RU2317866C2 - Method for producing cover hexahedral tube-blanks of low-ductile boron-containing steel for compacted storage of waste nuclear fuel - Google Patents

Abstract

FIELD: production of cover hexahedral tube-blanks of low-ductile boron steel for compacted storage of waste nuclear fuel, possibly manufacture of hexahedral tube-blanks of given size, restoration of rejected hexahedral blanks after boring, turning and repairing of their outer surfaces according to rolling-origin flaws.

SUBSTANCE: method comprises steps of rolling conversion tubes with size 290 x 12 x 2100-2200 mm; cutting tube lengths by means of hot cutting saw by tubes; marking out tubes for cutting by blanks; marking blanks; cutting tubes by blanks; measuring geometry parameters of blanks; straightening blanks with common curvature along length more than 3.0 mm; boring blanks for further quality control of their inner surface and inner diameter; marking blanks inside by means of paint; forming inner and outer chamfers; turning blanks in machine tools with servo system; technologically controlling wall thickness of blanks; inspecting and repairing defect zones of outer surface; measuring thickness of wall; repairing zones of outer surface having flaws and thickness of wall outside plus limit size; performing secondary turning if necessary; transferring number of blank by means of stamps onto outer surface of blanks; degreasing blanks; subjecting blanks to induction heat treatment, ultrasound flaw detection and to spectroscope control; drilling openings for drawing chain for profiling on marked ends of blanks; applying salt lubricant onto blanks; warm shaping of hexahedral blanks; controlling geometry sizes of hexahedral blanks; degreasing them; heat treating hexahedral blanks; controlling size 257 ± 2 x 6 + 1.75/-1.0 mm; correcting portions whose sizes are outside plus allowance field; controlling total curvature of faces along length of hexahedral blanks; marking out and cutting hexahedral blanks by measured length 4300+80/-20 mm; selecting templates in order to make samples for mechanical testing; transferring marking; removing fins, trimming and blowing through hexahedral blanks; straightening in press hexahedral blanks with curvature more than 3.0 mm along length of tube-blank; inspection after straightening curvature and controlling size; controlling hexahedral blanks for passing templates through them; straightening if necessary; controlling geometry size of hexahedral blanks; trimming portions of hexahedral blanks whose sizes are outside plus limit values along wall thickness and finish sizes; reception; brightening; testing metal templates of hexahedral blanks by mechanical properties; final reception; marking and packaging hexahedral tube-blanks. Blanks after boring, turning and repairing flaws of outer surface with wall thickness in repairing places less than 5.0 mm are fed for further operations of manufacturing process including degreasing of blanks and then flaw zones are repaired by electric arc surfacing under flux layer or in argon shield atmosphere by means of electrode of boron steel. Repaired zones are subjected to grinding till predetermined wall thickness and smooth joining with planes of hexahedron and then they are subjected to heat treatment at performing all next technological operations according to manufacturing process.

EFFECT: lowered metal consumption, reduced cost of commercial hexahedral tube-blanks.

3 cl, 1 tbl

Description

The invention relates to pipe production, in particular to a method for the production of sheathed hexagonal tubes-blanks of low plastic steel with a boron content of 1.3-1.8% for compacted storage of spent nuclear fuel, and can be used in the production of turnkey hexagonal tubes-blanks "measuring 257 ± 2 × 6 ^{+ l, 75 / -1.0} × 4300 ^{+ 80 / -20} mm from hot-rolled steel tubes measuring 290 × 12 × 11000-11500 mm, rolled at pipe-rolling plants with pilgrim mills, and correcting (restoring ) rejected hexagonal blanks last e boring, turning and repairing the external surface due to external defects of rolling origin, with actual wall thicknesses at the repair sites of at least 3.3 mm, by electric arc surfacing under a flux layer or in a protective argon atmosphere with a boron steel electrode, followed by grinding of the repair areas to the specified wall thickness, smooth pairing with the planes of the hexagonal workpiece, conducting heat treatment and performing all subsequent operations in the process.

