CN101941024A - Method for eliminating peeling of IF steel edge in hot continuous rolling process - Google Patents

Abstract

The invention provides a method for eliminating peeling of IF steel edge in a hot continuous rolling process, belonging to the technical field of steel rolling. The technical process comprises the following steps: detecting the phase change temperature of IF steel in the hot rolling process by adopting a physical simulation method; properly increasing the temperature of a tapping side of the furnace by a heating furnace by adopting micro positive pressure control to ensure that the transverse temperature difference of a plate blank is controlled to be not higher than 20 DEG C; regulating time sequence of rolling and descaling to avoid temperature of the strip edge from falling into a coexistence region; using an upstream spray pattern to replace side jet for cleaning descaling water of rough rolling and fine rolling to prevent the strip edge from water washing; and taking the temperature of the fine rolling inlet as a control target, which is controlled to be between 1,030 and 1,060 DEG C. The invention has the advantages of simple method and high efficiency. By using the method, the defect of edge peeling of the IF steel can be easily solved under a condition of not influencing the production situation and the performance of the IF steel.

Description

A kind ofly eliminate the method that skin is stuck up in IF steel limit portion in the hot continuous rolling process

Technical field

The invention belongs to technical field of steel rolling, particularly relate to a kind of method that skin is stuck up in IF steel limit portion in the hot continuous rolling process of eliminating, be applicable to that eliminating the hot rolling IF steel wire that strip edge portion cracking produces in the operation of rolling sticks up skin.

Background technology

The IF steel is as a kind of deep-draw steel of excellence, and the user generally is applied in automobile with it, and household electrical appliances etc. need high mouldability field, and the user is also more and more higher to its surface requirements.It is a kind of very common and influence a kind of very serious defective of its surface quality that the wire that strip edge portion occurs after the hot rolling is stuck up skin, this defective has very strong heredity, if will have the strip of this defective continues cold rolling, then can cause the cold rolled sheet surface spot to occur, broken belt also can take place in serious, and these stick up the wiping scuffing that Pi Haihui causes cold rolling touch roll.The measure of generally taking at present is skin excision back to be stuck up in hot-strip limit portion use, and adopts this method can cause great waste, has influence on band steel lumber recovery, but also can have influence on production efficiency.

Application (patent) number: thus in 200720067413.7 by making the slab corner angle be fillet the mold shape transformation, avoided the too fast cooling of corner part to eliminate and stuck up skin.This method is stuck up the skin improvement for limit portion and is truly had benefit, but need carry out big scrap build, and the most at present crystallizer of China Steel enterprise does not adopt this transformation.By to the microscopic appearance of this defective and researching and analysing of formation mechanism, find that it is to fall into the coexistence region because this place's temperature is low that the skin defective is stuck up in IF steel limit portion, due in distortion, ftractureing.This patent is intended to by adopting some little changes of some technology adjustment and control and equipment to solve this defective cost-effectively in the hot rolling stage, and this method also can not have influence on the performance of IF steel others.

Some enterprise also attempts guaranteeing that by the tapping temperature and the rolling temperature of integral body raising IF steel limit portion does not go out to stick up skin, but this method can have influence on strip surface quality, and temperature improved how much to spend the also notion of the concrete amount of neither one, the present invention accurately measures IF steel phase transition temperature in the operation of rolling by physical analogy in conjunction with production reality, and, be difficult for taking place thereby make limit portion stick up skin with the control parameter of this temperature as band steel minimum temperature in distortion.

Setting at the finish rolling inlet temperature, most literature and producer only with the roughing outlet temperature as a technology controlling and process point, but think that the finish rolling inlet temperature can not influence limit portion and stick up skin, analyze after deliberation and experimental verification, the high-pressure water descaling that the band steel goes out to advance after the roughing before the finish rolling is very big to the influence of finish rolling inlet temperature, if this temperature is not controlled, limit portion also can take place and stick up the skin defective in the band steel in the finish rolling interval.

