RU2297892C2 - Method for producing in tube rolling plants with pilger mills seamless hot deformed large- and mean-diameter tubes for steam boilers, steam pipes and collectors of plants with high and supercritical parameters of steam - Google Patents

Abstract

FIELD: rolled tube production, namely production of seamless hot deformed tubes from solid and hollow ingots of electroslag refining, possibly in tube rolling plants with pilger mills having also helical rolling mills.

SUBSTANCE: method comprises steps of melting ingots in electric and Martin furnaces on base of direct reduction at using processes for treating with liquid slag in ladle, electroslag refining and direct reduction of steels of given (in specification) kinds; forging ingots to forged pieces with forging ration 2 - 3 depending upon steel kind; continuously casting steel of given (in specification) kinds treated with synthetic slag; continuously casting steels of given kinds from evacuated or non-evacuated metal treated with synthetic slag for further forging them to blanks with forging ration no less than 1.5; cutting off ends of forged pieces at removing bottom and shrinkage portions; melting ingots of given kinds of steel by means of electroslag refining; mechanically working forged pieces and ingots of electroslag refining to predetermined-diameter blanks with allowance +10/-5 mm; heating ingots and blanks till plastic temperature depending upon kinds of steel; piercing them in skew rolling mills on mandrels whose diameter depend upon geometry size of sleeves; rolling tubes in pilger mills at elongation values depending upon diameter and wall thickness; calibrating and straightening tubes. Ingots of electroslag refining of given kinds of steels are heated till plastic temperature without drilling central opening in them; before piercing centering them from bottom end along axis; piercing in skew rolling mills to sleeves and rolling them in pilger mills to tubes of predetermined size. Hollow ingots of electroslag refining are used as conversion tube blanks of steel of given kinds. Hollow ingots of electroslag refining of given kinds of steel are heated till plastic temperature and rolled in pilger mills to tubes. Hollow ingots of electroslag refining of given kinds of steel are heated till plastic temperature and rolled in pilger rolling mills to tubes depending upon diameter and wall thickness.

EFFECT: improved manufacturing process due to lowered metal consumption for conversion of solid or hollow ingot of electroslag refining to boiler tube, reduced cost of boiler tubes.

3 cl, 1 tbl

Description

The invention relates to pipe rolling production, and in particular to a method for the production of seamless hot-deformed boiler pipes of large and medium diameters for steam boilers, steam pipelines and collectors of installations with high and supercritical parameters of steam from hollow ingots of electroslag remelting (ESR) and can be used on pipe rolling plants with pilgrim camps.

In the practice of pipe-rolling production, there is a method of manufacturing seamless hot-deformed pipes of large and medium diameters on pipe-rolling plants with pilgrim mills for steam boilers, steam pipelines and manifolds of plants with high and supercritical steam parameters from forged billets of steel grades 20, 15GS, 15XM, 12X1MF, 15X1MF, 15X1MF , 10Х9МФБ, 12Х11В2МФ, 08Х16Н9М2, 12Х18Н12Т and 10Х13Г12БС2Н2Д2 with specified requirements for mechanical properties, including smelting of ingots in electric and open-hearth furnaces, based on pit recovery, treatment with liquid synthetic slag in a ladle, electroslag remelting and direct reduction of steels 20, 15GS, 12Kh1MF, forging of ingots into forgings with a scrap from 2.0 to 3.0 depending on the steel grade, continuous casting of steel grades 20 and 15GS, processed by synthetic slag, or continuous casting of steel grades 12X1MF, 15X1M1F and 15XM from vacuum or non-vacuum metal treated with synthetic slag, followed by forging of continuously cast billets into forgings with a casting of at least 1.5, cutting the ends of the forgings with a die shrink and bottom parts, or smelting ingots of these grades of steel by electroslag remelting, machining forgings and ingots of electroslag remelting into billets for a given diameter with a tolerance of + 10 / -5 mm, heating the billets and ingots to a plasticity temperature depending on the grade of steel, centering ingots and billets from the bottom end along their axis, piercing them into sleeves in oblique rolling mills on mandrels, the diameter of which depends on the geometrical dimensions of the sleeves, rolling the sleeves on pilgrim mills into pipes of a given size ra with a wall tolerance of + 20 / -5% with hoods, depending on the diameter and wall thickness, calibration and straightening of pipes (TU 14-1-2560-78 "Forged pipe billet for boiler pipes", TU 14-3-460 -2003 and TU 14-3R-55-2001 "Seamless steel pipes for steam boilers and pipelines" and TU 14-3-420-75 "Pipes for steam boilers and pipelines made of 15GS and 15X1M1F steel".

