JIS G3106 SM400B Carbon Steel for Spiral Submerged Arc Welded (SSAW) Pipe
JIS G3106 SM400B Carbon Steel for Spiral Submerged Arc Welded (SSAW) Pipe - Properties & Equivalents
In-depth analysis of JIS G3106 SM400B steel, widely used for spiral submerged arc welded (SSAW) pipes. Includes chemical composition, mechanical properties, thermal & electrical data, international equivalents, and application guidelines.
Hot rolling, controlled rolling, normalizing; pipe forming by spiral welding
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JIS G3106 SM400B Carbon Steel for Spiral Submerged Arc Welded Pipe Introduction
JIS G3106 SM400B is a carbon-manganese structural steel designed for welded structures, including spiral submerged arc welded (SSAW) pipes. It offers a balanced combination of strength, toughness, and weldability, suitable for general structural and pressure-containing applications. The steel is typically supplied in hot-rolled, normalized, or controlled-rolled condition. Key features include:
- Minimum yield strength of 245 MPa for thicknesses up to 16 mm
- Tensile strength range of 400–510 MPa
- Guaranteed Charpy impact energy of 27 J at 0 °C for plates over 12 mm (upon agreement)
- Good formability and excellent weldability, making it ideal for large-diameter SSAW pipes
The SSAW pipe form extends its use to water, oil, gas transmission, and structural piling.
JIS G3106 SM400B Carbon Steel for Spiral Submerged Arc Welded Pipe Chemical Composition
The chemical composition of SM400B according to JIS G3106 ensures sufficient strength and toughness while maintaining good weldability. Limits are specified for ladle analysis. For thickness ≤50 mm, the carbon content is restricted to ≤0.20%; for thicker sections, a slight increase to ≤0.22% is allowed. Manganese is kept within 0.60–1.40% to improve strength without impairing ductility. Phosphorus and sulfur are tightly controlled to minimize brittleness and hot shortness.
| Element | Standard Value (wt%) | Remarks |
|---|---|---|
| C | ≤0.20 (≤0.22 for t >50 mm) | Ladle analysis |
| Si | ≤0.35 | Ladle analysis |
| Mn | 0.60 – 1.40 | Ladle analysis |
| P | ≤0.035 | Ladle analysis |
| S | ≤0.035 | Ladle analysis |
JIS G3106 SM400B Carbon Steel for Spiral Submerged Arc Welded Pipe Thermal & Electrical Physical Properties
The following physical properties are typical for carbon structural steels (0.15–0.25% C) and are not specified in JIS G3106. They are provided as design guidance. Actual values may vary slightly depending on temperature and processing history.
| Property | Standard Typical Value | Unit | Test Condition / Remarks |
|---|---|---|---|
| Density (ρ) | 7.85 | g/cm³ | Room temperature |
| Elastic Modulus (E) | 205 – 210 | GPa | Room temperature |
| Shear Modulus (G) | 80 | GPa | Room temperature |
| Poisson's Ratio (ν) | 0.29 – 0.30 | - | Room temperature |
| Thermal Expansion Coefficient (α) | 11.7×10⁻⁶ | K⁻¹ | 20–200 °C |
| Thermal Conductivity (λ) | 53 | W/(m·K) | At 20 °C |
| Specific Heat Capacity | 486 | J/(kg·K) | At 20 °C |
| Electrical Resistivity (ρ_e) | 0.15 – 0.20 | μΩ·m | At 20 °C |
JIS G3106 SM400B Carbon Steel for Spiral Submerged Arc Welded Pipe Mechanical Properties
Mechanical properties are derived from JIS G3106 for SM400B. Values depend on thickness. Yield strength decreases as thickness increases. Tensile strength is specified as a range. Charpy impact testing is normally required for products with thickness >12 mm at 0 °C, unless otherwise agreed. The bend test ensures formability without cracking.
