Inland Steel Company

Shashi B Agarwal

Richard A Nickola

Brian A Sok

Coatings of a powdered protective metallic material or refractory material and mixtures thereof are formed on a ferrous metal strip as a wet film dispersion in a resin binder composition of a synthetic organic resin and a volatile organic solvent compatible with said resin, and the coated strip is heated to effect curing said resin binder and forming a flexible non-tacky dry film. The metal strip having the cured dry film containing powdered protective metallic material can be subjected to varying heat treatments to provide a wide range of protective coatings having improved surface properties, including iron-protective metal diffusion alloy coatings, such as iron-aluminum diffusion alloy coatings having a surface concentration of aluminum between about 8 and 10 wt. percent aluminum, which have improved high temperature oxidation resistance after being severely strained during fabrication at room temperature.

Powder metal and/or refractory coated ferrous metals

A solid solution iron-aluminum diffusion alloy coated steel strip is formed by hot-dip aluminum coating a cold rolled low alloy low carbon steel strip preferably having all the carbon in the steel combined with titanium by hot-dip aluminum coating the steel strip and subjecting the aluminum coated low alloy steel strip to a controlled diffusion heat treatment in a non-oxidizing atmosphere for a period and at a temperature which avoids significantly increasing the grain size of the steel, and which effects diffusion of the hot-dip aluminum coating into the steel to establish a critical surface concentration of aluminum in the iron-aluminum diffusion alloy coating of at least about 8 wt. percent and below an aluminum surface concentration which results in crazing and cracking of the diffusion alloy coating when the diffusion alloy coated strip is fabricated at room temperature. A solid solution iron-aluminum diffusion alloy coated titanium containing low carbon steel strip having an aluminum surface concentration between about 8 and about 10 wt. percent does not exhibit objectionable crazing and cracking of the diffusion alloy coating when the coated steel is severely strained during fabrication at room temperature and has good high temperature oxidation resistance when the diffusion alloy coated steel strip is exposed to oxidizing gasses having temperatures between about 816.degree. C. (1500.degree. F.) and 982.degree. C. (1800.degree. F.) after being severely strained at room temperature.

Diffusion treated hot-dip aluminum coated steel

Coatings of a powdered protective metallic material or refractory material and mixtures thereof are formed on a ferrous metal strip as a wet film dispersion in a resin binder composition of a synthetic organic resin and a volatile organic solvent compatible with said resin, and the coated strip is heated to effect curing said resin binder and forming a flexible non-tacky dry film. The metal strip having the cured dry film containing powdered protective metallic material can be subjected to varying heat treatments to provide a wide range of protective coatings having improved surface properties, including iron-protective metal diffusion alloy coatings, such as iron-aluminum diffusion alloy coatings having a surface concentration of aluminum between about 8 and about 10 wt. percent aluminum, which have improved high temperature oxidation resistance after being severely strained during fabrication at room temperature.

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Griffith, IN, United States of America

Shashi B Agarwal