Composition limits of ferritic solid solutions in silicon steels at 950–1100°C

Abstract

For iron alloys containing 1.4–2.9%Si and various Mn and Al contents, the activity of carbon was determined at the ferrite/(ferrite + austenite) phase boundaries by equilibrating the alloys with known mIxtures of hydrogen and methane at atmospheric pressure and temperatures of 940–1080°C. With the aid of available thermodynamic data the measured carbon activities were converted to the corresponding carbon concentrations in order to evaluate the effect of carbon in solution on the position of the γ loop in the temperature–composition phase equilibrium diagram for the iron–silicon alloys.