Title of Invention	A METHOD OF MAKING HOT-STRIP ROLLED STOCK AND AN APPARATUS FOR MAKING HOT-STRIP ROLLED STOCK
Abstract	Abstract A METHOD AND A SYSTEM FOR PRODUCING HOT-ROLLED STRIP SILICON STEEL BASED ON THIN SLABS The invention relates to a method and a system for the production of hot-rolled strip silicon-alloy steel for further processing into grain-oriented sheets, such as electrical sheets, wherein a cast product, in this case a thin slab, for example, with a maximum thickness of 120 mm, is subjected to thermal pretreatment and to a subsequent rolling process on a hot-rolling line to set a desired recrystallizations state. The invention proposes an intake temperature (Tin) of the cast product (2) into the hot-rolling line (9a or 9b) of at least 1200°C, and preferably in excess of 1250°C, which should be controlled during pretreatment by adding at least one preheating stage (3) and one intensive heating stage (6) to ensure the final rolling temperature (TFR).

Title of Invention

A METHOD OF MAKING HOT-STRIP ROLLED STOCK AND AN APPARATUS FOR MAKING HOT-STRIP ROLLED STOCK

Abstract

Abstract A METHOD AND A SYSTEM FOR PRODUCING HOT-ROLLED STRIP SILICON STEEL BASED ON THIN SLABS The invention relates to a method and a system for the production of hot-rolled strip silicon-alloy steel for further processing into grain-oriented sheets, such as electrical sheets, wherein a cast product, in this case a thin slab, for example, with a maximum thickness of 120 mm, is subjected to thermal pretreatment and to a subsequent rolling process on a hot-rolling line to set a desired recrystallizations state. The invention proposes an intake temperature (Tin) of the cast product (2) into the hot-rolling line (9a or 9b) of at least 1200°C, and preferably in excess of 1250°C, which should be controlled during pretreatment by adding at least one preheating stage (3) and one intensive heating stage (6) to ensure the final rolling temperature (TFR).

