JIS G3106 SM400A Welding Structural Carbon Steel Plate
JIS G3106 SM400A Welding Structural Carbon Steel Plate - Properties & Equivalents
Comprehensive material data for SM400A carbon steel plate for welded structures according to JIS G3106: chemical composition, mechanical and physical properties, international equivalents, and applications.
Hot rolling, normalizing (optional), cutting, welding, bending, machining
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JIS G3106 SM400A Welding Structural Carbon Steel Plate Introduction
JIS G3106 SM400A is a hot-rolled carbon steel plate intended for welded structures. It offers a minimum yield strength of 235–245 MPa and a tensile strength of 400–510 MPa, with good weldability and formability. The 'A' designation indicates no impact test requirement, making it suitable for general structural applications where notch toughness is not critical. The steel is typically supplied in the as-rolled condition. Common applications include bridges, buildings, shipbuilding, rolling stock, and industrial machinery. Key characteristics:
- Good weldability for shielded metal arc and gas metal arc processes
- Moderate strength with guaranteed tensile properties
- Available in thicknesses up to 100 mm under the standard
- Cost-effective choice for non-critical welded assemblies
JIS G3106 SM400A Welding Structural Carbon Steel Plate Chemical Composition
The chemical composition of SM400A is controlled to ensure adequate strength and weldability. No deliberate additions of microalloying elements are required. For thicknesses ≤50 mm and >50–100 mm, slight variations in carbon content are permitted. Typical values:
| Element | Standard Value | Remarks |
|---|---|---|
| C | ≤0.23 (thk ≤50 mm); ≤0.25 (thk 50–100 mm) | Ladle analysis, % |
| Si | — | Usually 0.15–0.35 for deoxidation; no specified range |
| Mn | ≥2.5×C (min 0.60) | Required to ensure strength; ladle analysis, % |
| P | ≤0.035 | Maximum |
| S | ≤0.035 | Maximum |
JIS G3106 SM400A Welding Structural Carbon Steel Plate Physical Properties
Physical properties given below are typical for carbon-manganese structural steels similar to SM400A. They are not part of the mandatory standard but serve as engineering reference.
| Property | Typical Reference Value | Unit | Test Condition |
|---|---|---|---|
| Density (ρ) | 7.85 | g/cm³ | Room temperature |
| Modulus of Elasticity (E) | 210 | GPa | Room temperature |
| Shear Modulus (G) | 81 | GPa | Room temperature (estimated) |
| Poisson's Ratio (ν) | 0.3 | — | Room temperature |
| Thermal Expansion (α) | 11.1 | 10⁻⁶/K | 20–100°C |
| Thermal Expansion (α) | 12.2 | 10⁻⁶/K | 20–200°C |
| Thermal Expansion (α) | 12.9 | 10⁻⁶/K | 20–300°C |
| Thermal Conductivity (λ) | 51.9 | W/(m·K) | At 20°C |
| Specific Heat Capacity | 486 | J/(kg·K) | At 20°C |
| Electrical Resistivity (ρₑ) | 0.142 | μΩ·m | At 20°C |
JIS G3106 SM400A Welding Structural Carbon Steel Plate Mechanical Properties
Mechanical properties are guaranteed for SM400A according to JIS G3106. Values depend on plate thickness. The tensile test specimen and direction are specified in the standard. Bending test is applicable for plates up to 100 mm. Impact test is not required for grade A.
