Effects of temperature and straining on the oxidation behavior of electrical steels

The effect of Si content (in the range of 0.01-1.91 wt%) on scale formation of electrical steels in dry air at temperatures ranging from 850 to 1200°C was investigated. The effect of applied tensile strain on oxidation behavior was also explored. A thermo-mechanical simulator (Gleeble machine) was employed to conduct the oxidation tests at different load conditions. The experimental results showed that at 1000°C the oxidation rate decreased with increasing Si content in the steel. The formation of an inner scale, mainly consisting of amorphous silica, was responsible for the improved oxidation resistance. However, a substantial increase in oxidation rate due to the formation of molten eutectic fayalite (Fe ₂SiO ₄) was observed when the temperature was raised to 1200°C. Under straining conditions at a very short oxidation time, the inner scale structure was slightly modified though the scale thickness remained almost unchanged for the steel containing 1.91 wt% Si.