Full Text	The invention relates to a method o£ and an apparatus for making hot-strip starting material of silicon-alloy steel for further processing to grain-oriented sheets such as, for example, electro sheet metal. The further processing is not subject matter of the present invention; it takes place in a cold-rolling mill. Various methods and apparatuses of the generic type are known from the state of the art; the following two publications are referred to by way of example: Methods and apparatuses for the rolling of strips and sheets from the casting heat are known, for example, described in Stahl & Eisan vol. 2, 1993, p. 37ff. In the mill described in it a thin slab is produced by a billet-casting machine with a special ingot mold, divided into sections, and fed for temperature condensation to a roller heath furnace. The slab is subsequently accelerated to the distinctly higher entry speed of the following rolling train, decaled and supplied to the rolling train. In a stationary production operation with a casting rate of 5.5 m/min the thin slab reaches the roller-hearth furnace with an average temperature of 1080_C. The energy necessary for the rolling method is thus supplied almost completely from the heat in the cast billet. In the rolling mill the temperatures are controlled by changing the rolling speed, by cooling and by roller contact, so that a final rolling temperature of 880_C is attained. A slow cooling off in a cooling stretch follows as well as a subsequent winding up. Multistage temperature-adjustment systems for heating up a cast work piece before it enters into a rolling train are known from EP 1,469,954 [DS 2005/0072499 & 2008/0000559]. Furthermore, EF 0,415,987 9 [US 5,307,864] teaches a method of continuously making strip steel or steel sheet from thin slabs approximately 50 mm thick, which thin slabs are produced on continuous-casting equipment with a horizontal output. The method comprises the steps of: Rolling the thin SLAPS after hardening of the billet in a curved guide at temperatures of more than llOOEc, cooling the slabs during irradiation or decaling, inductive reheating to a temperature of approximately llOOEC as well as rolling of the thin slab in at least one rolling train. Temperature is adjusted in the slab by heating in such a manner that a temperature gradient is adjusted on the deformation apparatuses on the rolling train in such a manner that during the first pass into the rolling stand the temperature is within the range that is still sufficient for good deformation. Here, the temperature of the rolled stock has dropped, for example, to 988EC in the third and last rolling stand of the rolling train and is sufficient as first pass temperature for the last deformation step. The rolled stock leaves the last rolling stand with a temperature of 953_C or less and is then separated at an even lower temperature into the desired lengths, stacked or wound. If required, one or more stages of inductive intermediate heating can be provided between the individual rolling stands. Both known methods have the common feature that the entry temperature into the finish-rolling stage is adjusted in such a manner that the set final rolling temperature can be maintained. Starting from EB 0,415,987, the basic object of the invention is to use the known heat-treatment method and apparatus to produce hot-strip starting material from Si-alloyed steels for further processing to grain-oriented sheets. The problem Is solved by the method described In claim 1. For the first time an entry temperature Into the finish train is adjusted in a simple manner with the method in accordance with the invention that ensures a favorable separation morphology in the rolled stock. One-stage temperature-adjustment systems known in the prior art are not capable of heating the cast work piece to the high temperature of preferably above 12S0_C entry temperature into the rolling train required for adjustment of the recrystallizations state desired/required here. The high temperatures are advantageously achieved In the claimed method with a two-stage preheating of the cast work piece comprising a primary-energy fired stage and an inductively heated stage. The claimed two-stage heat pretreatment has the further advantage that it allows the cast work piece to be heated not only, If required, to a temperature above 1250EC but also to lower entry temperatures if this should be required for setting other desired structural states or recrystallizations states; and to this extent the claimed method can be used universally. Control of the temperature in the subsequent finish rolling train is set In accordance with the final structure to be achieved and is set via a combination of rolling speed and the use of intermediate structure cooling. In a preferred embodiment of the method of the present invention, the final rolling temperature (THE) and the final rolling speed of the rolled stock are adjusted to values at which no complete recrystallizations of the steel takes place any more and the rolled stock is quenched after the last pass in the hot-rolling train from the final rolling temperature (Tm) to a temperature (TA) that ensures setting and freezing of a desired recrystallizations state via the strip thickness. It is recommended here in accordance with a further design feature of the present invention that the final rolling temperature (THE) of the rolled stock be adjusted to a temperature of at least 950EC, preferably above lOOOEC, and then subsequently, preferably immediately afterward, the rolled stock is quenched to a temperature (Tx) of at the most 650EC, preferably below 600EC, especially preferably below 450EC within 10 sec. This suppresses complete recrystallizations of the hot strip. The amount of the recrystallized structure through the strip thickness is set