| Property | Standard Required Value | Unit | Test Conditions / Remarks |
|---|---|---|---|
| Yield Strength (ReH) | ≥245 | MPa | Thickness ≤16 mm |
| Yield Strength (ReH) | ≥235 | MPa | Thickness 16–40 mm |
| Yield Strength (ReH) | ≥215 | MPa | Thickness 40–100 mm |
| Tensile Strength (Rm) | 400 – 510 | MPa | Room temperature, all thicknesses |
| Elongation (A) | ≥18 | % | Gauge length 200 mm, thickness 5–16 mm |
| Elongation (A) | ≥22 | % | Gauge length 200 mm, thickness 16–50 mm |
| Charpy Impact (KV) | ≥27 (longitudinal) | J | 0 °C, V-notch, thickness >12 mm (by agreement) |
| Bend Test (180°) | Inside diameter = 1.0 × thickness | - | Thickness ≤16 mm, no cracks |
| Bend Test (180°) | Inside diameter = 1.5 × thickness | - | Thickness 16–40 mm, no cracks |
| Bend Test (180°) | Inside diameter = 2.0 × thickness | - | Thickness 40–100 mm, no cracks |
JIS G3106 SM400B Carbon Steel for Spiral Submerged Arc Welded Pipe Full Equivalent Grades & Replaceable Designations
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| Japan | JIS G3106 | SM400B | Original grade; welded structural steel |
| USA | ASTM A36/A36M | A36 | Comparable yield & tensile, slightly lower impact requirements |
| EU | EN 10025-2 | S275JR | Higher min yield (275 MPa), tensile 410–560 MPa, similar trade-off |
| International | ISO 630-2 | S235J0 | Tensile range 360–510 MPa, impact at 0 °C, close but min tensile slightly lower |
| China | GB/T 700 | Q235B | Tensile min 370 MPa, not fully meeting min 400 MPa; often used interchangeably in less demanding cases |
| Korea | KS D 3515 | SM400B | Identical to JIS G3106 |
JIS G3106 SM400B Carbon Steel for Spiral Submerged Arc Welded Pipe Application Introduction
SM400B is extensively used for spiral submerged arc welded (SSAW) pipes in medium-pressure fluid transmission and structural applications. The material's good weldability and toughness make it a cost-effective choice for large-diameter pipes. Typical applications include:
Product Applications: Spiral welded steel pipes (SSAW/LSAW), Welded H-beams and built-up sections, Pressure vessels (low to medium pressure), Storage tanks, Piling pipes and caissons
Processed into products: Pipeline spools and risers, Casing and conductor pipes, Structural column casings, Bridge arch tubes, Bollards and marine fenders, Penstock pipes for hydropower
Application industries: Oil & gas (onshore and offshore pipelines), Water supply and sewage treatment, Civil engineering and construction (pile foundations, structural columns), Shipbuilding (non-critical hull structures, stiffeners), Bridge construction (girders, arch ribs)
JIS G3106 SM400B Carbon Steel for Spiral Submerged Arc Welded Pipe Similar / Substitute Material Grades
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| Japan | JIS G3106 | SM400A | Same strength, but no Charpy requirement (impact not guaranteed) |
| Japan | JIS G3106 | SM400C | Higher impact energy (47 J at 0 °C), otherwise similar |
| China | GB/T 700 | Q235B | Lower tensile minimum; suitable for non-critical structural uses |
| China | GB/T 1591 | Q345B | Higher strength (345 MPa yield), may need adjusted welding procedures |
| EU | EN 10025-2 | S235JR | Lower yield & tensile, but widely available; consider for thin-wall pipes |
| EU | EN 10025-2 | S355JR | Higher strength, impact at +20 °C; use where higher strength is needed |
Notes:
For SSAW pipe orders, additional testing (hydrostatic, NDT, weld hardness) may be required per pipe standards such as API 5L or ISO 3183. SM400B is not intended for sour service without qualification. When substituting with equivalent grades, verify minimum tensile strength and impact requirements to match service conditions. Welding consumables should be compatible with the carbon equivalent (CEV typically 0.38 max when specified by agreement).
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