RU2322317C2 - Method for producing by electrolag refining ingot-blanks of hard-to-form steels and alloys and for rolling of them commercial tubes of large and mean diameters in tube rolling plants with pilger mills and conversion tubes for further rerolling in tube cold rolling mills - Google Patents

Abstract

FIELD: production of ingot-blanks by electroslag refining of hard-to-form steels and alloys, rolling of them commercial tubes of large and mean diameters in tube rolling plants with pilger mills and conversion tubes for rerolling in tube cold rolling mills.

SUBSTANCE: method comprises steps of casting ingots by electroslag refining with size 420-620 x 1750±50 mm; mechanically working-turning them to blanks with size 400-600 x 1750±50 mm; boring inner diameter by 30 - 35 mm more than drift diameter; heating them till yielding temperature; piercing ingot-blanks with diameter 400-500 mm in skew rolling mill to sleeves; rolling sleeves and bored ingot-blanks in pilger mill with backing carbon rings to commercial or conversion tubes with diameter 219 - 325 mm; subjecting ingot-blanks with diameter 540 -600 mm to first piercing to sleeves on mandrel with diameter 250 - 275 mm; secondary heating of sleeves from hot or cold fit till yielding temperature; secondary piercing- rolling out of sleeves in skew rolling mill on mandrel with diameter exceeding drift diameter by 20-25 mm; rolling sleeves to commercial or conversion tubes in pilger mill with backing carbon rings. Hollow ingots of electroslag refining are made built-up -bimetallic along height; bottom portion of refining ingots forming pilger head at rolling tubes in pilger mill is cast of ductile carbon steel kinds and main part of ingot is cast of steels and alloys according to orders. Height of bottom portion of ductile carbon steel is determined from expression Lb = KH where H -total height of hollow electroslag refining ingot of hard-to-form steels and alloys,mm; Lb - height of bottom portion of hollow ingot of ductile carbon steel, mm; K = 0.15 -0.20 - coefficient for determining height of bottom portion of hollow ingot of ductile carbon steel whose larger values correspond to larger diameter ingots and larger wall thickness. Hollow ingots are turned and bored to hollow ingot-blanks at taking metal of hard-to-form steels and alloys from shrinkage part till fusion boundary of two metals or at shifting to side of ductile carbon steel along length 50 - 100 mm. Transition along outer diameter of ingot-blanks from basic metal to ductile carbon steel is made smooth in the form of truncated cone along length 80 - 100 mm. Heating of built-up hollow ingot-blanks of electroslag refining is realized in mode of heating steel of main kind. On shrinkage end portions of hollow ingot-blanks on outer surface along length Lc = (1.5 - 2.0)Sw cone is formed with blunting h > 2.0Sc where Sw -wall thickness of hollow ingot-blanks of electroslag refining, mm; Sc - wall thickness of commercial or conversion tube, mm; Lc - length of cone portion on outer surface of hollow ingot-blanks at transition of main metal to ductile carbon steel,mm; h - blunting value of hollow blanks of electroslag refining, mm. Commercial and conversion tubes are rolled with their shrinkage end turned forward.

EFFECT: lowered consumption of metal, improved efficiency.

8 cl, 1 tbl.

Description

The invention relates to metallurgical and pipe production, in particular to a method for the production of ingot billets by electroslag remelting from hardly deformable grades of steel and alloys, rolling from them large and medium diameter tubes in tube rolling plants with pilgrim mills and conversion tubes for subsequent rolling on HPT mills, and can be used in the manufacture of ingots-billets by the method of electroslag remelting and rolling from them commodity pipes in accordance with GOST 9940 at pipe-rolling plants with pilgrim mills and dressing in accordance with GOST 9941 on HPT mills.