by the selection of the winding temperature. According to a further design feature of the present invention it is provided that in the preheating stage the temperature of the cast work piece is set to values between 1000 and llOOEC and that in the following intensive-heating stage the temperature is raised to values of 1250EC. In a preferred embodiment the preheating stage is carried out here in a gas-heated or oil-heated furnace and the subsequent intensive-heating stage in an induction-heating stage. This has the special advantage that preheating can take place in a roller-hearth furnace whereas the heating step up to a tamperature above 1200_C is shifted into an inductive heating zone. This prevents the roller-hearth furnace from being stressed too much, which could possibly result in its thermal destruction. In order to avoid the disadvantageous effect of a heavily heated primary scale layer on the surface of the rolled stock, the slab surface is decaled. To this end and in accordance with a further design feature of the present invention decaling is carried out in a descaler between the preheating stage and the intensive stage. Adjustment of the entry temperature into the finish-rolling stage therefore takes place subsequently with the induction-heating stage. The finish-rolling stage can consist here of a single-stand or multitude roughing train and of a multitude final train. The distance between these two can be bridged by a roller bed or a tunnel oven. In order to further improve the surface quality, a further design feature of the present invention provides that a further descaling is carried out in a second descaling stage downstream of the intensive-heating stage. In addition, removal of the scale is carried out by itself or in addition to the cited descaling upstream of the roller-hearth furnace already in order to protect the rollers of the furnace from accumulations of scale and the slab bottom from undesired markings and to improve the thermal transfer into the slab. The above-cited object of the invention is furthermore attained by the apparatus claimed in claim 8. As regards the advantages accruing from it, in order to avoid repetitions the above-described advantages of the method in accordance with the invention are referred to. In the preferred embodiment of the apparatus in accordance with the invention the device for cooling the rolled stock comprises elements for quenching the rolled stock to a temperature below 600EC, preferably below 450EC. It is recommended according to a further design feature of the present invention that the hot-rolling train is a compact finish train. An alternative design feature provides that the hot-rolling train is divided into at least one roughing train and at least one final rolling train. Further advantages and details of the invention result from the sub claims and from the following description in which the embodiments of the invention shown in the figures are explained in detail. In addition to the above-cited combinations of features, features that are alone or in other combinations are essential for the invention. FIG. 1 shows a schematic view of a plan for carrying out the method in accordance with the invention. FIG. 1 shows a mill 1 for manufacturing rolled stock in the form of sheets or strips of silicon-alloyed steel for further processing to grain-oriented sheets such as, for example, electro sheet metal that are heat-treated and rolled to room temperature without intermediate cooling so that the rolled stock subsequently has the desired structural properties. The mill 1 comprises a billet caster la. The billet in the form of a strand workplace 2 cast close to the final dimensions is cut upstream of the roller-hearth furnace 3 by shears 4 into slabs that then, still at the casting- temperature, enter directly into the roller-hearth furnace 3 in order to be heated to a temperature of 1000 to llOOC and for temperature compensation. The slabs are preferably thin slabs with a thickness of up to 120 mm. The heated slabs subsequently preferably run through a descaler 5 and then into an intensive-heating stage 6. Here, the slabs are heated in a short, rapid heating method to an entry temperature of 1100 to 1300_C, preferably above 1250_C. The preheating stage 3 is a gas-heated or oil-heated furnace such as a roller-hearth furnace 3 and the following intensive-heating stage 6 is an induction heater. The intensive-heating stage 6 must be set up so as to ensure an entry temperature Toni of cast workpiece 2 into the rolling mill of more than 1200EC. The preheating stage 3 and intensive-heating stage 6 form a temperature-adjustment system 7. The heat-treatment means comprises the preheating stage 3, intensive-heating stage 6 as well as intermediate cooler frames 10. After passing through the intensive-heating stage 6 the cast workplace(s) 2 are descaled again (second descaling stage 8) and introduced into a hot-rolling train 9a or 9b. The hot-rolling train 9a or 9b can be a compact finish train or be divided into a roughing train and into final train 9b. The number of stands in each of the two partial trains is not fixed. The method in accordance with the invention provides that in order to adjust the final rolling ten^erature THE/ an entry temperature Tein of the cast workpiece 2 into the hot-rolling train 9a or 9b of the rolling mill of at least 1200EC, preferably above 1250EC, is set by a multistage heat treatment, during which the cast strsuid coming directly from the casting heat directly preheated. The multistage heating pretreatment is done by the temperature-adjustment system 7 that comprises the preheating stage 3 for preheating the cast workpiece 2 and cranprises the intensive-heating stage 6 for adjusting the entry tenperature Tei„ of the cast worl^iece 2 into the hot-rolling train. In the