RU2547362C2 - METHOD TO PRODUCE HEXAHEDRAL STOCK PIPES WITH FLAT-TO-FLAT DIMENSION 175×2,5+0,3/-0,2×2680+20/-0 mm FROM STEEL OF GRADE "16Х12МВСФБР-Ш (ЭП823-Ш)" FOR FAST FEEDER REACTORS - Google Patents

Abstract

FIELD: technological processes.

SUBSTANCE: invention relates to metallurgical and pipe rolling industries. Electroslag melting bars with size off 485×1600±25 mm are cast and turned into cakes with size of 470×1600±25 mm. A through hole is drilled with a diameter of 100±5 mm. Cakes are heated to temperature of 1120-1140°C and pierced in a cross-rolling mill into blooms with size of 480×vn.315×2500 mm. Cakes are rolled into pig hot-deformed stock pipes with size of 337×28×8000 mm in a gauge 340 mm on burnishers 282/286 mm with drawing of µ_n=3.79, clamping by diameter Δ=29.8% and feed of blooms into a deformation site m=16-18 mm. Stock pipes are straightened using temperature of rolling heating and cut into two stock pipes with size of 337×28×4000 mm. Stock pipes are turned and ground. Rolling of stock pipes on cold pilgering mills 450 and 250 is carried out along the routes: 325×12×4000---273×8×6680---219×4×16100 mm. Pipes are cut and rolled on the cold pilgering mill 250 into stock pipes with size of 194×2.5×14100 mm. At one of ends of stock pipes they drill a hole for a pivot of a pulling chain. Stock pipes are profiled into hexahedral pipes with a flat-to-flat dimension of 175±0.4×2.5+0.3/-0.2×14100 mm.

EFFECT: reduced discharge coefficient of metal.

Description

The invention relates to metallurgical and pipe production, and in particular to a method for the production of hollow ingots by electroslag remelting from hard-to-deform steel of grade 16X12MVSFBR-Sh (EP823-Sh), turning and boring them into hollow ingots-blanks, to a method for producing ESW from hollow ingots-blanks TPU 8-16 ″ with 338 × 25 mm pilgrim mills for hot rolled pipe, machining them into 325 × 12 mm billet pipes with a tolerance of ± 0.8% in diameter and ± 10.0% in wall thickness, mechanical rolling processing billets of 325 × 12 mm in size at the KhPT 450 and KhPT 250 mills into conversion billets of 194 ± 1.2 × 2.5 + 0.3 / -0.2 mm in size, profiling of the billets into hexagonal pipes - turn-key blanks of 175 + 0.4 × 2.5 + 0.3 / -0.2 × 2680 + 20 / -0 mm, and can be used on electronic ballast installations for casting hollow ingots, machining them in hollow ingots-billets at OJSC “ZMZ”, rolling them at TPU 8-16 ″ with pilgrim mills of OJSC “ChTPZ” into hot-rolled billets of 338 × 25 mm in size, machined - boring and turning hot rolled pipes into conversion machined pipes with a size of 325 × 12 mm with a tolerance of ± 0.8% in diameter and a wall of ± 10.0%, rolled them at the KhPT 450 and KhPT 250 mills into converted cold-rolled billets of a size of 194 + 1.2 × 2.5 + 0.3 / -0.2 mm, redistribution of the billet pipes on the profiling “mill 400” into hexagonal tubes of the billet size 175 ± 0.4 × 2.5 + 0.3 / -0, 2 × 2680 + 20 / -0 mm for use in nuclear power plants incorporating a new generation of fast neutron reactors.

In pipe-rolling production, a method is known for producing hot-rolled commodity and conversion pipes of large and medium diameters from hard-to-deform steel grades in pipe-rolling plants with pilgrim mills from EShP ingots of steel grade 10X9MFB-Sh (TU 14-134-398-2003 "Billet pipe - ingots for boiler pipes EShP ”, TU 14-3R-55-2001“ Seamless steel pipes for steam boilers and pipelines ”, TI 158-Tr. TB1-56-2007“ Production of seamless hot-rolled pipes for steam boilers and pipelines according to TU 14-3R-55- 2001 ").

