Oxidation Kinetics of Steels Utilized in the Production of Valves in Automobile Industry

摘要

The oxidation kinetics of four Fe-Cr-Mn-Ni based steels, utilized in automobile industry, have been studied as a function of temperature (973-1273 K) and oxygen partial pressure (5-105 Pa). It has been shown that the rate of corrosion of these steels under isothermal conditions is determined by diffusion of reagents through the scale, which phase composition and morphology depend first of all on chromium and to some extend also on nickel and manganese contents. The highest oxidation resistance at high temperatures is observed in the case of the X33CrNiMn23-8 steel, containing highest chromium concentration, equal 23.4 wt.% and nickel equal 7.8 wt.%. The remaining three steels with virtually the same chromium content (≈ 20 wt.%), but lower than that in the first one, show comparable oxidation resistance. Small differences in the oxidation rates of these three steels may be related to different nickel and manganese contents. It has been found also that the rate of corrosion of all steels under investigation does not depend under steady state conditions on oxygen partial pressure.