Alloying elements (Cr, P, Cu, etc.): High P raises cold cracking risk; Cr/Mo boosts hardenability, prone to martensite in HAZ.
Strength grade: High-strength grades (e.g., Q690NH) with higher Ceq/Pcm are more crack-susceptible.
Thickness/condition: Thick plates risk HAZ grain coarsening; residual stress or thick scale harms fusion.
Mismatched composition (e.g., ordinary electrodes for SPA-H) creates corrosion weak zones.
Strength mismatch (e.g., low-strength wire for Q355NH) leads to insufficient joint strength.
Heat input: Excess causes HAZ toughness loss; insufficiency leads to incomplete fusion.
Preheating/post-heating: Lack of preheating (e.g., <100℃ for Q355NH below 0℃) induces cold cracking.
Welding method: GMAW needs proper shielding gas; SAW suits thick plates but not thin ones.
Poor design (small groove angle) causes defects; stress concentration (fillet welds) accumulates residual stress.
Rigid constraints prevent contraction, increasing residual stress.
High-corrosion environments (coastal/salt spray) accelerate joint corrosion if flawed.
Unremoved slag/spatter or un-repaired rust layer damages joint corrosion resistance.
