Grooving corrosion of oil coiled tubes manufactured by electrical resistance welding

The characteristics of grooving corrosion of oil coiled tubes by electric resistance welding were investigated by using electrochemical polarization tests and an immersed corrosion test. The welded tube exhibited severe localized corrosion in the welding zone. The post-weld heat treatments reduced the sensitivity of grooving corrosion. A corrosion groove occurred at the fusion line. The local heat treatment for the welding zone at 930 °C adding the whole heat treatment for tubes at 690 °C was beneficial to improve the resistance to the grooving corrosion. The reasons of the grooving corrosion were discussed from the microstructures and chemical compositions of the weld.

► Characteristics of localized corrosion in the welding zone of a CT80 steel.
► Methods to reduce the sensitivity of grooving corrosion in the welding zone.
► New insights into the grooving corrosion reasons and affecting factors.