A multi-degradation test rig for studying the synergy effects of tribocorrosion interacting with 4-point static and cyclic bending

Many offshore and marine components are exposed to wear in a corrosive environment, called tribocorrosion exposure. These components are usually structural elements, also supporting applied static and/or cyclic tensile stresses. There are no test apparatus or methodologies described in the literature for studying the multi-degradation mechanisms and performance of such complex degradation scenarios and engineered surface materials. The present work presents a new test apparatus developed to reproduce the multi-degradation phenomena at lab scale, by exposing test specimens to any combination of cyclic and static 4-point bending and reciprocating ball-on-plate sliding contact in a corrosive environment under electrochemical control. Initial multi-degradation tests of a 22% Cr duplex stainless steel show that the level of applied cyclic or static surface strain significantly changes the material loss and degradation mechanisms. The tribocorrosion test setup for these multi-degradation testing has been performed at open circuit potential (OCP). The reciprocating sliding action of an alumina counterpart (Ø 4.76 mm) has been established with an applied normal force of 70 N at a sliding frequency of 1 Hz. The multi-degradation tests have been conducted for 2 h at 90% and 12% of the yield strength during static straining. The cyclic strain testing was performed at a maximum stress of 90% and 60% of yield strength, with 9000 cycles applied at a 4-point bending frequency of 1.25 Hz. OCP, coefficient of friction and stresses were logged during testing.