Compared to high-strength steel (700MPa+)?
S355: Low cost, mature technology, easy welding, suitable for medium load-bearing structures.
High-strength steel: Lighter, more expensive, difficult to form, suitable for high-end/ultra-lightweight applications.
Common failure modes (automotive)?
Fatigue cracking (chassis/suspension alternating load)
Welding cold cracking (thick plates without preheating)
Bending cracking (too small radius)
Preventive measures?
Fatigue: Design rounded corners, avoid sharp corners, post-weld grinding
Welding: Control preheating/layer temperature, use low-hydrogen welding wire
Cold bending: Select bending radius according to grade
Mandatory inspection items for automotive procurement?
Yield strength/tensile strength/elongation
Impact toughness (by grade)
Bending test (180°, no cracks)
Surface/dimensional/flaw detection
Key points for European vehicle certification?
CE certification + EN standards + material report + impact/bending/welding performance, compliant with WV/TR/ISO automotive specifications.