ULTRA HIGH CARBON STEEL ALLOY AND PROCESSING THEREOF

摘要

An ultra high carbon steel having a composition of carbon in an amount of from about 0.8 weight percent up to the maximum solubility limit of carbon in austenite; silicon in an amount of from about 3 to about 7 weight percent; an effective amount of a stabilizing element acting to stabilize iron carbide against graphitization in the presence of silicon; and the balance iron. Preferably, the silicon is present in an amount of about 3 weight percent, and the stabilizing element is chromium. The ultra high carbon steel may be processed to a form suitable for subsequent superplastic forming by any technique which reduces its grain size to about 10 microns or less, and preferably to about 0.4 to about 2 microns. The silicon and the stabilizing element act to produce a stable iron carbide particle array to retain the fine grain size during superplastic processing, and to increase the eutectoid temperature so that superplastic processing may proceed at high strain rates and low stress levels at elevated temperature.