CN101618396A - Method for rolling interstitial free steel ferrite on traditional hot rolling mills - Google Patents

Abstract

The invention relates to an IF steel rolling method, in particular to a method for rolling interstitial free steel ferrite on traditional hot rolling mills, which mainly solves the technical problem that finish rolling of the traditional IF steel austenite-region rolling is easy to fall into a two-phase region. The method for rolling interstitial free steel ferrite on traditional hot rolling mills comprises the steps of heating a slab through a heating furnace, performing rough rolling in a rough rolling mill, performing finish rolling in a finish rolling mill, performing laminar cooling and coiling. The method is characterized in that rough rolling is performed in an austenite region; the slab is cooled to the temperature at which an austenite structure is basically changed into a ferrite structure after rough rolling is over; finish rolling is performed in a ferrite region; the heating temperature of the slab is 1,130 +/- 20 DEG C; the inlet temperature of finish rolling is 850 +/- 20 DEG C; the final rolling temperature is 820 +/- 20 DEG C; the coiling temperature is 710 +/- 20 DEG C; and the thickness of an intermediate slab is 36 to 40 mm. The method mainly performs IF steel rolling on the traditional hot rolling mills.

Description

On traditional hot milling train group, realize the ferrite rolling method of gapless atomic steel

Technical field

The present invention relates to a kind of IF steel rolling method, particularly a kind of ferrite rolling method that on traditional hot milling train group, realizes the IF steel.

Background technology

IF steel (Interstitial-Free Steel) is a gapless atomic steel.The basic characteristics of this class steel are that phosphorus content is extremely low, have superior deep drawability, are having broad application prospects aspect automobile, the tame electroplax.

The rolling of traditional IF steel carries out in the austenitic area, i.e. roughing, final rolling temperature are all at Ar ₃More than, but the Ar of IF steel ₃Point higher (880～920 ℃), when rolling thin slab product, it is bigger to dispel the heat, and finish rolling is easy to fall into two-phase section, and this performance to steel has adverse effect.When C content less than 0.0218% the time, have single-phase ferrite area, regional when rolling at this, resistance of deformation and austenitic area are more or less the same when rolling, so ferrite area rolling be feasible on technology.And hot rolled plate is after subsequently cold rolling and annealing, shows as on texture is formed that strong { texture of 111} (110) annealing makes material have good deep drawability.

At present, the ferrite area Research of Rolling Process of IF steel is limited to laboratory study more, the industrial production aspect aspect CSP research and use morely, on the traditional hot milling train, carry out the rolling research in the plain tagma of IF iron and steel and use less.

Summary of the invention

The purpose of this invention is to provide a kind of ferrite rolling method that realizes the IF steel on traditional hot milling train group, the finish rolling that mainly solves the rolling existence in austenitic area of traditional IF steel falls into the technical problem of two-phase section easily.The percentage by weight of the molten steel chemical composition of IF steel of the present invention is C :≤0.0050%; Si :≤0.030%; Mn:0.10-0.20%; P≤0.020%; S≤0.010%; Ti:0.040-0.060%; All the other are Fe and unavoidable impurities.

The present invention realizes the ferrite rolling method of IF steel on traditional hot milling train group, may further comprise the steps: slab carries out roughing in the roughing unit after the heating furnace heating, carry out finish rolling again in mm finishing mill unit, through the laminar flow cooling, batches at last then.In the method, roughing is carried out in the austenitic area, is cooled to a temperature that is essentially ferritic structure after roughing finishes, and finish rolling is carried out at ferrite area.The main points of processes control of hot rolling is: 1130 ℃ ± 20 ℃ of slab heating temperatures, 850 ± 20 ℃ of finish rolling inlet temperatures, 820 ± 20 ℃ of finishing temperatures, 710 ± 20 ℃ of coiling temperatures, intermediate blank thickness is 36-40mm, the rolling reduction ratio of two passages is more than or equal to 15% after the finish rolling, finish rolling 7 frames are lubricated to come into operation, and laminar flow adopts the back segment cooling.

On the basis of the furnace temp that does not reduce the traditional hot roll process, rolling 7 passages by the roughing reversable mill, increase roughing de-scaling group number, reduced the finish rolling inlet temperature, assurance finish rolling is carried out at ferrite area, and has increased intermediate blank thickness, adopt increasing speed rolling, guarantee the high volume temperature of getting, strengthen the back passage and depress, guarantee the answer of ferrite crystal grain.The method helps the production of IF steel thin slab product.The benefit that the heating furnace temperature remains unchanged is to heat with other steel grade mixing shove charge, and what help producing carries out continuously.

The invention has the beneficial effects as follows:

(1) improved microstructure texture after cold rolling and the annealing, formed that strong { texture of 111} (110) annealing has improved the deep drawability of material.

