SU1359319A1 - Method of producing zinc-plated steel strips for particularly complex drawing - Google Patents

Abstract

The invention relates to metallurgy and can be used in the preparation of galvanized steel strips intended for particularly complex drawing. The goal is to increase the mechanical characteristics. After hot rolling, the steel is first annealed in a bell-type furnace at 690-720 ° C with a preliminary charge for 3 to 12 hours at 530-600 0, and then in the zinc line with heating to 520-540 ° C at a rate of 7- 14 deg / s and further up to 550-590 ° C with a speed of 0.5-1.5 deg / s. After firing, cooling, overdrying of the zinc coating is carried out and training of the finished sheet is carried out. 1 tab. fQ (L from 01 from 00 aL X)

Description

The invention relates to metallurgy and can be used in the preparation of galvanized steel strips intended for particularly complex stretching.

The aim of the invention is to increase the mechanical characteristics.

Example 1. Steel grade 08U was melted into oxygen by one converter and cast in a continuous casting plant. After hot rolling of the slab, a strip with a thickness of 3.0 mm was etched in salt-water baths and cold rolled to a thickness of 0.8 mm.

Before applying the zinc coating, the cold-rolled strip was subjected to annealing in a bell-type furnace and the line of the galvanizing unit in accordance with the invention (limit and average values) according to the following mode: in bell-type furnaces, heating to 530, 565, held at these temperatures 3, 7, 12 h; a further increase in temperature up to 690, 705, 720 ° С and a shutter speed of 5 hours; 110 °

From to

excerpt D-h; cooling to shielding gas, then in air; in the line of the galvanizing unit it is heated up to 520, 530, 540 ° С at a speed of 7, 10, 14 deg / s; a further increase in temperature to 550, 570, 590 ° С at a rate of 0.5; one; 1.5 degrees / s and exposure at these temperatures for 50 s, cooling, overdrying and applying a zinc coating; training of mountains of a galvanized strip with compression of 0.8%,

The quality of the steel obtained after such processing is given in the table (examples 1-3).

Example 2. The same steel before applying a zinc coating under.

we call stepwise annealing in accordance with | with a prototype for mode 1–1: in the cluster furnaces, the heating is up to 670 ° С and the shutter speed 5 is protective

h; cooling to. 110 C in gas, then - in the air;

in the line of the galvanizing unit up to 680 ° С with a peak of 30 s;

heat oh; - | azhde

five

0

five

0

zinc coating, digestion and application.

The quality of steel after such processing and training with compression of 0.8% is given in the table (example 4).

In all cases, nitrogen gas with a content of 4.8% hydrogen was used as a protective medium.

The table shows that the proposed method of heat treatment of galvanized steel strips for particularly complex stretching reduces the yield strength by 6–13%, increases the relative elongation by 4–10%, and increases the yield of steel for higher exhaust heat by 9–11 %

The proposed heat treatment modes for galvanized steel strips for particularly complex stretching are optimal.

Claims (1)

Invention Formula The production method of galvanized steel strips for particularly complex drawing, including a two-stage annealing, cooling, perevarivanie and applying a zinc coating, characterized in that, in order to improve the mechanical characteristics, in the first stage, annealing is conducted stepwise with an exposure first at 530-600 ° C for 3-12 hours and then at 690-720 ° C, and in the second stage - with heating up to 520-540 C at a speed of 7-14 g rad / s and then up to 550-590 C with a fraction of 0.5-1, 5 degrees / s 00 CVJ Cg vf ft 00 n about s f 00 r CN | about  tN 1L 00 at about i about (§