The Influence of Humidity-Temperature Variation and High-Salt-Particles on the Degradation of Cr, Cu and Mn Based Alloy Steel
Start date: 22 May 2019
Chromium (Cr), Copper (Cu) and Manganese (Mn) based Alloy Steel is one of the key alloy materials being used in automotive, aerospace, locomotive and defence applications. In this research samples of the same constituents and composition to those of a high value vehicle were prepared and were tested in simulated operational conditions. These conditions were: humidity-temperature variations and environment containing high-salt-particles. This was to simulate two distinct operational conditions depicting sheltered (somewhat environmentally controlled) and non-sheltered (environmentally uncontrolled) scenarios. A series of tests were performed on uncoated samples to analyse material resistance against chemical degradation at the above conditions. At the end of tests, formation of oxide-layers on the samples were measured and analysed. A 5.40 mm2 oxide-layer was measured on a sample of 534 mm2 at 18°C and 55% humidity after 125 hours of exposure in humidity-temperature variation test. Morphology of the oxide-layer showed lepidocrocite (γ-FeOOH) and goethite (γ- Fe2O3) characteristics, which are distinctive for an oxide-layer formed in a non-polluted environment. However 100% oxide-layers were developed within 48 hours on the samples which were exposed to high-salt-particles environment.