Republic Steel Corporation

Anthony T Davenport

George M Waid

David W Dickinson

Daniel R DiMicco

A new precipitation hardened, high strength plate product has been developed that attains 80 ksi minimum strength together with excellent toughness, high formability and weldability without heat treatment or the need to cool at rates faster than air cooling. The optimum mechanical properties are achieved by a critical balance of carbon in the range of from 0.20-0.26%, manganese in the range of from 1.0-1.7%, vanadium in the range of from 0.08-0.20%, and at least one of from 0.01 to 0.025 nitrogen and from 0.01 to 0.10 columbium, processing the steel to obtain interphase precipitation strengthening, and by a controlled rolling procedure in which there is no substantial rolling below the Ar.sub.3 temperature.

Method of making as-hot-rolled plate

Process of making as-pierced tubular steel casing having a yield strength of 80-110 ksi, a minimum tensile strength of 100 ksi, and a minimum elongation of 121/2% in two inches. The steel is stengthened by precipitation of vanadium carbides, including carbonitrides, and has a ferrite-pearlite microstructure with a ferrite grain size of about ASTM 7 or finer.

Method of making as-pierced tubular products

A welded tubular steel product having a high ultimate tensile strength of at least 95 ksi and a relatively low yield strength in a range of from 55 to 80 ksi is made by alloying a plain carbon-manganese steel solely with chromium.

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Shaker Heights, OH, United States of America

Anthony T Davenport