In pipe-rolling production, there is a known method for the production of ingot billets by electroslag remelting from alloyed steel grades, rolling from them large and medium-sized pipes of large and medium diameters in accordance with GOST 9940 at pipe-rolling plants with pilgrim mills, including casting of ingots by electroslag remelting, machining of ingots into ingots (turning), drilling a central hole with a diameter of 100 ± 5.0 mm, heating ingot blanks to a temperature of plasticity, piercing ingot blanks with a diameter of 400-500 mm of alloyed steel grades in an oblique rolling mill into sleeves, rolling the sleeves on a pilgrim mill into commodity or conversion pipes according to GOST 9940 with carbon-based underlay rings (USSR author's certificate No. 430908, class B21B 21/00, 1972 and No. 732043, class . B21B 21/00, 1980).

However, this method of manufacturing commodity and conversion pipes of large and medium diameters according to GOST 9940 from ESR ingots has the following disadvantages: the operation of manufacturing and heating carbon pipes (rings) is time-consuming due to the need to manufacture different sizes in diameter and wall for each sleeve size and leads to reduce the performance of the pilgrim mills due to the loss of time putting them on the mandrel before rolling the sleeves into pipes and removal from the mandrel after rolling the pipes, as well as the loss of productivity of the pilgrims movyh mill due to the increase of auxiliary heating and the rolling time in the other rings reheating furnace.

In the pipe industry, there are known methods for the production of seamless hot-rolled pipes in tube-rolling plants with pilgrim mills with the rolling of the pilgrim head on a free mandrel, i.e. without fixing the rear end of the sleeve is relatively mandrel, which include the "Method of hot rolling of pipes from forged billets and ingots (continuously cast, ESR and VDP) in installations with pilgrim mills" (RF patent No. 2207201, class. VB 21/00, 21 / 04, Bull. No. 18, 2003) and "Method for the production of pipes from hard-to-deform grades of steel and alloys with an increased coefficient of linear expansion" (RF patent No. 2221656, class. B21B 21/00, 21/04, Bull. No. 2, 2004).

However, these methods of preparing billets (sleeves) for pilgrim rolling of pipes can only be used when rolling pipes from low alloy steel grades, and when rolling commodity and conversion pipes from stainless and difficult to deform steel grades and alloys, running the pilgrim heads on a free mandrel leads to tightening of the mandrels, t .e. the inability to extract the mandrel from the pipe, as well as the loss of productivity of the pilgrim mills due to the following additional technological operations:

- time to stop the rolling process with a shortage of 100-200 mm liners, (determined visually), s;

- time to lift the upper roll by 1-3 turns of the pressure screws, s;

- time to extract (pull) the mandrel from the pipe by 1.5-2.5 m (determined visually), s;

- time to install the upper roll to the "point", s;

- time for rolling the remaining shortage of the sleeve until the formation of the minimum pilgrim head or its full rolling, depending on the wall thickness of the rolled pipes (determined visually), p.

In pipe production, in order to reduce the loads on oblique rolling mills in the production of hot-rolled commodity and conversion pipes of large and medium diameters from corrosion-resistant hard-to-form steel grades and alloys on TPA with pilgrim mills, a double-flashing method of ingot blanks is used, including the first flashing of ESR ingots with a diameter of 460-600 mm in a piercing mill with an extractor μ = 1.2-1.4 at a working rotation speed of 15-25 rpm, and the second and subsequent, if necessary, rolling-ups with lifting or landing with a diameter of not more than 5.0% and an exhaust hood μ = 1.4-1.75 at a speed of rotation of the work rolls of 25-50 rpm, cold sleeves after the first flashing with a diameter of 460-600 mm with a ratio of D / S = 3.0 -4.5 is kept on grates at a temperature of 400-500 ° C for 50-70 min, depending on the diameter and wall thickness, then heated to a plasticity temperature of 1100-1260 ° C at a speed of 1.6-1.8 ° / min depending on the grade of steel, and the sleeves after the piercing mill with a temperature of 600-800 ° C are uniformly heated to the ductility temperature at a speed of 1.7-2.0 ° / min, They are pressed for 45-60 minutes at a ductility temperature with a tilting in 10-15 minutes at an angle of ≈180 °, the process of flashing from grabbing ESR ingots or workpieces to being completely on the mandrel is carried out with a decrease in the number of revolutions of work rolls from 25 to 15, a steady firmware is carried out at 15-20 rpm, at the exit of the sleeve from the rolls, the number of revolutions is increased to 35-40, the firmware-rolling process from gripping the sleeve to being completely on the mandrel is carried out with a decrease in the number of revolutions of the work rolls from 50 to 20, the steady-state rolling process at 20-25 rpm, and at the exit the number of revolutions from the rolls is increased to 45-50, and the pipes are rolled on a pilgrim mill with an extractor μ = 3.0-5.0 and the pilgrim head is pulled out onto a carbon ring "Method for the production of hot-deformed and conversion pipes of large and medium diameters from corrosion-resistant persistent hardly deformable grades of steel and alloys on TPA with pilgrim mills "(RF patent No. 22427612, cl. B21B 21/00, bull. No. 7, 2005) and "A method for preparing billets (sleeves) of alloyed steel and alloy grades for pilgrim rolling of pipes" (RF patent No. 2207199, cl. 7 B21B 21/00, bull. No. 18, 2003).

