JIS G3103 SB450M Mo-Alloy Pressure Vessel Steel Plate
JIS G3103 SB450M Pressure Vessel & Boiler Steel Plate – Mo-Alloy High Temperature Strength
Detailed material data for JIS G3103 SB450M molybdenum-alloy steel plate used in boilers and pressure vessels, including chemical composition, mechanical properties, and physical properties.
Welding, bending, hot forming (followed by normalizing), machining
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JIS G3103 SB450M Mo-Alloy Pressure Vessel Steel Plate Introduction
SB450M is a molybdenum-alloy steel plate specified in JIS G3103 for boilers and pressure vessels. Key characteristics:
- Improved elevated temperature strength compared to carbon steel
- Good weldability and formability in normalized condition
- Creep resistance up to approximately 500°C
- Typically supplied in normalized or stress-relieved condition
This grade is widely used for medium-temperature pressure parts where the addition of molybdenum enhances strength and resistance to graphitization.
JIS G3103 SB450M Mo-Alloy Pressure Vessel Steel Plate Chemical Composition
Chemical composition according to JIS G3103 for SB450M, ladle analysis. The addition of molybdenum (0.45-0.60%) provides enhanced high-temperature properties.
| Element | Standard Value (%) | Remarks |
|---|---|---|
| C | ≤ 0.18 (for thickness ≤ 25 mm); ≤ 0.21 (thickness > 25 - 50 mm); ≤ 0.23 (thickness > 50 - 100 mm); ≤ 0.25 (thickness > 100 mm) | Varies with plate thickness |
| Si | 0.15 - 0.40 | |
| Mn | ≤ 0.90 | Lower limit not specified but generally ≥ 0.40 for product analysis |
| P | ≤ 0.030 | |
| S | ≤ 0.030 | |
| Mo | 0.45 - 0.60 | Essential alloying element |
| Cr | ≤ 0.25 (residual, if any) | Not intentionally added |
| Ni | ≤ 0.25 (residual, if any) | Not intentionally added |
| Cu | ≤ 0.25 (residual, if any) | Not intentionally added |
JIS G3103 SB450M Mo-Alloy Pressure Vessel Steel Plate Thermal and Electrical Physical Properties
Typical physical properties for carbon-molybdenum steel like SB450M. These are not specified in JIS G3103 but provide engineering reference for design. Values at room temperature unless otherwise noted.
| Property | Standard Required Value (Typical) | Unit | Test Condition |
|---|---|---|---|
| Density (ρ) | 7.85 | g/cm³ | 20°C |
| Modulus of Elasticity (E) | 205 | GPa | 20°C |
| Shear Modulus (G) | 80 | GPa | 20°C (calculated) |
| Poisson's Ratio (ν) | 0.30 | - | 20°C |
| Thermal Expansion Coefficient (α) | 11.5 | 10⁻⁶ / K | 20 - 100°C |
| Thermal Expansion Coefficient (α) | 12.7 | 10⁻⁶ / K | 20 - 200°C |
| Thermal Expansion Coefficient (α) | 13.5 | 10⁻⁶ / K | 20 - 300°C |
| Thermal Conductivity (λ) | 44 | W/(m·K) | 100°C |
| Thermal Conductivity (λ) | 42 | W/(m·K) | 200°C |
| Thermal Conductivity (λ) | 39 | W/(m·K) | 300°C |
| Specific Heat Capacity (c) | 460 | J/(kg·K) | 20 - 300°C average |
| Electrical Resistivity (ρ_e) | 0.20 | μΩ·m | 20°C |
JIS G3103 SB450M Mo-Alloy Pressure Vessel Steel Plate Mechanical Properties
Mechanical properties at room temperature as per JIS G3103. Yield point or yield strength, tensile strength, elongation, and bend test depend on plate thickness. The steel is supplied in normalized condition.