Summary of the invention

The object of the present invention is to provide a kind of method that skin is stuck up in IF steel limit portion in the hot continuous rolling process of eliminating, adjustment by technology in course of hot rolling and equipment is simple to be transformed and eliminates IF steel limit portion and stick up this method of skin with physical analogy and actual the combining of production, method is simple, applicability is strong, and effect is remarkable.

Produced on-site flow process of the present invention comprises that continuous casting steel billet heating → thick de-scaling → Fixed width forcing press → roughing → coiled sheet case → flying shear crop end → smart de-scaling → finish rolling (6 frames or 7 frame four-high mills) → laminar flow cools off → coil into coil of strip, the following parameter of control in the technology:

(1) slab adopts pressure-fired 15～30Pa when heating furnace heats, and prevents the burner air draught, improves the tapping side temperature in bringing-up section, and tapping temperature is controlled at 1250～1300 ℃, and the slab transverse temperature difference is controlled within 20 ℃;

(2) adopt contrary spray to sweep water after each passage de-scaling of roughing and replace the side spray to sweep water, prevent that strip edge portion is subjected to washing away of water, contrary water spray pressure is controlled at 0.1～0.5MPa;

(3) roughing outlet temperature is controlled at 1040～1080 ℃, and the finish rolling inlet temperature is controlled at 1030～1070 ℃.

(4) to adopt the coiled sheet case for the band steel of finished product thickness below 3.5mm,, avoid being with steel afterbody temperature to drop into the coexistence region with homogeneous band steel toe tail temperature.

It is described that to avoid dropping into the coexistence region with steel afterbody temperature be that the step of utilizing Gleeble-1500 thermal simulation machine to measure the phase transition temperature of IF steel is:

(1) take a sample on strand, be processed into sample as shown in Figure 1, the thermocouple of burn-oning on sample puts behind the quartz ampoule fixingly in the operating room, vacuumizes, and carries out argon shield (argon stream amount 1L/min);

(2) on the thermal simulation machine sample is being heated to a certain temperature between 1250～1350 ℃ with 5～20 ℃/s, insulation 3～5min, with a certain cooling rate between 1～10 ℃/s sample is chilled to 1000～1100 ℃ of a certain temperature then, carries out 20～60% distortion, rate of deformation is 0.5～10s ^-1After the distortion sample is cooled to a certain temperature between 850～950 ℃ with a certain cooling rate between 1～10 ℃/s, distortion once more, engineering strain is 20～50%, rate of deformation is 1～10s ^-1Respectively with cooling velocity cool to room temperature different between 0.5～80 ℃/s, finish physical simulation experiment at last.

(3) will test after the compression sample along perpendicular to flatten cylinder axis to mid-sectional, through grind away, polishing, adopt 4% nital etch, under light microscope, carry out structure observation.

(4) temperature-strain that the thermal simulation machine is noted, and temperature-time curve also calculates the phase transition temperature of this steel grade under different temperatures in conjunction with (3) observed situation of organizing.

(5) with the phase transition temperature peak under different cooling speed of this steel grade control point as band steel minimum temperature in distortion.

Description of drawings

Fig. 1 is a thermal simulation experiment sample manuscript.

The process route of Fig. 2 thermal simulation experiment.

Concrete embodiment

Utilize involved in the present invention to method and control device move on the steel 2250mm hot continuous rolling production line at Shoudu Iron and Steel Co and carried out M3A33, M3A20, these three kinds of IF steel of M3A22 rolling, rolling specs is 3.0 * 1375mm and 4.0 * 1375mm.Wherein thickness is that 3.0mm uses the coiled sheet case, and thickness is that 4.0mm does not use the coiled sheet case.

This three class IF steel has representative preferably, because M3A33 is the Ti-IF steel, M3A20 is the Nb-IF steel, and M3A22 is the Ti+Nb-IF steel.

