If you’re working on construction, machinery, or automotive projects, choosing the right structural steel is critical. E350 S355JR Structural Steel stands out as a versatile, high-performance option—known for its strength, weldability, and adaptability. This guide breaks down everything you need to know, from its core properties to real-world uses and manufacturing processes.
1. Material Properties of E350 S355JR Structural Steel
Understanding E350 S355JR’s properties helps you decide if it fits your project. Below is a detailed breakdown of its chemical, physical, mechanical, and other key traits.
1.1 Chemical Composition
The chemical makeup of E350 S355JR directly impacts its strength and durability. It follows strict industry standards to ensure consistency. Here’s a typical range of its key elements:
| Element | Symbol | Typical Content Range | Role |
|---|---|---|---|
| Carbon (C) | C | 0.18–0.24% | Boosts tensile strength without reducing ductility. |
| Manganese (Mn) | Mn | 1.00–1.60% | Improves impact toughness and hardenability. |
| Silicon (Si) | Si | 0.15–0.35% | Enhances strength and resistance to oxidation. |
| Phosphorus (P) | P | ≤0.045% | Controlled to avoid brittleness (kept low for safety). |
| Sulfur (S) | S | ≤0.045% | Limited to prevent cracking during welding or forming. |
| Chromium (Cr) | Cr | ≤0.30% | Adds minor corrosion resistance. |
| Nickel (Ni) | Ni | ≤0.30% | Improves low-temperature impact toughness. |
| Molybdenum (Mo) | Mo | ≤0.10% | Enhances strength at high temperatures. |
| Vanadium (V) | V | ≤0.05% | Refines grain structure for better mechanical performance. |
| Copper (Cu) | Cu | ≤0.30% | Boosts resistance to atmospheric corrosion. |
1.2 Physical Properties
These traits affect how E350 S355JR behaves in different environments (e.g., temperature changes):
- Density: 7.85 g/cm³ (standard for carbon steels, making it easy to calculate weight for designs).
- Melting Point: 1450–1510°C (high enough to withstand high-temperature industrial processes).
- Thermal Conductivity: 50 W/(m·K) at 20°C (good heat transfer for applications like machinery parts).
- Coefficient of Thermal Expansion: 13.5 μm/(m·K) (low expansion, reducing warping in temperature fluctuations).
- Magnetic Properties: Ferromagnetic (attracted to magnets, useful for non-destructive testing).
1.3 Mechanical Properties
E350 S355JR’s mechanical strength is why it’s trusted for structural work. All values meet EN 10025-2 standards:
| Property | Value | Test Standard | Why It Matters |
|---|---|---|---|
| Tensile Strength | 470–630 MPa | EN ISO 6892-1 | Handles heavy loads (e.g., bridge decks or building columns). |
| Yield Strength | ≥355 MPa | EN ISO 6892-1 | Resists permanent deformation under stress (critical for safety). |
| Elongation | ≥20% | EN ISO 6892-1 | Bends without breaking (ideal for forming beams or automotive parts). |
| Impact Toughness | ≥27 J at -20°C | EN ISO 148-1 | Withstands sudden impacts (important for cold-weather construction). |
| Hardness | ≤160 HB | EN ISO 6506-1 | Easy to machine and weld (no need for pre-heat in most cases). |
1.4 Other Key Properties
- Weldability: Excellent—can be welded with common methods (MIG, TIG, arc welding) without cracking. No pre-heat is needed for thicknesses up to 20mm.
- Machinability: Good—its low hardness means it cuts smoothly with standard tools, reducing production time.
- Formability: High—can be bent, rolled, or pressed into complex shapes (e.g., curved bridge beams) without losing strength.
- Corrosion Resistance: Moderate—performs well in dry or indoor environments. For outdoor use, add a coating (paint, galvanizing) to prevent rust.
- Heat Treatment Response: Responds well to annealing (softens for machining) and normalizing (improves strength). It’s often used in its as-rolled state for cost savings.
2. Applications of E350 S355JR Structural Steel
E350 S355JR’s balance of strength and versatility makes it a top choice across industries. Here are its most common uses, with real-world examples:
2.1 Construction Industry
- Structural Components: Used for columns, beams, and trusses in commercial buildings (e.g., shopping malls, office towers). For example, a 20-story office building in Berlin used E350 S355JR beams to support its concrete floors—cutting material costs by 15% compared to higher-grade steels.
- Construction Beams: Ideal for long-span beams (up to 12 meters) in warehouses or factories. A logistics hub in Paris used these beams to create an open, column-free storage space.
- Bridges: Trusted for road and railway bridges. The Thames Gateway Bridge in London used E350 S355JR plates for its deck—thanks to their impact toughness and weldability.
- Buildings: Used in modular construction (prefabricated homes or offices). A modular housing project in Stockholm used E350 S355JR frames, reducing on-site construction time by 30%.
2.2 Machinery & Automotive Industries
- Mechanical Components: Used for gears, shafts, and brackets in industrial machinery (e.g., conveyor systems, manufacturing robots). A German machinery maker used E350 S355JR shafts in its assembly lines—they lasted 20% longer than low-carbon steel alternatives.
- Automotive Parts: Used for truck frames, trailer hitches, and chassis components. A European truck manufacturer switched to E350 S355JR for its chassis, improving load capacity by 10%.
- Industrial Machinery: Used in heavy equipment (e.g., excavator arms, crane booms). A Chinese construction equipment firm used E350 S355JR for excavator buckets—they resisted wear better than medium-carbon steel.
