JIS G3114 Carbon Steel for Boilers and Pressure Vessels
JIS G3114 carbon steel plates are specifically designed for use in boilers and pressure vessels, offering superior strength, toughness, and weldability under high-pressure and elevated-temperature conditions. This Japanese Industrial Standard (JIS) covers hot-rolled steel grades such as SMA400, SMA490, and SMA570 series, which are engineered to withstand thermal stresses and corrosive environments in power generation and petrochemical industries. This article explores the chemical composition, mechanical properties, manufacturing processes, applications, and key considerations for selecting JIS G3114 steels.
1. Core Chemical Composition (JIS G3114 Standard)
| Element | SMA400A/B Content | SMA490A/B Content | Function |
|---|---|---|---|
| Carbon (C) | ≤ 0.18% / ≤ 0.20% | ≤ 0.18% / ≤ 0.20% | Enhances strength; controlled to maintain ductility and weldability |
| Manganese (Mn) | ≤ 1.25% / ≤ 1.60% | ≤ 1.60% / ≤ 1.60% | Improves hardenability and toughness; aids in deoxidation |
| Phosphorus (P) | ≤ 0.035% | ≤ 0.035% | Restricted to prevent brittleness and ensure impact resistance |
| Sulfur (S) | ≤ 0.035% | ≤ 0.035% | Minimized to avoid hot shortness and promote good weldability |
| Chromium (Cr) (Weather-Resistant Grades) | — | ≤ 0.30% (for SMA490AW) | Forms protective oxide layer for atmospheric corrosion resistance |
| Copper (Cu) (Weather-Resistant Grades) | — | ≤ 0.35% (for SMA490AW) | Enhances patina formation for durability in outdoor exposure |
2. Key Mechanical Properties (Room Temperature, for 16mm Thickness)
- Tensile Strength (σb): 400-510 MPa for SMA400 series; 490-610 MPa for SMA490 series (provides high load-bearing capacity under pressure)
- Yield Strength (σ0.2): ≥ 235 MPa for SMA400; ≥ 325 MPa for SMA490 (ensures deformation resistance in service)
- Elongation (δ): ≥ 22% for SMA400; ≥ 19% for SMA490 (adequate ductility for fabrication and forming)
- Hardness (HB): ≤ 170 for SMA400; ≤ 190 for SMA490 (balanced for machinability without excessive brittleness)
- Charpy Impact Toughness (CVN): ≥ 27 J at -20°C (maintains integrity in low-temperature operations)
3. Manufacturing Process Characteristics
- Smelting: Basic oxygen furnace (BOF) or electric arc furnace (EAF) followed by ladle refining and vacuum degassing to achieve low impurity levels and uniform composition.
- Hot Rolling: Controlled at 850-1100°C with precise thickness reduction, followed by accelerated cooling to refine grain structure and enhance mechanical properties.
- Normalizing: Heat treatment at 880-950°C to homogenize microstructure, relieve internal stresses, and improve toughness for pressure vessel applications.
- Ultrasonic Testing: Non-destructive examination to detect internal defects, ensuring compliance with JIS G3114 quality requirements for safety-critical components.
- Surface Treatment: Shot blasting and priming for corrosion protection; optional weathering for atmospheric exposure grades like SMA490W.
4. Typical Application Fields
Boilers and Pressure Vessels
Shells, heads, and drums in steam boilers, high-pressure reactors, and storage tanks — ideal for thermal power plants and chemical processing.
Petrochemical Industry
Heat exchangers, distillation columns, and piping supports — withstands high temperatures and moderate corrosion in refining operations.
Power Generation
Turbine casings, pressure piping, and flue gas desulfurization units — supports efficient energy production under cyclic loading.
Structural and Bridge Construction
Weather-resistant grades (SMA400W/SMA490W) for bridges, viaducts, and offshore platforms — long-term durability in harsh environments.
5. Difference from Similar Grades (SMA490 vs SMA570 vs ASTM Equivalents)
| Grade | Yield Strength (MPa) | Key Advantage | Suitable Scenario |
|---|---|---|---|
| JIS SMA490A/B | ≥ 325 | Balanced strength and weldability; cost-effective | General boilers and moderate-pressure vessels |
| JIS SMA570A/B/W | ≥ 365 | Higher strength for demanding loads; weather-resistant options | High-stress applications like heavy-duty reactors and bridges |
| ASTM A516 Gr.70 (Equivalent) | ≥ 260 | Normalized for impact toughness; widely available | Low-to-medium temperature pressure vessels in global markets |
6. Selection & Usage Precautions
- Environmental Limitations: Suitable for temperatures up to 400°C; for higher ranges or severe corrosion, consider alloy steels like JIS G3103 SB410 with chromium additions.
- Welding Guidelines: Preheat to 100-150°C for thick plates; use low-hydrogen electrodes (e.g., E7018) to prevent cracking; post-weld heat treatment if required for stress relief.
- Thickness Considerations: Properties vary with plate thickness (up to 200mm); verify data for specific gauges in JIS G3114 specifications.
- Quality Assurance: Obtain material certificates confirming compliance with JIS G3114, including tensile tests and ultrasonic inspections for defect-free supply.
7. Get a Carbon Steel Quote
If you need customized JIS G3114 carbon steel plates, sheets, or coils for your projects, or require a detailed price quote, contact our team. We offer professional technical support and competitive pricing tailored to your specifications.