On the pitting corrosion resistance of nitrogen alloyed cold worked austenitic stainless steels U. Kamachi Mudali * , P. Shankar, S. Ningshen, R.K. Dayal, H.S. Khatak, Baldev Raj Metallurgy and Materials Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, India Received 4 January 2001; accepted 8 January 2002 Abstract Pitting corrosion studies were carried out on cold worked (5%, 10%, 15%, 20%, 30% and 40%) nitrogen-bearing (0.05%, 0.1% and 0.22% N) type 316L austenitic stainless steels in neutral chloride medium. Potentiodynamic anodic polarisation study revealed that cold workingupto20%enhancedthepittingresistance,andthereafterasuddendecreaseinpitting resistance was noticed at 30% and 40% cold working. Increase in nitrogen content was ben- eficialupto20%coldworkinimprovingthepittingcorrosionresistance,beyondwhichithad a detrimental effect at 30% and 40% cold working. The role of nitrogen in influencing the deformation band width and dislocation configuration is explained based on the results of transmissionelectronmicroscopyinvestigations.Scanningelectronmicroscopyobservationof the pitted specimens indicated decreasing size and increasing density of pits, along the de- formationbandswithincreasingnitrogenfor40%coldworkedspecimens.Themacrohardness values increased as the cold working increased from 0% to 40%. X-ray diffraction studies revealedtheincreasedpeakbroadeningofaustenitepeak{022}withincreaseincoldworking. The relationship between pitting corrosion and deformation structures with respect to nitro- genadditionandcoldworkingisdiscussed. Ó 2002ElsevierScienceLtd.Allrightsreserved. Keywords: Stainless steels; Polarisation, SEM, TEM, XRD; Pitting corrosion, Effects of strain www.elsevier.com/locate/corsci Corrosion Science 44 (2002) 2183–2198 * Corresponding author. Fax: +91-4114-480301. E-mail address: kamachi@igcar.ernet.in (U. Kamachi Mudali). 0010-938X/02/$ - see front matter Ó 2002 Elsevier Science Ltd. All rights reserved. PII:S0010-938X(02)00035-5