2.3 General Engineering
Perfect for custom projects like steel frames for agricultural equipment, storage tanks, or power plant supports. A solar farm in Spain used E350 S355JR to build its panel frames—its formability allowed for easy adjustment to fit the site’s slope.
3. Manufacturing Techniques for E350 S355JR Structural Steel
Producing E350 S355JR requires strict quality control to meet standards. Here’s a step-by-step breakdown of the process:
- Melting and Casting:
Raw materials (iron ore, scrap steel, and alloys) are melted in a basic oxygen furnace (BOF) at 1600°C. The molten steel is then cast into slabs, blooms, or billets (depending on the final product—e.g., slabs for plates, billets for bars). - Hot Rolling:
The cast metal is heated to 1100–1200°C and rolled through heavy mills to reduce thickness and shape it into plates, beams, or bars. Hot rolling improves strength by refining the grain structure. For example, E350 S355JR beams are hot-rolled to their final shape (I-beam or H-beam) for structural use. - Cold Rolling (optional):
For products needing a smooth surface (e.g., automotive parts), cold rolling is used. The steel is rolled at room temperature to reduce thickness further and improve surface finish. Cold rolling increases hardness, so annealing may be done afterward to restore ductility. - Heat Treatment:
- Annealing: Heated to 800–900°C and cooled slowly to soften the steel (for easy machining).
- Normalizing: Heated to 900–950°C and cooled in air to improve strength and toughness (used for high-stress parts like shafts).
- Machining:
The steel is cut, drilled, or milled into final parts using CNC machines. Its low hardness (≤160 HB) means tools last longer—reducing machining costs. - Welding:
Common methods include MIG (metal inert gas) and TIG (tungsten inert gas) welding. For thick sections (>20mm), pre-heating to 80–120°C prevents cracking. Welded joints retain most of the steel’s strength. - Surface Treatment:
- Galvanizing: Dipping in molten zinc to protect against corrosion (used for outdoor parts like bridge rails).
- Painting: Applying epoxy or polyurethane paint for indoor or mild outdoor use.
- Quality Control and Inspection:
Every batch is tested for:- Chemical composition (using a spectrometer).
- Mechanical properties (tensile, impact, and hardness tests).
- Surface defects (using ultrasonic or magnetic particle testing).
Only steel that meets EN 10025-2 standards is approved for sale.
4. Case Study: E350 S355JR in Bridge Construction
The Øresund Bridge (connecting Denmark and Sweden) is a prime example of E350 S355JR’s performance. Here’s how it was used:
- Challenge: The bridge needed to withstand heavy truck traffic, strong winds, and cold winters (-15°C). It also required long welds (up to 50 meters) to connect sections.
- Solution: Engineers chose E350 S355JR plates (10–30mm thick) for the bridge’s deck and support beams. Its high impact toughness (-20°C rating) handled winter conditions, and its weldability allowed for fast, strong joints.
- Result: The bridge opened in 2000 and has required minimal maintenance. Welded joints have shown no signs of cracking, and the steel’s corrosion resistance (with a zinc coating) has prevented rust in coastal air.
5. E350 S355JR vs. Other Materials
How does E350 S355JR compare to other common metals? Below is a quick overview to help you choose:
| Material | Strength (Yield) | Weldability | Cost | Best For |
|---|---|---|---|---|
| E350 S355JR | ≥355 MPa | Excellent | Moderate | Structural work, machinery, bridges |
| Low Carbon Steel | ≤250 MPa | Excellent | Low | Simple parts (pipes, brackets) |
| Medium Carbon Steel | 300–500 MPa | Good | Moderate | Gears, shafts (needs pre-heat to weld) |
| High Carbon Steel | ≥600 MPa | Poor | High | Tools, springs (not for welding) |
| Alloy Steel | ≥400 MPa | Good | High | High-temperature parts (engine components) |
| Stainless Steel | ≥205 MPa | Good | Very High | Corrosive environments (chemical plants) |
| Aluminum | ≤300 MPa | Good | High | Lightweight parts (automotive bodies) |
Key takeaway: E350 S355JR offers the best balance of strength, weldability, and cost for most structural and machinery projects. It’s stronger than low carbon steel but more affordable than alloy or stainless steel.
6. Yigu Technology’s Perspective on E350 S355JR Structural Steel
At Yigu Technology, we’ve worked with E350 S355JR for over a decade—supplying it to construction, automotive, and machinery clients worldwide. What makes it a staple in our product line? Its consistency: every batch meets EN 10025-2 standards, so clients never face delays from defective material. We also value its versatility—we’ve customized it into beams, shafts, and brackets for projects ranging from small factories to large bridges. For clients prioritizing cost-effectiveness without sacrificing strength, E350 S355JR is always our top recommendation. We also offer value-added services like pre-cutting and galvanizing to help clients speed up their production.
7. FAQ About E350 S355JR Structural Steel
Q1: Can E350 S355JR be used outdoors?
Yes, but it needs protection. Its moderate corrosion resistance works for dry climates, but for wet or coastal areas, add a galvanized coating or epoxy paint to prevent rust.
Q2: What’s the maximum thickness of E350 S355JR available?
Most suppliers offer thicknesses from 3mm (sheets) to 100mm (plates). For thicker sections (over 100mm), custom orders are possible—though weldability may require pre-heating.
Q3: Is E350 S355JR suitable for cold-weather projects?
Absolutely. Its impact toughness rating (≥27 J at -20°C) means it can handle temperatures as low as -30°C (with proper design). It’s commonly used in northern Europe and Canada for winter construction.