US2535284A

US2535284A - Cold-drawing steel wire

Info

Publication number: US2535284A
Application number: US777119A
Authority: US
Inventors: Arch W Harris
Original assignee: American Steel and Wire Company of New Jersey
Current assignee: American Steel and Wire Company of New Jersey
Priority date: 1947-09-30
Filing date: 1947-09-30
Publication date: 1950-12-26
Anticipated expiration: 1967-12-26

Description

Patented Dec. 26, 1950 T :i

uu rso STATES PATENT OFFICE 7 2,535,284 i :COLDJ- DBAWING STEEL WIRE Arch. W. Harris, Euclid, Ohio, ass'ignor to The American Steeland Wire Company of ,New Jersey, a corporation of New Jersey Nolnrawing. .Application SeptemberBO, 1947,

' Serial No. 777,119

This invention relates to cold-drawing steel wire and more particularly to the preparation of steel wire and the surface thereof for drawing.

Steel wire is conventionally given a so-called patent anneal at an intermediate stage in its manufacture in order to impart the desired physical properties thereto and to toughen it sufficiently to withstand drastic reductions effected by cold drawing. It is necessary in this practice to acid clean the wire after the anneal to remove the scale therefrom since it is harmful to the dies. Following cleaning, the wire is lime coated and baked to remove embrittlement resulting from the acid cleaning.

Accordingly, it is an object of this invention to overcome the foregoing disadvantages to provide an improved method of preparing wire for cold drawing.

It is a further object to produce cold drawn wire in an efficient and economical manner.

In accordance with the teachings of my invention, high carbon steel wire containing between .50 and 1.00% carbon, .60 and 1.25% manganese and other elements in the usual residual amounts present in plain carbon steel wire is produced by conventional steel making and drawing practice. In order to prepare the wire for cold drawing and, in the case of wire drawn to a size approaching that desired in the final product, to improve the final physical properties, the wire is patent annealed. This essentially comprises heating the wire to above its transformation temperature followed by quenching it. This strengthens and toughens the wire to withstand drastic cold reductions. By my improved method, the wire is patent annealed by continuously heating it in a nonoxidizing atmosphere to a temperature between 1450 and 1900 F. The nonoxidizing atmosphere may be any inert gases such as nitrogen, helium and argon or reducing gases such as cracked ammonia, etc. The wire being annealed will have a clean scale-free surface due to prior cold drawings but may have a slight amount of drawing lubricant thereon. This however will burn off without affecting the wire surface so that due to the nonoxidizing atmosphere, the wire will retain its bright cold drawn surface.

After heating and without exposure to any oxidizing influences, the wire is immediately quenched in a lead bath, which according to the teachings of my invention is maintained at a temperature between 800 and 1100 F. I have found that molten lead will begin to dissolve the lead oxide which forms on the surface of the 2 molten lead at about 800 F. If bright-surfaced steel is introduced into molten lead maintained above such temperature whereby it contains dissolved lead oxide, a chemical replacement occurs in accordance with the following reaction:

Thus the annealed steel wire having a clean surface resulting from treating in the foregoing manner will receive a very thin oxide film which is substantially all ferrous oxide (FeO) during its passage through the lead bath.

The wire with this film of oxide thereon may be cold drawn with improved results as compared to the conventional practice of removing scale, applying a lubricant and then drawing. However, if desired, the wire with the film of oxide may be coated with any conventional coatings such as silicates, borates, phosphates, soaps, alkalies or mixtures thereof. The prime purpose of such coatings is to prevent rusting or formation of higher iron oxides on the surface of the wire prior to cold drawing it and thus retain the film of ferrous oxide thereon.

While I have shown several specific embodiments of my invention, it will be understood that these embodiments are merely for the purpose of description and that various other forms may be devised within the scope of my invention, as defined in the appended claims.

I claim:

1. A method of preparing wire for cold drawing, comprising annealing substantially scalefree wire in a nonoxidizing atmosphere and without exposure to oxidizing influences quenching said annealed wire in a lead bath containing lead oxide to produce a film of ferrous oxide thereon.

2. A method of preparing high carbon steel wire for cold drawing, comprising annealing substantially scale-free wire in a nonoxidizing atmosphere and without exposure to oxidizing infiuences quenching said wire in a lead bath containing lead oxide to produce a thin film of ferrous oxide thereon.

3. A method of preparing carbon steel wire for cold drawing, comprising annealing substantially scale-free wire in a reducing atmosphere at a temperature between 1450" and 1900 F. and without exposure to oxidizing influences im mediately quenching the same in a lead bath containing lead oxide maintained at a temperature between 800 and 1100 F. to produce a ferrous oxide film thereon.

4. A method of cold-drawing steel wire c0m- 3 prising annealing substantially scale-free wire in a reducing atmosphere at a temperature between 1450 and 1900 F. and then without exposure to oxidizing influences immediately quenching the annealed wire in a lead bath containing lead oxide maintained at a temperature between 800 and 1100 F. to produce a film of ferrous oxide thereon and cold drawing the wire with said oxide film thereon.

5. A method of drawing high carbon steel wire comprising annealing substantially scale-free wire in a reducing atmosphere at a temperature between 1450 and 1900 F. and then without exposing the wire to oxidizing influences immediately quenching it in a lead bath containing lead oxide maintained at a temperature between 800 and 1100 F. to produce a film of ferrous oxide thereon, coating said ferrous oxide coating with 4 an oxidation resistant material and drawing the wire with the ferrous oxide film thereon.

ARCH W. HARRIS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS m Number Name Date 279,295 Watson et al June 12, 1883 2,369,805 Schultz Feb. 20, 1945 FOREIGN PATENTS 15 Number Country Date 511,628 France Sept. 27, 1920 249,649 Italy- Aug. 4, 1926

Claims

4. A METHOD OF COLD-DRAWING STEEL WIRE COMPRISING ANNEALING SUBSTANTIALLY SCALE-FREE WIRE IN A REDUCING ATMOSPHERE AT A TEMPERATURE BETWEEN 1450* AND 1900*F. AND THEN WITHOUT EXPOSURE TO OXIDIZING INFLUENCES IMMEDIATELY QUENCHING THE ANNEALED WIRE IN A LEAD BATH CONTAINING LEAD OXIDE MAINTAINED AT A TEMPERATURE BETWEEN 800* AND 1100*F. TO PRODUCE A FILM OF FERROUS OXIDE THEREON AND COLD DRAWING THE WIRE WITH SAID OXIDE FILM THEREON.