The disadvantage of this method is that the pipes after rolling have a large number of defects on the inner surface in the form of captures and grids of high cracks, require subsequent machining - boring and turning with metal removal of 8-10 mm per side. This steel grade has a hot ductility range of 1160–900 ° C and an increased coefficient of linear expansion. If the ESR ingots-billets are heated to a temperature of 1160 ° C, then when the ingots are pierced in the cross-helical rolling mill into the sleeves, the metal temperature in the deformation zone at the mandrel-inner surface of the sleeves increases by 50-70 ° C depending on the diameter of the ingot. When rolling sleeves on a pilgrim mill into commodity pipes with an outer surface temperature of 1160 ° C or less, the end of rolling occurs at a temperature of 800-850 ° C depending on the diameter and wall thickness, which leads to tightening of mandrels even with a taper of 4-5 mm instead 1.0 according to TI 158-Tr. TB1-56-2007. The heating of the ESR ingots-blanks of this steel grade above 1160 ° C leads to overheating of the inner surface of the sleeves and the mass formation of internal captures and grids of high-cracking. These pipes must be rejected or bored onto a smaller wall with metal removal of more than 10 mm per side, which in turn leads to increased metal consumption and an additional laborious operation - boring of pipes with defects on the inner surface.

The well known tube-manufacturing method for manufacturing pipes of hard steels and alloys with a high coefficient of linear expansion, comprising: heating a working portion of the mandrel to an average temperature equal to or higher than the necessary front end of the tube temperature at the time of its descent from T mandrel _{sr.d lane} ≥T _.kt , where T _cf.d is the average temperature of the mandrel before rolling, ° C; T _per.kt - the required temperature of the front end of the pipe at the moment of its descent from the mandrel, ° C, heating of the working part of the mandrel with a temperature difference along the length of the working part of not more than 100 ° C, i.e. T _max -T _min <100 ° C, where T _max is the maximum temperature of the working part of the mandrel in the zone of intense deformation, ° C; T _min - the minimum temperature of the working part of the mandrel, ° C (RF Patent No. 2214312, class B21B 21/00, 10/20/2003, bull. No. 29).

The disadvantage of this method is that it is aimed at reducing the number of puffs of mandrels during rolling of pipes from hard to deform steel grades and alloys with an increased coefficient of linear expansion by heating the mandrels before rolling and during the rolling process. This method does not solve the main technological issues: roll-up of sleeves - break-in of pilgrim heads at temperatures below the lower hot plasticity interval of these grades of steel and alloys and, all the more, the technology of producing high-quality shell sleeves on the inner surface during the flashing of ESR ingots-blanks and firmware-rolling of blanks-blanks in the sleeves in the cross-rolling mill.

In the pipe industry, there is also a known method for the production of hot-rolled commodity and conversion pipes of large and medium diameters from hard-to-deform steel grades and alloys in pipe rolling plants with pilgrim mills, including the casting of hollow ingots 1750-2100 mm high on electroslag remelting plants. The ingots are grinded and bored to remove scale and microcracks to a diameter of 400-620 mm with a ratio of diameter to wall thickness D / S = 3.0-4.0, large values of which correspond to ingots-blanks of smaller diameter. Then, the ingot blanks are heated to the temperature of ductility and stitched - rolled in a cross-helical rolling mill into sleeves with hoods µ = 1.5-1.7, large values of which correspond to sleeves of a larger diameter. Sleeves stitched - rolled with hoods µ = 1.5-1.6, rolled on pilgrim mills into conversion tubes, and sleeves stitched - rolled with hoods µ = 1.6-1.7 - into commodity pipes (RF Patent No. 2311979 , CL B21B 21/00, 12/10/2007).

The disadvantage of this method is that it only partially reduces the formation of defects on the inner surfaces of the sleeves by reducing the drawing coefficient (squeezing the sleeve blanks along the wall) in the deformation zone during firmware - rolling the sleeve blanks from corrosion-resistant hard-deformed steel grades and alloys with low temperature hot ductility interval and high coefficient of linear expansion in cross-helical rolling mills. This method does not solve the technological issues of heating hollow ingots-blanks ESR from steel grade 12Kh12M1BFRU-Sh, piercing and rolling conversion tubes from hard-to-form steel grades and alloys with a low temperature range of hot ductility and a high coefficient of linear expansion and rolling them on HPT mills into conversion tubes 194 ± 1.2 × 2.5 + 0.3 / -0.2 mm in size for their subsequent profiling into hexagonal billets of turnkey size 175 + 0.4 × 2.5 + 0.3 / -0 , 2 × 2680 + 20 / -0 mm for new generation reactors on fast neutrons.

