Steel materials and method for preparation thereof
AssigneeHonda Giken Kogyo Kabushiki Kaisha
InventorMitsuo Kuwabara
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Abstract
A raw steel is coated with or surrounded by a boron compound (step S1). A coating film of h-BN is formed on the surface of the raw steel. Then, the raw steel is nitrided by a nitriding gas while being heated (step S2). B from the boron compound and N from the nitriding gas are diffused into the raw steel, turning the raw steel into a steel material containing B and N. Most of B and N are present as an Fe (B, N) solid solution or an Fe (C, B, N) solid solution in the structure of the steel material. The raw steel is heated and nitrided under conditions such that B and N are contained ranging from 7 to 30 ppm by weight and ranging from 10 to 70 ppm by weight, respectively.
Claims9
A steel material containing B ranging from 7 to 30 ppm by weight and n ranging from 10 to 70 ppm by weight, wherein B and N are contained as an Fe (B, N) solid solution or an Fe (C, B, N) solid solution with Fe which is a constituent element of the steel material.
(Cancelled)
A method of manufacturing a steel material containing B ranging from 7 to 30 ppm by weight and N ranging from 10 to 70 ppm by weight, comprising the steps of:
- covering or surrounding a raw steel with a boron compound;
- and
- nitriding said raw steel with a nitriding gas while heating said raw steel in a temperature range from 1100 to 1750 K.
Dependencies are inferred from the claim text.