SU1766985A1 - Method of steel wire processing - Google Patents

Description

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(21) 4914067/02 (22) 02.22.91 (46) 07.10.92. Bul Nfc37

(71) Branch of the All-Union Scientific Research and Design Institute of Metallurgical Engineering named. A.I. Tselikova, Slav KSK

(72) N.G. Boydenko, A.N. Shpak, P.P. Stroykin and Yu.Ya. Österzon

(56) Tsybulina A. Production of metal cord.-M., 1979, p. 13-16.

USSR Author's Certificate No. 755863, cl. C 21 D 9/52, 1980. (54) METHOD FOR PROCESSING STEEL WIRE

(57) The invention relates to ferrous metallurgy, in particular to the hardware industry, and can be used in the manufacture of steel wire. The wire 1 with a copper-zinc coating in the area 2 between the current-carrying rollers 3 and 4 is heated in air by the electrocontact method with the help of a power source 5 to 900 ° C with a speed of more than

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1000 ° C / s. In the cooling section 6 formed by one incomplete turn of the cooled wire in contact with the surface of the current-carrying roller 4 along the arc, the wire is cooled from 900 to 350 ° C at a rate of 500 ° C / s. In section 7 between the current-carrying rollers 4 and 8, the wire is heated in air by the electrocontact method from 350 to 500 ° С with the help of source 9 and then the wire is cooled from 500 to 300 ° С in air, and in section 11 - from 300 to 50 70 ° C in water. 1 tab., 2 Il.

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The invention relates to ferrous metallurgy, in particular to the hardware industry, and can be used in the manufacture of steel wire.

A known method of treating steel wire, including patenting, consists in heating the steel wire in a muffle gas or electric furnace to 900–940 ° C, holding it at this temperature, isothermally cooling it in a lead bath at 500–520 ° C, and cooling it in air. After patentability, the steel wire is subjected to chemical and electrochemical etching, galvanic copper plating and galvanizing, and then a thermodiffusion treatment at 420-600 ° С in a muffle electric furnace.

The disadvantages of this method of heat treatment of the wire are low productivity due to the duration of the technological cycle, significant energy losses due to low efficiency of furnace heating, significant production areas occupied by the process equipment, harmful working conditions caused by the use of lead-melted baths.

The closest technical solution to the one proposed as a prototype is a method of treating steel wire, including sequential deposition of copper and zinc coatings on the initial wire billet, patenting and thermal diffusion treatment, carried out jointly by heating the steel wire with a copper-zinc coating in the molten synthetic slag to austenitic state at 900 ° C for 15 s, and subsequent slow cooling in air.

The disadvantage of this method is low productivity due to both the duration of heating the wire to the austenization temperature and the cooling time of the wire in the air required to form the sorbitol steel structure, as well as significant energy costs for maintaining the high temperature of the slag melt in the bath furnace. , low speeds of heat treatment of wire contribute to structural heterogeneity of steel, resulting in deterioration of fatigue and rheological properties of wires .

The aim of the invention is to improve the performance of the heat treatment process and the level of mechanical properties of the wire.

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This goal is achieved by the fact that in the method of treating steel wire, which includes the sequential electrolytic deposition of copper and zinc layers, heating to austenization temperature and air cooling, heating to austenization temperature is carried out at a speed of more than 300 ° C / s in an electric contact method, followed by cooling at a speed of at least 500 ° C / s up to 350-400 ° C by contacting the wire with a current-supplying roller, and prior to cooling in air, additional electrocontact heating is conducted from this temperature ry up to 480-520 ° С. In addition, the diameter of the current-carrying cooling roller Dp and its working temperature Tp are determined by the formula

 U-SP-T2) -360 °

DpUcp p-p (1)

 0.5 (Ti + Ta) + 0.25 l - d for Cn SpA a „(a, Tro - 1) 1 +0.25 d2 for C, Vcp a0 Oa;

where V is the speed of movement of the wire during heat treatment;

Ti is the temperature of the wire at the inlet of the cooling roller;

Ta is the temperature of the wire at the exit of the cooling roller;

VCp is the average rate of cooling of the wire at the site of its contact with the cooling roller;

9 - angle of coverage of the cooling roller;

d - wire diameter;

y is the specific density of the wire material;

Cn — specific heat capacity of the wire material;

a0 is the coefficient of thermal resistance of thermal contact wire-cooling roller TRO 25 ° C;

Oa is the temperature coefficient of thermal resistance of the thermal contact wire-cooling roller.

