SU1258523A1 - Method of producing cold-rolled high-strength strip - Google Patents

Abstract

The invention relates to rolling production and can be used in the manufacture of cold rolled hard carbon and spring steel tapes used for motor chains. The purpose of the invention is to increase ductility and uniformity of properties while maintaining strength. The method consists in the fact that cold rolling is carried out with a reduction of 30-60%, and annealing is carried out at a temperature below the recrystallization temperature of 40-200 C. Table 4. (fl C

Description

11258523

The invention relates to rolling production and can be used

In the manufacture of cold-rolled carbon steel and spring steel used in mechanical engineering for the manufacture of motor chains, clutch discs and other parts.

The purpose of the invention is to increase the plasticity and uniformity of properties while maintaining strength.

In tab. 1 are given the modes of annealing and the properties of carbonized tape.

T and b l and ji a 1

From the data table. 1 it follows that the temperature of the onset of recrystallization

Example 1. A hot rolled strip of steel 3.2 mm thick, 1400 mm wide is subjected to a longitudinal dissolution to a 450 mm wide strip, then etched in a continuous line. After etching, the ribbons are rolled up to a weight of 10 tons and the softening annealing of the coil is carried out, after which cold rolling is carried out with a reduction of 31.3% to a thickness of 2.2 mm. After cold rolling, the coiled-up coils have an inner diameter of 750 mm, an outer diameter of 2000 mm. Annealing of coil 35 is carried out in a single-color bell-type furnace with a set weighing 50 tons and heated in a gas environment (4-6% H, 94-96 NJJ). The heating rate at the leading point of the load is 100 s / h, in the lagging

65G cold-rolled steel strip - At a set point of 12.5 C / h. After heating

It is around 600 ° C. Annealing the ribbon at a temperature below the recrystallization temperature is 40–200 ° C, i.e. at 400-580 ° C, it provides strength properties within the normal range for hard-rolled tape. The ductility of the tape from steel 65G, made by the proposed method, is 3 times higher than from the tape, made by a known method.

Processing at 350 ° C and below does not provide a strength of less than 1200 MPa.

Processing at a temperature higher than the temperature of the onset of recrystallization

five

0

(620 C and above) leads to intensive softening, at annealing temperature the strength of the tape is reduced to 675 MPa (according to the standards, the strength of the stretched tape must be at least 750 MPa).

The treatment according to the proposed method provides a high-strength tape with properties, d4) fermented according to strength classes Hi (over 750 to 900) H2 (more than 900 to 1050), NC (over 1050 to 1200). Annealing at 550-580 ° С ensures the obtaining of class H1 strength, annealing at 450-500 C - class H2, and at 400-450 C - class NC. Any of these three modes provides tape with class H strength (over 750 to 1200).

Example 1. A hot rolled strip of steel 3.2 mm thick, 1400 mm wide is subjected to a longitudinal dissolution to a 450 mm wide strip, then etched in a continuous line. After the pickling, the ribbons are rolled into a weight of 10 tons and the softening annealing of the coil is carried out, after which cold rolling is performed with a reduction of 31.3% to a thickness of 2.2 mm. After cold rolling, the coiled-up coils have an inner diameter of 750 mm, an outer diameter of 2000 mm. Annealing of coils 5 is carried out in a single-color bell-type furnace with a set weighing 50 tons and heated in a gas environment (4-6% H, 94-96% NJJ). The heating rate at the leading point of the load is 100 s / h, in the lagging

five

0

Released for 10 hours to equalize the temperature across the thickness of the coil winding. At the end of the migration, cooling to 150 ° C is carried out. For those 45, the rolls are cooled at the warehouse to ambient temperature, subjected to longitudinal dissolution with a cut edge on cutting units with edge winders and mechanical testing.

50 The test results of the mechanical properties of high-strength tape of steel made by the proposed method are given in table. 2

Processing at a temperature of 400-430 С provides obtaining strength in the range of 1050-1200 MPa (class NC) at 4 0-500 0 - obtaining strength in the range of 900-1050 MPa (class H2); at 500-550 С - obtaining strength 3 within 750 - 900 MPa (class H1) 30

Example 2. A hot rolled strip of steel with a thickness of 6.0 mm and width of 1,400 mm is subjected to dissolution into a strip 450 mm wide, then etched, softening annealing, with cold

25

33.3 400-430 480 33.3 500-530 681

table 2

prok; ke to thickness, 4.0 mm (33.3% tolerance), winding into a roll weighing 10 tons and annealing by the proposed method as described in example 1. The chemical coagulation of steel has the following,%: С 0.50; Si), 28; Mp 0.68; S 0.024; P 0.030; Cr J, 04; Ni 0.07; Si 0.13; A1 0.005.

The test results of the mechanical properties of the tape from steel by strength class H (750-1100), HI (750-950), H2 (-900-1100) and plasticity are presented in Table. 3 and 4.

| T a b i c a 3

957

1042 935

3.2

8.2 9.7

Lower edge for annealing

Middle width; ribbons

Edge upper

Lower edge for annealing

Tape width average 861 - Edge top for annealing

Lower edge for annealing

The width of the tape 823 "I

Edge annealed

Annealing at a temperature below the recrystallization temperature of more than 200 ° C does not provide the necessary increase in ductility of the tape. When the ribbon is cut with edge trimming on the cutting units with heels, the edge is wound unstable, due to insufficient ductility often breaks, which reduces the performance of the cutting units

Table A

1052

8.5

27

269

Averaged values of mechanical properties

838

1033

9.6

28,283

Annealing at a temperature below the recrystallization temperature of less than 40 s results in a decrease in the strength of the welded tape below the standards. The maximum annealing temperature must be below the recrystallization temperature in order for the y4ectb fluctuations in the temperature of the onset of recrystallization due to the variations in the chemical composition of the metal from the melt.

71

ki to smelting and non-uniformity of deformation from strip to strip, caused by longitudinal and transverse thickness variation of hot-rolled steel.

The implementation in the method of cold rolling with a relative compression of 30-60% provides a reduction in the production cycle, increased productivity and energy savings.

Cold rolling with a reduction of less than 30% is irrational from the point of view of cold mill productivity. rolling. Compression of more than 60% leads to tears on the edge, which reduces the yield in the production of the tape.

The economic efficiency of the proposed method as compared with the known one is to increase the productivity of the cold rolling process, to obtain a tape from carbon and spring steel with high ductility while maintaining strength.

The productivity of the process of longitudinal dissolution with trimming is increased due to the possibility of trimming high-strength tape on edge-cutting machines. Besides

Editor O. Golovach Order 5061/10

Compiled by V. Vasiliev

Tehred A. Kravchuk-. Proofreader. Shekmar

Circulation 518 Subscription

VNIIPI USSR State Committee

for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5

Production and printing company, Uzhgorod, st. Project, 4

0

8523

eight

In addition, it creates the possibility of making high-strength carbon steel spring tape in thicknesses of 1-4 mm with differentiated strength in accordance with the norms. In the implementation of the proposed method, an increase in the homogeneity of metallic properties over the thickness of the tape and the yield of a suitable material is achieved, as well as a high uniformity of the strength properties. So, the run-up on strength within one roll weighing 10-12 tons does not exceed 60 MPa.

Claims (1)

15 Formula of the invention A method of manufacturing cold-rolled high-strength tape, predominantly of carbon and spring steel, including hot rolling, softening, cold rolling, annealing and longitudinal dissolving of the tape with trimming, in order to improve ductility and uniformity of properties while maintaining strength cold rolling is carried out with a reduction of 30-60%, and annealing is carried out at a temperature below the recrystallization temperature for 40-200 s.