method according to the invention the final rolling temperature Tn and the final rolling speed of the rolled stock are set to values at which no con^lete recrystallization of the steel takes place any more. The rolled stock is quenched after the hot-rolling train in a post-heating treatment from the final rolling tan^erature Tn to a tenqperature TA that ensures the desired recrys-tallization state of the rolled stock at the end of the hot-rolling train through the strip thickness. The final rolling temperature Tm of the rolled stock is set to a tenperature of at least 950_C, preferably above 1000_C, and the rolled stock is subsequently quenched to a ten^erature T^ of at most 650_C, preferably below 600_C and espacially preferably below 450_C within 10 sec. FIG. 1 The post-heating treatment after rolling is a combination of a rapid cooler 12 and normal cooling beams with water cooling 13. The cooled-down rolled stock is subsequently wound on a winding apparatus 14. List of reference numerals 1 mill for manufacturing hot strip la billet casting mill 2 cast strand workpiece (billet) 3 apparatus for preheating (roller-hearth furnace) 4 shears 5 descaler 6 intensive-heating stage 7 temperature-adjustment system 8 second descaler 9a c 9b roughing rolling train and final rolling train of the hot- rolling train 10 intermediate structure cooler 11 device for cooling down (cooling stretch) 12 rapid cooler 13 cooling beams with water cooling 14 winding apparatus Claims: 1. A method of making hot-strip rolled stock from a cast strand workpiece, for example, a thin slab, of silicon-alloy steel for further processing to grain-oriented sheets such as electrical sheets, which cast workpiece (2) is subjected in the first step to a preheating treatment and in a second step the preheated cast workpiece is subjected to a rolling procedure in a hot-rolling train, and in which the rolled stock is converted in this manner into a recrystallizations state suitable for subsequent further processing at a desired final rolling temperature (Twc) , characterized in that for preheating the cast workpiece (2) runs through at least one preheating stage (3) and one intensive-heating stage (6) in order to adjust the final rolling temperature (THE) of the rolled stock in the hot-rolling train and is heated in this manner to an entry temperature (T.^^) of at least 1200°C for before entering the hot-rolling train (9a or 9b); and that upstream of the preheating stage (3) a descaling is carried out in a descaling device. 2. The method according to claim 1, characterized in that the final rolling temperature (T^) and the final rolling speed of the rolled stock are set to values at which no complete recrystallizations of the steel takes place any more and the rolled stock is quenched after the last pass in the hot-rolling train from the final rolling temperature to a temperature (Ta) that ensures freezing of the desired recrystallizations state set at the end of the hot-rolling train through the strip thickness. 3. The method according to claim 2, characterized in that the final rolling temperature (THE) of the rolled stalk is set to a temperature of at least 950°C, preferably above l000C, and that after the hot-rolling the rolled stock is quenched to a temperature {T;^) of at the most SSO^C, preferably below 600°C, especially preferably below 450°C within 10 sec. 4. The method according to one of claims 1 to 3, characterized in that in the preheating stage (3) the temperature of the cast workpiece (2) is set to between 1000 and 1100°C, and that in the subsequent intensive-heating stage (6) the temperature is raised to 1250°C. 5. The method according to one of claims 1 to 4, characterized in that the preheating stage (3) is carried out in a gas-heated or oil-heated furnace and the subsequent intensive-heating stage (6) in an induction heater. 6. The method according to one of claims 1 to 5, characterized in that descaling is carried out in a descaler (5). 7. The method according to one of claims 1 to 6, characterized in that downstream of the intensive-heating stage (6) a further descaling is carried out in a second descaling stage (8). 8. An apparatus (1) for making hot-strip rolled stock for a subsequent further processing to grain-oriented sheets such as, for example, electrical sheets, from the cast workpiece in the form of silicon-alloy steel by using the method according to one of claims 1 to 7, the apparatus comprising: a billet caster (la) for making the cast workpiece (2); a temperature-adjustment system (7) for preheating the cast workpiece; as well as a rolling device (9a or 9b) connected downstream of the temperature-adjustment system (7), the temperature-adjustment system (7) and the rolling device (9) serving to convert the cast workpiece (2) into the rolled stock with a recrystallizations state suitable for the subsequent further processing at a certain final rolling temperature (TE) , characterized in that the temperature-adjustment system (7) for adjusting the final rolling temperature (T^) of the rolled stock in the rolling train comprises a preheating stage (3) for preheating the cast workpiece (2) and an intensive-heating stage (6) for intensively heating the casting produce (2) to an entry temperature (T.^^) into the hot-rolling train above 1200"C, preferably above 1250"C; and the apparatus (1) has a device (11) for cooling the workpiece components to a temperature below 600°C, preferably below 450°C, that is formed by a rapid cooler (12) and a cooling sprayer with water cooling (13). 9. The apparatus according to claim 8, characterized in that the hot-rolling train is a compact finish train (9a). 10. The apparatus according to one of claims 8 or 9, characterized in that the hot-rolling train is divided into at least one roughing train and at least one final rolling train (9b).

