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

Abstract

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 (5-10 5 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.

The Prospects In Designing New Generation Of High Temperature Coatings In Automobile Engines

“…In the case of the uncoated X50CrMnNiNbN21-9 steel, the chromium concentration, being on the level of 20 wt. %, is not high enough for selective oxidation of chromium and the formation of the continuous Cr 2 O 3 oxide layer [13,18]. Thus, a heterogeneous scale is formed, the protective properties of which are much worse than that assured by chromium oxide.…”

“…In addition, new generations of car engines are characterized by increased working temperature with the simultaneous decrease in fuel consumption. It should be noted that according to the present experience in this area, the engine temperature growth as well as the application of alternative fuels, creates serious danger of enhanced corrosion of engine valves [7,8,13].…”

Thermal Shock Corrosion of Valve Steels Utilized in Automobile Industry

“…It has been found earlier that under isothermal conditions, the corrosion resistance of these materials in oxidizing atmospheres at temperatures 873-1,273 K depends first of all on chromium concentration [1][2][3]. The higher, namely, the concentration of chromium, the better is the corrosion resistance of these steels.…”

Thermodynamic properties of V, Cr, Mo, and Fe metals and their binary alloys

“…Alloy systems in the same manner as Cr-Mo, Cr-Fe, Cr-Al, Cr-Mo, Cr-Nb, and Cr-Fe-Mo represent a group of alloy systems having superb high-temperature strength and high flexibility with moderate corrosion. The stated properties have brought alloy systems much attention from researchers in various useful applications, such as in steel production and surgical implants [1,2], including the aerospace and automobile industries [3].…”