GB/T 16270 Q550D Introduce
This GB/T 16270 standard applies to quenched and tempered steel plates of thickness not higher than 150 mm. The standard defines the grade, shape, size, and weight of various steel products. It also defines the chemical composition, mechanical properties, impact energy, and so on. This standard also sets requirements for fatigue strength, corrosion resistance, thermal ageing properties, and machinability.
Smelting temperature:1261°C - 1235°C
Application:Quenched and tempered steel plate for high strength structure
GB/T 16270 Q550D Material Chemical Composition
The chemical composition of the GB/T 16270 Q550D steel are as follows:
| Element | Min | Max |
|---|---|---|
| Vanadium (V) | - | 0.1200 |
| Titanium (Ti) | - | 0.2000 |
| Silicon (Si) | - | 0.6000 |
| Sulfur (S) | - | 0.0250 |
| PhOsphorus (P) | - | 0.0300 |
| Nickel (Ni) | - | 0.8000 |
| Niobium (Nb) | - | 0.1100 |
| Nitrogen (N) | - | 0.0150 |
| Molybdenum (Mo) | - | 0.3000 |
| Manganese (Mn) | - | 2.0000 |
| Copper (Cu) | - | 0.8000 |
| Chromium (Cr) | - | 0.8000 |
| Carbon (C) | - | 0.1800 |
| Boron (B) | - | 0.0040 |
| Aluminum (Al) | 0.0150 | - |
GB/T 16270 Q550D Material Mechanical Properties
The mechanical properties of the GB/T 16270 Q550D steel are as follows:
| YieldRp0.2 | ≤ 822 (MPa) |
| TeileRm | ≤ 949 (MPa) |
| ImpactKV/Ku | 42(J) |
| ElongationA | 43% |
| Reduction in cross section on fractureZ | 44% |
| As-Heat-Treated Condition | Solution and Aging, Annealing, Ausaging, Q+T,etc |
| Brinell hardness (HBW) | 342 |
GB/T 16270 Q550D Material Thermal Properties
The thermal performance parameters of the GB/T 16270 Q550D steel are as follows:
| Temperature (°C) | 12 | 117 | 763 |
| Modulus of elasticity (GPa) | - | 279 | - |
| Mean coefficient of thermal expaion ×10-6/(°C) | - | - | 34 |
| Thermal conductivity (W/m·°C) | - | 23.3 | 11.2 |
| Specific thermal capacity (J/kg·°C) | - | 313 | - |
| Specific electrical resistivity (Ω mm²/m) | 0.21 | - | - |
| Deity (kg/dm³) | - | - | 314 |
| Poisson’s coefficient, ν | - | - | 423 |
GB/T 16270 Q550D Material Machining Technology
The compatibility of tools with GB/T 16270 Q550D steel is important in order to achieve optimal results during machining operations. The tools should have high wear resistance and be hard enough to cut through the steel without wearing out. High-speed steel, cobalt, and tungsten carbide tools are generally recommended as they are hard enough to cut through steel and also have high wear resistance. Carbide and ceramic tools are also recommended for turning operations as they can improve surface finish.