GB/T 3077 40-B Introduce
GB/T 3077 40-B is one of the most commonly used Chinese structural steels especially for low to medium strength applications. It is well suited for hot forming and cold forming, and it is often used for medium strength mechanical parts. Its tensile strength is from 370 to 500MPa and yield strength from 310 to 390MPa. GB/T 3077 40-B is widely used for the production of hot rolled steels for machine building, brakes and press components, crankshafts, gears, shafts for engines, hydraulic power units and parts for oil-field industry. It is also suitable for manufacturing heat-resistant parts, vehicle load components, shafts, and such.
Smelting temperature:1787°C - 1898°C
Application:Alloy structural steel
GB/T 3077 40-B Material Chemical Composition
The chemical composition of the GB/T 3077 40-B steel are as follows:
| Element | Min | Max |
|---|---|---|
| Carbon (C) | 0.3700 | 0.4400 |
| Silicon (Si) | 0.1700 | 0.3700 |
| Manganese (Mn) | 0.6000 | 0.9000 |
| Sulfur (S) | - | 0.0350 |
| PhOsphorus (P) | - | 0.0350 |
| Chromium (Cr) | - | 0.3000 |
| Nickel (Ni) | - | 0.3000 |
| Boron (B) | 0.0005 | 0.0035 |
| Molybdenum (Mo) | - | 0.1500 |
| Copper (Cu) | - | 0.3000 |
GB/T 3077 40-B Material Mechanical Properties
GB/T 3077 40-B is generally suitable for forging and hot forming, cold forming, and heat treatment. It is mainly used in the form of bars and plates, however, some grades can be used as thin-walled tube, thin plate, and thin wire products. After cold forming, the mechanical properties of GB/T 3077 40-B are slightly improved.
The mechanical properties of the GB/T 3077 40-B steel are as follows:
| YieldRp0.2 | ≤ 239 (MPa) |
| TeileRm | ≤ 812 (MPa) |
| ImpactKV/Ku | 32(J) |
| ElongationA | 13% |
| Reduction in cross section on fractureZ | 21% |
| As-Heat-Treated Condition | Solution and Aging, Annealing, Ausaging, Q+T,etc |
| Brinell hardness (HBW) | 244 |
GB/T 3077 40-B Material Thermal Properties
The thermal performance parameters of the GB/T 3077 40-B steel are as follows:
| Temperature (°C) | 41 | 633 | 627 |
| Modulus of elasticity (GPa) | - | 816 | - |
| Mean coefficient of thermal expaion ×10-6/(°C) | - | - | 33 |
| Thermal conductivity (W/m·°C) | - | 14.3 | 24.2 |
| Specific thermal capacity (J/kg·°C) | - | 323 | - |
| Specific electrical resistivity (Ω mm²/m) | 0.13 | - | - |
| Deity (kg/dm³) | - | - | 323 |
| Poisson’s coefficient, ν | - | - | 324 |
GB/T 3077 40-B Material Machining Technology
GB/T 3077 40-B has excellent mechanical properties, good weldability, good cold and hot processing performance, good corrosion resistance, and mostly non-heat treatable hardening. In addition, it has relatively high thermal conductivity, good oxidation resistance, and good machinability.