Kobe Steel, Ltd.

Tomotada Maruo

Hidenori Sakai

Mikako Takeda

Takashi Onishi

Takeshi Kuroda

Takuya Kochi

Takaaki Minamida

Hiroshi Yaguchi

Shogo Murakami

Shohei Nakakubo

Masumi Nishimura

A high carbon steel wire material which is made of high carbon steel as a raw material for wire products such as steel cords, bead wires, PC steel wires and spring steel, allows for these wire products to be manufactured efficiently at a high wire drawing rate and has excellent wire drawability and a manufacturing process thereof. This high carbon steel wire material is made of a steel material having specific contents of C, Si, Mn, P, S, N, Al and O, and the Bcc-Fe crystal grains of its metal structure have an average crystal grain diameter (D) of 20 &#x3bc;m or less and a maximum crystal grain diameter (D) of 120 &#x3bc;m or less, preferably an area ratio of crystal grains having a diameter of 80 &#x3bc;m or more of 40% or less, an average sub grain diameter (d) of 10 &#x3bc;m or less, a maximum sub grain diameter (d) of 50 &#x3bc;m or less and a (D/d) ratio of the average crystal grain diameter (D) to the average sub grain diameter (d) of 4.5 or less.

Process for manufacturing a high carbon steel wire material having excellent wire drawability

The present invention aims at providing a method for production of a steel product which surely retains scale during cooling, storage, and transportation and permits scale to scale off easily at the time of mechanical descaling and pickling that precede the secondary fabrication. The steel product is produced by heating and hot rolling a steel billet and spraying the hot-rolled steel product with steam and/or water mist having a particle diameter no larger than 100 &#x3bc;m, for surface oxidation.

Method for production of steel product with outstanding descalability; and steel wire with outstanding descalability

An FeO layer including fine crystal grains having random orientation is formed as inner layer scale on the surface of the steel wire rod containing C: 0.05-1.2 mass % (hereinafter referred to as '%'), Si: 0.01-0.50%, Mn: 0.1-1.5%, P: 0.02% or below, S: 0.02% or below, N: 0.005% or below, an FeSiOlayer with the thickness: 0.01-1.0 &#x3bc;m is formed in the boundary face between the FeO layer of the inner layer scale and steel, and the thickness of the inner layer scale is 1-40% of the total scale thickness. In another aspect, the maximum grain size of the crystal grain of the inner layer scale is 5.0 &#x3bc;m or below and the average grain size is 2.0 &#x3bc;m or below.

Steel wire rod

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Kobe, Japan

Tomotada Maruo