| Property | Standard Required Value | Unit | Test Condition |
|---|---|---|---|
| Yield Strength (ReH) | ≥245 | MPa | thk ≤16 mm, transverse direction |
| Yield Strength (ReH) | ≥235 | MPa | 16 < thk ≤ 40 mm, transverse |
| Yield Strength (ReH) | ≥215 | MPa | 40 < thk ≤ 100 mm, transverse |
| Tensile Strength (Rm) | 400–510 | MPa | thk ≤100 mm, transverse |
| Elongation (A) | ≥23 | % | thk ≤5 mm, test piece No.5, transverse |
| Elongation (A) | ≥18 | % | 5 < thk ≤16 mm, test piece No.1A, transverse |
| Elongation (A) | ≥22 | % | 16 < thk ≤50 mm, test piece No.1A, transverse |
| Elongation (A) | ≥24 | % | thk >40 mm, test piece No.4, longitudinal |
| Bend Test (180°) | d = 1.0a (thk ≤16 mm); d = 1.5a (thk >16–100 mm) | — | a = specimen thickness; no cracks on outside of bend |
| Impact Energy (KV) | Not required | J | No Charpy impact test specified for SM400A |
JIS G3106 SM400A Welding Structural Carbon Steel Plate Direct Equivalent Standards and Substitute Grades
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| Japan | JIS G3106 | SM400A | Original standard – welding structural steel, no impact test |
| China | GB/T 1591-2018 | Q235B | Similar strength (yield ≥235 MPa, tensile 370–500), but SM400A tensile lower limit 400 MPa; Q235B requires impact test at +20°C; close match for many applications |
| EU | EN 10025-2:2019 | S275JR | Yield ≥275 MPa, tensile 410–560 MPa for t≤16 mm; JR grade requires impact at +20°C; slightly higher strength than SM400A; directly interchangeable in many static applications |
| USA | ASTM A36/A36M-19 | A36 | Yield ≥250 MPa (t≤200 mm), tensile 400–550 MPa; A36 does not require impact test; closely matches SM400A in strength and formability |
| International | ISO 630-2:2021 | Fe 430B | Yield ≥275 MPa, tensile 410 MPa min (t≤16 mm); with impact verification at 20°C for quality group B; strength range slightly narrower but compatible |
| Korea | KS D 3515 | SM400A | Identical to JIS G3106 SM400A |
JIS G3106 SM400A Welding Structural Carbon Steel Plate Application Introduction
SM400A steel plate is widely used in welded structural applications that do not require low-temperature toughness. It is easy to weld, cut, and form, making it a cost-effective solution for general engineering. Typical products and components include:
Product Applications: Bridge girders, cross beams, stiffeners, Building columns and beams, Ship hull plates and stiffening members, Railcar underframes and body panels, Storage tank shells and roofs, Machine frames and heavy equipment structures
Processed into products: Welded I-beams and built-up sections, Flanges and webs for plate girders, Ship longitudinal and transverse bulkheads, Railway wagon side and end walls, Tank bottom plates and shell courses, Excavator arms and loader frames, Support brackets and base plates
Application industries: Construction and civil engineering (bridges, buildings, stadiums), Shipbuilding (hulls, decks, superstructures – non-critical parts), Railway rolling stock (frames, bogies, wagon bodies), Industrial machinery (frames, bases, supports), Pressure vessels and storage tanks (where Charpy not mandated), Agricultural and mining equipment
JIS G3106 SM400A Welding Structural Carbon Steel Plate Similar/Comparable Material Recommendations
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| Japan | JIS G3106 | SM400B | Same strength range, but requires Charpy impact test at 0°C (min 27 J); better notch toughness than SM400A |
| Japan | JIS G3101 | SS400 | General structural rolled steel; no compositional limits on Mn, P, S tightness; mechanical properties are guaranteed for thickness ≤16 mm (yield ≥245, tensile 400–510) but not intended for welding; SM400A preferable for welded structures |
| China | GB/T 1591 | Q345B | Higher strength low-alloy steel (yield ≥345 MPa); offers better load-carrying capacity but may require preheating for thick sections; not a direct substitute but used in upgraded designs |
| EU | EN 10025-2 | S235JR | Lower strength (yield ≥235 MPa, tensile 360–510); suitable where SM400A is overspecified; check design requirements before substitution |
| International | ISO 630-2 | Fe 430A | No impact test requirement, similar to SM400A; yield ≥275 MPa, tensile 410–560 for t≤16 mm |
Notes:
All provided data are based on JIS G3106:2015. For thicknesses above 100 mm, properties shall be agreed upon. SM400A is typically supplied without Charpy V-notch test; if toughness is required, consider SM400B or SM400C. During welding, low hydrogen processes are recommended to avoid cracking, especially in thicker sections. Preheating may be applied when plate thickness exceeds 25 mm and carbon equivalent is high. Verify specific purchase order requirements for supplementary testing.
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