The disadvantage of this method is the high energy intensity of the process associated with heating and deformation (forging) of the ingots and NLZ into forgings, followed by trimming the ends, trimming, turning and drilling of the central hole, heating the workpieces to the ductility temperature, piercing and rolling them into pipes on pilgrim mills with the tolerance on the wall is + 20 / -5%, increased metal consumption (metal expenditure coefficient) during redistribution of an ingot or NL3 - forging - billet - pipe and, as a result, the high cost of pipes.

Known in pipe rolling are methods of flashing ingots (billets) for lifting (expansion - 3-7%), size in size and posad (settling - 2-5%), where, with a change in the stress-strain state diagram, deformation expressed by the amount of drawing also changes (F.A. Danilov et al. Hot rolling of pipes. M.: Metallurgizdat, 1982, p. 300, table 34).

The disadvantage of these methods of firmware is the inability to provide the necessary deformation of the ingot, which allows to obtain the mechanical properties, structure and density of the metal pipes, which are obtained by production from forged billets.

In pipe rolling production, there is also known a method for manufacturing large diameter gas lift pipes from 09G2S steel ingots for ESW and VDP melting (RF Patent No. 2119395 class B21B 19/04), where the ingots are deformed in the piercing mill along the crystals, setting the ingots in the mill with the head part ( shrink) and stitch with a fit in diameter by the amount

D = 2S _g (1-sinα) S _c ,

where S _g - wall thickness of the sleeve, mm;

S _with - wall thickness of the drilled ingot ESR, mm;

α is the angle of inclination of the crystallization front to the axis of the ingot, deg.

The disadvantage of this method of manufacturing large diameter pipes from ingots of ESR and VDP steel grade 09G2S is the need to manufacture macro templates to determine the angle of inclination of the crystallization front to the axis of the ingot, and the piercing of the ingots with shrink (head) part forward leads to the formation of defects in the form of internal captures at the front ends of the sleeves .

The closest technical solution is a method for the production of large diameter boiler pipes from ESR ingots (patent RU No. 2180874, class B21B 19/04), which reduces energy costs, reduces metal consumption and, as a result, reduces the cost of boiler pipes through the use of large diameter ingots and conducting the firmware process with a posad in diameter equal to 8-16%.

The disadvantages of this method are the increased load on the drive of the piercing mill when flashing ESHB ingots of steels of grades 15X1M1F, 12X2MFSR, 10X9MFB, 12X11V2MF, 08X16H9M2, 12X18N12T and 10X13G12BS2N2D2 with a fit with a diameter of 8-16% with a diameter of more than 400 mm, and also it is impossible by drilling 100 ± 5 mm of steels of grades 10Kh9MFB, 12Kh11V2MF, 08Kh16N9M2, 12Kh18N12T and 10Kh13G12BS2N2D2.

The objective of the proposed method (invention) is to reduce energy costs by using hollow ESR ingots and eliminating the process of flashing and rolling sleeves in piercing mills, reducing metal consumption during redistribution of an ESR hollow ingot-boiler pipe by using a higher quality and ductile metal that does not have central liquation porosity and non-metallic inclusions.