In the process of heating the steel wire with a copper-zinc coating to the austenization temperature of steel 900–950 ° C, carried out by the electrocontact method at a speed of at least 300 ° C / s, simultaneously with the formation of austenite, there is a complete mutual diffusion of zinc and copper to form a –latt and diffuse the brass layer into steel. Since the austenization temperature is reached by the wire, it is intensively cooled by the heat-contact method to 350-400 ° C at a speed of at least 500 ° C / s. At the same time, due to the high heating rate and the short residence time of the wire at high temperature, unacceptable oxidation and dezincification of the wire coating in air does not occur. The required cooling rate of the wire and its temperature at the exit of the cooling roller are ensured by choosing its diameter Dp and maintaining the temperature Tp determined from expressions (1) and (2). From the moment the wire leaves the contact with the cooling roller, it is heated at high speed in air from 350-400 to 480-520 ° C. At the same time, rapid decomposition of acetenite to sorbitol occurs in steel, which provides the necessary mechanical properties of the wire. After accelerated heating of the supercooled austenite, the pro-die is cooled in air from 480-520 ° to 300 ° C and finally cooled from this temperature to 50-70 ° C in water.

The electrolytic coating of the wire during its heat treatment provides protection for the steel base against oxidation, as well as reliable electrical contact with the current-carrying rollers in the heating sections and reliable thermal contact with the cooling roller in the accelerated cooling section. Thus, to ensure non-oxidative heating, there is no need for complicating the process equipment and no additional costs.

FIG. 1 shows a diagram of an apparatus for carrying out a method for treating steel wire; in fig. 2 is a plot of temperature distribution in selected portions of the wire in a steady state heat treatment process.

Example. The wire is heat treated with a diameter of 1 mm carbon wire. steel brand art. 60 after drawing, surface preparation and deposition of an electrolytic copper-zinc coating with a total thickness of 2 µm and the following chemical composition: copper 70%, zinc 30%. The speed of the wire during the heat treatment is 1 m / s.

The wire 1 with a copper-zinc coating in section 2 with a length of 870 mm, enclosed between the current-carrying rollers 3 and 4, is heated in air by an electrocontact method using a power source 5 to 900 ° C at a speed of more than 1000 ° C / s. On the cooling section b formed by one incomplete turn of the cooled wire in contact with the bronze cylindrical surface of the current-carrying roller 4 along the arc (p 340 °, the wire is cooled from 900 to 350 ° C

speed of 500 ° C / s. In this case, the working diameter of the current lead-cooling roller Dp for given conditions is

according to expression (1) 370 mm, and the operating temperature of the roller Tp according to expression (2) should be maintained at 140 ° C. On section 7, 240 mm long, enclosed between the current-carrying rollers

4 and 8, the wire is heated in air by the electrocontact method from 350 to 500 ° C using source 9 at a speed of 625 ° C / s. Next, in section 10, the wire is cooled from 500 to 300 ° C in air, and

section 11 - from 300 to 50-70 ° С in water 12. Steel wire with a brass coating, obtained by the above processing method, was subjected to mechanical tests, and its brass coating - to chemical and

X-ray structural analysis. The results of the mechanical tests and the results of the analyzes of the brass coating show that the properties of the wire comply with the requirements imposed on the steel brass-plated wire used as a blank for the manufacture of the cord.

Comparative heat treatment data on the proposed and known methods are given in the table.

The use of the proposed method of processing steel wire provides in comparison with existing methods the following advantages;

1. Improving the performance of the process by reducing the heat treatment time,

2. Improving the fatigue and rheological properties of the wire by increasing

structural homogeneity of steel.

3. Reducing the cost of the process by reducing energy losses.

4.Improve working conditions by eliminating the use of molten baths.

lead, salt and synthetic slag that have a harmful effect on the environment.

Claims (2)

The expected annual economic effect as a result of using the proposed method of treating steel wire will be 45,569 thousand rubles. Claim 1. Method of treating steel wire, including sequential electrolytic deposition of copper and zinc layers, heating to austenization temperature and air cooling, characterized in that, in order to increase productivity and level of mechanical properties, heating to austenitization temperature is carried out at a speed of more than 300 ° C / s using the electrocontact method, followed by cooling at a speed of at least 500 ° C / s to a temperature of 350-400 ° C by contacting the wire with a current-conducting roller, and before cooling in air t additional electric contact heating from this temperature to 480-520 ° С. 2. A method according to claim 1, characterized in that the diameter Dp of the current-carrying cooling roller and its operating temperature Tp are determined by the formula V (Ti - T2) 360 ° DD mm Ucp t 0.5 (Ti + Ta) + 0.25 l y C „Usr a0 (a, Tro - 1) p1 + 0.25 - lg-d2 - y Civ Vcp - Zo-a where V is the speed of movement of the wire during heat treatment; Original wire Famous Offered Ti is the temperature of the wire at the inlet of the cooling roller (austenation temperature); Ta is the temperature of the wire at the exit 5 of the cooling roller; VCp is the average rate of cooling of the wire at the site of contact with the cooling roller; p is the angle of coverage of the cooling roller; d is the diameter of the wire; y is the specific density of the wire material; Cn is the specific heat capacity of the wire material 15; a0 is the coefficient of thermal resistance of the thermal contact wire-cooling roller at a temperature cooling roller 25 ° С; 0eta is the temperature coefficient of thermal resistance of the thermal contact wire-cooling roller. 5 G, C