Welding Rods Explained: E6013 vs E7018 for Structural Work

Grab the wrong rod and the weld looks fine on Monday and cracks on Friday. Sri Lankan sites live on two mild-steel rods — E6013 and E7018 — and knowing which one each job demands is ten minutes of learning that saves rework for years.

How to read the code

In E7018: E = electrode. 70 = 70,000 psi (about 490 MPa) tensile strength of the weld metal. 1 = all-position welding. 8 = low-hydrogen iron powder coating, DC reverse polarity preferred. E6013 decodes the same way: 60,000 psi (about 410 MPa), all-position, rutile coating that runs happily on AC or DC.

E6013 — the everyday rod

• Strikes and restrikes easily, forgiving on poor fit-up and on cheap AC welders
• Clean, flat beads with light slag that pops off
• Right for gates, grills, railings, farm repairs, sheet and light-section mild steel
• Not rated for structural load-bearing joints — treat it as general repair rod

E7018 — the structural rod

• Stronger weld metal (490 MPa) with much better toughness in the cold
• Low-hydrogen: the coating is baked dry so hydrogen cannot get into the weld metal — this is what prevents the cold cracks that fail structural joints
• Demanded for beams, columns, base plates and any welded joint an engineer has signed
• Runs on DC positive; the trade-off is it must stay bone dry

Match the rod size to your machine

• 2.5 mm: roughly 70–100 A — sheet, thin sections, first passes
• 3.15 mm: roughly 100–140 A — the site all-rounder on 6–12 mm steel
• 4.0 mm: roughly 140–180 A — heavy sections and fill passes

Too many amps cause undercut along the joint edges; too few cause the rod to stick. Start mid-range for the size and adjust by ear and bead shape.

Storage: where E7018 lives or dies

Damp low-hydrogen rods put hydrogen straight into the weld metal — the cause of delayed cracking. Keep E7018 in sealed packs until use, and on site keep the working quiver in a rod oven or at minimum a sealed, warm container. Rods left out overnight in monsoon humidity should be re-dried per the manufacturer before structural use. E6013 is far more forgiving, but dry rods always strike better.

FAQ

Can I weld structural steel with E6013? For load-bearing joints an engineer signs off — use E7018. E6013 is for non-structural repair and light fabrication.

Why does my E7018 keep sticking? Usually damp rods or low amps. Dry the rod properly and step the amperage up; E7018 also needs a slightly longer arc hold when striking than E6013.

Seegaan stocks welding rods including E6013 and E7018 in 2.5–4.0 mm, plus safety gear for the welding bay, from Colombo with island-wide delivery. Call +94 11 239 6384 for box and carton rates, or request a quote.

AI-generated (Flux via Writeseed), 2026-11-10