In the pipe industry, a method is known for producing cold-rolled large and medium-diameter pipes from hard-deformed steel grades and alloys with increased accuracy on the wall, including rolling the welded billet in calibers with a variable radius into a cold-rolled commodity pipe with a maximum diameter with an extractor μ = 1.4-1, 7 and compression on the wall of at least 25%, while during subsequent rolls, the hood gradually increases by 0.05-0.10 to 1.7-2.0, and large values of hoods and wall compressions are taken for steels with a high content m of chromium and nickel, the conversion pipe billet is rolled into a commodity or conversion cold-rolled pipe of maximum diameter with a ratio of diameter to wall thickness of the pipe D / S = 40-50, which during subsequent rolling is rolled into pipes of smaller diameter with an increase in the D / S ratio from 2 to 10, and the last roll is performed with the ratio D / S = 50-75.

The disadvantage of this method is that it is aimed at the technology for the production of cold-rolled large and medium diameter pipes from hard-deformed steel and alloys with increased accuracy on the wall from welded billets and does not solve technological and structural issues in the production of turn-key hexagonal tubes-billets 175 ± 0.4 × 2.5 + 0.3 / -0.2 × 2680 + 20 / -0 mm from steel grade 16Kh12MVSFBR-Sh (EP823-Sh) for new generation fast-neutron reactors.

There is also known a method for the production of prototypes of hexagonal billet pipes with a turnkey size of 181.3 × 3.5 × 3750 + 20 / -0 mm from steel grade 12Kh12M1BFRU-Sh (EP450U-Sh) for new generation fast-neutron reactors ( protocol No. 60/11 of 08/03/2011 and TU 1367-043-00186654-2012 (experimental batch) "Seamless cold-deformed hexagonal pipes of steel grade 12X12M1BFRU-Sh (EP450U-Sh)"), including ingot casting by electroslag remelting, size 485 × 1540 mm, turning of ingots into ingots-blanks of size 470 × 1540 mm, drilling in ingots-blanks of a central hole of di ameter 100 ± 5 mm, heating to a temperature of 1180-1200 ° C, piercing in a cross-helical rolling mill into sleeves of size 480 × ext. 315 × 2400 mm, rolling the sleeves on pilgrim mills into red hot-formed pipe billets of 344 × 31 mm in caliber 351 mm, a hot-saw blade for cutting technological waste — pilgrim heads and seed ends, straightening pipes and machining — boring and turning into pig tubes 325 × 12 mm in size with a tolerance of ± 1.0% in diameter and ± 12 wall thickness, 5%) with metal removal on the outer and inner surfaces 9.5 mm each with a surface finish of R _z ≤30 μm, rolling of machined pipes of size 325 × 12 mm at the mills ХПТ 450 and ХПТ 250 into conversion pipes with a size of 202 × 3.5 mm with a diameter tolerance of ± 0.8% and wall thickness ± 10.0%).

The disadvantage of this method is that when redistributing ingots-blanks of ESRs of 470 × 1540 mm in size to hot-rolled hot-rolled pipes of 325 ± 3.25 × 12 ± 1.5 mm in size, even with a triple roll on cold mills HPT 450 and HPT 250, cold-rolled pipes 175 × 2.5 mm in size with a tolerance of ± 1.2 mm in diameter and a wall of + 0.3 / -0.2 mm is problematic to obtain. In the production of hot-rolled chimneys with a size of 325 × 12 mm, increased waste in multiplicity is obtained. The piercing of ESR blanks in a cross-helical rolling mill at a heating temperature of 1180-1200 ° C leads to a temperature increase at the border of the mandrel with the inner surface of the sleeves to 1250-1270 ° C, which for this steel grade is fraught with overheating of the inner surface and the formation of a grid of high-level cracks, which, in turn, leads to marriage or an increase in metal removal during boring of hot-rolled pipes into redistributed machined pipes with a size of 325 × 12 mm. This method is aimed at the production of hexagonal tubes-blanks from steel 12X12M1FBRU-Sh and does not solve the technological and construction issues of the production of hexagonal tubes-blanks with a turnkey size of 175 ± 0.4 × 2.5 + 0.3 / -0.2 × 2680 + 20 / -0 mm from steel grade 16Kh12MVSFBR-Sh (EP823-Sh) for new generation fast-neutron reactors.