The use of these methods, although it allows the production of commodity and conversion pipes of large and medium diameters from hard-to-deform grades of steel and alloys in tube rolling plants with pilgrim mills without pilgrim heads with multiple (2-3 times) use of carbon rings, reduces the likelihood of jamming (tightening) of mandrels in pipes, reduce the cost coefficient of expensive metal, and therefore the cost of pipes, but it has the same disadvantages associated with double heating (ESR ingots and first firmware sleeves i) double firmware (flashing ESP ingots and rolling the sleeves on mandrels of a larger diameter), which lead to a decrease in the performance of the pilgrim mills due to the loss of time for the first firmware of the sleeves and their re-rolling (both pilgrim mills are idle at the moment), and with the manufacture and heating of carbon pipes (rings), putting them on the mandrel before rolling the sleeves into pipes and removing it from the mandrel after rolling the pipes, which reduces the productivity of the mills and increases the cost of the pipes.

In tube rolling production, there is also a known method of rolling conversion tubes in plants with pilgrim mills of corrosion-resistant hard-to-deform steel grades and alloys of type 20X25H25TY-Sh of size 325 × 40 mm for the manufacture of water-cooled furnace rollers of size 295 × 22 × 2750 mm and heat-resistant pipes of size 325 × 25 mm according to GOST 9940 from steel grade 06KHN28MDT (EI-943), including drilling and boring of ingots of size 460 × 1600 mm for a diameter of 275 and 325 ± 5.0 mm, heating them to a ductility temperature, rolling in a pilgrim mill in a tube of size 325 × 40 and 325 × 25 mm with p full carbon rings with subsequent turning and boring on pipes with specified geometric parameters (protocol No. 1031 for agreeing on the conditions for the supply of steel pipes 20Kh25N25TYu-Sh and 06KhN28MDT dated 12/14/2000 and a letter indicating pilot-industrial rolling of conversion tubes 325 × 40 in size and 325 × 25 mm).

The disadvantages of these methods are the use of bored ingot sleeves with an inner diameter greater than the diameter of the mandrel by 25-35 mm, because with a smaller gap on the inner surface of the pipes defects are formed in the form of flaws, puffs are dorn, even with increased taper, and this in turn leads to increased consumption of expensive metal, additional costs for the manufacture and heating of carbon pipes (rings) and a decrease in the performance of pilgrim mills for by increasing the auxiliary time for transporting the rings by crane to the mill, putting them on the mandrel before rolling the sleeves into pipes and removing it from the mandrel after rolling the pipes, which in turn leads to higher cost of pipes.

The closest technical solution is a method for the production of hot-rolled conversion tubes of large and medium diameters from hard-to-deform steel grades and alloys in tube-rolling plants with pilgrim mills, including heating to the ductility temperature of drilled ESR ingots, which are expanded into hollow billet sleeves with hood μ = 1.2 -1.8 without lifting in diameter, grind and bore them to remove forging defects, heat to ductility temperature and roll on pilgrim mills with a hood μ≤5.0 and and ESR drilled ingots are expanded into hollow shell blanks with a hood μ = 0.9-1.5, with a diameter rise of 1.05 to 1.4, and then grind and bore them to remove forging defects, heated to ductility temperature and rolled on pilgrim mills with a hood μ≤5.5 with the removal of the pilgrim heads on carbon rings “Method for the production of hot rolled conversion pipes of large and medium diameters from hard-to-deform grades of steel and alloys on tube rolling plants with pilgrim mills" (RF patent No. 2242302, l. 7 B21B 21/04, bull. No. 35, 2004).

