Armco Inc.

Baltimore Specialty Steels Corporation

Joseph C Jasper

James N Cordea

Harshad V Sheth

Steel alloys containing chromium may be hot dip aluminized in a bath having up to 15% silicon with improved wettability by using a bright preannealing practice in a box furnace having a substantially pure hydrogen atmosphere. The surfaces of the preannealed steel are easily coated if the box annealing furnace has a dew point of less than -60.degree. C. (-75.degree. F.). The preannealing should also include a minimum soak of at least 1 hour at a temperature of 675.degree. C. to 785.degree. C. (1250.degree. F. to 1450.degree. F.). It is important that the surfaces of the strip after preannealing are not removed prior to aluminizing. During the aluminizing operation, the strip temperature does not need to be heated to much above the bath temperature since the strip has already been preannealed. The furnace is maintained to avoid oxidation with an atmosphere which is typically a nitrogen, hydrogen or a hydrogen-nitrogen mixture. The surfaces of the steel prior to entering the aluminum bath have improved wettability and result in far less uncoated spots due to the improved surfaces provided by the preanneal in the dry box anneal. For ferritic stainless steels, such as Type 409, the surfaces have an iron enriched layer.

Aluminized steel alloys containing chromium

Aluminized steel alloys containing chromium and method for producing same

A nonmagnetic austenitic stainless steel and articles such as drill collars or boat shafts fabricated therefrom, the steel having a 0.2% yield strength of at least 100 ksi (689 N/mm.sup.2), improved resistance to intergranular stress corrosion, good ductility, good corrosion resistance and low magnetic permeability, and consisting essentially of, in weight percent, from greater than 0.05% to about 0.10% carbon, greater than 14% to about 18% manganese, about 15% to about 20% chromium, about 1% to about 3.5% nickel, about 0.3% to about 0.55% nitrogen, about 0.10% to about 0.5% vanadium, about 1.0% maximum copper, about 1.0% maximum molybdenum, about 1.0% maximum silicon, about 0.04% maximum phosphorous, about 0.03% maximum sulfur, and balance essentially iron.

Austenitic stainless steel combining strength and resistance to

A non-magnetic austenitic stainless steel, and a drill collar fabricated therefrom solely by hot forging, the steel having a 0.2% yield strength of at least 85 ksi in the hot worked condition, high stress corrosion cracking resistance, good ductility, and low magnetic permeability even if cold worked, and consisting essentially of, in weight percent, from 0.12% to 0.20% carbon, 11% to 14% manganese, about 16% to about 19% chromium, 1.5% to 2.7% nickel, 0.30% to 0.45% nitrogen, 0.5% to 1.0% copper, about 0.75% maximum molybdenum, about 0.80% maximum silicon, about 0.04% maximum phosphorus, about 0.025% maximum sulfur, and balance essentially iron, with the carbon:nitrogen ratio not greater than 0.6:1.

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Middletown, OH, United States of America

Joseph C Jasper