Effects of Millscale on Corrosion of ASTM A 36 Steel in 3% NaCl

Millscale is an oxide layer formed during the manufacturing processes of the pipe. Standard corrosion specimen preparation as recommended by ASTM G1 includes the cleaning and removal of the millscale layer, often by abrasion or acid pickling. These cleaning techniques can act to change the mechanical surface properties and can result in hydrogen charging. These standard corrosion tests do not show the true nature of the corrosion. The effects of millscale generally have been ignored in the past first due to the large amount of scatter that can be introduced into the results and second due to the belief that the millscale has negligible effects on the overall corrosion rate. This paper explores the effects of millscale on the corrosion conditions of hot rolled ASTM A36 steel with and without mill scale in dearated 3% NaCl solution at various pH levels through polarization experiments.