SU1527288A1 - Method of producing broad-strip ferrite stainless steel - Google Patents

Abstract

The invention relates to ferrous metallurgy, namely to the hot rolling of stainless steel strips. The aim of the invention is to increase the yield by reducing the breakage of the ends and welds of the strips during rolling and reducing waste. The slab of steel 15X25 is heated at a rate of 15 ° C / s to 1320 ° C, then rough rolling with a reduction of 24% and simultaneous cooling is carried out, and in the interval 1210-1100 ° C, rough rolling is carried out with cooling at 40 ° C / with. After the rough rolling, the metal passes through a continuous furnace at a temperature of 960 ° C for 70 s. Finishing rolling with a reduction in the last pass of 25% is carried out with cooling at a rate of 10 ° C / s to 850 ° C. Cooling from the end of rolling to the coiling temperature is conducted at a speed of 25 ° C / s. 2 hp ff, 1 tab.

Description

The invention relates to ferrous metallurgy, namely to the hot rolling of stainless steel strips of type 15X25T.

The aim of the invention is to increase the yield by reducing the breakage of the ends and welds of the strips during rolling, rolling, welding and reducing waste due to the unsatisfactory quality of their surface.

Example. Mill 2300/1700 LPTs-1 Chelyabinsk Metallurgical Plant, when rolling hot rolled strips of 15X25 steel, implements modes that include the conditions of both known and proposed solutions. The data are given in the table.

From the data in the table it is clear that rolling on the known

the method (experiments 1-3) is accompanied by deterioration of the strip surface due to the presence of prints from rolls, broken ends during coiling and welds, during welding and etching. The rolling results of the proposed method are given in experiments 4-6. Deviation | FROM the recommended values of the proposed parameters is accompanied by a decrease in yield and quality.

Increasing the heating temperature for rolling up to (experiment 7) reduces the yield due to metal breaks in the mill, and lowering the heating temperature to 1260 ° C (experiment 8) reduces the surface quality due to the presence of imprints from the rolls.

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The mind (1 bP yenke heating rate under the prokalu to C / s (test 9) reduces the yield due to breaks in the ends and smooth seams, while increasing the heating rate to 20 ° С / s (test 10) requires special measures to increase the heat capacity of the furnace, accompanied by metal breaks in the mill and cannot be used continuously due to the reduced resistance of the refractory masonry. Chernov rolling at 1260-1100 ° C (test 11) requires heating for rolling above i13 iO C and is accompanied by a decrease in yield due to gusts of metal in the mill Chernova rolling at 1210-10 80 ° C (run 12) reduces the yield due to the fact that the temperature required is not provided for the end operation, the end of the rolling temperature is below 750 ° C, and imprints from the rolls appear on the strip.

The cooling rate at 1210-, equal to 5 ° C / s (experiment lA), does not provide for the equalization of temperature across the strip width, which leads to a loss of flatness during finish rolling, poor winding and a decrease in the yield.

Reducing the cooling rate at 1210-1 10P ° C to (experiment 13) requires a special device and reduces the yield due to the disconnections of the ends of the cross-section and the welds.

Increasing the cooling rate during finish rolling (test 15) reduces the quality of the surface due to the fact that the rolling end temperature is not ensured and prints from the rolls appear on the strip, and reducing the cooling rate to 3 C / s reduces the yield suitable because of breaks in the ends and welds (experiment 1b)

Isometric exposure at a higher temperature (experiment 19) requires heating for rolling above and is accompanied by the destruction of the metal in the mill line. Reducing the temperature of isothermal exposure to (experiment 20) reduces the quality of the surface due to imprints from the rolls on the strip.

An increase in the duration of isothermal exposure to CO with (experiment 18) is accompanied by breaks in metal ends and welds. An isothermal holding time of 20 s (test 17) is accompanied by poor winding due to unsatisfactory flatness of metal tape.

Cooling before winding at a speed of 29 ° C / s (test 22) reduces output due to poor winding and surface quality, and when cooled at a speed of 10 C / s (test 21), the yield decreases due to breaks in the ends of the bands and seams .

The application of the proposed method will increase the yield by reducing the breaks in the ends of the strips and welds; to improve the quality of the surface of the strips by eliminating the prints from the rolls and to reduce the heat loss of the buffer metal

Claims (2)

1. Method of production of broadband ferritic stainless steel, including metal heating, rough and finish rolling with simultaneous cooling and with isothermal holding between them in a predetermined temperature range and compression in the last pass 15-25%, the end of rolling at 850-750 C, cooling before coiling followed by welding and etching, differing The fact that, in order to increase the yield, heat is conducted to 1280-13 O C at a speed of 5-15 C / s, cooling during rough rolling in the range of 1210-1100 ° C is carried out at a speed of 20-40 ° C / s, isothermal aging is carried out for 40-120 s, cooling during finish rolling is carried out at a speed, and before winding cooling is performed at a speed of 15-25 ° C / s. 2. A method according to claim 1, characterized in that the isothermal aging is carried out at 10 0 to 9 ° C.