In pipe production, a method is known for producing sheathed hexagonal billets made of low plastic steel with a boron content of 1.3-1.8% for compacted storage of spent nuclear fuel, which involves the smelting of steel by a vacuum-arc (VD) method in ingots with a diameter of 460 mm followed by forging them into bars (billets) with a diameter of 225-230 mm and machining (turning) to a size of 215 × 1850-1950 mm, heating to plasticity temperature, rolling on TPA-350 with an automatic mill of conversion pipes measuring 288 × 11 × 6000 ± 100 mm at a temperature of 8 50–950 ° С (Research report “Mastering the technology for the production of large-diameter hot-rolled pipes from steel ChS 82 in TPA-350 UTZ conditions, Dnepropetrovsk 1988), the supply of conversion tubes to ChTPZ OJSC, acceptance, mechanical processing of pipes - preparations on machines with a tracking system (turning and boring), degreasing, induction heat treatment, ultrasonic testing, drilling holes for the pulling chain during profiling, coating pipes with salt grease, warm profiling, degreasing, heat treatment of pipes, turnkey size control, boom control deflection, times etku and cutting of the pipes to length, selection of templates for manufacturing samples for mechanical testing of the profiled portion of the tube, straightening tube on the press-pieces with a curvature greater than the allowable, control of geometric sizes of hexagons, final acceptance, labeling and packing of hexagonal pipes.

The disadvantage of this method is interstate transportation (Chelyabinsk - Nikopol - Chelyabinsk), the laborious operation of forging ingots with a diameter of 460 mm into bars (billets) with a diameter of 225-230 mm, followed by machining (turning) and cutting to a size of 215 × 1850-1950 mm, large the expenditure coefficient of the metal during the redistribution of the ingot is a hexagonal workpiece equal to 6.53, due to the large rejection of the workpieces due to defects of rolling origin on the outer surface and the wall thickness exceeded the minus tolerance during their repair and, as a result, In fact, the high cost of conversion pipes and finished products (hexagonal billets).

There is also known a method for the production of steel tubes from low plastic steel with a boron content of 1.3-1.8%, including casting ESR ingots of 460 × 1600-1750 mm in size (Mechel OAO, Chelyabinsk), drilling a central hole with a diameter of 100 mm in ingots ESR from the bottom end to the length L = Н-В, where Н - ingot height, mm; C - the under-drilled part of the ingot, equal to 100-120 mm, heating them to the temperature of plasticity, feeding lubricants in the form of a mixture of graphite with table salt (50/50)% into the ingots, piercing the ingots in the oblique rolling mill with the speed of rotation of the work rolls 40-45 revolutions per minute when filling the deformation zone, from ingot capture by rolls until the sleeve is completely on the mandrel, the roll rotation speed is reduced by 20-25% - 30-35 rpm, and at the outlet of the sleeve from the deformation zone the roll rotation speed is reduced by 30-35 % - 25-30 revolutions per minute, I roll sleeves on a pilgrim mill in conversion pipes with an extractor hood μ = 9.0-10.5 and compression of 35-40% in diameter, followed by their conversion into hexagonal billet pipes according to the existing technological conversion (RF Patent No. 2255820 "Method for the production of conversion pipes from low plastic steel with a boron content of 1.3-1.8%. "Bull. No. 10 of 07/10/2004).

The disadvantage of this method is also the large expenditure coefficient of the metal during the redistribution of the ingot - a hexagonal billet pipe equal to 4.52, due to the large rejection of the workpieces due to defects of rolling origin on the outer surface and the wall thickness exceeded the negative tolerance during their repair and, as the consequence is the high cost of conversion pipes and finished products (hexagonal billets).

The closest technical solution is a method for the production of sheathing hexagonal tubes-blanks from low-ductile steel with a boron content of 1.3-1.8%, which includes rolling conversion tubes-lashes on tube-rolling plants with pilgrim mills, cutting them into tubes of 2-fold length, mechanical processing (boring and turning) of krats on machines with a tracking system, degreasing, induction heat treatment, ultrasonic testing, drilling holes for the pulling chain during profiling, coating pipes with saline grease and warm pipe profiling - agotovok produce double length value which is determined from the expression

L _tr. = 2L _cr. + L _per. + L _o + L _c.o. ,

where L _cr. - the length of the hexagonal pipe billet, mm; L _lane - the length of the transition section from the cylinder to the hexagon, mm; L _o - the length of the cylindrical part of the pipe-workpiece for drilling an axial hole for the pin of the pulling chain, mm; L _K.o. - the length of the end trim, mm,

and cutting pipes into measured lengths, selecting templates for making samples for mechanical testing and removing end trim after checking the geometric dimensions and marking the hexagonal pipe lashes, taking templates for making samples for mechanical testing is carried out from the transition zone from the circle to the hexagon on the side adjacent to to a hexagonal profile (RF Patent No. 2226363, "Method for the production of sheathing hexagonal pipes from low plastic steel with a boron content of 1.3-1.8%." Bull. No. 5 from 02/20/2005).

