Creep-resistant steel

Abstract

A creep-resistant steel comprises carbon (in wt.%) (0.l0-0.15), chromium (8-13), manganese (0.1-0.5), nickel (2-3), molybdenum and / or tungsten (0.5-2) when both elements are present, a maximum total of (3), niobium (0.02-0.2), tantalum (0.05-2), vanadium (0.1-0.4), palladium (0.005-2), nitrogen (0.02-0.08), silicon (0.03-0.15), boron (80-120), maximum about 100 ppm of aluminum, maximum about 150 ppm of phosphorous, maximum about 250 ppm of arsenic, maximum about 120 ppm of tin, maximum about 30 ppm of antimony, maximum about 50 ppm of sulfur, and remaining iron and unavoidable impurities.

Description

technical field [0001] The invention relates to a steel based on 8-13% chromium, which are used for rotors in the field of power generation. The present invention involves the selection and content determination of specific alloying elements capable of establishing exceptionally good creep resistance in such materials at temperatures of 550°C and above. The steel according to the invention can also have good fatigue resistance at low loading cycles (LCF=Low Cycle Fatigue) and good toughness after long-term aging, so that it can be used not only in gas turbines but also in steam turbines use. Background technique [0002] Martensitic hardening steel based on 9-12% chromium is a widely used material in the field of power generation. They have been developed for use in steam generators operating at temperatures above 600°C and steam pressures of 250 bar to increase generator efficiency. The creep and oxidation resistance of the material under these operating conditions is of...

AI Technical Summary

Problems solved by technology

Si is advantageous in steel as a non-oxidant for the melting moment, but on the other hand retains a part of it as an oxide, which is disadvantageous in reducing toughness

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