The technical result is achieved by the fact that in the known method for the production of seamless hot-deformed pipes of large and medium diameters on tube rolling plants with pilgrim mills for steam boilers, steam pipelines and manifolds of plants with high and supercritical steam parameters, including ingot smelting in electric and open-hearth furnaces based on direct reduction , treatment with liquid synthetic slag in a ladle, electroslag remelting and direct reduction of steels 20, 15GS, 12X1MF, forging of ingots in forging with a die from 2.0 to 3.0 depending on the steel grade, continuous casting of steel grades 20 and 15GS treated with synthetic slag, or continuous casting of steel grades 12X1MF, 15X1M1F and 15XM from vacuum or non-vacuum metal treated with synthetic slag, with the subsequent forging of continuously cast billets into forgings with a weft of at least 1.5, the cutting of the ends of the forgings with the removal of the shrink and bottom parts, or the smelting of ingots of these grades of steel by electroslag remelting, the mechanical processing of forgings and ingots of electroslag remelting into billets for a given diameter with a tolerance of + 10 / -5 mm, heating the billets and ingots to a plasticity temperature depending on the steel grade, centering the ingots and billets from the bottom end along their axis, piercing them into sleeves in oblique rolling mills on mandrels , the diameter of which depends on the geometric dimensions of the sleeves, rolling the sleeves on the pilgrim mills into pipes of a given size with hoods, depending on the diameter and wall thickness, use hollow ingots of electroslag remelting steel as a pipe billet th marks 15H1M1F, 12H2MFSR, 10H9MFB, 12H11 V2MF, 06H16N9M2, and 12H18N12T 10H13G12BS2N2D2 hollow electroslag remelting ingots of steels 15H1M1F marks 12H2MFSR, 10H9MFB, 12H11V2MF, 06H16N9M2, 12H18N12T 10H13G12BS2N2D2 and heated to plasticity and rolled in pilger mills in the pipe.

Comparative analysis with the prototype shows that the inventive method for the production of seamless hot-deformed pipes of large and medium diameters on tube rolling plants with pilgrim mills for steam boilers, steam pipelines and manifolds of plants with high and supercritical steam parameters differs in that hollow electroslag ingots are used as the conversion tube billet remelting of steels of grades 15Х1М1Ф, 12Х2МФСР, 10Х9МФБ, 12Х11В2МФ, 06Х16Н9М2, 12Х18Н12Т and 10Х13Г12БС2Н2Д2, which are heated to a plastic temperature STI and bypassing the piercing mill, is rolled on a tube pilger mills predetermined dimensions. Thus, the claimed method meets the criterion of "inventive step".

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 distinguish the claimed method from the prototype, which corresponds to the patentability of "inventive step".

A method for the production of seamless hot-deformed large and medium-diameter pipes in tube-rolling plants with pilgrim mills for steam boilers, steam pipelines and manifolds of plants with high and supercritical parameters of steam from forged billets, solid and hollow ingots of ESR tested on TPA 8-16 "with piligrim mills of JSC" ChTPZ "when rolling pipes 377 × 30 mm in size from steel grade 15X1M1F and 377 × 25 mm, from steel grade 12X18H12T and 08X16H9M2. Forged billets (forgings of steel grade 15X1M1F were delivered by Mechel OAO, and solid and hollow ingots ESRs of steels of grades 12X18H12T, 08X16H9M2 and 15X1M1F were delivered to ZMZ OJSC. Forgings at ChTPZ OJSC were peeled and drilled into billets of 540 × 100 × 1750 mm in size. Solid and hollow ingots of ESR were processed (machined) into ZZ OJSC billets. According to the existing technology, boiler tubes made of 15X1M1F steel are made from forged drilled billets and ESR ingots. According to the existing technology, 5 forgings 570 × 1750 mm in size and 5 ESH ingots with dimensions 550 × 750 mm were set into production. The weight of 5 forgings amounted to 17.526 tons, and 5 ingots of ESR 16.320 tons. ESR billets and ingots were heated to a plasticity temperature, ESR 16.320 tons. ESR billets and ingots were heated to the ductility temperature, stitched in an oblique rolling mill on a mandrel with a diameter of 325 mm in sleeves of 570 × 340 × 2360 mm in size and rolled on a pilgrim mill in pipes of 377 × 30 mm in size according to TU 14-3R-55-2001 . Out of 5 billets, 48.5 m of pipes 377x30 mm in size, with a total weight of 13.297 tons, were taken in accordance with TU14-3R-55-2001. The expenditure coefficient from forging to the finished pipe was 1.318. The weight of 5 ESR ingots with a size of 550 × 1750 mm amounted to 16.320 tons. 50 m of pipes 377 × 30 mm in size were rolled from ESR ingots; the UTK was adopted in accordance with TU14-zR-55-2001 49.0 m or 13.475 tons. The expenditure coefficient of the metal from the ESR ingot to the pipe was 1.212. According to the proposed technology, pipes of this size were rolled from ESW hollow ingots of 550 × 105 × 3000 mm in size, which were turned and bored into workpieces of 540 × 100 × 3000 mm in size, heated to ductility temperature and, bypassing the piercing mill, were rolled in a pilgrim mill into pipes of size 377x30 mm. Five hollow ESR ingots with a total weight of 17.276 tons were assigned to production. The UTK was adopted for 54.5 m of pipes measuring 377 × 30 mm with a total weight of 14.942 tons. The expenditure coefficient of the metal amounted to 1,157.

