ASTM A240/A240M Grade 255 Introduce
ASTM A240/A240M Grade 255 is a valuable reference for anyone who has to procure stainless steel products for general and stress relieved pressure vessels. It also provides comprehensive product guidance and manufacturing instructions, making it an invaluable tool for engineers, quality control personnel, and stainless steel product manufacturers.
Smelting temperature:1246°C - 1438°C
Application:Heat-resistant chrome and chrome-nickel stainless steel sheets, sheets and strips for pressure vessels
ASTM A240/A240M Grade 255 Material Chemical Composition
The chemical composition of the ASTM A240/A240M Grade 255 steel are as follows:
| Element | Min | Max |
|---|---|---|
| Nitrogen (N) | 0.1000 | 0.2500 |
| Copper (Cu) | 1.5000 | 2.5000 |
| Molybdenum (Mo) | 2.9000 | 3.9000 |
| Nickel (Ni) | 4.5000 | 6.5000 |
| Chromium (Cr) | 24.0000 | 27.0000 |
| PhOsphorus (P) | - | 0.0400 |
| Sulfur (S) | - | 0.0300 |
| Manganese (Mn) | - | 1.5000 |
| Silicon (Si) | - | 1.0000 |
| Carbon (C) | - | 0.0400 |
ASTM A240/A240M Grade 255 Material Mechanical Properties
Tensile strength is a measure of the mechanical strength of a material and is often expressed in terms of pounds per square inch (psi). This is the maximum force a substance can withstand before it breaks or tears. ASTM A240/A240M Grade 255 steel typically has a tensile strength of about 55,000 psi and can be strengthened further by heat treatments, such as quenching and tempering.
The mechanical properties of the ASTM A240/A240M Grade 255 steel are as follows:
| YieldRp0.2 | ≤ 855 (MPa) |
| TeileRm | ≤ 165 (MPa) |
| ImpactKV/Ku | 44(J) |
| ElongationA | 34% |
| Reduction in cross section on fractureZ | 31% |
| As-Heat-Treated Condition | Solution and Aging, Annealing, Ausaging, Q+T,etc |
| Brinell hardness (HBW) | 122 |
ASTM A240/A240M Grade 255 Material Thermal Properties
The thermal performance parameters of the ASTM A240/A240M Grade 255 steel are as follows:
| Temperature (°C) | 31 | 925 | 126 |
| Modulus of elasticity (GPa) | - | 297 | - |
| Mean coefficient of thermal expaion ×10-6/(°C) | - | - | 12 |
| Thermal conductivity (W/m·°C) | - | 13.3 | 13.2 |
| Specific thermal capacity (J/kg·°C) | - | 244 | - |
| Specific electrical resistivity (Ω mm²/m) | 0.14 | - | - |
| Deity (kg/dm³) | - | - | 122 |
| Poisson’s coefficient, ν | - | - | 442 |
ASTM A240/A240M Grade 255 Material Machining Technology
ASTM A240/A240M Grade 255 steel is more difficult to work with due to its high temperature strength, low ductility, and high yield strength. When machining, the tool must be sharp, and a wider cutting edge must be used to avoid tool failure. Additionally, stainless steel is not suitable for welding, as it requires special procedures to prevent cracking or corrosion.