Influence of the chemical composition of 20MoCrS4 and low‐alloyed TRIP steel on the intensity of high temperature corrosion

Material behaviour in a corroding medium varies depending on its properties. These properties are affected by the treatment, alloy elements and last but not least its surface condition. The sensitivity of a material to iron scale formation and decarburisation limits some technological processes, especially those where materials are exposed to a corroding medium at high temperatures for a very long time. A typical example is the heating of semi‐products to forming temperature. Considering that similar materials can react differently under the same heating conditions, it is important to know the characteristic behaviour of a material in certain production processes. A comparison of two kinds of steels during model treatment was carried out in order to be able to determine the influence of different heating parameters. The model treatment consisted of three different heating temperatures at three different time durations. The intensity of the oxidation process was analysed by means of mass increments and the thickness of the oxide layer was detected via metallography. The depth and intensity of the surface layer decarburisation was evaluated from the profile of the microhardness change curve.