For the oilfield application for “crude oil and natural gas” corrosion phenomena play an important role and are limiting the lifetime of tribological systems. In a lot of different studies that synergistic effects between mechanical sliding and corrosion often lead to increased volume losses when compared to their individual contributions. Low-alloyed C-steel was used as base material and was tribologically loaded in a novel close-to-reality test rig under reciprocating sliding contact against spray Ni - based coating counterpart. Within this work the tribological performance of low-alloyed C-steel under sliding / corrosion conditions at specific oxygen-free environment using CO2 - atmosphere and brine were analysed and characterised. Additionally, pure sliding tests were carried out under N2 - atmosphere with distilled water and also pure corrosion tests with CO2 - atmosphere with brine for comparison. FEM - simulation shows the contact pressure and stresses, which have and influence on sliding / corrosion contact and damage mechanisms. For the understanding concerning sliding-corrosion phenomena different microscopic methods were applied (e.g., optical light microscope, SEM (scanning electron microscope) -FIB (Focused Ion Beam)). The results show a significant influence of the microstructure on the tribological performance under sliding-corrosion conditions; where the formation of corrosion siderite layers (FeCO3) plays a crucial role for the tribological performance.