Full Text

The invention relates to a method o£ and an apparatus for making hot-strip starting material of silicon-alloy steel for further processing to grain-oriented sheets such as, for example, electro sheet metal. The further processing is not subject matter of the present invention; it takes place in a cold-rolling mill.
Various methods and apparatuses of the generic type are known from the state of the art; the following two publications are referred to by way of example:
Methods and apparatuses for the rolling of strips and sheets from the casting heat are known, for example, described in Stahl & Eisan vol. 2, 1993, p. 37ff. In the mill described in it a thin slab is produced by a billet-casting machine with a special ingot mold, divided into sections, and fed for temperature condensation to a roller heath furnace. The slab is subsequently accelerated to the distinctly higher entry speed of the following rolling train, decaled and supplied to the rolling train. In a stationary production operation with a casting rate of 5.5 m/min the thin slab reaches the roller-hearth furnace with an average temperature of 1080_C. The energy necessary for the rolling method is thus supplied almost completely from the heat in the cast billet. In the rolling mill the temperatures are controlled by changing the rolling speed, by cooling and by roller contact, so that a final rolling temperature of 880_C is attained. A slow cooling off in a cooling stretch follows as well as a subsequent winding up.

Multistage temperature-adjustment systems for heating up a cast work piece before it enters into a rolling train are known from EP 1,469,954 [DS 2005/0072499 & 2008/0000559].
Furthermore, EF 0,415,987 9 [US 5,307,864] teaches a method of continuously making strip steel or steel sheet from thin slabs approximately 50 mm thick, which thin slabs are produced on continuous-casting equipment with a horizontal output. The method comprises the steps of: Rolling the thin SLAPS after hardening of the billet in a curved guide at temperatures of more than llOOEc, cooling the slabs during irradiation or decaling, inductive reheating to a temperature of approximately llOOEC as well as rolling of the thin slab in at least one rolling train. Temperature is adjusted in the slab by heating in such a manner that a temperature gradient is adjusted on the deformation apparatuses on the rolling train in such a manner that during the first pass into the rolling stand the temperature is within the range that is still sufficient for good deformation. Here, the temperature of the rolled stock has dropped, for example, to 988EC in the third and last rolling stand of the rolling train and is sufficient as first pass temperature for the last deformation step. The rolled stock leaves the last rolling stand with a temperature of 953_C or less and is then separated at an even lower temperature into the desired lengths, stacked or wound. If required, one or more stages of inductive intermediate heating can be provided between the individual rolling stands.

Both known methods have the common feature that the entry temperature into the finish-rolling stage is adjusted in such a manner that the set final rolling temperature can be maintained.
Starting from EB 0,415,987, the basic object of the invention is to use the known heat-treatment method and apparatus to produce hot-strip starting material from Si-alloyed steels for further processing to grain-oriented sheets.
The problem Is solved by the method described In claim 1.
For the first time an entry temperature Into the finish train is adjusted in a simple manner with the method in accordance with the invention that ensures a favorable separation morphology in the rolled stock. One-stage temperature-adjustment systems known in the prior art are not capable of heating the cast work piece to the high temperature of preferably above 12S0_C entry temperature into the rolling train required for adjustment of the recrystallizations state desired/required here. The high temperatures are advantageously achieved In the claimed method with a two-stage preheating of the cast work piece comprising a primary-energy fired stage and an inductively heated stage. The claimed two-stage heat pretreatment has the further advantage that it allows the cast work piece to be heated not only, If required, to a temperature above 1250EC but also to lower entry temperatures if this should be required for setting other desired structural states or recrystallizations states; and to this extent the claimed method can be used universally.
Control of the temperature in the subsequent finish rolling train is set In accordance with the final structure to be

