The influence of various parameters on pitting corrosion of 316 L and zoz stainless steel

Dissertant

Abbud, Taha Hasan

University

University of Technology

Faculty

-

Department

Department of Chemical Engineering

University Country

Iraq

Degree

Master

Degree Date

2008

English Abstract

The present work is aimed to investigate the effect of some variables on the pitting corrosion of two types of stainless steel (316L arid 202) and study their electrochemical behavior in NaCl solution using the polarization technique. The experiments were carried out under static conditions at different temperatures (298,308and318) K and different NaCl concentration solutions (3.5, 2.5 and 1.5)%. In order to study the effect of velocity on the electrochemical behavior at different rotation speeds (100, 200 and 300) r.

p.

m., rotating cylinder electrode were used for (3,5 and 2.5) % of NaCl solutions at temperatures (298, 308 and 318) K. The above experiments were repeated for Ihe two types of SS, i.

e, (316L and 202). The scan rate effect (10, 15, 30, and 40)mV / min.

on the electrochemical behavior of 316L SS at 308K in 3.5 % NaCl solution was investigated also, It was found experimentally that increasing in temperatures and NaCl concentration leads to decrease in the breakdown potential (Eb).

For 316L SS, the decreases was from (-80 to -220) mV, while for 202 SS it was from (-120 to -260) mV.

Also it is clear that in the present investigation, stagnant solution is the favorite to pitting corrosion. It can be confirm that at 40 mV / min., the passivation region observed clearly while, this region is difficult observed at another scanning rates (10, 15, 20, 30) mV / min..

This give a good evidence that the passivation region depends on critical scanning rates, therefore the scanning rate must be chosen carefully to obtain a steady state response for passive region dependent on the type of alloys and the electrolyte, The influence of rotational speed (100-300) r.

p.

m.

on the pitting corrosion of two types of stainless steei, showed the small variation m corrosion current density (icorr).

Tor 316L SS (0.0014-0.0015,0.0018-0.0019) mA / cmA2 at (2,5and3.5) % NaCl solution and 298K, (0.0016-00018,0.0018-0.0023 ) mA / cmA2 at (2.5and3.5) % NaCl solution at 30SK, (0,0025-Q.0028,0.0028-0.0028)mA / cmA2 at (2.5and3.%) %NaCl solution at 31andK while for 202 SS (0.0021-0,002,0.004-0.002) mA / emA2 at (2,5and3.5) % NaCl solution at 298K, (0.006-0.006,0.005-0.0063 ) mA / cmA2 at (2,5and3.5) % NaCl solution at 308K, (0.006-0.0068,0.0013-0.005) mA / cm*2 at (2,5and3.5) % NaCl solution at 318K. It was found that increasing in the NaCl concentration leads to increase the corrosion current density for two types of stainless steel.

For 316L SS the increasing was from (0.0012 to O.0O27) mA / cmA2, while for 202 SS, it was from (0.0016 to 0.009) mA / cmA2. The pitting resistance of 316L SS was higher than that of 202 SS in chloride solutions at the same conditions (Eb for 316L SS higher than of Eb of 202 SS).

Main Subjects

Materials Science , Minerals

Topics

• Stainless steel

• APA
• MLA
• AMA

Language

English

Data Type

Arab Theses

Record ID

BIM-305138