1. Key Temperature Ranges & Property Changes
(1) Low Temperatures (-40°C to 0°C)
Yield/Tensile Strength: Slightly increases (5–10%) as temperature drops. For example, yield strength (≤16mm thickness) rises from 355 MPa (20°C) to ~370–380 MPa at -20°C.
Ductility (Elongation): Gradually decreases. At -40°C, elongation may fall to 15–18% (from ≥22% at 20°C for 3–40mm thickness), but remains sufficient to avoid brittle deformation.
Impact Toughness: The most sensitive property. S355J0WP is rated for 0°C impact resistance (≥27 J), but toughness drops sharply below this:
At -10°C: Impact energy (KV) decreases to ~20–25 J (near the brittle-ductile transition).
At -20°C to -40°C: Falls to <20 J, increasing the risk of brittle fracture under dynamic loads (e.g., impacts, sudden stress).
(2) Ambient Temperature (0°C to 100°C)
Yield/Tensile Strength: Stable and consistent with standard values (yield ≥335–355 MPa, tensile 470–680 MPa). Minimal variation (<3%) within this range.
Ductility: Optimal-elongation stays at the specified ≥16–22% (by thickness), ensuring good fabricability (bending, welding) and damage resistance.
Impact Toughness: Meets the EN 10025-5 requirement (≥27 J at 0°C) and remains reliable at 20–100°C (KV ≥30–40 J), with no brittle fracture risk.
(3) Moderate High Temperatures (100°C to 300°C)
Yield/Tensile Strength: Gradually decreases as temperature rises. By 300°C:
Yield strength drops by ~20–25% (e.g., 355 MPa → ~270–290 MPa for ≤16mm thickness).
Tensile strength decreases by ~10–15% (e.g., 470–630 MPa → ~400–540 MPa).
Ductility: Increases slightly (elongation +2–3%), making the steel more deformable but less rigid.
Impact Toughness: Remains adequate (KV ≥25–30 J), as high temperatures above ambient do not trigger brittleness.
(4) High Temperatures (>300°C)
Yield/Tensile Strength: Accelerated decline. Above 400°C, yield strength drops by 40–50% (vs. ambient), and structural rigidity is significantly reduced.
Ductility: Continues to rise, but the steel becomes prone to creep (slow plastic deformation under sustained load) - not suitable for long-term service at >300°C.
Impact Toughness: Remains ductile but irrelevant for high-temperature applications, as creep is the primary failure risk.
2. Core Implications for Applications
Low-temperature limits: Avoid using S355J0WP in environments below -10°C for load-bearing or impact-prone structures (e.g., cold-region bridges, outdoor machinery). For -20°C to -40°C, choose S355J2WP (rated for -20°C impact resistance) instead.
Ambient/moderate temperatures: Ideal for most outdoor structural applications (guardrails, cladding, retaining walls) - properties are stable, and performance aligns with design expectations.
High-temperature scenarios: Not suitable for long-term service in heat-exposed components (e.g., near industrial furnaces, exhaust systems) - use heat-resistant steels (e.g., EN 1.4903) if temperatures exceed 300°C.
