Q235A Steel for SSAW Pipe
Q235A Steel for SSAW Pipe: Composition, Properties & Global Equivalents
Comprehensive data sheet for Q235A carbon structural steel used in SSAW pipes, including chemical composition, mechanical & thermal properties, and international equivalents.
Hot rolling, cold forming, welding (SAW), machining, drilling, cutting
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Q235A Steel for SSAW Pipe Introduction
Q235A is a carbon structural steel grade specified in Chinese standard GB/T 700, widely used in the manufacture of spiral submerged arc welded (SSAW) pipes. It offers a balance of moderate strength, good weldability, and formability, making it suitable for fluid transmission pipelines, structural piling, and general construction. With a minimum yield strength of 235 MPa (for thickness ≤ 16 mm) and a tensile strength range of 370–500 MPa, Q235A is designed for non-critical applications where no impact toughness requirements are specified. The material is typically supplied in hot-rolled condition and can be formed into coils or plates before pipe forming.
Q235A Steel for SSAW Pipe Chemical Composition
The chemical composition of Q235A as per GB/T 700-2006 is limited to five elements. Residual elements like Cr, Ni, and Cu are typically ≤0.30% each and do not constitute a delivery requirement. The steel has relatively high permissible phosphorus and sulfur compared to higher-quality grades, reflecting its use in non-critical applications.
| Element | Standard Value (max, %) | Remarks |
|---|---|---|
| Carbon (C) | 0.22 | Heat analysis |
| Silicon (Si) | 0.35 | Max |
| Manganese (Mn) | 1.40 | Max |
| Phosphorus (P) | 0.045 | Max |
| Sulfur (S) | 0.050 | Max |
| Residual Cr, Ni, Cu | ≤0.30 each | Informative; not mandatory |
Q235A Steel for SSAW Pipe Thermal and Electrical Physical Properties
The following physical properties are typical for carbon structural steel similar to Q235A. They are not mandatory in the standard but are widely accepted for engineering calculations. Data are approximate and may vary with processing history.
| Property | Typical Value | Unit | Test Condition |
|---|---|---|---|
| Density (ρ) | 7.85 | g/cm³ | 20 °C |
| Modulus of elasticity (E) | 200–210 | GPa | Ambient |
| Shear modulus (G) | 79–81 | GPa | Ambient |
| Poisson's ratio (ν) | 0.28–0.30 | - | Ambient |
| Thermal expansion (α) | 11.5–12.5 ×10⁻⁶ | K⁻¹ | 20–100 °C |
| Thermal conductivity (λ) | 53 | W/(m·K) | 20 °C |
| Specific heat capacity | 486 | J/(kg·K) | 20 °C |
| Electrical resistivity (ρₑ) | 0.16–0.18 ×10⁻⁶ | Ω·m | 20 °C |
Q235A Steel for SSAW Pipe Mechanical Properties
Mechanical properties are based on transverse test pieces unless otherwise specified. Yield strength varies with thickness; tensile strength is independent of thickness above 3 mm. Elongation is measured on a gauge length of 5.65√S₀ (proportional). Q235A does not require impact testing or bend testing by default; bend test requirements apply only to grades with B, C, D suffixes.
| Property | Standard Requirement | Unit | Condition / Thickness |
|---|---|---|---|
| Yield strength (ReH) | ≥235 | MPa | Thickness ≤ 16 mm |
| Yield strength (ReH) | ≥225 | MPa | Thickness >16–40 mm |
| Yield strength (ReH) | ≥215 | MPa | Thickness >40–60 mm |
| Yield strength (ReH) | ≥205 | MPa | Thickness >60–100 mm |
| Yield strength (ReH) | ≥195 | MPa | Thickness >100–150 mm |
| Yield strength (ReH) | ≥185 | MPa | Thickness >150–200 mm |
| Tensile strength (Rm) | 370–500 | MPa | Thickness ≤ 200 mm (all ranges) |
| Elongation (A) | ≥26 | % | Thickness ≤ 40 mm |
| Elongation (A) | ≥25 | % | Thickness >40–60 mm |
| Elongation (A) | ≥24 | % | Thickness >60–100 mm |
| Elongation (A) | ≥22 | % | Thickness >100–150 mm |
| Elongation (A) | ≥21 | % | Thickness >150–200 mm |
| Bend test | Not specified | - | Not required for Q235A |
Q235A Steel for SSAW Pipe Identical or Closely Matching International Standards & Substitute Grades
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| China | GB/T 700 | Q235A | Original grade |
| — | — | — | No exact foreign match because Q235A waives impact testing. Grades listed below have impact requirements or slight differences in chemical composition. |
Q235A Steel for SSAW Pipe Application Introduction
Q235A finds extensive use in construction and general engineering where impact resistance is not a critical requirement. When fabricated into SSAW pipes, it is employed in low- to medium-pressure fluid transportation and structural piling. The material's good weldability and cold formability enable efficient pipe forming. Users should verify project-specific requirements for toughness and consider upgrading to Q235B or Q235C if dynamic loading or low-temperature service is expected.
Product Applications: SSAW steel pipes (API 5L Gr. B / GB/T 9711 equivalent usage), Structural hollow sections, Steel plates for general fabrication, Transmission poles and towers, Piling pipes
Processed into products: Pipe elbows and reducers, Flanges and pipe fittings (for low-pressure service), Structural pipe connectors and welding collars, Steel casing for bored piles, Machine bases and brackets
Application industries: Oil & gas transmission (low-pressure water, gas, and crude oil lines), Water supply and drainage systems, Civil engineering and infrastructure (piling, bridge structural pipes), Construction (building columns, trusses, scaffolding), Machinery manufacturing (frames, supports, non-critical components)
Q235A Steel for SSAW Pipe Similar or Comparable Grade Recommendations
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| China | GB/T 700 | Q235B | Impact energy ≥27 J at +20°C; otherwise similar chemistry and strength |
| China | GB/T 700 | Q235C | Impact energy ≥27 J at 0°C |
| China | GB/T 700 | Q235D | Impact energy ≥27 J at -20°C |
| International | ISO 630-2 | S235JR | Yield 235 MPa min, tensile 360–510 MPa; impact KV ≥27 J at +20°C; C ≤0.17%, Mn ≤1.40%, P ≤0.035%, S ≤0.035% |
| Japan | JIS G3101 | SS400 | Yield ≥245 MPa (t≤16mm), tensile 400–510 MPa; no impact requirement; chemistry loosely defined |
| USA | ASTM A283/A283M | Grade D | Yield ≥230 MPa, tensile 415–550 MPa; no impact; C ≤0.27% (plates) may be higher |
| USA | ASTM A36/A36M | A36 | Yield ≥250 MPa, tensile 400–550 MPa; impact not required for general structural use |
| Europe | EN 10025-2 | S235JR (1.0038) | Impact KV ≥27 J at +20°C; carbon ≤0.17%, P ≤0.035%, S ≤0.035% |
Notes:
Disclaimer: All data are based on publicly available standards. For SSAW pipe production, the steel strip/coil must meet the specified chemistry and mechanical values; the welding consumables and process shall be qualified separately per relevant pipe standard. For critical applications, it is strongly recommended to specify supplementary testing for toughness, non-destructive examination, and product analysis as per project requirements. The physical properties provided are typical and may vary with heat treatment and manufacturing route.
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