SU1528800A1 - Method of thermomechanical treatment of steel plate - Google Patents

Abstract

The invention relates to rolling production, in particular to the manufacture of thick sheets of low alloyed steels intended for products operating at low temperatures or high pressures. The purpose of the invention is to increase the strength and viscosity properties of rolled products. Ingots from steel 22K were heated in furnaces up to 1150–1200 ° C and rolled into a finished hot rolled sheet 20–140 mm thick with a rolling end temperature of 950–980 ° C, depending on the sheet thickness. Hot-rolled sheet at the exit of the mill was sent to the installation of accelerated cooling, where it was cooled at a speed of 5 to 20 degrees / s to 770 - 700 ° C. After accelerated cooling in air to 760 - 690 ° C, the sheet was quenched. 1 hp f-ly, 2 tab.

Description

The invention relates to rolling production, in particular to the manufacture of thick sheets of low alloyed steels intended for products operating at low temperatures or high pressures.

The purpose of the invention is to increase the strength and viscosity properties of rolled products.

The ingots (slabs) for rolling are heated in furnaces to a temperature of 1200 IISO C and rolled onto a finished hot rolled sheet with a thickness of 20-1.0 mm mm with a rolling end temperature of 950-880 C, depending on the thickness of the sheet. The resulting hot rolled sheet, on leaving the mill, is immediately transported to an installation of accelerated cooling of a laminar or water / air type located on the outlet roller table of the mill, where it is subjected to accelerated cooling at a speed of 5-20 degrees / s to the temperature of the upper part of the two-phase region Ar Ar-ar

After the accelerated cooling, the sheet is cooled in air to a temperature of 760-690 ° C, transporting it along the roller table from the accelerated cooling unit to the quenching tank. The transportation speed is chosen so that during the transportation time the content of the agglomerate in the steel before hardening soybean: l

to

eo

00

approximately 10-30%, depending on the level of strength required.

The content of residual austenite is controlled by the magnitude of the magnetic permeability of steel. With reference to low-alloyed steel, m and air cooling are carried out for 20-60 s. Then the sheet using tilting device on the table. 1 shows the mechanical properties of the finished place | as well as the power parameters and the performance of the proposed method compared with the known, based on the same processing parameters.

Compared with the known treatment, the proposed method provides

and toughness as well as cold resistance while maintaining plasticity.

In tab. Figure 2 shows the data confirming that the cooling rate is 5–20 degrees / s is best suited for obtaining sheets with increased strength and viscosity.

They are placed in a quenching tank with water and a great strength (by 30-50 MPa) is heated to room temperature, which ensures the transformation of austenite into bainite and martensite,

PRI me R 1. On a plate mill 5000, thermomechanical js processing of 22K steel was carried out with the following chemical composition, wt.%: C 0.22; Mp Oh, W; Si 0.36; S 0.015; P 0.012; V 0.02; Ti 0.02. Critical points of steel at cooling С, Ag ro 670 ° С. The metal according to the proposed method was processed according to the technology that includes heating the slabs up to 1130 ° C, rolling mill sheets with a thickness of 0 mm with a rolling end temperature of 25,900 ° C, and accelerated cooling of dushar10 degrees / s

Formula

invented

with water at a rate of up to 750 ° CJ air cooling for 30 s before quenching in the quenching tank to room temperature. During the rolling process, the rolling force was measured and, to calculate the productivity, rolling cycles were recorded,

EXAMPLE 2. The rolling and thermomechanical processing conditions given in Example 1 were followed. The speed of the accelerated cooling after rolling was varied: n: 3.5.10 and 20 degrees / s.

thirty

35

40

Claims (2)

1. The method of thermomechanical treatment of steel sheets, including heating, hot rolling from the end in the austenitic region, accelerated cooling at a given speed and deposition in air, characterized in that, in order to improve the strength and viscous properties of the rolled product, accelerated cooling is taken to a temperature Ag ... .Ar.j-Ar one ., air cooling in to a temperature not lower than Ar ,, and then cooled in water. 2. The method according to claim 1, wherein the accelerated cooling is performed at a speed of 520 degrees / second. Heating temperature for rolling P50 C. and impact strength and cold resistance while maintaining plasticity. In tab. Figure 2 shows the data confirming that the cooling rate of 5-20 degrees / s best responds to the preparation of sheets with increased strength and viscosity. greater strength (30-50 MPa) Formula the invention 1. The method of thermomechanical processing of steel sheets, including heating, hot rolling with the end in the austenitic region, accelerated cooling at a given speed and cooling in air, characterized in that, in order to increase the strength and viscosity properties of rolled products, accelerated cooling is carried out to a temperature Ar ... Ar. jr Ar 1 ., air cooling lead to a temperature not lower than Ar ,, and then cooled in water. 2. The method according to claim 1, wherein the accelerated cooling is performed at a speed of 520 deg / s. Table I Hot rolling, t, yOO-880 ° C-, accelerated cooling to 750 ° C, cooling in air for 30 s to, cooling in water. Editor M.Nedoluzhenko Order 7616/23 VNIIPI State Committee for Inventions and Discoveries at the State Committee on Science and Technology of the USSR P3035, Moscow, Kh-35, Raushsk nab. d. TS / Production and Publishing Combine Patent, g, Uzhgorod, Gagarin st., 101 Table 2 Compiled by T, Homeland Tehred L. Serdyukova Proofreader N. Korol Circulation 530 Subscription