achieved and is set via a combination of rolling speed and the use of intermediate structure cooling.
In a preferred embodiment of the method of the present invention, the final rolling temperature (THE) and the final rolling speed of the rolled stock are adjusted to values at which no complete recrystallizations of the steel takes place any more and the rolled stock is quenched after the last pass in the hot-rolling train from the final rolling temperature (Tm) to a temperature (TA) that ensures setting and freezing of a desired recrystallizations state via the strip thickness. It is recommended here in accordance with a further design feature of the present invention that the final rolling temperature (THE) of the rolled stock be adjusted to a temperature of at least 950EC, preferably above lOOOEC, and then subsequently, preferably immediately afterward, the rolled stock is quenched to a temperature (Tx) of at the most 650EC, preferably below 600EC, especially preferably below 450EC within 10 sec. This suppresses complete recrystallizations of the hot strip. The amount of the recrystallized structure through the strip thickness is set by the selection of the winding temperature.
According to a further design feature of the present invention it is provided that in the preheating stage the temperature of the cast work piece is set to values between 1000 and llOOEC and that in the following intensive-heating stage the temperature is raised to values of 1250EC. In a preferred embodiment the preheating stage is carried out here in a gas-heated or oil-heated furnace and the subsequent intensive-heating stage in an induction-heating stage. This has the special advantage that

preheating can take place in a roller-hearth furnace whereas the heating step up to a tamperature above 1200_C is shifted into an inductive heating zone. This prevents the roller-hearth furnace from being stressed too much, which could possibly result in its thermal destruction.
In order to avoid the disadvantageous effect of a heavily heated primary scale layer on the surface of the rolled stock, the slab surface is decaled. To this end and in accordance with a further design feature of the present invention decaling is carried out in a descaler between the preheating stage and the intensive stage. Adjustment of the entry temperature into the finish-rolling stage therefore takes place subsequently with the induction-heating stage. The finish-rolling stage can consist here of a single-stand or multitude roughing train and of a multitude final train. The distance between these two can be bridged by a roller bed or a tunnel oven.
In order to further improve the surface quality, a further design feature of the present invention provides that a further descaling is carried out in a second descaling stage downstream of the intensive-heating stage.
In addition, removal of the scale is carried out by itself or in addition to the cited descaling upstream of the roller-hearth furnace already in order to protect the rollers of the furnace from accumulations of scale and the slab bottom from undesired markings and to improve the thermal transfer into the slab.

The above-cited object of the invention is furthermore attained by the apparatus claimed in claim 8. As regards the advantages accruing from it, in order to avoid repetitions the above-described advantages of the method in accordance with the invention are referred to.
In the preferred embodiment of the apparatus in accordance with the invention the device for cooling the rolled stock comprises elements for quenching the rolled stock to a temperature below 600EC, preferably below 450EC.
It is recommended according to a further design feature of the present invention that the hot-rolling train is a compact finish train. An alternative design feature provides that the hot-rolling train is divided into at least one roughing train and at least one final rolling train.
Further advantages and details of the invention result from the sub claims and from the following description in which the embodiments of the invention shown in the figures are explained in detail. In addition to the above-cited combinations of features, features that are alone or in other combinations are essential for the invention.
FIG. 1 shows a schematic view of a plan for carrying out the method in accordance with the invention.
FIG. 1 shows a mill 1 for manufacturing rolled stock in the form of sheets or strips of silicon-alloyed steel for further processing to grain-oriented sheets such as, for example, electro sheet metal that are heat-treated and rolled to room temperature without intermediate cooling so that the rolled stock subsequently