The closest technical solution (prototype) is a method for the production of hexagonal tubular sheath pipes with a turnkey size of 257 + 2 / -3 × 6 + 2 / -1 × 4300 + 80 / -30 mm from low-ductility steel with a boron content of 1.3-1 , 8%, including mechanical processing - boring and turning, degreasing, induction treatment, ultrasonic testing, drilling holes for the pulling chain during profiling, coating pipes with salt grease and warm profiling pipes of two to three times the length, the value of which is determined from the expression: L _tr - ( 2-3) L _cr + L + L _{KO lane,} where L _mp - length hex zagotovki- Pipes, mm; L _cr - the length of the cylindrical part of the billet-pipe for drilling an axial hole for the pin of the pulling chain, mm; L _KO - the length of the end trim, and pipe cutting to a measured length, the selection of templates for the manufacture of samples for mechanical testing and removal of the end trim after controlling the geometric dimensions and marking of the hexagonal tubing-lashes (RF Patent No. 222436363, class B21B 23/00 May 20, 2005).

This method is aimed at the production of hexagonal pipes from steel with a boron content of 1.3 to 1.8% for storage and transportation of spent nuclear fuel and does not solve the technological and construction issues of the production of hexagonal tubes-blanks with a size of 175 ± 0.4 × 2.5 + 0.3 / -0.2 × 2680 + 20 / -0 mm from steel grade 16Kh12MVSFBR-Sh (EP823-Sh) for new generation fast-neutron reactors.

The objective of the proposed method is the development of the production of cold rolled pipes in size of 194 × 2.5 mm with a diameter tolerance of ± 1.2 mm (± 0.6%>) and a wall thickness of + 0.3 / -0.2 mm (+8, 5 / -5.5%) instead of ± 0.8% in diameter and ± 10% in the wall (GOST 9941 high precision), exclusion from the technological process of flashing ingot-blanks EShP from steel grade 16Kh12MVSFBR-Sh (EP823-Sh) in to a cross-helical rolling mill (the most defect-forming operation), reduction of metal consumption during redistribution hollow ingot-billet ESR - hot rolled pipe - redistributed fur personally processed pipe - a hexagonal pipe-billet due to changes in heating technology and the deformation scheme of hollow ESR ingots-billets on a pilgrim mill in the manufacture of hot rolled tubes, mastering the production of turn-key hexagonal tubes-billets 175 ± 0.4 × 2.5 + 0.3 / -0.2 × 2680 + 20 / -0 mm from hollow ingots-blanks of EHPs of steel grade 16X12MVSFBR-Sh (EP823-Sh) for equipping nuclear power plants with new generation fast-neutron reactors, and, consequently, reducing the cost of hexagonal billet pipes with a low temperature range of mountains whose plasticity.

The technical result is achieved by the fact that in the known method for the production of hexagonal tube blanks with a turnkey size of 175 ± 0.4 × 2.5 + 0.3 / -0.2 × 2680 + 20 / -0 mm from steel grade 16X12MVSFBR- Ш (ЭП823-Ш) for fast neutron reactors, including casting ESR ingots of size 485 × 1600 ± 25 mm, turning them into ingot blanks of size 470 × 1600 ± 25 mm, drilling a through hole with a diameter of 100 ± 5 mm, heating ingots -workings to a temperature of 1120-1140 ° C, their piercing in a cross-helical rolling mill into sleeves of size 480 × ext. 315 × 2500 mm, rolling them on pilgrim mills in front hot-deformed blank tubes 337 × 28 × 8000 mm in size in caliber 340 mm on mandrels 282/286 mm with hood µ _n = 3.79, diameter reduction Δ = 29.8% and feed sleeves into the deformation zone m = 16- 18 mm, removal from pipes by a hot cutting saw of technological waste - pilgrim heads and seed ends, dressing of billet pipes using rolling heating temperature in a six-roll straightening machine, cutting of billet pipes into two billet pipes 337 × 28 × 4000 mm in size, boring and turning into billet pipes of size 325 × 12 × 4000 mm with a diameter tolerance of ± 0.8%> and wall ± 10.0%), rolling of the billet pipes at the KhPT 450 and KhPT 250 mills along the routes 325 × 12 × 4000-273 × 8 × 6680-219 × 4 × 16100 mm, cutting pipes 219 × 4 × 16100 mm into two billet pipes 219 × 4 × 8050 mm in size and rolling at the KhPT 250 mill into billet pipes of 194 × 2.5 × 14100 mm in size, drilling holes from one end of the billet pipes for the pull chain pin, profiling pipes of blanks in the milling “mill 400” into hexagonal pipes of “turnkey” size 175 ± 0.4 × 2.5 + 0.3 / -0.2 × 14100 mm, removal of the technological edge - transition zone from the round billet pipe to hex and trim at the opposite end, cutting pipes into dimensional hexagonal billets measuring 175 ± 0.4 × 2.5 + 0.3 / -0.2 × 2680 + 20 / -0 mm with all subsequent operations on the hexagonal pipe manufacturing process - billets and their acceptance for compliance with NTD, while the nominal outer diameter and tolerances for the diameter of round pipes for the production of hexagonal billets are determined by the formulas:

where B is the nominal size of the turnkey hexagonal pipe billet, mm; tg30 ° is the angle between the diameter of the circumscribed circle and the face of the hexagonal pipe-workpiece, deg; n is the number of faces, pcs .; r is the inner radius of the rounding of the faces of the hexagon, mm; s is the nominal wall thickness of the hexagonal billet pipe, mm; γ = (1.015-1.03) - coefficient taking into account the magnitude of the tightening of the perimeter of a round pipe when profiling it into a hexagonal pipe billet; ± 0.4 - tolerance on the size of the "key" of the hexagonal pipe billet, mm.

A comparative analysis of the proposed solution with the prototype shows that the claimed method differs from the known one in that ESR ingots are cast with a size of 485 × 1600 ± 25 mm, machined into ingot blanks with a size of 470 × 1600 ± 25 mm, and a through hole is drilled with a diameter of 100 ± 5 mm , the ingot blanks are heated to a temperature of 1120–1140 ° C, stitched in a cross-mill mill into sleeves of size 480 × ext. 315 × 2500 mm, their pilgrim mills are rolled into converted hot-deformed blanks of size 337 × 28 × 8000 mm in caliber 340 mm on mandrels 282/286 mm with you yazhkoy μ _n = 3,79, swaging diameter Δ = 29,8% and feeds the sleeves into the rolling gap m = 16-18 mm, are removed from the tubes with hot saw cutting processing wastes - pilger seed heads and the ends, producing a straightening tube blanks using the temperature of rolling heating in a six-roll straightening machine, cutting blanks into two blanks of 337 × 28 × 4000 mm in size, boring and turning into blanks of 325 × 12 × 4000 mm in diameter with a diameter tolerance of ± 0.8% and wall ± 10.0%), rolling of billet pipes at the KhPT 450 and KhPT 250 mills along the routes: 325 × 12 × 4000--273 × 8 × 6680--2 19 × 4 × 16100 mm, cutting pipes of 219 × 4 × 16100 mm in size into two billet pipes of 219 × 4 × 8050 mm in size and rolling at the KhPT 250 mill into billet pipes of 194 × 2.5 × 14100 mm in size, drilling with one of the ends of the billet pipe holes for the pull pin of the pull chain, profiling the billet pipes in the profiling “mill 400” into six-sided hexagonal pipes 175 ± 0.4 × 2.5 + 0.3 / -0.2 × 14100 mm, removal of technological trim - transition zone from a round billet pipe to a hexagonal one and trimming of the opposite end, cutting of pipes into dimensional hexagonal billet pipes of 175 ± 0.4 size × 2.5 + 0.3 / -0.2 × 2680 + 20 / -0 mm with all subsequent operations on the production process of hexagonal tubes-blanks and their acceptance for compliance with technical documentation, while the nominal outer diameter and tolerances for diameter of round pipes for manufacturing hex

billet pipes are determined by the formulas:

where B is the nominal size of the turnkey hexagonal pipe billet, mm; tg30 ° is the angle between the diameter of the circumscribed circle and the face of the hexagonal pipe-workpiece, deg; n is the number of faces, pcs .; r is the inner radius of the rounding of the faces of the hexagon, mm; s is the nominal wall thickness of the hexagonal billet pipe, mm; γ = (1.015-1.03) - coefficient taking into account the magnitude of the tightening of the perimeter of a round pipe when profiling it into a hexagonal pipe billet; ± 0.4 - tolerance on the size of the "key" of the hexagonal pipe billet, mm. Thus, the claimed method meets the criterion of "inventive step".

