Metal treatment – Stock – Ferrous
Patent
1995-11-28
1998-03-10
Yee, Deborah
Metal treatment
Stock
Ferrous
148333, C22C 38026
Patent
active
057256896
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates a steel wire rod of high strength and a steel wire of high strength excellent in fatigue characteristics used for an extra fine steel wire of high strength and high ductility which is used for a steel cord, a belt cord, and the like for reinforcing rubber and organic materials such as those in tires, belts and hoses, and for a steel wire of high strength which is used for a rope, a PC (Prestressed Concrete) wire, and the like.
BACKGROUND OF THE INVENTION
In general, a drawn extra fine wire of high carbon steel used for a steel cord is usually produced by optionally hot rolling a steel material, cooling under control the hot rolled steel material to give a wire rod having a diameter of 4.0 to 5.5 mm, primary drawing the wire rod, final patenting the wire, plating the wire with brass, and finally wet drawing the wire. Such extra fine steel wires are in many cases stranded to give, for example, a two-strand cord or five-strand cord, which is used as a steel cord. These wires are required to have properties such as mentioned below:
Accordingly, steel materials of high quality, in accordance with the demand, have heretofore been developed.
For example, Japanese Unexamined Patent Publication (Kokai) No. 60-204865 discloses the production of an extra fine wire and a high carbon steel wire rod for a steel cord which exhibit less breakage during stranding, and a high strength and a high ductility, by adjusting the Mn content to less than 0.3% to inhibit supercooled structure formation after lead patenting and controlling the amounts of elements such as C, Si and Mn. Moreover, Japanese Unexamined Patent Publication (Kokai) No. 63-24046 discloses a steel wire rod for a highly tough and ductile extra fine wire the lead patented wire of which rod is made to have a high tensile strength with a low working ratio of wire drawing by adjusting the Si content to at least 1.00%.
On the other hand, oxide type nonmetallic inclusions can be mentioned as one of factors which exert adverse effects on these properties.
Inclusions having a single composition such as Al.sub.2 O.sub.3, SiO.sub.2, CaO, TiO.sub.2 and MgO are in general highly hard and nonductile, among oxide type inclusions. Accordingly, increasing the cleanliness of molten steel and making oxide type inclusions low-melting and soft are necessary for producing a high carbon steel wire rod excellent in drawability.
As methods for increasing the cleanliness of steel and making nonductile inclusions soft as mentioned above, Japanese Examined Patent Publication (Kokoku) No. 57-22969 discloses a method for producing a steel for a high carbon steel wire rod having good drawability, and Japanese Unexamined Patent Publication (Kokai) No. 55-24961 discloses a method for producing an extra fine steel wire. The fundamental idea of these techniques is the composition control of oxide type nonmetallic inclusions of the ternary system Al.sub.2 O.sub.3 --SiO.sub.2 --MnO.
On the other hand, Japanese Unexamined Patent Publication (Kokai) No. 50-71507 proposes an improvement of the drawability of steel wire products by locating nonmetallic inclusions thereof in the spessartite region in the ternary phase diagram of Al.sub.2 O.sub.3, SiO.sub.2 and MnO. Moreover, Japanese Unexamined Patent Publication (Kokai) No. 50-81907 discloses a method for improving the drawability of a steel wire by controlling the amount of Al to be added to molten steel to decrease harmful inclusions.
Furthermore, Japanese Examined Patent Publication (Kokoku) No. 57-35243 proposes, in relation to the production of a steel cord having a nonductile inclusion index up to 20, a method for making inclusions soft comprising the steps of blowing CaO-containing flux into a molten steel in a ladle together with a carrier gas (inert gas) under complete control of Al, predeoxidizing the molten steel, and blowing an alloy containing one or at least two of substances selected from Ca, Mg and REM.
However, a steel wire having an even higher strength, higher ductility and h
REFERENCES:
patent: 5211772 (1993-05-01), Ashida et al.
Nakashima Junji
Nishida Seiki
Ochiai Ikuo
Serikawa Osami
Nippon Steel Corporation
Yee Deborah
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