Study the Effect of Nickel Coating on Fatigue Life of Low Carbon Steel Exposed to Corrosive Environments

Abstract

Nickel electroplating on low carbon steel are widely used in many industrial application due to its benefit in improving corrosion fatigue life, increasing coating thickness provide good protection against corrosion but in other hand reduce fatigue life in addition to its high cost so applying a relatively thin layer of the electroplated nickel may give an acceptable corrosion protection in low cost. In this paper the effect of relatively  thin layer ( 6 µ m )  electroplated nickel deposited by Watts type bath on the corrosion fatigue life of low carbon steel specimens exposed to lab air and 3% NaCl solution as  a corrosive environments was studied. Five groups of standard low carbon steel specimens were prepared for fatigue tests, Mechanical grinding was done for the all45 test specimens and after that Nickel electroplating coating was carried out to 18 specimens and mechanical polishing performed on the remaining 27specimens. Fatigue tests were carried out in air for nine specimens immediately after polishing and the remaining specimens were tested after exposing to lab air and 3% NaCl solution as corrosive environments for a period of 30 day using a reverse bending fatigue machine. Results indicate that fatigue life of relatively thin layer Nickel electroplated specimens was shorter by 4% than that of the uncoated mechanical polished specimens immediately tested in air and not exposed to corrosive environments, but it’s corrosion fatigue life was higher by 11.46%than that of polished specimens when both exposed to lab air for 30 day and by 21.68% higher when both exposed to 3% NaCl solution for 30 day , this study indicate that relatively thin layer ( 6 µ m )   Nickel electroplating decrease fatigue live of low carbon steel specimens exposed to un corrosive environment, but it improved corrosion fatigue life of low carbon steel specimens exposed to cyclic load and corrosive environment.

Keywords: Nickel Plating; surface treatment; fatigue life; corrosion fatigue.