SU1346290A1 - Method of rolling reinforced sections from low-alloyed steels - Google Patents

Abstract

The invention relates to rolling production and can be used in the production of reinforcing steel type 20 HS, 35 HS, heat-strengthened in the hot rolling mill line. The purpose of the invention is to increase the plastic properties of rolled products while reducing the energy-force parameters of the rolling process. In the course of rolling the oval peal, the passage through the lead wiring, the cooling device, the lead wiring, enters the finishing gauge. Rolling speed of 8 m / s. By setting the cooling device at different distances from the finishing gauge, time intervals can be varied after cooling before finishing rolling. Keeping the time interval during rolling in the range of 0.1-0.3 s after the end of cooling, an increase in plastic properties of 1.1-1.2 times (65 12.3-13.5%) is achieved in comparison with the method of the prototype, and the power rolling parameters will be 0.85-0.95 of the rolling effort of the unstressed roll. 6 ill., 2 tab. f (L co 4 05 GO co

Description

The invention relates to rolling production and can be used in the production of reinforced steel heat-treated in a hot rolling mill line.

The aim of the invention is to increase the plastic properties of the rolling stock while reducing the power parameters of the rolling process.

FIG. 1 shows the flow chart for the implementation of the proposed method; in fig. 2 - cooling device with the workpiece before entering the finishing caliber, transverse section; in fig. 3 is a diagram of the deformation stresses when rolling an oval billet in the finishing caliber; in fig. 4 is a schematic of thermal stresses in the workpiece with intensive cooling; in fig. 5 shows the scheme of thermal stress distribution after intensive cooling in the range of 0.1-0.3 s; in fig. 6 the distribution of residual stresses in the cross-section of rolled products.

Example. The proposed snoot is examined in a laboratory mill 210.

Samples of sizes 13X 17X 300 and 20X ZOX 300 are heated in a muffle furnace to average temperatures on the surface of 950–980 ° C. During rolling, the heating temperature, pressure of the metal on the rolls and its dose established between the rolls HjeeK rolls are measured. rolling and load current of the motor with registration on the axis: lo1 rafe.

Rolling is carried out in three modes:

1st mode (but known G | method). Immediately after 1 heat treatment, without forcing, the sample taken out of the tongue is rolled in p; fly. Measurements of roll pressure, rolling moment and load current give the following results: 29.3 tons; 1.2 tm; 210 A.

11th mode, (by a known 2 method). The heated sample is placed in front of the entrance to the deformation zone in a special introductory wiring, into which water is supplied to meet the movement of the sample to the roll. The cooling time and intensity are experimentally determined, and immediately after cooling, the surface of the samples cools down to 720 730 ° C, and after heating it becomes 890-920 C. Then the sample, thus cooled, rolled into the cage immediately after oh, 1) 1 and. Measured results are as follows: pressure on the wa. 31.2 t; rolling moment 1.32 tm; load current 227 A.

P1-th re: Kim {according to the proposed method). Heated up to 950 ° C and pushed under pressure at mode 11, the samples were not rolled into the stands at once noc; i.e., cooling, but during a temporary iggerwal after () x, 11 wait, equal to 0.08 --- 0, G s; 0.2 s; 0.3 s; 0.4 s.

The cooling is carried out according to the scheme (Fig. 1), including the finishing 1 and pre-calibration caliber 2, the input 3 and the output 11th 4 wiring; cooling device 5; channels 6 to provide non-uniform cooling of the oval and a cooled workpiece 7.

When rolling, the oval profile 7 comes out of gauge 2, passes through lead wiring 4, cooling device 5, and through lead wiring 3 is sent to finishing gauge 1.

The cooling device 5 has the same length of the cooling unit, equal to 40 cm, as the input wiring 3, and it can be shifted between the cages 1 and 2, providing a different time between the end of the cooling

0 in the cooling device 5 and the deformation in the finishing caliber. Rolling speed 8 m / s.

An analysis of the results of the experiment showed that the greatest reduction in the power rolling parameters occurs at a time interval after the end of cooling, equal to 0.1-0.3 s.

The power and force parameters of rolling in the proposed time interval are presented in Table. one.

