Effect of Radial Expansion of Cr-Mo Steel Tubes on Their Corrosion Behavior in Sea Water

A. C. Seibi, P. Rostron, A. Elramady, B. Mishra, O. Al Nazer, S. Al Ameri

Chemistry Department, Petroleum Institute, Abu Dhabi, UAE.
Mechanical Engineering Department, Petroleum Institute, Abu Dhabi, UAE.
Metallurgical & Materials Engineering Department, Colorado School of Mines, Golden, USA.

DOI: 10.4236/msa.2012.39084                

Abstract

This paper studies the effect of expansion ratio on the corrosion rate of the expanded tubes exposed to sea water as well as the microstructure changes caused by the expansion of Cr-Mo steel tubes to large permanent deformations. 2.25 Cr-1.0 Mo steel (schedule 40 and schedule 80) tubes were subjected to various expansion ratios of 10%, 15%, 20%, and 25% by pushing conical mandrels through them using a piston. The microstructure was also studied to determine the effect of the expansion on the grain structure of the material. Microscopic examination of the expanded tubes revealed that grains elongate along the direction of the hoop stress and this elongation increases with an increase of expansion ratio. Moreover, it was found that corrosion rate and hardness increase with an increase in expansion ratio.

Keywords

Expanded Tubes; Corrosion in Seawater; Potentiostat; Hardness; Enlarged Grain Size

Conflicts of Interest

The authors declare no conflicts of interest.

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