Comparison of the claimed solution (method), not only with the prototype, but also with other technical solutions in this technical field, did not reveal the signs that distinguish the claimed solution from the prototype, which allows us to conclude that the patentability condition is “inventive step”.

The method was tested at ZMZ OJSC when casting hollow ingots on an ESH machine with a size of 490 × ext. 290 × 3000 ± 25 mm, turning and boring them into hollow ingots-blanks with a size of 480 × ext. 300 × 3000 ± 25 mm and at OAO ChTPZ ”during rolling of conversion pipes with a size of 338 × 25 × 11800 mm at a pipe-rolling installation with pilgrim mills 8-16 ″, cutting into two pipe billets of 338 × 25 × 5900 mm, machining - boring and turning them into conversion pipes of 325 × 12 × 5900 mm with a tolerance of ± 1.0% in diameter and ± 10.0% in wall thickness, rolling them at the KhPT450 and KhPT 250 mills into conversion pipes of size 194 ± 1.2 × 3.5 + 0.3 / -0.2 mm and when profiling them in the profiling “mill 400” into hexagonal pipe blanks with a “turnkey” size 175 ± 0.4 × 2.5 + 0 , 3 / -0.2 × 2680 + 20 / -0 mm. According to the existing technology, 2 ingot blanks with a size of 470 × 100 × 1540 mm with a total weight of 4040 kg were heated in a methodical furnace to a temperature of 1160 and 1170 ° C. The piercing of ingot blanks in a cross-helical rolling mill was performed on a mandrel with a diameter of 300 mm. When flashing on the liners there were internal captives and small flaws. Sleeves were rolled on a pilgrim mill in rolls with a caliber of 351 mm on mandrels with a diameter of 283/287 mm and a taper of 4.0 mm into transfer tubes of 344 × 31 × 6600 mm in size. The pipes were rolled with carbon-based washers with feeds of sleeves to the deformation zone m — 20-22 mm.

The pipes went off the mandrel satisfactorily, because the temperature of the end of rolling was 860-870 ° C. On the inner surface of the pipes were captives and transverse flaws. The pipes were straightened on a straightening machine and cut into two pipe blanks measuring 344 × 31 × 3300 mm. Billet pipes were bored to remove internal defects, and then turned to a diameter of 325 mm. The wall thickness of the pipes ranged from 10 to 12.5 mm. Pipes were transferred to workshop No. 5 and on the KhPT 450 and KhPT 250 mills were rolled into conversion pipes measuring 194 × 2.5 mm along the routes: 325 × 12 × 3300-273 × 8 × 5500 --- 219 × 4 × 13100 mm Pipes of 219 × 4 × 13100 mm in size were cut into two billet pipes of 219 × 4 × 6550 mm in size, and then rolled at the KhPT 250 mill into conversion pipes of 194 × 2.5 × 11400 mm in size. Cold-rolled pipes measuring 194 × 2.5 × 11400 mm were cut into three billets of equal length (3800 mm). 24 billet pipes with a size of 194 × 2.5 × 3800 mm were specified for profiling. 24 hexagonal billet pipes with dimensions of 175 ± 0.6 × 2.6 + 0.5 / -0.6 × 2680 + 20 / -0 mm were profiled. One hexagonal billet pipe is rejected along the wall (1.9 mm) from one end. Hexagonal billet pipes are accepted as conditionally suitable. The total expenditure coefficient of the metal according to the existing technology for redistributing an ESR ingot of 470 × 1540 mm in size is a hot-rolled conversion machined pipe of 325 × 12 × 3300 mm in size - a cold-rolled conversion pipe in a size of 194 × 2.5 × 3800 mm is a commodity hexagonal billet pipe in size 175 ± 0.6 × 2.5 + 0.5 / -0.6 × 2680 + 20 / -0 mm was 5.758.