The use of this method for the production of hot-rolled conversion pipes of large and medium diameters from hard-to-deform grades of steel and alloys in tube-rolling plants with pilgrim mills, although it can improve the performance of pilgrim mills by eliminating double heating, piercing ESR ingots into sleeves and rolling cartridges on a larger diameter mandrel and rolling them into pipes without pilgrim heads with multiple (2-3 times) use of carbon pipes, reduces the likelihood of jamming (puffs) ov in the pipes, reduces the consumption of expensive metal, and consequently the cost of the pipes, but has drawbacks associated with the additional operation of expanding the ESR ingots into hollow billet sleeves, and therefore, increasing their cost, manufacturing and heating of carbon pipes (rings), which lead to a decrease in the performance of pilgrim mills and an increase in the cost of pipes.

The objective of the proposed method is the development of a new technological process for the production of ingot billets by electroslag remelting from hard-to-deform grades of steel and alloys and rolling from them large and medium diameter tubes in pipe rolling plants with pilgrim mills with rolling of pilgrim heads made of carbon plastic metals and conversion tubes for subsequent rolling on HPT mills, exclusion from the process flow of manufacturing and heating of carbon backing rings, increasing zvoditelnosti pilger mills, reduced consumable metal ratios, and consequently, lower cost commodity and metal recycling pipes of hard-alloy grades of steel and alloys.

The technical result is achieved by the fact that in the known method for the production of ingots-billets by electroslag remelting from hard-to-deform grades of steel and alloys and rolling from them large and medium-diameter commodity pipes in pipe rolling plants with pilgrim mills and conversion tubes for subsequent rolling on HPT mills, including ingot casting electroslag remelting with a size of 420-620 × 1750 ± 50 mm, machining them turning them into workpieces with a size of 400-600 × 1750 ± 50 mm, drilling a central hole with a diameter of 100 ± 5.0 m m or a bore of an internal diameter 30-35 mm larger than the diameter of the mandrel, heating ingot blanks and shell blanks to plasticity temperature, piercing drilled ingot blanks with a diameter of 400-500 mm in an oblique rolling mill into sleeves, rolling sleeves, expanded and bored sleeves - preparations on a pilgrim mill with lining carbon rings into commodity or conversion pipes with a diameter of 219-426 mm, the first piercing of ingot blanks with a diameter of 540-600 mm into sleeves without diameter rise on a mandrel with a diameter of 250-275 mm, re-heating of sleeves with g a hot or cold embedment to a temperature of plasticity, re-flashing-rolling in an oblique rolling mill on a mandrel with a diameter larger than the mandrel diameter by 20-25 mm, rolling sleeves into commodity or conversion pipes on a pilgrim mill with lining carbon rings, electroslag remelting ingots are cast hollow, composite - bimetallic in height, the bottom of electroslag remelting ingots forming a pilgrim head during pipe rolling on a pilgrim mill is cast from plastic carbon steel grades, and the oval part of the ingots from steels and alloys in accordance with the portfolio of orders, the height of the bottom part from the plastic carbon steel grade is determined from the expression L _d = K N, where N is the total height of the hollow ingot of electroslag remelting from hardly deformed steel and alloy grades, mm; L _d - the height of the bottom of the hollow ingot from a plastic carbon steel grade, mm; K = 0.15-0.20 is a coefficient for determining the height of the bottom of a hollow ingot made of plastic carbon steel, large values of which refer to ingots of larger diameter and greater wall thickness, hollow ingots are machined and bored into hollow ingots with removal of metal that is difficult to deform grades of steel and alloys from the shrinkage to the border of the fusion of two metals or with a shift to the side of ductile carbon steel by a length of 50-100 mm, the transition along the outer diameter of the ingot blanks from the base metal to ductile carbon steel are performed smoothly in the form of a truncated cone at a length of 80-100 mm, the heating process of the composite hollow ingots-billets of electroslag remelting is carried out according to the heating mode of the main steel grade, at the shrinkable ends of the hollow ingots-billets, a cone is made from the outer surface at a length L _to = ( 1.5-2.0) S _c with blunting h≥2,0S _t , where S _c is the wall thickness of the hollow ingots-billets of electroslag remelting, mm; S _t - wall thickness of a commodity or conversion pipe, mm; L _to - the length of the conical part on the outer surface of the hollow ingots-billets during the transition from the base metal to ductile carbon steel, mm; h is the thickness of the blunting of hollow billets of electroslag remelting, mm, and the process of rolling commodity and conversion pipes on a pilgrim mill is shrunken forward.

