ASTM A656/A656M Type 7 Grade 345 Introduce
ASTM A656/A656M Type 7 Grade 345 steel grade is most commonly used in the construction of buildings, bridges, and other structures because of its superior strength and corrosion resistance. Its excellent thermal properties make it a great choice for use in thermal energy applications such as in boilers and heat exchangers, as well as in demanding applications that require thermal shock resistance, such as power generating systems. It is also used in offshore applications because of its excellent corrosion resistance.
Smelting temperature:1195°C - 1985°C
Application:High-strength low-alloy hot-rolled structural steel plate with improved forgeability
ASTM A656/A656M Type 7 Grade 345 Material Chemical Composition
The chemical composition of the ASTM A656/A656M Type 7 Grade 345 steel are as follows:
| Element | Min | Max |
|---|---|---|
| Carbon (C) | - | 0.1800 |
| Manganese (Mn) | - | 1.6500 |
| PhOsphorus (P) | - | 0.0250 |
| Sulfur (S) | - | 0.0300 |
| Silicon (Si) | - | 0.6000 |
| Vanadium (V) | - | 0.1500 |
| Nitrogen (N) | - | 0.0300 |
| Niobium (Nb) | - | 0.1000 |
| Sulfur (S) | - | 0.0350 |
| Niobium (Nb) | - | 0.1000 |
ASTM A656/A656M Type 7 Grade 345 Material Mechanical Properties
Yield strength is an indication of a material's ability to resist deformation when subject to an applied stress. Yield strength, measured in ksi, is one of the most important properties of ASTM A656/A656M Type 7 Grade 345 steel. It is the stress at which a piece of the material will no longer continue to elongate in length but will instead deform irreversibly. The minimum specified yield strength for ASTM A656/A656M Type 7 Grade 345 steel is 50 ksi.
The mechanical properties of the ASTM A656/A656M Type 7 Grade 345 steel are as follows:
| YieldRp0.2 | ≤ 243 (MPa) |
| TeileRm | ≤ 558 (MPa) |
| ImpactKV/Ku | 23(J) |
| ElongationA | 32% |
| Reduction in cross section on fractureZ | 33% |
| As-Heat-Treated Condition | Solution and Aging, Annealing, Ausaging, Q+T,etc |
| Brinell hardness (HBW) | 441 |
ASTM A656/A656M Type 7 Grade 345 Material Thermal Properties
The thermal performance parameters of the ASTM A656/A656M Type 7 Grade 345 steel are as follows:
| Temperature (°C) | 43 | 189 | 546 |
| Modulus of elasticity (GPa) | - | 162 | - |
| Mean coefficient of thermal expaion ×10-6/(°C) | - | - | 33 |
| Thermal conductivity (W/m·°C) | - | 11.3 | 32.2 |
| Specific thermal capacity (J/kg·°C) | - | 233 | - |
| Specific electrical resistivity (Ω mm²/m) | 0.13 | - | - |
| Deity (kg/dm³) | - | - | 142 |
| Poisson’s coefficient, ν | - | - | 231 |
ASTM A656/A656M Type 7 Grade 345 Material Machining Technology
Welding of ASTM A656/A656M Type 7 Grade 345 can be done with conventional welding techniques. A preheat of materials prior to welding is generally not required. Post- weld heat treatment should be considered if any part of the fabrications require a low temperature toughness test. Common welding techniques for ASTM A656/A656M Type 7 Grade 345 are arc welding processes such as shielded metal arc welding, gas metal arc welding, and flux-cored arc welding.