has the desired structural properties. The mill 1 comprises a billet caster la. The billet in the form of a strand workplace 2 cast close to the final dimensions is cut upstream of the roller-hearth furnace 3 by shears 4 into slabs that then, still at the casting- temperature, enter directly into the roller-hearth furnace 3 in order to be heated to a temperature of 1000 to llOOC and for temperature compensation. The slabs are preferably thin slabs with a thickness of up to 120 mm. The heated slabs subsequently preferably run through a descaler 5 and then into an intensive-heating stage 6. Here, the slabs are heated in a short, rapid heating method to an entry temperature of 1100 to 1300_C, preferably above 1250_C. The preheating stage 3 is a gas-heated or oil-heated furnace such as a roller-hearth furnace 3 and the following intensive-heating stage 6 is an induction heater. The intensive-heating stage 6 must be set up so as to ensure an entry temperature Toni of cast workpiece 2 into the rolling mill of more than 1200EC. The preheating stage 3 and intensive-heating stage 6 form a temperature-adjustment system 7. The heat-treatment means comprises the preheating stage 3, intensive-heating stage 6 as well as intermediate cooler frames 10.
After passing through the intensive-heating stage 6 the cast workplace(s) 2 are descaled again (second descaling stage 8) and introduced into a hot-rolling train 9a or 9b. The hot-rolling train 9a or 9b can be a compact finish train or be divided into a roughing train and into final train 9b. The number of stands in each of the two partial trains is not fixed.

The method in accordance with the invention provides that in order to adjust the final rolling ten^erature THE/ an entry temperature Tein of the cast workpiece 2 into the hot-rolling train 9a or 9b of the rolling mill of at least 1200EC, preferably above 1250EC, is set by a multistage heat treatment, during which the cast strsuid coming directly from the casting heat directly preheated. The multistage heating pretreatment is done by the temperature-adjustment system 7 that comprises the preheating stage 3 for preheating the cast workpiece 2 and cranprises the intensive-heating stage 6 for adjusting the entry tenperature Tei„ of the cast worl^iece 2 into the hot-rolling train.
In the method according to the invention the final rolling temperature Tn and the final rolling speed of the rolled stock are set to values at which no con^lete recrystallization of the steel takes place any more. The rolled stock is quenched after the hot-rolling train in a post-heating treatment from the final rolling tan^erature Tn to a tenqperature TA that ensures the desired recrys-tallization state of the rolled stock at the end of the hot-rolling train through the strip thickness. The final rolling temperature Tm of the rolled stock is set to a tenperature of at least 950_C, preferably above 1000_C, and the rolled stock is subsequently quenched to a ten^erature T^ of at most 650_C, preferably below 600_C and espacially preferably below 450_C within 10 sec. FIG. 1
The post-heating treatment after rolling is a combination of a rapid cooler 12 and normal cooling beams with water cooling

13. The cooled-down rolled stock is subsequently wound on a
winding apparatus 14.
List of reference numerals
1 mill for manufacturing hot strip
la billet casting mill
2 cast strand workpiece (billet)
3 apparatus for preheating (roller-hearth furnace)
4 shears
5 descaler
6 intensive-heating stage
7 temperature-adjustment system
8 second descaler
9a c 9b roughing rolling train and final rolling train of the hot-
rolling train
10 intermediate structure cooler
11 device for cooling down (cooling stretch)
12 rapid cooler
13 cooling beams with water cooling
14 winding apparatus

Claims:
1. A method of making hot-strip rolled stock from a cast strand workpiece, for example, a thin slab, of silicon-alloy steel for further processing to grain-oriented sheets such as electrical sheets, which cast workpiece (2) is subjected in the first step to a preheating treatment and in a second step the preheated cast workpiece is subjected to a rolling procedure in a hot-rolling train, and in which the rolled stock is converted in this manner into a recrystallizations state suitable for subsequent further processing at a desired final rolling temperature (Twc) , characterized in that for preheating the cast workpiece (2) runs through at least one preheating stage (3) and one intensive-heating stage (6) in order to adjust the final rolling temperature (THE) of the rolled stock in the hot-rolling train and is heated in this manner to an entry temperature (T.^^) of at least 1200°C for before entering the hot-rolling train (9a or 9b); and that upstream of the preheating stage (3) a descaling is carried out in a descaling device.
2. The method according to claim 1, characterized in that the final rolling temperature (T^) and the final rolling speed of the rolled stock are set to values at which no complete recrystallizations of the steel takes place any more and the rolled stock is quenched after the last pass in the hot-rolling train from the final rolling temperature to a temperature (Ta) that

