440C 9Cr18MoV Stainless Steel Round Bar 9Cr18MoV High Carbon
Stainless Steel For Knife
440C Stainless steel is a type of modern steel and famous for its
high corrosion resistant, wear resistance, strength and hardness
qualities, among all the stainless alloys, capable of attaining
(after heat treatment) the highest hardness (60 HRC). It has good
resistance to the atmosphere, fresh water and mild acids. It has
best resistance in the hardened, tempered and passivated condition.
It allows creating a smooth polished surface and Razor sharp edges.
It is being used in cutting instruments, rolling element bearings,
valve seats, high quality knife blades, surgical instruments,
chisels, ball bearings and valve parts and most commonly used in
the production of Cutting tools, including Haircutting Scissors,
daggers and swords.
Grades 440A and 440B are identical except for slightly lower carbon
contents (0.60 – 0.75% and 0.75 – 0.95% respectively), they attain
lower hardness but have slightly higher corrosion resistances.
Although all three versions of this grade are standard grades, in
practice 440C is more available than the A or B variants.
Another alloy 440F (UNS S44020) also exists, with the same high
carbon content as 440C.
440 Steel family, there is a new modern kind of steel, known as
440V steel. Basically, it is the advancement of 440C steel. This
steel has same level of hardness like 440C, but it has more
corrosion resistant ability and more machine-ability.
Heat Resistance:
Not recommended for use in temperatures above the relevant
tempering temperature, because of reduction in mechanical
properties by over-tempering.
Heat Treatment:
Annealing – Full anneal – 850-900C, slow furnace cool to about 600C
and then air cool. Sub-critical Annealing – 735-785C and slow
furnace cool.
Hardening – Heat to 1010-1065C, followed by quenching in warm oil
or air. Oil quenching is necessary for heavy sections. Immediately
temper at 150-370C to obtain a wide variety of hardness values and
mechanical properties as indicated in the accompanying table.
Tempering in the range 425-565C is to be avoided because of reduced
impact resistance and corrosion resistance. Tempering in the range
590-675C results in lower hardness (the product become machinable)
and high impact resistance.
Welding
If welding is necessary pre-heat at 250C and follow welding with a
full anneal. Grade 420 filler will give a high hardness weld (not
as high as the 440C). Generally welding of 440C is not recommended
due to its hardening capability which can lead to the formation
cracks within or near the weld.
Machining
In the annealed condition this grade is relatively easily machined;
approximately the same as for high speed steel. If this grade is
hardened machining becomes very difficult and probably impossible.
Composition
Chemical Composition ranges of 440C stainless steel
| Grade440C |
| Ingredients | Min. | Max. |
| Carbon | 0.95 | 1.20 |
| Manganese | – | 1.00 |
| Silicon | – | 1.00 |
| Phosphorus | – | 0.040 |
| Sulphur | – | 0.030 |
| Chromium | 16.00 | 18.00 |
| Molybdenum | – | 0.75 |
| Iron | Balance |
440C Physical Properties
Physical properties for grade 440 stainless steels.
| Grade | Density (kg/m3) | Elastic Modulus (GPa) | Mean Coefficient of Thermal Expansion (mm/m/C) | Thermal Conductivity (W/m.K) | Specific Heat
0-100C (J/kg.K) | Electrical Resistivity (nW.m) |
| 0-100C | 0-200C | 0-600C | at 100C | at 500C |
| 440A/B/C | 7650 | 200 | 10.1 | 10.3 | 11.7 | 24.2 | – | 460 | 600 |
440C Related Specifications
| USA | Germany | Japan | Australia |
ASTM A276-98b 440C
SAE 51440C AISI 440C
UNS S44004 | W.Nr 1.4125 X105CrMo17 | JIS G4303 SuS 440C | AS 2837-1986 440C |
