Abstract
Three simple high-purity steels containing between 0.10 and 0.55 wt.-% titanium and 0.02–0.11% carbon have been examined after direct transformation of austenite to ferrite by subcritical isothermal transformation in the range 600–800°C and by continuous cooling. Electron microscopy has shown that titanium carbide occurs in a fine banded form during the γ→α transformation, the dispersion parameters being very dependent on the transformation temperature. The finer dispersions were measured by field ion microscopy. The mechanical properties in tension at room temperature were determined as a function of transformation temperature for the three alloys and compared with the properties obtained by quenching and tempering in the, same temperature range. Fracture toughness measured by a COD test was determined on two titanium steels with 0.26% and 0.48%Ti. The results emphasize the importance of transformation temperature or rate of cooling through the transformation in determining the fracture toughness. The results have been analysed to determine the contribution of the titanium carbide dispersions to the strength, and their relevance to the development of high-strength low-alloy steels containing Ti is discussed.
Get full access to this article
View all access options for this article.