According to the proposed technology, 2 hollow ESR ingots with a size of 490 × ext. 290 × 3000 mm with a total weight of 5768 kg were turned and bored into hollow ingots-blanks with a size of 480 × ext. 300 × 3000 mm with a total weight of 5191 kg. The ingot billets are heated in a methodical furnace to a temperature of 1140 ° C and rolled on a pilgrim mill in a hot-rolled pipe mill measuring 338 × 25 × 11800 mm. Pipes are cut into two equal parts, bored and turned into steel machined billet pipes measuring 325 × 12 × 5900 mm with a tolerance of ± 0.8% in diameter and ± 10.0% in wall thickness. Machined billet pipes were rolled at the KhPT 450 mill along the route 325 × 12 × 5900 --- 273 × 8 × 10000 mm. Pipes 273 × 8 × 100 mm in size were cut into two billet pipes of 273 × 8 × 3350 and 273 × 8 × 6650 mm in size and rolled on the KhPT 250 mill into conversion pipes of 219 × 4 × 7900 and 219 × 4 ×, respectively 16000 mm. Pipes with a size of 219 × 4 × 16000 mm were cut into two billet pipes with a size of 219 × 4 × 8000 mm. Pipes 219 × 4 × 7900 and 219 × 4 × 8000 mm in size were rolled at the KhPT 250 mill into billet pipes of 194 × 2.5 × 13800 and 194 × 2.5 × 14000 mm, respectively, which were profiled in profiling 400 "into hexagonal pipes of turnkey size 175 + 0.4 × 2.5 + 0.3 / -0.2 × 13800 mm and 175 ± 0.4 × 2.5 + 0.3 / -0, 2 × 14000 mm, and then cut into dimensional hexagonal billets measuring 175 ± 0.4 × 2.5 + 0.3 / -0.2 × 2680 + 20 / -0 mm with all subsequent operations on the manufacturing process hexagonal billet pipes and are accepted for compliance with NTD. Four pipes with a size of 194 × 2.5 × 13800 mm and 8 pipes with a size of 194 × 2.5 × 14000 mm were specified for profiling. 60 hexagonal tubes-blanks with a size of 175 ± 0.4 × 2.5 + 0.3 / -0 × 2680 + 20 / -0 mm were profiled. Two hexagonal billet pipes are rejected along the wall (wall 2.9 and 3.0 instead of 3.3 mm). 58 hexagonal tube blanks with a total mass of 1834 kg were adopted.

The expenditure coefficient of the metal according to the proposed technology for redistribution is a hollow ingot of ESR with a size of 490 × ext. 290 × 3000 mm — a hollow billet of an ESR with a size of 480 × ext. 300 × 3000 mm — a hot-rolled conversion machined pipe with a size of 325 × 12 × 5900 mm — a cold-rolled conversion pipe with a size of 194 × 2.5 × 13800-14000 mm - a product hexagonal pipe a workpiece with a size of 175 ± 0.4 × 2.5 + 0.3 / -0.2 × 2680 + 20 / -0 mm was 3.145. Thus, when redistributing 2 hollow ingots with a size of 490 × ext. 290 × 3000 mm, 58 hexagonal workpieces with a size of 175 ± 0.4 × 3.5 + 0.3 / -0.2 × 2680 + 20 / -0 mm were obtained total mass of 1834 kg.

Data on rolling hot-rolled machined tubes of 325 × 12 mm in size from steel grade 16Kh12MVSFBR-Sh (EP823-Sh), rolling them at KhPT 450 and KhPT 250 mills into conversion tubes with increased accuracy in diameter and wall size 194 ± 1, 2 × 2.5 + 0.3 / -0.2 mm along the routes: 325 × 12--273 × 8--219 × 4--194 × 2.5 mm and profiling them into hexagonal pipes on a turnkey basis 175 ± 0.4 × 2.5 + 0.3 / -0.2 × 2680 + 20 / -0 mm according to the existing and proposed technologies are shown in table 1. It can be seen from the table that when redivising 2 hollow ingots-blanks size 480 × ext. 300 × 3000 mm according to the proposed technology and received 58 high-quality hexagonal tubes-blanks with a total mass of 1834 kg. The total expenditure coefficient of the metal amounted to 3.145. Thus, a decrease in the expenditure coefficient of the metal by 2613 kg was obtained for each ton of hexagonal workpieces. The defect-forming operation is excluded - the flashing of ingots-blanks of ESR into the sleeves in a cross-helical rolling mill - and the operation of boring of converted hot-rolled tubes of 344 × 31 mm in size with defects on the inner surface into converted machined tubes of 325 × 12 mm in size.

