300M BMS 7-26 Steel Alloy
Steel 300M, also known as AISI 4340 Modified, is a low-alloy steel that is renowned for its high strength, fatigue resistance, and toughness. These characteristics make it valuable and useful in aerospace, aviation, automotive, and racing. Its core components include chromium, molybdenum, and vanadium. The vacuum-melted steel is easy to form and machine due to its ductility. When heat-treated, it possesses higher strength and toughness. There are different options to choose from in terms of form, such as bars, sheets, and plates. When working with this material use cutting tools with a positive rake angle to get the best results. Also, remember not to weld it when it is hardened.
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300M BMS 7-26 Physical Properties
- Density: 0.284 lb/in3 (7.85 g/cm3)
- Thermal conductivity: 23.1 BTU/(hr·ft·°F) (40 W/m-K)
- Specific heat capacity: 0.11 BTU/lb·°F (460 J/kg-K)
- Mean coefficient of thermal expansion: 6.13×10-6 in/(in·°F) (11.0×10-6m/(m·K))
300M BMS 7-26 Chemical Composition
| Element | min | max |
| Carbon | 0.40 | 0.45 |
| Manganese | 0.60 | 0.90 |
| Silicon | 1.45 | 1.80 |
| Phosphorus | — | 0.010 |
| Sulfur | — | 0.010 |
| Chromium | 0.70 | 0.95 |
| Nickel | 1.65 | 2.00 |
| Molybdenum | 0.30 | 0.50 |
| Vanadium | 0.05 | 0.10 |
| Copper | — | 0.35 |
300M BMS 7-26 Mechanical Properties
- Ultimate tensile strength: 280 ksi (1931 MPa)
- Yield strength: 230 ksi (1586 MPa)
- Elongation at break: 10%
- Modus of elasticity: 30 x106 psi (207 GPa)
- Shear modulus: 11.5 x 106 psi (79.3 GPa)
- Poisson’s ratio: 0.3
Fabrication and Working Instructions
Given Steel 300M’s machinability, it can be worked using standard methods like sawing, turning, drilling, cutting, boring, and grinding. The material is usually supplied in both normalized and tempered conditions. Clients may also purchase it in its annealed condition and then easily machine it to the desired shape. The ideal approach to machining this alloy is to use a coarse lamellar pearlitic or a spheroidized structure.
As the material’s strength increases, its machinability decreases, which is why it is less ideal to machine it in its hardened or tempered state. If welding is required, do such when the material is annealed to get the best mechanical properties, not when tempered or hardened as it increases the risk of quench cracking.
When welding the steel, preheat it to around 400-580 °F (≈200-300 °C), then subject it to after-welding stress relief of 1020-1200 °F (≈550-650 °C). For tempered-condition material, the stress relief should be 60 °F (15 °C) lower than the tempering temperature.
Steel 300M is suitable for hot and cold forming, including forging, extrusion, and rolling. However, make sure that the material is heated uniformly to avoid cracking during formation. After forming, cool it slowly to avoid any residual stresses.
Heat Treatment
The most common heat treatment for Steel 300M is oil quenching and tempering. First, it is normalized at 1700 °F (927 °C) for some hours, exceeding its upper critical temperature. This helps to refine the grain structure of the material and improve its mechanical properties. The next step is austenitizing, which entails heating the steel to 1600°F (872°C), at which point it becomes fully austenitic. It is then quenched in oil or water to achieve a martensitic structure.
The rapid cooling rate of quenching causes the steel to harden, but it also makes it brittle or distorted. To improve its toughness and ductility, the steel is then tempered by heating it to a temperature below its critical range, typically around 900 °F (482 °C) for 4 hours. It is then cooled in still air to achieve a pearlitic structure.
It is advised that only professionals with the required equipment and skills should perform this procedure, and that should be done in a safe environment. In addition, following the recommended heat treatment specifications is crucial for the specific steel grade and shape in use.
What is Steel BMS7-26?
BMS 7-26 is a modification of the basic 300M low-alloy steel. Developed by The Boeing Company, it is used in aerospace and motorsport due to its high tensile strength and high impact resistance.
Properties of BMS7-26
BMS 7-26 steel contains 0.40-0.44% carbon, 0.08% vanadium, 0.75% manganese, 1.60% silicon, 0.82% chromium, 0.40% molybdenum, and 1.8% nickel.
Applications of BMS7-26
BMS 7-26 steel is widely used in aerospace, motorsports, defense, and other high-performance industries that require exceptional strength-to-weight ratio and toughness. Aerospace is an excellent case in point; BMS7-26 steel is used to manufacture aircraft components like landing gears, engine mounts and drive shafts, that are designed to withstand high stresses.
Advantages of BMS7-26
BMS 7-26 offers several advantages over standard 300M steel, including improved hardenability, strength, and fracture toughness. It is also highly resistant to fatigue, making it an ideal material for high-stress applications.
BMS7-26 BAR
Friend Metals Co is your one-stop shop for the best grade BMS7-26 steel available on the market. We are delighted to be the go-to supplier for aerospace-grade metals, all thanks to our unwavering support for quality delivery and excellent customer support.
Precision and reliability are critical factors to take into account in all aerospace applications, and we at Friend Metals Co understand this. As a result, we only provide BMS7-26 steel that meets or surpasses the most demanding industry standards. Our product line comes in various sizes and configurations. Each steel material is designed to meet the unique needs of our esteemed clients.
We pride ourselves on competitive pricing and fast delivery to guarantee our customers an experience of a lifetime. Whether you need BMS7-26 steel bars, sheets, or forgings, rest assured that we have you covered.
BMS7-26 FORGING
When it comes to high-quality BMS7-26 forgings, Friend Metals Co is the name to trust. We employ cutting-edge tools and techniques to manufacture forgings of the highest quality. Our rigorous quality control process ensures that they meet the most stringent requirements.
We are on speed dial to discuss your needs and help you choose the best steel product for any application. Whether it centers around forgings or standard products, we will provide you with a reliable and cost-effective solution.
At Friend Metals Co, we are dedicated to being your reliable partner for all your BMS7-26 steel needs. Contact us today to learn more about our products and services, and discover why we are the best choice for aerospace-grade metals.
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