JIS SM570 Structural Steel: A Guide for High-Strength Projects

When your project demands top-tier strength—like ultra-tall skyscrapers or heavy-load bridges—JIS SM570 structural steel stands out. As a high-strength low-alloy (HSLA) steel, it delivers exceptional durability without being overly difficult to work with. This guide breaks down its key traits, real-world uses, manufacturing steps, and how it compares to other steels. Our goal is to help you determine if it’s the right material for your most demanding builds.

1. Material Properties of JIS SM570 Structural Steel

To leverage JIS SM570 effectively, start with understanding its material properties—the foundation of its high-performance reputation.

Alloy Composition & Carbon Content

JIS SM570 is a carefully formulated HSLA steel, with an alloy composition that balances strength and workability:

• Carbon Content: 0.18% max (kept low to maintain weldability, even with its high strength)
• Manganese: 1.60% max (enhances mechanical strength and toughness)
• Silicon: 0.55% max (improves heat resistance during manufacturing)
• Phosphorus: 0.030% max (minimizes brittleness, critical for structural safety)
• Sulfur: 0.025% max (reduces welding cracks)
• Niobium/Vanadium: Trace amounts (0.05% max combined, refine grain structure for extra strength)

Mechanical Strength & Key Metrics

JIS SM570’s mechanical strength is its biggest selling point. Below is a table of its core mechanical properties (tested at room temperature):

Other Important Properties

• Magnetic Properties: Like most structural steels, it’s ferromagnetic. This allows easy non-destructive testing (e.g., magnetic particle inspection) to detect hidden cracks.
• Low-Temperature Toughness: It maintains ductility down to -40°C (depending on the grade), making it suitable for cold regions like northern Japan or Canada.

2. Applications of JIS SM570 Structural Steel

JIS SM570’s high yield strength and tensile strength make it ideal for projects that push structural limits. Let’s explore its key applications with real-world examples.

Construction and Infrastructure

Nearly all JIS SM570 is used in high-stakes construction and infrastructure projects:

• High-Rise Buildings: Its strength lets engineers design thinner, lighter structures. For example, Tokyo’s 63-story Torch Tower (set to open in 2027) uses JIS SM570 for its core columns. This cut the building’s steel usage by 25% compared to using SM490, while still supporting its 300-meter height.
• Bridges and Beams: Long-span and heavy-load bridges rely on it. The Kanmon Bridge (connecting Honshu and Kyushu, Japan) used over 8,000 tons of JIS SM570 for its main suspension beams. Its strength ensures the bridge can handle 100,000 daily vehicles and strong maritime winds.
• Industrial Buildings: Factories with extreme loads (e.g., shipyards) use it for columns and girders. A Hyundai Heavy Industries shipyard in Ulsan, South Korea, uses JIS SM570 to support cranes that lift 1,000-ton ship hulls—its high strength prevents deformation over time.

General Engineering Use

Beyond construction, JIS SM570 is used in:

• Offshore oil platforms (resists saltwater corrosion and wave impacts)
• Heavy-duty truck frames (handles repeated heavy loads)
• Railway tunnels (supports soil pressure and train vibrations)

3. Manufacturing Processes for JIS SM570 Structural Steel

JIS SM570’s strength comes from precise manufacturing processes that optimize its alloy potential. Here’s how it’s made:

1. Hot Rolling: The primary step. Steel billets are heated to 1,280°C (hotter than mild steels) and rolled into plates, beams, or bars. This aligns the grain structure, boosting mechanical strength. POSCO, a leading producer, uses hot rolling for 95% of its JIS SM570 products.
2. Pickling: After rolling, the steel is dipped in nitric-hydrochloric acid mix to remove rust and scale. This ensures a clean surface for welding or coating—vital for offshore or coastal projects.
3. Annealing: Some products undergo annealing (heating to 850°C, cooling slowly) to reduce internal stress. This is common for steel used in pressure vessels, where stress could cause failure.
4. Welding: While it’s stronger than mild steel, JIS SM570 is still weldable. Fabricators use low-hydrogen welding rods (e.g., E11018-G) and pre-heat thick plates (over 25mm) to prevent cracking. A Chinese bridge builder welded 500 tons of JIS SM570 in 4 weeks, with zero weld failures.
5. Heat Treatment: For ultra-high-strength needs, it’s quenched and tempered (heated to 900°C, cooled rapidly, then reheated to 600°C). This raises yield strength to over 500 MPa, used in offshore platforms.

4. Standards and Specifications for JIS SM570 Structural Steel

JIS SM570 is regulated by strict standards and specifications to ensure consistency. Here’s what you need to know:

• Primary Standard: JIS G 3106 (Japanese Industrial Standard for Weldable Structural Steels). This standard defines its alloy composition, minimum yield strength (460 MPa), and testing requirements.
• International Equivalents: It aligns with global high-strength standards, including:
• ASTM A572 Grade 65 (U.S. standard)
• EN 10025 S460JR (European standard)
• GB/T 1591 Q460 (Chinese standard)
• Quality Control & Conformance Testing: To be certified, it must pass:
• Tensile tests (verify tensile strength and yield strength)
• Charpy V-notch tests (check low-temperature toughness)
• Chemical analysis (confirm carbon content and alloy levels)
• Material Certification: Reputable suppliers provide a Material Test Certificate (MTC) with JIS-accredited lab stamps. Always request this to avoid counterfeit steel.

5. Comparison with Other Materials

How does JIS SM570 stack up against common structural steels? The table below highlights key differences:

When to Choose JIS SM570 Over Others

• For projects with extreme loads (e.g., ultra-tall buildings, offshore platforms)
• For cold climates (needs toughness below -20°C)
• When reducing steel weight is critical (cuts construction and transport costs)

Yigu Technology’s View on JIS SM570 Structural Steel

At Yigu Technology, we’ve supplied JIS SM570 to 200+ high-stakes projects, from offshore wind farms to skyscrapers. We see it as a game-changer for ambitious builds—it lets clients do more with less steel, lowering costs while boosting safety. We often pair it with our ceramic anti-corrosion coatings for coastal projects, extending its lifespan by 25 years. While it’s pricier than SM490, its strength often eliminates the need for extra support structures, making it cost-effective long-term.

FAQ About JIS SM570 Structural Steel

1. Do I need special equipment to weld JIS SM570?

For plates thicker than 25mm, yes—pre-heating to 150–200°C prevents cracking. You’ll also need low-hydrogen welding rods (e.g., E11018-G). For thinner plates, standard MIG welders work, but always follow the WPS (Welding Procedure Specification).

2. Can JIS SM570 be used in saltwater environments?

Yes, but it needs protection. Uncoated, it will corrode over time. We recommend hot-dip galvanizing or our ceramic coating—this protects it from saltwater for 20+ years, making it ideal for offshore platforms or coastal bridges.

3. What’s the lead time for ordering JIS SM570?

Standard plates (up to 50mm thick) have a 2–3 week lead time. Custom sizes (over 100mm thick) or large quantities (1,000+ tons) take 4–6 weeks, as they require special rolling at mills like Nippon Steel or POSCO.