for best results.


431 machines best in the hardened and tempered as supplied condition and is regarded as being readily machineable with all operations such as turning and drilling etc. capable of being carried out satisfactorily. It does not work harden to the same extent as the 300 series austenitic stainless steels, but is more similar in this respect to the low alloy high tensile steels such as 4140 etc.Allowing therefore for its high tensile properties, all machining should be carried out as per machine manufacturers recommendations for suitable tool type, feeds and speeds.
440C due to its high carbon content has low machinability. It machines best in the fully annealed condition and chip curlers and breakers are recommended as chips tend to be strong and stringy. All operations such as drilling, turning and milling etc. should be carried out as per machine manufacturers recommendations for suitable tool type, feeds and speeds.
Grinding and Polishing
440C in the hardened and tempered condition requires care with finish grinding and polishing to avoid overheating as this can lower the hardness and corrosion resistance.
Welding 440C in the annealed as supplied condition is not recommended due to its high air hardening capability which can lead to the formation of brittle martensite, resulting in cold cracking due to contraction stresses within the weld and heat affected zone.
Welding 440C in the hardened and tempered condition should not be attempted.
If welding is really necessary in the annealed condition the following welding procedure and post-weld heat treatment may be taken as a guide only.
Welding Procedure
Welding electrodes or rods should be low hydrogen types and as *similar to the base metal as possible when high strength is required, otherwise an austenitic stainless *electrode or rod may be used, resulting in a more ductile weld if strength is not so critical.Pre-heat at 260oC and maintain interpass temperature at 260oC minimum. On completion of welding cool slowly as possible to 260oC minimum, followed immediately by: Post-weld sub-critical anneal at 730oC - 770oC or full anneal at 840oC - 900oC and harden and temper as required.*Please consult your welding consumables supplier.


Interlloy believes the information provided is accurate and reliable. However no warranty of accuracy, completeness or reliability is given, nor will any responsibility be taken for errors or omissions.

316L due to its low carbon content has greater resistance to intergranular corrosion than all the austenitic stainless steel grades except 304L grade and 321 titanium stabilized grade.