An introduction to the mechanical properties and chemical composition of A516GR70 steel plate
1. Chemical Composition (ASTM A516/A516M Standard)
1.1 Standard Requirements
| Element | Content (Max or Range, %) | Role & Impact |
|---|---|---|
| Carbon (C) | ≤0.27 | Increases strength but reduces weldability and toughness if excessive. |
| Manganese (Mn) | 0.85–1.20 | Enhances strength, refines grain structure, and reduces hot brittleness. |
| Phosphorus (P) | ≤0.025 | Harmful; causes cold brittleness (reduces low-temperature toughness). |
| Sulfur (S) | ≤0.025 | Forms sulfide inclusions, reducing ductility and impact resistance. |
| Silicon (Si) | 0.15–0.40 | Acts as a deoxidizer; improves strength but may reduce toughness if excessive. |
1.2 Optional Microalloying Elements
Niobium (Nb), Vanadium (V), Titanium (Ti):
Improve strength and low-temperature toughness via grain refinement (optional).
Copper (Cu), Nickel (Ni):
Enhance corrosion resistance (e.g., for acidic environments in petrochemical equipment).
1.3 Impurity Control
Residual elements: Chromium (Cr) ≤0.25%, Molybdenum (Mo) ≤0.08% (to avoid welding/heat treatment issues).
2. Mechanical Properties
2.1 Basic Mechanical Properties (Room Temperature)
| Property | Standard Value | Practical Significance |
|---|---|---|
| Tensile Strength (MPa) | 485–620 | Resistance to fracture; higher values may reduce ductility. |
| Yield Strength (MPa) | ≥260 (thickness ≤50mm) | Critical stress for plastic deformation; affects vessel wall thickness design. |
| Elongation (%) | ≥17 (50mm gauge length) | Measures ductility; higher values indicate better deformation capacity. |
| Charpy V-Notch Impact | ≥20J @ -46°C | Low-temperature toughness; essential for cryogenic applications. |
2.2 Thickness-Dependent Properties
Yield strength decreases with thickness:
Thickness ≤50mm: ≥260 MPa
50mm < Thickness ≤100mm: ≥250 MPa
100mm < Thickness ≤200mm: ≥240 MPa
Impact test temperature: Can be customized (e.g., -29°C or -60°C per agreement).
2.3 High-Temperature Performance
Maximum design temperature: 345°C (beyond this, creep/oxidation must be considered).
Yield strength reduction at 300°C: ~85% of room-temperature value.
3. Relationship Between Composition & Properties
Carbon Equivalent (Ceq):
Formula: *Ceq = C + Mn/6 + (Cr+Mo+V)/5 + (Ni+Cu)/15*
For A516 Gr.70: Typically ≤0.43 (good weldability with preheat).
Manganese-to-Carbon Ratio (Mn/C):
Ideal range: 3–5 (avoids banded microstructure or insufficient strength).
4. Processing & Performance Control
4.1 Welding
Preheating:
Thickness ≤25mm: Optional (required if ambient temperature <5°C).
Thickness >25mm: 100–150°C.
Post-Weld Heat Treatment (PWHT):
595–675°C (hold time based on thickness) to relieve residual stresses.
4.2 Hot Forming
Hot working temperature: 870–900°C (avoid grain coarsening).
Finish rolling temperature: ≥850°C (ensures fine grain structure).
5. Performance Matching in Applications
Cryogenic tanks (-46°C): Require ≥20J impact energy @ -46°C and strict P/S control.
High-pressure vessels: Adjust Mn or add microalloys for higher strength.
Corrosive environments: Use HIC-resistant variants (e.g., A516 Gr.70 HIC).
6. Comparison with Other Steels
| Property | A516 Gr.70 | Q345R (GB 713) | P265GH (EN 10028-2) |
|---|---|---|---|
| Yield Strength (MPa) | ≥260 | ≥345 | ≥265 |
| Impact Test Temp. | -46°C | -20°C | -50°C |
| P/S Control | 0.025% | 0.020% | 0.025% |
7.YUXIN Steel Company
Yuxin (Tianjin) International Trade Co., Ltd. is a steel agent. The main business of our company is: medium and thick plates, ductile cast iron pipe, seamless pipes, deformed bars, etc. of Angang, Hangang, Wugang, Nangang, Shagang and other steel plants, as well as a variety of steel related products. Yuxin steel can customize various specifications, sizes, materials of the plates and building materials for users with fast delivery time, reliable quality, and favorable prices. The company provides various materials and specifications of steel in stock all year round: high construction steel, Z-direction steel, high construction Z-direction steel, bridge U-ribs, pipeline steel, bridge plates, Q345qD bridge steel plates, shipbuilding plates, high-strength medium plates, boiler vessel plates, low alloy medium plates, ordinary carbon medium plates, etc.