Using the proposed method for the production of commercial hexagonal tubes-blanks of turnkey size 175 ± 0.4 × 3.5 + 0.3 / -0.2 × 2680 + 20 / -0 mm from steel grade 16X12MVSFBR-Sh (EP823-Sh ) for a new generation of fast neutron reactors, it will make it possible to obtain hexagonal billet tubes with given geometric dimensions, reduce the expenditure coefficient of the metal when redistributing a hollow ESR ingot - a hollow ESR ingot ingot - a hot rolled machined pipe with a size of 325 × 12 mm with a diameter tolerance ± 0.8% and wall thickness ± 10.0% - conversion ho boat-rolled pipe with a size of 194 ± 1.2 × 2.5 + 0.3 / -0.2 mm - commodity hexagonal billet pipe with a size of 175 ± 0.4 × 3.5 + 0.3 / -0.2 × 2680 + 20 / -0 mm, and therefore, reduce their cost.

Claims (1)

Method for the production of turnkey hexagonal tube blanks 175 ± 0.4 × 2.5 + 0.3 / -0.2 × 2680 + 20 / -0 mm from steel grade 16Kh12MVSFBR-Sh (EP823-Sh) for reactors Fast neutron nuclear power plants, including casting ESR ingots of size 485 × 1600 ± 25 mm, turning them into ingot blanks of size 470 × 1600 ± 25 mm, drilling a through hole with a diameter of 100 ± 5 mm, heating ingot blanks to a temperature of 1120–1140 ° C, flashing them in a cross-helical rolling mill into sleeves of size 480хвн. 315 × 2500 mm, rolling them on pilgrim mills into hot-deformed pipe blanks of size 337 × 28 × 8000 mm in caliber 340 mm on mandrels 282/286 mm with hood µ _n = 3.79, diameter reduction Δ = 29.8% and feeds of sleeves into the deformation zone m = 16-18 mm, removal from pipes by a saw hot cutting of technological waste - pilgrim heads and seed ends, straightening pipe blanks using rolling heat in a six-roll straightening machine, cutting pipe blanks into two pipe blanks measuring 337 × 28 × 4000 mm, boring and turning into blank tubes of size 325 × 12 × 4000 mm with a tolerance of ± 0.8% in diameter and ± 10.0% in the wall), rolling of billet pipes at KhPT 450 and HPT 250 along routes: 325 × 12 × 4000 --- 273 × 8 × 6680 --- 219 × 4 × 16100 mm, cutting of pipes of size 219 × 4 × 16100 mm into two billet pipes of 219 × 4 × 8050 mm and rolling at the KhPT 250 mill into billet pipes measuring 194 × 2.5 × 14100 mm, drilling holes from one of the ends of the billet pipes for the pin of the pull chain, profiling the billet pipes in the profiling “mill 400” into hexagonal pipes of “turnkey” size "175 ± 0.4 × 2.5 + 0.3 / -0.2 × 14100 mm, removal of the technological edge - the transition zone from the round billet pipe to the hexagonal one, and trimming the opposite end, cutting pipes into six early billet pipes with a size of 175 ± 0.4 × 2.5 + 0.3 / -0.2 × 2680 + 20 / -0 mm with all subsequent operations on the production process of hexagonal billet pipes and their acceptance for scientific compliance -technical documentation, while the nominal outer diameter and tolerances on the diameter of round pipes for the production of hexagonal tubes-blanks are determined by the formulas:

where B is the nominal size of the turnkey hexagonal pipe billet, mm;
tg30 ° - the angle between the diameter of the circumscribed circle and the face of the hexagonal pipe-workpiece, deg .;
n is the number of faces, pcs .;
r is the inner radius of the rounding of the faces of the hexagon, mm;
s is the nominal wall thickness of the hexagonal billet pipe, mm;
γ = (1.015-1.03) - coefficient taking into account the magnitude of the tightening of the perimeter of a round pipe when profiling it into a hexagonal pipe billet;
± 0.4 - tolerance on the size of the "key" of the hexagonal pipe billet, mm.