The effect of manganese additions on the high temperature oxidation behaviour of the high-vanadium cast iron

Highlights: • 3 wt.% Mn relieved the oxidation behaviour of the high-vanadium cast iron. • A Cr₂O₃ nanolayer (50–200 nm) was identified by FIB-TEM at initial oxidation. • Mn additions promoted refinement of the V₄C₃ precipitation particles. • Severe cracking occurred due to the thermal stress-induced breakaway. • A kinetic model of high temperature oxidation procedure was proposed. Manganese (Mn) addition was found to remarkably relieve the weight gain of the wear-resistant high vanadium cast iron during oxidation at 950 °C. The mechanism of such oxidation behaviour in the associated cast iron was investigated through adding different Mn contents. During oxidation process, the decrease in weight gain was sensitive to Mn addition, where the smallest weight gain corresponded to an optimal content of 3.0 wt.% Mn. Meanwhile, the degree of macrocracks was closely dependent on Mn contents. Using FIB-TEM site-specific sample preparation technique, an initial Cr₂O₃ layer with a thickness of 50–200 nm was identified between the matrix cast iron and the post layer of other oxidation products. In addition, Mn additions promoted to refine the precipitating V₄C₃ particles that uniformly distributed in the matrix cast iron. The relationship between Mn and cracking was then analysed subsequently. Based on oxidation tests and microstructural characterization, the kinetic mechanism of oxidation behaviour of the high-vanadium cast iron at high temperature was then proposed.