The essence of the method is that electroslag remelting ingots are cast hollow, composite - bimetallic in height, the bottom part of electroslag remelting ingots forming a pilgrim head during pipe rolling on a piligrim mill is cast from plastic carbon steel grades, and the bulk of the ingots are made from steels and alloys according to the order book, the height of the bottom portion of the plastic carbon steel grade is determined from the expression L = R _d N, where H - the total height of the hollow ingot electroslag remelting of labor nodeformiruemyh steels and alloys mm; L _d - the height of the bottom of the hollow ingot from a plastic carbon steel grade, mm; K = 0.15-0.20 - coefficient for determining the height of the bottom of a hollow ingot of plastic carbon steel, large values of which relate to ingots of larger diameter and greater wall thickness, hollow ingots are machined and bored into hollow ingots with removal of metal that is difficult to deform grades of steel and alloys from the shrinkage to the border of the fusion of two metals or with a shift to the side of ductile carbon steel by a length of 50-100 mm, the transition along the outer diameter of the ingot blanks from the base metal to ductile carbon steel are performed smoothly in the form of a truncated cone at a length of 80-100 mm, the heating process of the composite hollow ingots-billets of electroslag remelting is carried out according to the heating mode of the main steel grade, at the shrinkable ends of the hollow ingots-billets, a cone is made from the outer surface at a length L _to = ( 1.5-2.0) S _c , with blunting h≥2.0 S _t , where S _c is the wall thickness of the hollow ingots-blanks of electroslag remelting, mm; S _t - wall thickness of a commodity or conversion pipe, mm; L _to - the length of the conical part on the outer surface of the hollow ingots-billets during the transition from the base metal to ductile carbon steel, mm; h is the thickness of the blunting of hollow billets of electroslag remelting, mm, and the process of rolling commodity and conversion pipes on a pilgrim mill is shrunken forward.

A comparative analysis of the proposed solution with the prototype shows that the claimed method differs from the known one in that in the manufacture of ingot billets by electroslag remelting from hard to deform steel grades and alloys and rolling from them large and medium diameters pipes in pipe rolling plants with pilgrim mills and conversion tubes for subsequent rolling at the HPT mills, electroslag ingots are cast hollow, composite - bimetallic in height, the bottom of electroslag ingots the remelting that forms the pilgrim head during pipe rolling on the pilgrim mill is cast from plastic carbon steel grades, and the bulk of the ingots from steel and alloys in accordance with the order portfolio, the height of the bottom part from the plastic carbon steel grade is determined from the expression L _d = K N, where H is the total height of the hollow ingot of electroslag remelting from hardly deformable grades of steel and alloys, mm; L _d - the height of the bottom of the hollow ingot from a plastic carbon steel grade, mm; K = 0.15-0.20 - coefficient for determining the height of the bottom of a hollow ingot of plastic carbon steel, large values of which relate to ingots of larger diameter and greater wall thickness, hollow ingots are machined and bored into hollow ingots with removal of metal that is difficult to deform grades of steel and alloys from the shrinkage to the border of the fusion of two metals or with a shift to the side of ductile carbon steel by a length of 50-100 mm, the transition along the outer diameter of the ingot blanks from the base metal to ductile carbon steel are performed smoothly in the form of a truncated cone at a length of 80-100 mm, the heating process of the composite hollow ingots-billets of electroslag remelting is carried out according to the heating mode of the main steel grade, at the shrinkable ends of the hollow ingots-billets, a cone is made from the outer surface at a length L _to = ( 1.5-2.0) S _c with blunting h≥2,0S _t , where S _c is the wall thickness of the hollow ingots-billets of electroslag remelting, mm; S _t - wall thickness of a commodity or conversion pipe, mm; L _to - the length of the conical part on the outer surface of the hollow ingots-billets during the transition from the base metal to ductile carbon steel, mm; h is the thickness of the blunting of hollow billets of electroslag remelting, mm, and the process of rolling commodity and conversion pipes on a pilgrim mill is shrunken forward. Thus, these differences allow us to conclude that the criterion of "inventive step" is met.

