The Effect of Cyclic and Static Tensile Stresses on the Tribocorrosion Behavior of Austenitic and Duplex Stainless Steels in Marine Environment

The effect of cyclic and static tensile stresses on the tribocorrosion behavior of austenitic and super duplex stainless steels in marine environment

 

C. B. von der Ohe ^{* 1,2}, R. Johnsen ² and N. Espallargas ²

 

 

¹ National Oilwell Varco Norway AS, 4604 Kristiansand, Norway, christian.von.der.ohe@nov.com

² NTNU, Faculty of Engineering Science and Technology, Dept. Engineering Design and Materials. N-7491 Trondheim, Norway

 

Abstract

In many engineering applications, component surfaces are exposed to wear in a corrosive environment. Such tribological components are usually structural elements, also supporting applied static and/or cyclic tensile loading. There are no research and test methodologies available for evaluating the multidegradation mechanisms of such realistic degradation scenarios.

A new test apparatus has been developed to reproduce the multidegradation phenomena in the laboratory, by exposing test specimens to any combination of cyclic and static 4-point bending and reciprocating sliding contact in a corrosive environment under electrochemical control.

The multidegradation tests show that the level of applied cyclic or static surface strain significantly changes the material loss. The tribocorrosion test setup for these multidegradation testing has been performed at both open circuit potential (OCP) and at imposed potential (potentiostatic tests). The reciprocating sliding action of alumina counterparts (Ø 4.76mm) has been established with an applied normal force of 70N on each ball and a sliding frequency of 1 Hz. The multidegradation tests have been conducted for 2 hours at maximum stress of 90% and 50% of material yield stress for the cyclic testing and 90% and 10% of the yield stress of the material during static straining. The applied cyclic 4-point bending has been performed at 1.25 Hz and 2.5Hz.

This paper show the interaction of fatigue and tensile stresses, known as Corrosion Fatigue (CF) and Stress Corrosion Cracking (SCC) mechanisms, in a tribocorrosion situation simulating a piston rod operating in the splash zone on a offshore drilling vessel.

*Corresponding author

Keywords: multidegradation testing, tribocorrosion, wear-corrosion-fatigue.