Flow Stress at Low Temperatures and Strain Aging of High Cr-Fe Alloys with Small Amounts of C and N

Abstract

Mechanical properties and aging responses of 1mm thick plate specimens of 24-26% Cr-Fe alloys with small amounts of C and N were studied in the temperature range from-196 to 200°C.
The thermal components of the flow stress at low temperatures (<-20°C) were found to be independent of the heat treatments employed for the specimen preparation. However, in the specimens solution treated above 1200°C and subsequently quenched, the sotid solution hardening due to interstitial atoms was identified to contribute significantly to the flow stress increases at higher temperatures. The air cooled and the aged (1h at 400°C) specimens were identical in the yield stress and the tensile strength, while they were different in the Luders elongation. Some of strain aging characteristics of the aging at 200°C were similar to those of the aging of the pure iron. Water quenched specimens showed the highest low-temperature ductility.