Comparison of the proposed method not only with the prototype, but also with other technical solutions in the art did not allow them to identify signs that differ the claimed solution from the prototype, which corresponds to the patentability of "inventive step".

The method was carried out at ZMZ OJSC in the production of hollow, composite - bimetallic height ingots of 540 × 340 × 2800 and 540 × 310 × 2800 mm in size by electroslag remelting from 06ХН28МДТ steel (5 ingots of each size), which are from the bottom end to 400 ± 10 mm in height were cast in accordance with the claims from grade 20 steel. The ingots were turned at OAO ZMZ into ingot blanks of sizes 520 × 360 × 2400 and 520 × 330 × 2400 mm and delivered to OAO ChTPZ. Hollow ingots were turned and bored into hollow ingots with metal removal of 06KHN28MDT steel from the shrink part to the fusion border of two metals or with a shift to the side of carbon steel by a length of 50-100 mm (visually determined). The transition along the outer diameter of the ingot billets from the base metal to ductile carbon steel was carried out smoothly in the form of a truncated cone at a length of 80-100 mm for better capture of the metal by rollers when rolling this volume of metal. To shrink the ends of the hollow ingots-billets, in order to improve the conditions for the capture of metal during seed, a cone was made in accordance with the claims on a length of 160 and 180 mm with blunts of 50 and 80 mm, respectively. At the same time, 10 ingots of this steel grade 540 × 1750 mm in size were cast using current technology for comparison. Ingots and hollow ingots-billets were delivered to ChTPZ OJSC. At ChTPZ OJSC, the ingots were drilled to a diameter of 100 ± 5.0 mm, and then bored to a diameter of 360 and 330 mm, respectively, for rolling commodity pipes 377 × 20 mm in size and conversion pipes 377 × 35 mm in size. Drilled ingots and ingot ingots were simultaneously planted for heating in methodical furnace No. 2 in the following sequence: 5 ingots 520 × 360 × 1750 mm in size, then 5 hollow ingot blanks with a size of 520 × 360 × 2800 mm, 5 ingots with a size of 520 × 330 × 1750 mm and 5 ingot blanks measuring 520 × 360 × 2800 mm. The heated ingots and ingot billets were heated according to the 06KhN28MDT steel mode. Pipe rolling from bored ingots according to the existing technology was carried out with carbon rings, which were heated in the first zone of furnace No. 1. The average heating time of the underlay carbon rings was 5.0 hours. Pipes were rolled on the pilgrim mill according to the existing technology with the bottom end forward, and according to the proposed technology, shrink end forward. Data on rolling of commodity pipes 377 × 20 mm in accordance with GOST 9940 and conversion tubes 377 × 35 mm in size on TPA 8-16 "with pilgrim mills from EShP ingots of 06ХН28МДТ steel according to the existing and proposed technologies are given in the table. The table shows that when rolling commodity pipes 377 × 20 mm in size according to the existing technology, 15.724 tons of 06KHN28MDT steel were set into production (weight of 5 ingots 540 × 1750 mm in size) 38 m rolled 377 × 20 mm pipes with a total weight of 6.73 tons. amounted to 2,337, i.e. for the production of one ton of pipes was israel 2,337 tons of metal were consumed. According to the proposed technology, 5 ingot blanks with a total weight of 13.02 tons were specified for the production of pipes of this size. 9,564 tons of pipes were accepted. The consumption coefficient of the metal was 1,362, i.e., in the production of pipes of this size using the proposed technology, metal savings of 975 kg per ton. The same picture is observed when rolling pigs 377 × 35 mm in size. The metal consumption coefficient for pipes rolled using the existing technology was 2.119, and for the proposed technology 1.351. The metal savings per ton of pipes amounted to 766 kg. Since pipe rolling using existing technology was carried out with carbon rings, the auxiliary time for rolling commodity pipes 377 × 20 mm in size increased from 285 to 585 seconds, and when rolling steel pipes in size 377 × 35 mm, it increased from 290 to 580 seconds, i.e. e. ≈ twice. The rolling time of one running meter of pipes with a size of 377 × 20 mm (the main indicator of mill productivity) by the proposed technology decreased by 46.6%, and during rolling of conversion pipes with a size of 377 × 35 mm by 50.8%, i.e. also ≈ twice.

