I. Basic Definition
S355JOH is a low alloy high-strength structural steel under the European Standard (EN 10025), belonging to the S355 series of steels, with high yield strength (≥355MPa) and excellent overall mechanical properties, widely used in construction, bridge and heavy machinery manufacturing13. It has high yield strength (≥355MPa) and excellent comprehensive mechanical properties, and is widely used in construction, bridge and heavy machinery manufacturing.
Naming rules and performance indexes
Naming meaning:
S: stands for 'structural steel' (Structural Steel);
355: Minimum yield strength of 355MPa;
JOH: identification of specific impact toughness and processing characteristics ('J' for normal temperature impact properties, 'O'). impact properties, 'O' may be a quality grade or special process marking, 'H' may stand for high strength or heat-treated condition).
Mechanical properties:
Yield strength: ≥355MPa;
Tensile strength: 470-630MPa;
Elongation: ≥22% (reflecting good ductility);
Impact toughness: impact work at room temperature (20°C) ≥ 27J.
Third, the chemical composition
The main elements are controlled as follows (mass per cent)
Carbon (C): ≤ 0.22%;
Silicon (Si): ≤0.55%;
Manganese (Mn): ≤ 1.60%;
Phosphorus (P), sulfur (S): ≤ 0.025% (strict control of impurities to enhance weldability and corrosion resistance).
Fourth, the core characteristics
High strength: yield strength higher than ordinary carbon steel, suitable for load-bearing structural components.
Excellent weldability: supports a variety of processes such as manual electric arc welding and submerged arc welding, with stable performance of welded joints.
Corrosion resistance: strong corrosion resistance in conventional atmospheric environments, and some variants (e.g. S355J0W) further enhance weather resistance by adding alloying elements.
Processing performance: good cold/hot workability, easy to cut, bend and mould.
V. Application Areas
Building structure: high-rise building frames, bridge supports and other load-bearing parts.
Heavy machinery: construction machinery parts, crane structural parts and other scenes that need to withstand high dynamic loads.
Special environments: Weather-resistant versions (such as S355J0W) can be used in marine engineering, humid and corrosive environments.
VI. Differences with similar materials
Compare S355JR:
S355JOH has better impact toughness and machinability (through the 'JOH' marking) and is suitable for more demanding dynamic loading scenarios.
Compare Q355B (GB):
Mechanical properties are close, but S355JOH has better weldability and corrosion resistance, and complies with the strict limitations on impurities imposed by European standards.
Summary
S355JOH is a European low alloy high-strength structural steel, with high yield strength, excellent weldability and impact resistance as its core advantages, suitable for construction, bridges and heavy machinery manufacturing. The 'JOH' designation in its nomenclature reflects specific requirements for impact toughness and processing, differentiating it from common structural steels such as S355JR.