0 In the first mode, 5 tons of thermally hardened rolled products are rolled from 25GS steel, but in the second mode - 2 tons and in the third mode - 1.5 tons of reinforcing bars N ° 14 at the industrial mill 350. Samples are taken from the rolled rods to determine

5 mechanical properties. The mechanical properties of the rolled products obtained after treatment according to the modes are given in table. 2

As can be seen from the table. 2 strength properties of finished rolled products are almost the same, however, the plastic properties are the smallest when rolling without being chilled. As a result of rolling according to a known method, the plastic properties stabilize and increase relative to mode I, and the rolling properties of the proposed parameters increase the plastic properties 1.1 -1.2 times. This is due to the fact that the proposed method, like the well-known one, compensates for the unevenness of the deformation in width, and, consequently, the residual stresses of the deformational character. The compressive thermal stresses of the known and proposed methods (Fig. 5) in the central part of the rolling stock are compensated for by the tensile residual stresses of a deformation nature. But at the same time, the proposed method reduces the residual

5 deformation stresses in height, which are tensile at the center of the rolled product and compressive at the surface. Due to the peculiarity of the deformation in the calibers of the armature rods, as well as other round profiles, the deformation of the cross section elements occurs unevenly. The central metal layers (where the rod section is shown at a height) along the connector line of the gauges are mainly assembled (Fig. 3); they go to the drawing weaker than the surface layers, especially

c in the central parts of the cross section, and as a result, residual strain stresses occur in the cross section of the circular profile according to fig. 6. Such residual deformation scheme

0

five

0

the stress during the subsequent accelerated cooling, when tensile stresses act on the surface (Fig. 4), and compressive stresses in the center, aggravates the pattern of stress distribution, as the tensile stresses in the zones (Fig. 6) add up. At the same time, the austenite decomposition over the cross section of rolling is uneven in the zone of action of tensile stresses more intensively, and vice versa, which leads

manganese and silicon steel type 20GS. 20G2S, 35GS.

Claims (1)

Invention Formula The method of rolling reinforcing profiles of low-alloy steels containing manganese and silicon, including rolling an oval section billet in a round gauge with adjustable cooling before This, in turn, is structurally rolled by rolling with intensity that provides for stresses. In the central part of the reinforcing bar section, under the combination of these conditions, microcracks develop, which are easily detected if the accelerated temperature difference between the cooled and uncooled surface areas and between the cooled surface layer and the uncooled core of the workpiece in the dietemperature after rolling is within 30-100 ° C, characterized in that, in order to increase the plastic properties of the rolling stock while reducing the power parameters of the rolling process, after controlled cooling, an additional holding for 0.1-0.3 s, and then start rolling in a round caliber. Table 1 Let not finish at a temperature of 100-250 ° С with a total reduction of 370-450 ° С, and cool the rental to room temperature, i.e. 20-30 °. In this case, in the central part, the cross-section of the car along the vertical (Fig. 6) are formed not micro, but longitudinal along the entire length of the rolled macrocrack, well visible with the naked eye. When cooled to 20-30 ° of rolling with undercooling according to the proposed method, no cracks are observed in the vertical part of the rolled section. Compensation of the deformation residual stresses in the zones is carried out by imposing on the distribution pattern of the deformation stresses (Fig. 5) thermal stresses in the rod after local compression in the interval 0.1-0.3 s. The proposed method makes it possible to increase the plastic properties of thermomechanically hardened rolled products from low carbon and low alloyed while reducing the energy-force parameters of rolling. 25 Options t, s ABOUT, I :: °; L :: I 0.3 thirty and tm I, And 28.2 1.1 198 27.5 1.15 196 27.3 1.17 198 Cooling mode 88.4 87.2 93.5 86.2 88.3 83, A 85.6 manganese and silicon steel type 20GS. 20G2S, 35GS. Invention Formula The method of rolling reinforcing profiles of low-alloyed steels containing manganese and silicon, including rolling an oval section billet in a round gauge with adjustable cooling before  rolling with intensity, ensuring the temperature difference between cooled and uncooled surface areas - and between the cooled surface layer and the uncooled core of the workpiece in di-temperature after rolling in the range of 30-100 ° C, characterized in that in order to increase the plastic properties of the rolled product while reducing the energy-force parameters rolling, after controlled cooling, an additional exposure is carried out for 0.1–0.3 s, and then rolling in a round gauge begins. Table 1 range 100-250 ° С with a general decrease  range 100-250 ° С with total 25 Options t, s 50 ° C with a total decrease ABOUT, I :: °; L :: I 0.3 range 100-250 ° С with a general decrease and tm I, And 28.2 1.1 198 27.5 1.15 196 27.3 1.17 198 Table Continued table. 2 1 FIG. 2 Rolling direction at Fi.Z Line unloading Fig.FPhag. five Formation zones Compiled by Yu L mov Editor A. VorovnchTekhred I. VeresKorrektor A. Ilyin Order 4642/12 Circulation 480 Subscription VNIIG1I USSR State Committee on Inventions and Discoveries I 13035, Moscow, Zh-35, Raushsk nab. 4/5 Production and printing company, Uzhgorod, ul. Project, 4 6