Sichuan Liaofu Special Steel Company is one of the most experienced manufacturers and suppliers of 300m aisi 4340m ultra high strength tensile steel round bar in China. With over 20 years' experience, our factory offer high quality products made in China with competitive price. Welcome to contact us for wholesale service.
AMS6416 300M/4340M alloy steel
300m steel is a kind of low alloy high strength steel, has become the world's highest strength, comprehensive performance is best, the most widely used one of the best gear steel and reputation.Its mechanical properties with high strength, high transverse plastic, high fracture toughness, fatigue performance and good corrosion resistance, etc.In China in the mid - 80 - s began AMS6417 copied by American aerospace material standard, and in 1990 by metallurgical and two joint technical appraisal of aeronautics and astronautics
AISI 4340 ultra high strength tensile steel round bar for aerospace application
Standards:ASTM,JIS,GB,EN(DIN,BS,NF) Or Per as clients' requires.
Product Basic Information
| Size Range | |||
| Round Bar | Diameter(mm) | Length(mm) | -- |
| 30~1000 | 500~12000 | -- | |
| Chemical Composition(%) | ||||||||
| C | Mn | P | S | Si | Cr | Mo | Ni | V |
|
0.38-0.46 |
0.60-0.90 |
0.010Max. | 0.010max. | 1.45-1.80 | 0.70-0.95 | 0.30-0.65 | 1.65-2.00 | 0.05min. |
Chemical Composition and Mechanical Properties(In Quenched & Tempered State)
|
Material |
4340M |
||
|
Chemical Composition |
Mechanical Properties(In Quenched & Tempered State) |
||
|
C |
0.38-0.46 |
Tensile strength(MPA) |
1860 |
|
Si |
0.17-0.37 |
Yield strength (MPA) |
- |
|
Mn |
0.60-0.90 |
Elongation(δ5/%) |
- |
|
Cr |
0.70-0.95 |
Reduction in Area (ψ/%) |
25 |
|
Mo |
0.30-0.65 |
Impact (J) |
23 |
|
P |
≤0.010 |
Hardness (Anealed Condition) |
≤241HB |
|
S |
≤0.010 |
||
|
Cu |
≤0.30 |
||
|
Ni |
1.65-2.00 |
||
|
V |
Min 0.05 |
||
Product Application Areas
4340M steel USES vacuum arc melting technology to improve purity, plasticity, toughness, etc. AMS6416 standard USES non-vacuum smelting, which is the general aviation quality level. Other parts of the standard use vacuum smelting to achieve high quality aviation quality level.
By the standard heat treatment oil quenching and tempering, the tensile strength of the steel can reach more than 1860MPa, which is currently the highest strength of low-alloy ultra-high strength steel. High strength can reduce the weight of the parts, improving the strength has been one of the main goals of landing gear parts design. The main wing bearing components of the American aircraft are also 300M steel and used to the highest strength level.
Cherecteristics
The fatigue resistance of 4340M steel is obviously better than that of 4340. This is extremely beneficial for the long life of the landing gear and other aircraft components and is the main reason why 300M steel is widely used in aircraft.
It contains 1.5% silicon, which improves the stress corrosion resistance of 300M steel.
Produce process
EAF + LF + VD + Forged + Heat Treatment -Annealed
Factory Pictures
Certifications
Factory Manufacture Process
Product photos
Polished bright bars
Packing & Shipping
FAQ
Q: Why does 300M require vacuum arc melting (VAR) compared to standard 4340?
A: VAR melting removes hydrogen, oxygen, and nitrogen, drastically improving transverse ductility and fracture toughness. At the 1860 MPa tensile level, standard air-melted steel is too brittle. VAR ensures the material can withstand severe landing gear loads without catastrophic failure.
Q: Can 300M steel rust if used in aerospace applications?
A: Yes, it has low chromium (0.70-0.95%) and is not stainless. It will rust in humid environments. Aerospace components made of 300M usually require protective coatings like cadmium plating or high-tech paint systems. We supply the raw material; you must apply the anti-corrosion treatment after machining.
Q: Do I need to worry about hydrogen embrittlement during heat treatment?
A: Yes, this is a major risk for ultra-high-strength steels. The material must be quenched in oil and immediately tempered. Avoid acid pickling; if it is necessary, bake the steel immediately afterward to remove hydrogen. Proper tempering is critical to restore toughness.
Q: What is the difference between 300M and standard AISI 4340?
A: 300M contains about 1.5% silicon (vs. 0.20% in 4340). This silicon addition allows higher tempering temperatures without losing strength, which significantly improves stress corrosion cracking resistance and fatigue life.
Q: Can you supply forged bars for large aircraft components?
A: Yes, the base material is produced at our in-house production base and forged to your dimensions. We supply rough-turned bars up to 1000mm diameter, leaving a machining allowance. All large forgings come with 100% ultrasonic testing (UT) to guarantee internal integrity.
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