The known method also has disadvantages. The yield of this technology is 80-82%. Out of 18-20% of rejected billet pipes, defects in the defects of the outer surface, which deduce the wall thickness beyond the negative tolerance field (less than 5.0 mm), range from 9.5 to 11.2%. The total expenditure coefficient in the production of hexagonal tubes-blanks using this technology (ESR ingot - hot rolled pipe - hexagonal tubes-blanks) is 4.15-4.35, which is also high.

The objective of the proposed method is the development of a new process for the production of sheathing hexagonal billets of low-plastic steel with a boron content of 1.3-1.8% for compacted storage of spent nuclear fuel, reducing or completely eliminating the rejection of pipe billets for defects of rolling origin, namely for defects on the outer surface of the billet pipes and the exclusion of transferring them to the category of rejects, reduction in the expenditure coefficient of the metal during the redistribution of the ESR ingot is a hexagonal billet pipe, and But, the reduction in the cost of the final product - hexagonal tubes made of steel ChS 82.

The technical result is achieved by the fact that in the known method for the production of sheathing hexagonal tubes-blanks of low plastic steel with a boron content of 1.3-1.8% for compacted storage of spent nuclear fuel, including rolling tailings-tube lengths 290 × 12 × 22000-23000 mm, cutting pipes, lashes with a hot cutting saw into pipes, marking pipes for cutting into workpieces, marking workpieces for cutting, cutting pipes into workpieces, measuring the geometric dimensions of workpieces and dressing workpieces with a total curvature of more than 3.0 in length m, boring of blanks with subsequent quality control of the inner surface and control of the inner diameter, marking the number of blanks inside the paint, making the outer and inner chamfers, turning the blanks on a machine with a tracking system, technological control of the wall thickness of the blanks, inspection and correction of defective sections of the outer surface, measurement wall thicknesses, correction of areas of the outer surface that have defects and wall thicknesses that go beyond plus size limits, re-turning if necessary sti, transfer of the workpiece number with stamps on the outer surface of the workpieces, degreasing of the workpieces, induction heat treatment, ultrasonic flaw detection and styloscopic control, drilling holes for the pulling chain for profiling at the marked ends of the workpieces, coating the workpieces with salt grease, warm profiling with hexagonal workpieces, geometric control sizes hexagonal blanks, degreasing, heat treated hex preforms size control "turnkey" 257 ± 2 × 6 ^{+ 1.75 / -1.0} mm, and board portions having dimensions extending beyond the plus tolerance range, controlling total curvature along the length of hexagonal faces blanks layout and cutting of hexagonal blanks to length 4300 ^{+ 80 / -20} mm, selection of templates for manufacturing samples for mechanical testing, marking transfer, removal deburring, stripping and blowing off hexagonal workpieces, dressing on a press of hexagonal workpieces with a curvature of more than 3.0 mm, checking after editing the turnkey size curvature, checking the hexagonal workpieces for passability with a caliber, editing when if necessary, checking the geometric dimensions of the hexagonal blanks, stripping sections of the hexagonal blanks having dimensions that go beyond the plus limit dimensions for wall thickness and turnkey size, with subsequent acceptance, clarification, testing the template metal hexagonal blanks for mechanical properties with subsequent acceptance, marking and packaging of hexagonal tubes-blanks, while blanks after boring, turning and correction of defects of the outer surface with wall thicknesses at the correction points of less than 5.0 mm they transfer to the following operations of the technological process, including prior to the operation, degreasing the workpieces, and then correct the defective places by electric arc surfacing under a flux layer or in a protective argon medium, an electrode made of boron steel, followed by grinding of the repair areas to a given wall thickness, smooth conjugation with the hexagon planes and produce heat treatment with the execution of all subsequent operations of the technological process, as an electrode when correcting defective places electrode traction welding in argon using a wire with a mass fraction of boron content exceeding content hexagonal preform, the amount burn it at welding, and at the arc surfacing used flux or electrode plaster introduction therein ferroboron, and correcting defective welding method places produce the depth

Δ≤0.45 · S _nom. ,

where S _nom. - nominal wall thickness of the hexagonal workpiece, mm.