The increase of (2) roughing rolling pass, one side has reduced the load of roughing milling train, on the other hand, has increased roughing de-scaling group number, helps the intermediate blank temperature drop, and entering single-phase ferrite area mill load during finish rolling does not increase.

(3) behind the process improving, (1.5～2.5mm) hot rolled plate is realized " with hot Dai Leng " to can be used to produce thin specification.

Description of drawings

Fig. 1 is a production line flow chart of the present invention

Among the figure: the 1-heating furnace; 2,4,7-De-scaling box; 3-roughing mill R1; 5-roughing reversable mill R2; The 6-Coil Box; 8-finish rolling F0-F7; The 9-cooling facility for laminar flow; The 10-coiling machine.

The specific embodiment

With reference to Fig. 1, in an embodiment, hot rolling technology comprises heating furnace 1, roughing, finish rolling, laminar flow cooling successively, batches.Roughing has two rolling mills, be respectively the irreversible milling train of two rollers-roughing mill R13, four roll reversing rollers-roughing reversable mill R25, a De-scaling box 2 is respectively arranged before and after the R1 milling train, 4, on the roughing reversable mill R25 de-scaling water nozzle is arranged, behind the roughing reversable mill R25 Coil Box 6 is set, a De-scaling box 7 is arranged before the finish rolling F0-F78, the big temperature drop of roughing mainly guarantees by the water spray cooling of De-scaling box and de-scaling water nozzle, the rolling pass of increase R2.7 frames of finish rolling F0-F78 all adopt lubrication and rolling.Finish rolling F0-F78 back sets gradually cooling facility for laminar flow 9 and coiling machine 10.

Embodiment 1: hot rolling technology is: 1148 ℃ of slab heating temperatures, 862 ℃ of finish rolling inlet temperatures, 810 ℃ of finishing temperatures, 704 ℃ of coiling temperatures, and intermediate blank thickness is 38mm, hot rolled plate thickness specification is 2.05mm.The chemical composition of molten steel is: C:0.0025%; Si:0.016%; Mn:0.16%; P:0.012%; S:0.0060%; Ti:0.048%.

Embodiment 2: hot rolling technology is: 1145 ℃ of slab heating temperatures, 850 ℃ of finish rolling inlet temperatures, 800 ℃ of finishing temperatures, 702 ℃ of coiling temperatures, and intermediate blank thickness is 38mm, hot rolled plate thickness specification is 2.1mm.The chemical composition of molten steel is: C:0.0022%; Si:0.015%; Mn:0.17%; P:0.013%; S:0.0056%; Ti:0.052%.

Embodiment 3: hot rolling technology is: 692 ℃ of 1135 ℃ of slab heating temperatures, 860 ℃ of finish rolling inlet temperatures, finishing temperature+815 ℃, coiling temperatures, and intermediate blank thickness is 38mm, hot rolled plate thickness specification is 1.8mm.The chemical composition of molten steel is: C:0.0025%; Si:0.018%; Mn:0.15%; P:0.015%; S:0.0062%; Ti:0.044%.

The performance of the hot rolled coil among the embodiment 1-3 is as shown in the table

Sequence number	Regulation disproportional extension strength Rp0.2 (MPa)	Tensile strength Rm (MPa)	Elongation after fracture A 80(％)	Strain hardening index n	Plane plasticity strain ratio r
						Embodiment 1	??190	??285	?44.0	??0.24	??1.24
Embodiment 2	??175	??265	?40.0	??0.24	??1.20
						Embodiment 3	??180	??270	?48.5	??0.25	??1.19
Pair rolling technology	??196	??290	?44.0	??0.24	??1.02

Claims (3)

1, on traditional hot milling train group, realize the ferrite rolling method of gapless atomic steel, may further comprise the steps: slab is after the heating furnace heating, in the roughing unit, carry out roughing, in mm finishing mill unit, carry out finish rolling again, cool off through laminar flow then, batch at last, it is characterized in that: roughing is carried out in the austenitic area, be cooled to a temperature that is essentially ferritic structure after roughing finishes, finish rolling is carried out at ferrite area, 1130 ℃ ± 20 ℃ of slab heating temperatures, 850 ± 20 ℃ of finish rolling inlet temperatures, 820 ± 20 ℃ of finishing temperatures, 710 ± 20 ℃ of coiling temperatures, intermediate blank thickness are 36-40mm.

2, the ferrite rolling method that realizes gapless atomic steel on traditional hot milling train group according to claim 1, it is characterized in that: the rolling reduction ratio of two passages is more than or equal to 15% after the finish rolling.

3, the ferrite rolling method that realizes gapless atomic steel on traditional hot milling train group according to claim 1 is characterized in that: laminar flow adopts the back segment cooling.

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