Thus, according to the results of the production of pilot industrial lots of commodity and conversion pipes 377 × 20 and 377 × 35 mm in size, steel grade 06KHN28MDT from ingot castings, cast at OAO ZMZ and rolled at TPA 8-16, with pilgrim mills at OAO ChTPZ "according to the existing and proposed technologies, it can be seen that the consumption coefficient of the metal during the redistribution of the ESR ingot - the commodity pipe is reduced by 975 kg, and when the redistribution of the ESR ingot - the conversion pipe is 766 kg per tonne of pipes, while increasing the performance of the pilgrim mills (rolling time per one per meter pipe) by reducing the auxiliary time for the issuance of lining carbon rings from the furnace, transporting them to the pilgrim mills, putting them on the mandrel, removing from the mandrel and transporting the used rings to the boxes for metal process waste by 46.6 and 50.8%, respectively and also an increase in the productivity of methodical heating furnaces was obtained by eliminating the heating time of the rings, which is t = 5.0 hours + the rolling time of commodity or conversion pipes made of 06XH28MDT steel.

Using the proposed method for the production of ingot billets by electroslag remelting from hard-deformed grades of steel and alloys and rolling from them large and medium-diameter commodity pipes at pipe rolling plants with pilgrim mills and conversion tubes for subsequent rolling at HPT mills will significantly reduce the consumption of expensive metal from alloyed difficult to deform grades steel and alloys by eliminating the operation of boring ingots for the geometrical dimensions of mandrels, increase the manufacturer the pilgrim mills due to the reduction of the auxiliary time for rolling pipes with carbon rings (delivery of rings from the furnace, transportation of rings to the mill, putting them on the mandrel, removal from the mandrel after rolling, transportation of used rings to boxes for technological waste), exclude the manufacturing process underlay carbon rings (heating defective ingots, flashing them in an oblique rolling mill into sleeves and then cutting them into rings) and increase the productivity of heating method whose due to exclusion from the technological cycle of heating rings, and therefore, reduce the cost of commodity and conversion pipes of this assortment.

Table Data on rolling of commodity pipes 377 × 20 mm in accordance with GOST9940 and conversion tubes 377 × 35 mm in size on TPA 8-16 ″ with pilgrim mills from EShP ingots of 06ХН28МДТ steel according to existing and proposed technologies Type of technology ESR Ingot Size The size of the gut. The amount assigned is stainless. metal Size Commodity pipes in accordance with GOST 9940 Size before. pipes Pilgrim mill pipe rolling Mandrel size Carbon size rings Heat time rings Wednesday pipe length Pipes delivered in accordance. with NTD Consumption. coefficient metal Rolling time of one pipe Proc. 1p. m T _mash. T _aux. T _cycle - mm mm PC. tons mm mm mm mm hour m m tons - sec sec sec sec Existence. 540 × 1750 520 × 360 × l750 5 15,724 377 × 20 - 340/345 520 × 360 × 350 5,0 7.6 38,0 6,730 2,337 225 585 810 94.2 520 × 330 × l750 5 15,724 - 377 × 35 311/316 520 × 330 × 350 5,0 5,0 25.0 7,423 2,119 150 580 730 122.7 Suggestion 540 × 340 × 2800 (2400 + 400) 520 × 360 × 2800 5 13,020 377 × 20 - 340/345 - - 10.8 54.0 9,564 1,362 309 285 594 50.3 540 × 310 × 2800 (2400 + 400) 520 × 330 × 2800 5 14,460 - 377 × 35 311/316 - - 7.2 36.0 10.69 1,353 205 290 495 60,4