The essence of the method lies in the fact that the workpieces after boring, turning and repairing defects on the outer surface with wall thicknesses at the repair sites less than 5.0 mm, which were previously rejected, it is proposed to ask for subsequent operations of the technological process inclusively before the degreasing of the workpieces, and then produce correction of defective places by the method of electric arc surfacing under a flux layer or in a protective argon atmosphere with a boron steel electrode, followed by grinding of the repair areas to a given wall thickness and, smoothly interfacing with the planes of the hexagon and performing heat treatment with performing all subsequent operations of the technological process, use an wire with a mass fraction of boron content exceeding its content in the hexagonal workpiece to repair the defective places by electric arc welding in argon medium, burnup value during welding, and in electric arc surfacing under a flux layer, flux or electrode coating with the introduction of ferroboron is used in them, repair of defective places using benches produce at a depth Δ≤0,45 · S _nom. where S _nom. - nominal wall thickness of the hexagonal workpiece, mm.

Comparative analysis with the prototype shows that the inventive method for the production of hexagonal sheathed tubes made of low plastic steel with a boron content of 1.3-1.8% for compacted storage of spent nuclear fuel is characterized in that the workpieces after boring, turning and repairing the defects of the outer surface with wall thicknesses at repair sites less than 5.0 mm, the workpieces are set for subsequent operations, including the degreasing of the workpieces before the operation, and then defective places are corrected using the electric arc surfacing under a flux layer or in a protective argon atmosphere with a boron steel electrode, followed by grinding of the repair areas to a given wall thickness, smoothly interfacing with the hexagonal planes and performing heat treatment with all subsequent operations in the process, as an electrode, when repairing defective places in an electric arc by surfacing in an argon medium, use a wire with a mass fraction of boron content exceeding its content in the hexagonal workpiece by the amount of burnout during welding and during electric arc surfacing under a flux layer, flux or electrode coating is used with the introduction of ferroboron, repair of defective places by welding is carried out to a depth of Δ≤0.45 · S nom., where S _nom. - nominal wall thickness of the hexagonal workpiece, mm. These differences allow us to conclude that 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 features that distinguish the claimed method from the prototype, which meets the condition of patentability "inventive step".

The method was carried out during rolling of conversion pipes with a size of 290 × 12 × 22000-23000 mm at TPA 8-16 with pilgrim mills in workshop No. 1 and their conversion into hexagonal tubes-blanks in workshop No. 5 of ChTPZ OJSC.

40 ESR ingots of steel of the ChS 82 grade were delivered to production at the Mechel OAO plant. Twenty ingots of 460 × 100 × 1700-1750 mm in size were rolled on 8-16 TPA with pilgrim mills into 290 × 12 × 22000-23000 mm pipes, which were cut into 11000-11500 mm pipes by a saw and sent to workshop No. 5 for conversion into hexagonal billets according to existing technology. The second batch of 20 ingots (40 pipes with a size of 11000-11500 mm) was sent to workshop No. 5 for conversion into hexagonal billets using the proposed technology. In workshop No. 5, the pipes were cut into slab pipes with a length of 5500-5750 mm and put into production for the manufacture of hexagonal billet pipes using existing and proposed technologies. Data on rolling of conversion pipes of 290 × 12 × 22000-23000 mm in size from ESR ingots of 460 × 100 × 1700-1750 mm in size and their conversion into turnkey hexagonal tubes-blanks of 257 ± 2 × 6 ^{+ 1.75 / -1.0} × 4300 ^{+ 80 / -20} mm according to the existing and proposed technologies are given in the table. The table shows that, according to the existing technology, 4 pipes were rejected due to the fault of workshop No. 1 (flaws) using the existing technology, and 5 pipes, or 5.0 and 6.25%, respectively. When redistributing pipes (boring and turning) in workshop No. 5 along a thin wall at repair sites (removal of external captures and tearing), 8 existing pipes were rejected according to the existing technology, and 9 billet pipes according to the proposed technology. In the first case, the billet pipes were rejected, and in the second (according to the proposed technology) repair sites (with the actual wall thickness from 3.5 to 4.7 mm), after the degreasing of the billet pipes, a correction (repair) was performed defective places by the method of electric arc welding in a protective environment of argon with an electrode with a mass fraction of boron content at the upper limit, namely 1.8%. After repair (surfacing), the repair sections were polished to a given wall thickness, i.e. smooth interfacing with the planes of the hexagon. After preliminary acceptance, these hexagonal billet pipes underwent heat treatment with all subsequent operations in the process. Hex tube blanks were accepted as “conditionally suitable” and sent to the customer for electronic enlightenment. All nine billet pipes passed the test and are included in the delivery of “suitable products”. The total expenditure coefficient of the metal in the production of a pilot batch of hexagonal billets according to the existing technology amounted to 4,052, and according to the proposed 3,575, i.e. a decrease in metal consumption of 477 kg was obtained for each ton of hexagonal billets.