When rolling pipes with a size of 377 × 25 mm from steel grade 12X18H12T according to the existing technology, ESR ingots of 550 × 1650 mm in size are used, which are machined by an outer diameter of 540 mm and drilled into billets of 540 × 100 × 1650 mm in size. Pipe rolling is carried out in two firmwares, i.e. a 540 × 100 × 1650 mm ESR blank is heated to the ductility temperature and stitched in a piercing mill on a mandrel with a diameter of 250 mm into a sleeve of 540 × 265 × 2100 mm in size. The height of the ingot 1650 mm was taken because during the second firmware (rolling) we cannot set the sleeve to the mill more than 2100 mm. Sleeves 540 × 265 × 2100 mm in size after flashing using hot posad were seated in a furnace, heated to a temperature of 1250-1260 ° C and rolled on a mandrel of 350 mm into 540 × 365 × 2930 mm sleeves, which were rolled on a pilgrim mill into tubes of size 377 × 25 × 11000 mm. Five ingots with a size of 550 × 1650 mm and a total weight of 15.484 tons were commissioned for production. Accepted UTK 54.5 m of pipes with a total weight of 11.897 tons. The expenditure coefficient of the metal for this batch of pipes was 1.302. According to the proposed technology, 5 hollow ESR ingots with a size of 550 × 100 × 3000 mm, a total weight of 16.744 tons, which were turned to a size of 540 × 95 × 3000 mm, heated to a temperature of 1245-1250 ° C and bypassing the piercing mill, were rolled into production a pilgrim mill in pipes measuring 377 × 25 mm. 63.2 m of pipes with a total weight of 13.796 tons were commissioned. The expenditure coefficient of the metal was 1.214. When rolling pipes of this batch according to the proposed technology, a decrease in the expenditure coefficient of the metal by 88 kg per each ton of pipes was obtained with a simultaneous increase in the productivity of pilgrim mills ≈ 2.0 times, because re-heating of the liners and two firmware on the piercing mill are excluded.

Pipe rolling with a size of 377 × 25 mm from 08Kh16N9M2 steel according to the existing technology is carried out from EShB ingots of 550x1650 mm in size with turning and drilling of the central hole to a size of 540 × 100 × 1650 mm. The billets, after heating to a ductility temperature of 1180-1200 ° C, are stitched in an oblique rolling mill on a mandrel with a diameter of 250 mm into sleeves of 540 × 265 × 2100 mm in size, reheated to the ductility temperature using a hot seat, stitched (rolled) on a mandrel with a diameter 350 mm in sleeves measuring 540 × 365 × 2930 mm and are rolled on a pilgrim mill into pipes of 377 × 25 mm in size. Two ESR ingots of 550 × 1650 mm in size with a total weight of 6.199 tons were assigned to production. UTK adopted 20.2 tons of pipes in accordance with TU14-ZR-55-2001, with a total weight of 4.41 tons. The expenditure coefficient of the metal from the ESR ingot to the pipe was 1.406. According to the proposed technology, two hollow ESR ingots of 550 × 100 × 3000 mm in size and a total weight of 6.698 tons were set into production. Hollow ingots were turned to a size of 540 × 95 × 3000 mm, heated to a temperature of 1185-1195 ° С and rolled on a pilgrim mill into pipes measuring 377 × 25 × 12500 mm. 25.0 m of pipes with a total weight of 5.475 tons were commissioned. The expenditure coefficient of the metal was 1.223, i.e. a decrease in metal consumption of 183 kg was obtained. The data on rolling and delivery of boiler pipes made of steel grades 15X1M1F, 12X18H12T and 08X16H9M2 according to the existing and proposed technologies are given in the table.

