Corrosion inhibition of weldment by Nephelium lappaceum peel extract in 3.5% NaCl solution

•Nephelium lappaceum peel extract (NPE) as Eco-friendly inhibitors of carbon steel weldment in 3.5% NaCl.•The weldment zones followed Langmuir isothermal adsorption.•On the weldment areas, there was physisorption (WM and HAZ), but on BM chemisorption physiochemisorption.•NPE acted as mixed type inhibitor on all weldment areas.•NPE has a strong effect (82%) on HAZ, compared to other weldment areas.