CS201335B1 - Method of producing high-strength wire - Google Patents

Description

The invention relates to a method of producing high strength carbon steel wire and solves the problem of increasing the wire strength properties in a state after heat treatment from an austenitization temperature and subsequent cold drawing.

Production of quality wire with carbon content from 0.4% to 1.2% by weight, manganese to 1.2% by weight, silicon up to 0.4% by weight. and with chromium, nickel and copper contents of up to 0,2% by weight. and with a fine perlite structure and high strength parameters and good cold formability, it is currently carried out mainly by either patenting in lead, molten salts or air, or in various ways controlled cooling of the wire from the rolling temperature. Patenting is a heat treatment that involves heating the wire to an austenitizing temperature and then cooling it with air or in molten lead or salts to break down austenite to ferritic-pearlitic structures. By processing in lead or in salts, an optimum microstructure of very fine perlite can be achieved in carbon steels with a minimum of other structural components. Such a steel structure exhibits very good cold-drawing formability and high wire strength and plasticity in the drawn state. The disadvantage of this processing is the high cost of heating the wire and the cooling environment (lead, salt). Controlled wire cooling uses post-rolling temperatures such as austenitization temperatures, and cooling is performed in most industrial plants by forced air flow, or else in environments with higher thermal conductivity, such as aqueous detergents or soaps, forming steam shells or swirl layers around cooled wire. metal oxides. The advantage of controlled cooling over patenting, especially when air cooled, is a much lower processing cost and a higher processing speed. The disadvantage is that the anisothermal austenite decomposition process, such as that under controlled cooling, does not allow the optimum wire microstructure to be obtained and consequently results in lower wire strength parameters both after heat treatment and in the drawn state.

These disadvantages are overcome by a process for producing high-strength wire from steel containing 0.4 to 1.2% by weight. % carbon, traces up to 1.2 wt. manganese, traces up to 0.04% silicon by weight, traces up to 0.2% by weight % of chromium, nickel and copper; and 0.10 to 0.25 wt. vanadium, by cold drawing, according to the invention. The principle of the invention is that the wire is cooled from austenitizing temperature of 950 ° C to 1100 ° C at a rate of 5 to 40 ° C / s prior to cold drawing until the wire temperature drops to 780 ° C and below, and then cooled freely in air .

By using the high strength wire manufacturing process according to the invention, the mechanical properties of the wire are increased while reducing the cost of preparing the cold drawing material with high overall removal rates.

According to an exemplary embodiment, a material of 0.7 wt. % of carbon, 0.55 wt. % manganese, 0.25 wt. % silicon, 0.02 wt. % nickel, 0.06 wt. % of chromium, 0.20 wt. % copper and microalloyed vanadium in an amount of 0.12 wt. After rolling, the controlled wire was cooled from a post-rolling temperature of 1050 ° C by water to 780 ° C and further by air at an average cooling rate of 12 ° C / s. In order to compare the tensile strength achieved, steel with the same content of carbon, manganese, silicon, chromium, nickel and copper, but without vanadium, was treated in the same way. This steel was also patented in lead. Table 1 shows the increase in the strength of the vanadium-micronized steered refrigerated wire against vanadium-free carbon steel, and the achievement of the patented carbon steel wire level by controlling the cooling of the vanadium microalloyed carbon steel.

Table 1

Mechanical properties of wire rod 0

5.5 mm

%C carbon 7o vanadium pulse. treatment MPa tensile strength 0.70 0 controlled cooling 980 0.70 0 patenting in lead 1150 0.70 0.12 controlled cooling 1160

This wire was drawn from the starting diameter

5.5 mm to a final diameter of 2.24 mm with partial cuts of 20 to 22%. After drawing, the values of tensile strength, number of alternating bends and number of torsion to fracture were obtained according to Table 2.

Claims (1)

Process for producing high strength wire from steel containing 0.4 to 1.2% carbon, traces up to 1.2% manganese, traces up to 0.04% silicon, traces up to 0.2% chromium, nickel and copper and 0.10 to 0 25% by weight of vanadium by cold drawing, characterized in that the wire is cooled from a post-rolling austenitizing temperature of 950 ° C to 1100 ° C at a rate of 5 to 40 ° C / s until the wire temperature drops to 780 ° C, whereupon it is freely cooled by air.