JIS G3101 SS490 Structural Steel
JIS G3101 SS490 Structural Steel - Composition, Properties & Global Equivalents
Detailed technical analysis of JIS G3101 SS490 carbon and low-alloy high-strength steel plate, including chemical composition, mechanical and physical properties, international equivalents, and typical applications.
Hot rolling, normalizing, cold forming, gas cutting, welding (SMAW, GMAW, SAW), drilling, machining
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JIS G3101 SS490 Structural Steel Introduction
SS490 is a general structural rolled steel grade defined in Japanese Industrial Standard JIS G3101. It belongs to the carbon and low-alloy high-strength steel category and offers a guaranteed minimum tensile strength of 490 MPa. The steel is widely used in building frames, bridges, machinery, and welded structures due to its balanced strength, good weldability, and consistent formability. Controlled chemical composition with limited carbon, silicon, manganese, phosphorus, and sulfur ensures reliable mechanical properties in hot‑rolled or normalized delivery conditions. SS490 is not intended for special impact requirements unless agreed upon, but it provides sufficient ductility for typical structural applications.
JIS G3101 SS490 Structural Steel Chemical Composition
The chemical composition of SS490 is controlled to ensure adequate strength and weldability. Maximum limits for carbon vary with product thickness to maintain toughness and prevent excessive hardenability. Silicon and manganese are kept within ranges that promote deoxidation and strength without impairing ductility. Phosphorus and sulfur are restricted to minimise hot shortness and improve weld quality.
Note: For thicknesses ≤40 mm, C max is 0.20%; for >40 mm to 100 mm ≤0.22%; for >100 mm ≤0.24%.
| Element | Standard Value (wt%) | Remarks |
|---|---|---|
| Carbon, C | ≤0.20 (t≤40 mm) / ≤0.22 (40 | Maximum limit depends on thickness |
| Silicon, Si | ≤0.55 | Deoxidising element; max value |
| Manganese, Mn | ≤1.60 | Strength and toughness control |
| Phosphorus, P | ≤0.040 | Maximum allowable |
| Sulfur, S | ≤0.040 | Maximum allowable, for hot workability |
JIS G3101 SS490 Structural Steel Thermal and Electrical Physical Properties
The physical properties below are typical for low‑carbon structural steel of this strength class. They are not mandated by JIS G3101 but are useful for design calculations. Values are at room temperature unless noted otherwise.
| Property | Typical Value | Unit | Test Condition / Remarks |
|---|---|---|---|
| Density (ρ) | 7.85 | g/cm³ | At 20 °C |
| Elastic Modulus (E) | 205 | GPa | Tensile modulus at 20 °C |
| Shear Modulus (G) | 80 | GPa | Calculated from E and ν |
| Poisson's Ratio (ν) | 0.3 | – | Within elastic range |
| Thermal Expansion Coefficient (α) | 11.7 | ×10⁻⁶/K | Between 20 °C and 100 °C |
| Thermal Conductivity (λ) | 51.9 | W/(m·K) | At 100 °C |
| Specific Heat Capacity (cp) | 486 | J/(kg·K) | At 20 °C |
| Electrical Resistivity (ρe) | 0.142 | μΩ·m | At 20 °C |
JIS G3101 SS490 Structural Steel Mechanical Properties
Mechanical properties are determined on test pieces taken transverse to the rolling direction. The yield strength requirement decreases with increasing plate thickness. Tensile strength remains within a fixed range. Elongation is measured on proportional test pieces according to JIS Z 2241. No mandatory impact or bend test is specified in the standard unless separately agreed.
| Property | Standard Requirement | Unit | Test Condition |
|---|---|---|---|
| Yield Strength (ReH) | ≥285 | MPa | Thickness t ≤ 16 mm |
| Yield Strength (ReH) | ≥275 | MPa | 16 mm < t ≤ 40 mm |
| Yield Strength (ReH) | ≥255 | MPa | 40 mm < t ≤ 75 mm |
| Yield Strength (ReH) | ≥245 | MPa | 75 mm < t ≤ 100 mm |
| Yield Strength (ReH) | ≥235 | MPa | t > 100 mm |
| Tensile Strength (Rm) | 490 – 610 | MPa | All thicknesses |
| Elongation (A) | ≥19 | % | t ≤ 5 mm (JIS No.5 specimen) |
| Elongation (A) | ≥15 | % | 5 mm < t ≤ 16 mm (JIS No.1A specimen) |
| Elongation (A) | ≥19 | % | 16 mm < t ≤ 50 mm (JIS No.1A specimen) |
| Elongation (A) | ≥21 | % | t > 50 mm (JIS No.10 specimen) |
JIS G3101 SS490 Structural Steel Full Equivalent Standards and Replaceable Grades
| Country / Region | Standard | Grade | Remarks |
|---|---|---|---|
| Japan | JIS G3101 | SS490 | Original specification |
| USA | ASTM A572/A572M | Grade 50 [345] | Equivalent tensile range but higher minimum yield (345 MPa). Typically further processed to meet SS490 requirements. |
| European Union | EN 10025‑2 | S355JR | Tensile 470‑630 MPa, yield 355 MPa. Approximate match with slightly higher strength. |
| China | GB/T 1591 | Q345B | Yield ≥345 MPa, tensile 470‑630 MPa; widely used structural equivalent. |
| International | ISO 630‑2 | E355 | Structural steel with min yield 355 MPa, comparable in many applications. |
JIS G3101 SS490 Structural Steel Application Introduction
SS490 is selected for projects where a predictable 490 MPa tensile strength is required and where normal structural ductility suffices. The steel works well in welded assemblies provided proper preheat and interpass temperatures are observed for thicker sections. It is not recommended for low‑temperature service without supplementary Charpy testing.
Product Applications: Multi‑storey building columns and beams, Steel bridge girders and decks, Offshore platform topside structures, Telescopic crane booms, Storage silos and tanks, Railway coach underframes
Processed into products: Welded I‑beams and H‑beams, Base plates and anchor plates, Gusset plates and stiffeners, Brackets and support angles, Flanged shaft couplings, Machine frames and press bodies
Application industries: Building and civil infrastructure, Bridge engineering, Machinery and equipment manufacturing, Shipbuilding (non‑critical hull members), Railway vehicle structures, Power generation and transmission towers
JIS G3101 SS490 Structural Steel Similar/Comparable Material Recommendations
| Country / Region | Standard | Grade | Remarks |
|---|---|---|---|
| Japan | JIS G3101 | SS400 | Lower strength (tensile 400‑510 MPa), suitable for less demanding structures. |
| Japan | JIS G3106 | SM490A | Welded structural steel with impact testing; superior toughness. |
| European Union | EN 10025‑2 | S275JR | Lower strength grade, tensile 410‑560 MPa; may be used with thickness adjustment. |
| USA | ASTM A36 | A36 | General purpose carbon steel with tensile 400‑550 MPa, lower yield. |
| China | GB/T 700 | Q275 | Tensile 410‑560 MPa, yield 275 MPa; lower overall strength but similar forming. |
| International | ISO 630‑2 | E275 | Comparable to S275JR, tensile 410‑560 MPa. |
Notes:
JIS G3101 does not mandate impact testing. If toughness guarantees are needed, the purchase order should specify Charpy V‑notch requirements (e.g., 27 J at 0 °C) based on JIS G3106 (SM490) or an agreement. For welding, low‑hydrogen processes are recommended; preheat (e.g., 100–150 °C) may be applied when thickness exceeds 40 mm to avoid cold cracking. The steel can be hot‑dip galvanised without significant property degradation. When ordering, the thickness‑dependent chemical composition limits must be clearly stated.
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