JIS G3106 SM400A ERW Pipe
JIS G3106 SM400A ERW Pipe: Weldable Structural Carbon Steel Tube
Comprehensive material data for SM400A electric resistance welded pipe according to JIS G3106, including chemical composition, mechanical and physical properties, international equivalents, and application guidance.
Welding (ERW, arc welding), bending, cold forming, machining, hot-dip galvanizing
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JIS G3106 SM400A ERW Pipe Introduction
JIS G3106 SM400A is a Japanese standard weldable structural carbon steel grade primarily supplied as hot-rolled plates, sheets, strips, and sections. In the form of ERW (Electric Resistance Welded) pipe, it is commonly produced by cold forming from hot-rolled coils and then longitudinally welded. SM400A is a general-purpose structural steel with excellent weldability, good formability, and moderate strength, making it suitable for a wide range of structural and mechanical applications. It does not require impact testing, which distinguishes it from the B and C grades of the same standard. The ERW pipe variant is widely used in piping systems, structural hollow sections, and general engineering where reliable mechanical properties and cost-effectiveness are required.
JIS G3106 SM400A ERW Pipe Chemical Composition
Chemical composition as specified in JIS G3106:2015 for SM400A steel. Silicon (Si) content is not mandated; manganese (Mn) is added when required by thickness or agreement. The values apply to product thickness ≤200 mm. For ERW pipe, typical wall thicknesses are well below the limits, so the lower carbon range generally applies.
| Element | Standard Value | Remarks |
|---|---|---|
| C (Carbon) | ≤0.23 (thickness ≤50mm), ≤0.25 (thickness >50–200mm) | Maximum depending on thickness |
| Si (Silicon) | Not specified | - |
| Mn (Manganese) | ≥2.5×C (min) when thickness >40mm or by agreement | Optional minimum, typically ~0.60 max |
| P (Phosphorus) | ≤0.035 | Maximum |
| S (Sulfur) | ≤0.035 | Maximum |
JIS G3106 SM400A ERW Pipe Thermal and Electrical Physical Properties
The following physical properties are typical for carbon steel similar to SM400A, as JIS G3106 does not specify thermal or electrical values. These data are provided for general design and engineering reference at room temperature (20°C) unless otherwise noted.
| Property | Typical Value | Unit | Test Condition / Temperature |
|---|---|---|---|
| Density (ρ) | 7.85 | g/cm³ | 20°C |
| Modulus of Elasticity (E) | 205 | GPa | 20°C |
| Shear Modulus (G) | 80 | GPa | 20°C |
| Poisson's Ratio (ν) | 0.3 | - | 20°C |
| Thermal Expansion Coefficient (α) | 11.5 | 10⁻⁶/K | 20–100°C |
| Thermal Expansion Coefficient (α) | 12.5 | 10⁻⁶/K | 20–200°C |
| Thermal Expansion Coefficient (α) | 13.5 | 10⁻⁶/K | 20–400°C |
| Thermal Conductivity (λ) | 53 | W/(m·K) | 20°C |
| Specific Heat Capacity | 486 | J/(kg·K) | 20°C |
| Electrical Resistivity (ρ_e) | 0.15 | μΩ·m | 20°C |
JIS G3106 SM400A ERW Pipe Mechanical Properties
Mechanical properties for SM400A steel according to JIS G3106, based on product thickness ranges. For ERW pipe with wall thickness typically ≤16 mm, the first set of values applies. The bending test uses a mandrel diameter of 1.5 times the specimen thickness. No impact test is required for SM400A.
| Property | Standard Required Value | Unit | Test Condition / Thickness Range |
|---|---|---|---|
| Yield Point or Yield Strength (ReH) | ≥245 | MPa | Thickness ≤16 mm |
| Yield Point or Yield Strength (ReH) | ≥235 | MPa | 16 < t ≤40 mm |
| Yield Point or Yield Strength (ReH) | ≥215 | MPa | 40 < t ≤100 mm |
| Tensile Strength (Rm) | 400–510 | MPa | All thicknesses |
| Elongation (A) | ≥23 (No.5 test piece) | % | Thickness ≤5 mm, longitudinal |
| Elongation (A) | ≥18 (No.1A test piece) | % | 5 < t ≤16 mm, longitudinal |
| Elongation (A) | ≥22 (No.1A test piece) | % | 16 < t ≤50 mm, longitudinal |
| Elongation (A) | ≥24 (No.4 test piece) | % | T >40 mm, longitudinal |
| Bend Test (bend angle 180°) | No cracks, mandrel diameter = 1.5×thickness | - | All thicknesses, applicable to plates and strips |
| Impact Energy (KV) | Not required for SM400A | J | - |
JIS G3106 SM400A ERW Pipe Full Equivalent Standards & Replaceable Grades
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| European Union | EN 10025-2 | S235JR | Closest equivalent in chemical and mechanical requirements, also non-impact tested |
| China | GB/T 700 | Q235B | Comparable carbon structural steel with similar strength level |
| Australia/New Zealand | AS/NZS 3678 | G250 | General structural steel with 250 MPa minimum yield |
JIS G3106 SM400A ERW Pipe Application Introduction
SM400A ERW pipe is widely used in structural and mechanical applications due to its good balance of strength, ductility, and weldability. It is suitable for both static and mildly dynamic loads. Typical environments include ambient temperature and non-corrosive conditions unless protective coatings are applied.
- Not recommended for low-temperature service requiring impact toughness.
- Suitable for hot-dip galvanizing to improve corrosion resistance.
- Can be cold formed and joined by conventional welding methods.
Product Applications: Structural hollow sections (SHS, RHS, CHS), Water, air, and gas utility pipes, Piping for non-critical process fluids, Poles and pillars, Greenhouse and agricultural structures, Pre-engineered building components
Processed into products: Pipe spools and fittings, Columns and beams, Truss members, Frame rails and cross members, Roll cage tubes, Support brackets and welded assemblies
Application industries: Building and construction (structural frames, scaffolding), Infrastructure (bridges, transmission towers), Automotive and transportation (chassis components, roll cages), Shipbuilding (internal structures, piping), Storage and handling (tanks, silos, racks), General manufacturing (machinery frames, conveyors)
JIS G3106 SM400A ERW Pipe Similar/Alternative Materials Recommendation
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| USA | ASTM A36/A36M | A36 | Common structural steel; slightly wider strength range and often used interchangeably |
| India | IS 2062 | E250A | Fe 410WA grade with similar weldability and mechanical properties |
| International | ISO 630-2 | S235B | Structural steel comparable to S235JR, may have minor chemical differences |
Notes:
- For ERW pipe, the base material mechanical properties may be slightly altered by the cold forming and welding process; the values listed are for the parent plate/strip per JIS G3106.
- ERW pipe produced from SM400A coils is often supplied to separate tubular standards such as JIS G3444 (STK400) or JIS G3452 (SGP), which may specify slightly different requirements. Always verify the applicable pipe standard.
- SM400A does not have guaranteed impact toughness; for dynamic or low-temperature applications consider SM400B or SM490 grades.
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