Chemical Composition & Carbon Equivalent (Weldability)
IS 2062 limits carbon, sulphur, phosphorus and — critically — the carbon equivalent (CE), tighter for the higher quality grades. Low CE is what makes the steel weldable per IS 816 without preheat or hydrogen-cracking; the chemistry is the root of the weldability and toughness the quality grade promises and the IS 800 connection design assumes.
Key Requirements
•C, S, P and carbon equivalent (CE) within the IS 2062 limits for the grade (tighter for higher quality)
•Low CE → weldable per IS 816 with controlled procedure; high CE → preheat/hydrogen-crack risk
•Chemistry verified by ladle/product analysis on a representative sample
•Killed/semi-killed steelmaking practice as required for the grade (cleanliness/toughness)
•CE governs the welding procedure — confirm before fabrication welding
Formulas
CE = C + Mn/6 + (Cr+Mo+V)/5 + (Ni+Cu)/15
Carbon equivalent — governs weldability (lower = more weldable)
CE = carbon equivalent (%)C/Mn/Cr/Mo/V/Ni/Cu = element % from analysis
Practical Notes
✓Weld cracking on structural steel usually traces to carbon equivalent / wrong quality grade — check CE and match the welding procedure (IS 816), don't just blame the welder.
✓The higher quality grades carry tighter CE precisely so they weld crack-free — that is what you are buying with the suffix.
Common Mistakes
⚠Welding a high-CE grade without the required procedure/preheat.
⚠Accepting chemistry on the mill tag without representative testing.
⚠Specifying a grade whose CE is unsuited to the planned welding.