Through physical analogy, the highest phase transition temperature of M3A33 is 885 ℃; The highest phase transition temperature of M3A20 is 900 ℃, and the highest phase transition temperature of M3A25 is 892 ℃, so be set as follows process system.

Table 1 main points of processes control, ℃

1. heating furnace adopts the 1.05MPa pressure-fired, when heating furnace is come out of the stove, utilizes temperature-measuring gun to measure slab both sides temperature all within above-mentioned scope, and temperature difference be controlled at ± 15 ℃ within;

2. the 1+5 pattern is adopted in roughing, and R1 rolls 1 passage, and R2 is reversible to roll 5 passages, and the de-scaling of R1 employing inlet, and R2 adopts 1,3,5 passage de-scalings, all adopts the contrary cleaning of spraying for de-scaling water;

3. the whole participation process controls of roughing outlet temperature and finish rolling inlet temperature, and all within target zone.

All under parsytec, observe surface topography for the every volume of these test volumes, find no limit portion and stick up the skin existence, check after the uncoiling that the coiled sheet quality is good.

Claims (2)

1. eliminate the method that skin is stuck up in IF steel limit portion in the hot continuous rolling process for one kind, production procedure is: continuous casting steel billet heating → thick de-scaling → Fixed width forcing press → roughing → flying shear crop end → coiled sheet case → smart de-scaling → finish rolling → laminar flow cools off → coils into coil of strip; It is characterized in that the following parameter of control in the technology:

(1) slab adopts pressure-fired 15～30Pa when heating furnace heats, and prevents the burner air draught, improves the tapping side temperature in bringing-up section, and tapping temperature is controlled at 1250～1300 ℃, and the slab transverse temperature difference is controlled within 20 ℃;

(2) adopt contrary spray to sweep water after each passage de-scaling of roughing and replace the side spray to sweep water, prevent that strip edge portion is subjected to washing away of water, contrary water spray pressure is controlled at 0.1～0.5MPa;

(3) roughing outlet temperature is controlled at 1040～1080 ℃, and the finish rolling inlet temperature is controlled at 1030～1070 ℃.

(4) to adopt the coiled sheet case for the band steel of finished product thickness below 3.5mm,, avoid being with steel afterbody temperature to drop into the coexistence region with homogeneous band steel toe tail temperature.

2. method according to claim 1 is characterized in that, described to avoid dropping into the coexistence region with steel afterbody temperature be that the phase transition temperature step of utilizing Gleeble-1500 thermal simulation machine to measure the IF steel is:

(1) take a sample on strand, be processed into sample, the thermocouple of burn-oning on sample puts behind the quartz ampoule fixingly in the operating room, vacuumizes, and carries out argon shield, argon stream amount 1L/min;

(2) on the thermal simulation machine sample is being heated to a certain temperature between 1250～1350 ℃ with 5～20 ℃/s, insulation 3～5min, with a certain cooling rate between 1～10 ℃/s sample is chilled to 1000～1100 ℃ of a certain temperature then, carries out 20～60% distortion, rate of deformation is 0.5～10s ^-1After the distortion sample is cooled to a certain temperature between 850～950 ℃ with a certain cooling rate between 1～10 ℃/s, distortion once more, engineering strain is 20～50%, rate of deformation is 1～10s ^-1Respectively with cooling velocity cool to room temperature different between 0.5～80 ℃/s, finish physical simulation experiment at last;

(3) will test after the compression sample along perpendicular to flatten cylinder axis to mid-sectional, through grind away, polishing, adopt 4% nital etch, under light microscope, carry out structure observation;

(4) temperature one strain of the thermal simulation machine being noted, and the metallographic situation that temperature-time curve integrating step (3) is observed calculates the phase transition temperature of this steel grade under different temperatures;

(5) with the phase transition temperature peak under different cooling speed of this steel grade control point as band steel minimum temperature in distortion.

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