ensures freezing of the desired recrystallizations state set at the end of the hot-rolling train through the strip thickness.
3. The method according to claim 2, characterized in that the final rolling temperature (THE) of the rolled stalk is set to a temperature of at least 950°C, preferably above l000C, and that after the hot-rolling the rolled stock is quenched to a temperature {T;^) of at the most SSO^C, preferably below 600°C, especially preferably below 450°C within 10 sec.
4. The method according to one of claims 1 to 3, characterized in that in the preheating stage (3) the temperature of the cast workpiece (2) is set to between 1000 and 1100°C, and that in the subsequent intensive-heating stage (6) the temperature is raised to 1250°C.
5. The method according to one of claims 1 to 4, characterized in that the preheating stage (3) is carried out in a gas-heated or oil-heated furnace and the subsequent intensive-heating stage (6) in an induction heater.
6. The method according to one of claims 1 to 5, characterized in that descaling is carried out in a descaler (5).
7. The method according to one of claims 1 to 6, characterized in that downstream of the intensive-heating stage (6) a further descaling is carried out in a second descaling stage (8).

8. An apparatus (1) for making hot-strip rolled stock for a subsequent further processing to grain-oriented sheets such as, for example, electrical sheets, from the cast workpiece in the form of silicon-alloy steel by using the method according to one of claims 1 to 7, the apparatus comprising:
a billet caster (la) for making the cast workpiece (2);
a temperature-adjustment system (7) for preheating the cast workpiece; as well as
a rolling device (9a or 9b) connected downstream of the temperature-adjustment system (7), the temperature-adjustment system (7) and the rolling device (9) serving to convert the cast workpiece (2) into the rolled stock with a recrystallizations state suitable for the subsequent further processing at a certain final rolling temperature (TE) , characterized in that
the temperature-adjustment system (7) for adjusting the final rolling temperature (T^) of the rolled stock in the rolling train comprises a preheating stage (3) for preheating the cast workpiece (2) and an intensive-heating stage (6) for intensively heating the casting produce (2) to an entry temperature (T.^^) into the hot-rolling train above 1200"C, preferably above 1250"C; and
the apparatus (1) has a device (11) for cooling the workpiece components to a temperature below 600°C, preferably below 450°C, that is formed by a rapid cooler (12) and a cooling sprayer with water cooling (13).

9. The apparatus according to claim 8, characterized in
that the hot-rolling train is a compact finish train (9a).
10. The apparatus according to one of claims 8 or 9,
characterized in that the hot-rolling train is divided into at
least one roughing train and at least one final rolling train (9b).

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Patent Number

279931

Indian Patent Application Number

457/CHENP/2009

PG Journal Number

06/2017

Publication Date

10-Feb-2017

Grant Date

03-Feb-2017

Date of Filing

23-Jan-2009

Name of Patentee

SMS GROUP GMBH

Applicant Address

EDUARD-SCHLOEMANN-STRASSE 4, 40237 DUSSELDORF

Inventors:

#	Inventor's Name	Inventor's Address
1	SUCKER, MARIO,	AM SCHEIN 17, 40470 DUSSELDORF,
2	NEIFER, HERIBERT,	KIRCHSTRASSE 284, 46539 DINSLAKEN,
3	SCHUSTER, INGO,	BONNENRING 83, 47877 WILLICH,
4	KLEIN, CHRISTOPH,	KIRBERGSTRASSE 28, 57223 KREUZTAL

PCT International Classification Number

C12D8/12

PCT International Application Number

PCT/EP07/05530

PCT International Filing date

2007-06-22

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	102007005015.3	2007-02-01	Germany
2	102006029589.7	2006-06-26	Germany