The table shows that the expenditure coefficient of the metal when rolling pipes of size 377 × 30 mm of steel grade 15X1M1F from continuous ingots of ESR according to the existing technology is lower than when rolling boiler pipes from forged billets, namely 106 kg per ton of pipe. When rolling pipes of this size from ESW hollow ingots according to the proposed technology (relative to the existing one), a reduction in the expenditure coefficient was obtained, respectively, by 161 and 55 kg per ton. When rolling pipes 377 × 25 mm in size from steel of grades 12X18H12T and 08X16H9M2 according to the proposed technology, they reduced the expenditure coefficient of the metal by 88 and 183 kg, respectively, while simultaneously increasing the productivity of the pilgrim mills ≈ 2 times.

Thus, the use of the proposed method for the production of large and medium diameter boiler pipes in pipe rolling plants with pilgrim mills for steam boilers, steam pipelines and collectors of plants with high and supercritical parameters of steam from ESR hollow ingots will significantly reduce energy costs by eliminating the heating of ingots for forging and forging ingots, re-heating the liners for rolling, to exclude the cost of drilling forgings and ingots, to exclude the operation of flashing ingots and billets into the liners s and their re-rollers, reduce the consumable metal ratio, when the mechanical properties of pipes at or above the metal, compared with forged billet at repartition ESR ingot-tube boiler, increase productivity pilger mills, and hence reduce the cost of boiler tubes.

Claims (3)

1. Method for the production of seamless hot-deformed pipes of large and medium diameters in tube-rolling plants with pilgrim mills for steam boilers, steam pipelines and collectors of plants with high and supercritical steam parameters, including ingot smelting in electric and open-hearth furnaces, based on direct reduction, treatment with liquid synthetic slag in a ladle, electroslag remelting and direct reduction of steels 20, 15GS, 12Kh1MF, forging of ingots into forgings with a weft from 2.0 to 3.0 depending on the steel grade, continuous casting of steel grades 20 and 15GS treated with synthetic slag, or continuous casting of steel grades 12X1MF, 15X1M1F and 15XM from vacuum or non-vacuum metal treated with synthetic slag, followed by forging of continuously cast billets into forgings with a minimum of 1.5 gutters, cutting the ends of forgings with the removal of shrinkage and bottom parts, or the smelting of ingots of these grades of steel became electroslag remelting, machining of forgings and ingots of electroslag remelting into blanks for a given diameter with tolerance + 10 / -5 mm, heating the billets and ingots to a plasticity temperature depending on the steel grade, centering the ingots and billets from the bottom end along their axis, piercing them into sleeves in oblique rolling mills on mandrels, the diameter of which depends on the geometric dimensions of the sleeves, rolling sleeves on pilgrim mills into pipes of a given size with hoods depending on the diameter and wall thickness, calibration and straightening of the pipes. 2. The method according to claim 1, characterized in that the hollow ingots of electroslag remelting of steels of grades 15X1M1F, 12X2MFSR, 10X9MFB, 12X11V2MF, 06X16N9M2, 12X18N12T and 10X13G12BS2N2D2 are used as a conversion pipe billet. 3. The method according to claim 2, characterized in that the hollow ingots of electroslag remelting of steels of grades 15Kh1M1F, 12Kh2MFSR, 10Kh9MFB, 12Kh11V2MF, 06Kh16N9M2, 12Kh18N12T, 10Kh13G12BS2N2D2 are heated to the ductility temperature and rolled in a saw mill.