| Property | Standard Required Value | Unit | Test Condition |
|---|---|---|---|
| Yield Point (ReH) or Yield Strength (ReL) | ≥ 245 | N/mm² | Thickness ≤ 50 mm (yield point), test piece: transverse |
| Yield Point (ReH) or Yield Strength (ReL) | ≥ 225 | N/mm² | Thickness > 50 - 100 mm (yield strength) |
| Yield Point (ReH) or Yield Strength (ReL) | ≥ 205 | N/mm² | Thickness > 100 - 150 mm (yield strength) |
| Tensile Strength (Rm) | 450 - 590 | N/mm² | All thicknesses |
| Elongation (A) | ≥ 22 (No. 1A or No. 10 test piece) | % | Thickness ≤ 25 mm, gauge length 200 mm (No. 1A) or 50 mm (No.10) |
| Elongation (A) | ≥ 19 | % | Thickness > 25 - 40 mm, gauge length 200 mm |
| Elongation (A) | ≥ 17 | % | Thickness > 40 - 50 mm, gauge length 200 mm |
| Elongation (A) | ≥ 13 | % | Thickness > 50 - 100 mm, gauge length 200 mm (No.10 test piece) |
| Elongation (A) | ≥ 11 | % | Thickness > 100 - 150 mm, gauge length 200 mm |
| Bend Test (180°) | No cracks on outside of bent portion | - | Bend diameter: 1.5 times thickness for plate thickness ≤ 25 mm; bend diameter: 2.0 times thickness for >25 - 50 mm |
JIS G3103 SB450M Mo-Alloy Pressure Vessel Steel Plate Exact Equivalent Material Standards and Substitute Grade Recommendations
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| Japan | JIS G3103 | SB450M | Original specification |
| United States | ASTM A204 / A204M | Grade B | Molybdenum-alloy steel plate for pressure vessels; similar chemistry (C-Mo) |
| Europe | EN 10028-2 | 16Mo3 (1.5415) | Yield and tensile properties comparable; used for elevated temperature service |
| China | GB/T 713 | 15MoG or 20MoG (Q345R with Mo) | Formerly 15Mo3; check latest revision for exact match |
| International | ISO 9328-2 | 15Mo3 | Molybdenum steel for pressure purposes |
| Korea | KS D 3560 | SB450M | Identical to JIS G3103 |
JIS G3103 SB450M Mo-Alloy Pressure Vessel Steel Plate Application Introduction
SB450M is designed for welded pressure vessels and boilers operating at moderate temperatures (up to approx. 450-500°C). Its molybdenum addition provides improved creep resistance compared to carbon steels, making it suitable for:
- Steam drums and shells in industrial and utility boilers
- Heat exchangers and reactor vessels in petrochemical plants
- High-temperature piping components such as flanges and fittings
- Pressure vessels for hydrogen service at elevated temperatures
The material is readily fabricated by welding with appropriate preheat and post-weld heat treatment.
Product Applications: Steam boilers and boiler drums, Pressure vessels (ASME Section VIII or JIS B 8265 construction), High-temperature reactors and columns, Heat exchangers (shells and channels), Steam separators and accumulators
Processed into products: Boiler shell plates and dish heads, Steam drum cylindrical sections, Flanges and blind covers, Tube sheets for heat exchangers, Transition joints in piping systems, Support rings and reinforcement pads for nozzles
Application industries: Power generation (thermal and nuclear conventional islands), Petrochemical and chemical processing, Oil and gas (refinery pressure vessels), Industrial boiler manufacturing, Heat exchanger fabrication
JIS G3103 SB450M Mo-Alloy Pressure Vessel Steel Plate Similar/Near Equivalent Material Recommendations
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| United States | ASTM A302 / A302M | Grade B | Mn-Mo-Ni steel with higher strength, but similar temperature range |
| Europe | EN 10028-2 | 13CrMo4-5 (1.7335) | Contains Cr in addition to Mo, higher creep strength, usable up to 550°C |
| China | GB/T 713 | 15CrMoR | Cr-Mo steel with enhanced high-temperature strength compared to plain Mo |
| Japan | JIS G4109 | SCMV 2 (0.5Mo steel plate for boilers) | Similar Mo content, used for thicker sections |
Notes:
Welding: Preheating (min. 100°C for thickness >25 mm) and post-weld heat treatment (PWHT) at 600-650°C is recommended to relieve stresses. Inspection: Ultrasonic examination may be required per JIS G0801 or other standards. Certification: Mill test certificates to EN 10204 3.1 or 3.2 are commonly provided. Limitations: For prolonged exposure above 500°C, consider Cr-Mo steels such as 1Cr-0.5Mo or 2.25Cr-1Mo.
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