Claims (8)

1. Method for the production of ingot billets by electroslag remelting from hardly deformable grades of steel and alloys and rolling from them large and medium diameter tubes in pipe rolling plants with pilgrim mills and conversion pipes for subsequent rolling on HPT mills, including casting of ingots by electroslag remelting with a size of 420-62020 × 1750 ± 50 mm, machining them turning them into workpieces of 400-600 × 1750 ± 50 mm in size, the bore of the inner diameter is 30-35 mm larger than the mandrel diameter, heating them to the ductility temperature, casting ingot blanks with a diameter of 400-500 mm in an oblique rolling mill into sleeves, rolling sleeves and bored ingot blanks in a pilgrim mill with lining carbon rings into commodity or conversion pipes with a diameter of 219-325 mm, the first piercing of ingot blanks with a diameter of 540-600 mm into sleeves without diameter rise on a mandrel with a diameter of 250-275 mm, reheating sleeves from a hot or cold seat to a ductile temperature, re-piercing-rolling in an oblique rolling mill on a mandrel with a diameter larger than the mandrel diameter by 20-25 mm, rolling liners in product or pig pipe pilger carbon with backing rings, characterized in that the electroslag remelting ingots cast hollow composite - bimetallic adjustment. 2. The method according to claim 1, characterized in that the bottom of the electroslag remelting ingots forming the pilgrim head during pipe rolling on the pilgrim mill is cast from plastic carbon steel grades, and the bulk of the ingots from steel and alloys in accordance with the order portfolio. 3. The method according to claim 1, characterized in that the height of the bottom of the plastic carbon steel grade is determined from the expression L _d = K N, where H is the total height of the hollow ingot of electroslag remelting from hardly deformable grades of steel and alloys, mm; L _d - the height of the bottom of the hollow ingot from a plastic carbon steel grade, mm; K = 0.15-0.20 - coefficient for determining the height of the bottom of a hollow ingot of plastic carbon steel, large values of which relate to ingots of larger diameter and greater wall thickness. 4. The method according to claim 1, characterized in that the hollow ingots are machined and bored into hollow ingots-billets with removal of metal of hard-deformed steel grades and alloys from the shrink part to the fusion border of two metals or with a shift to the side of ductile carbon steel 50- 100 mm 5. The method according to claim 3, characterized in that the transition along the outer diameter of the ingot blanks from the base metal to ductile carbon steel is performed smoothly in the form of a truncated cone over a length of 80-100 mm. 6. The method according to claim 1, characterized in that the process of heating composite hollow ingots-billets of electroslag remelting is carried out according to the heating mode of the main steel grade. 7. The method according to claim 3, characterized in that on the shrinkable ends of the hollow ingots-blanks, a cone is made on the outer surface along the length L _to = (1.5-2.0) S _c , with blunting h≥2,0 S _t , where S _c is the wall thickness of the hollow ingots-blanks electroslag remelting, mm; S _t - wall thickness of a commodity or conversion pipe, mm; L _to - the length of the conical part on the outer surface of the hollow ingots-billets during the transition from the base metal to ductile carbon steel, mm; h is the thickness of the blunting of the hollow billets of electroslag remelting, mm 8. The method according to claim 1, characterized in that the rolling process of commodity and conversion pipes on the pilgrim mill lead shrink end forward.