Thus, according to the results of the production of pilot batches of hexagonal pipes according to the existing and proposed methods, it can be seen that the expenditure coefficient of the metal during the redistribution of the ESR ingot — the hexagonal pipe billet according to the proposed method decreased by 477 kg.

Using the proposed method for the production of sheathed hexagonal tubes-blanks of low plastic steel with a boron content of 1.3-1.8% for compacted storage of spent nuclear fuel will significantly reduce metal consumption by reducing or completely eliminating process wastes due to rolled defects (external films and tears) ) with the actual wall thickness at the repair sites not less than 0.45 · S _nom. or ≥3.3 mm, and therefore, reduce the cost of commodity hexagonal billets.

Table Data on rolling conversion pipes of 290 × 12 × 22000-23000 mm in size from ESR ingots of 460 × 100 × 1700-1750 mm in size and for their conversion into turnkey hexagonal tube blanks of 257 × 6 × 4300 mm in size according to the existing and proposed technology Type of technology Conversion pipe production in workshop No. 1 Production of hexagonal billets in workshop No. 5 Set ingots (pcs / t) Laminated pipes (pcs / t) Shipped to workshop No. 5 (pcs / t) Asked at random. (pcs / t) Zabrakov. along the wall (pcs / t) Zabrakov. for other defects (pcs / t) Shelf life was delivered. (Pcs / t) Total consumption. odds metal Existence. twenty 40 76 76 8 7 61 4,052 45.720 35.178. 33,419 34,320 3,520 3,080 11,285 Suggestion twenty 40 75 75 9 6 69 3,575 45.630 35,375 33,164 34,442 3.980 2,653 12,765

Claims (3)

1. Method for the production of hexagonal sheath blank tubes made of low plastic steel with a boron content of 1.3-1.8% for compacted storage of spent nuclear fuel, including rolling tailings-lashes 290 × 12 × 22000-23000 mm in size, cutting lashes a hot cutting saw into pipes, marking pipes for cutting into workpieces, marking workpieces for cutting, cutting pipes into workpieces, measuring the geometric dimensions of workpieces and dressing workpieces with a total curvature of more than 3.0 mm in length, boring workpieces with subsequent quality control the inner surface and control of the inner diameter, marking the number of blanks inside the paint, making the outer and inner chamfers, turning the blanks on a machine with a follow-up system, technological control of the wall thickness of the blanks, inspection and correction of defective sections of the outer surface, measurement of wall thickness, correction of sections of the outer surface, having defects and wall thickness that goes beyond the plus size limits, re-turning if necessary, transferring the workpiece number with hallmarks to the outer surface roughness of blanks, degreasing of blanks, induction heat treatment, ultrasonic flaw detection and styloscopic inspection, drilling holes for the pulling chain for profiling at the marked ends of the blanks, coating the blanks with salt grease, warm profiling to produce hexagonal blanks, checking the geometric dimensions of the hexagonal blanks, degreasing, heat treatment preforms size control "turnkey" 257 ± 2 × 6 ^{+ 1.75 / -1.0} mm, fixing portions having dimensions exceeding the plus howling field tolerance, control the overall length of the curvature faces hexagonal blanks layout and cutting of hexagonal blanks to length 4300 ^{+ 80 / -20} mm, selection of templates for manufacturing samples for mechanical testing, marking transfer, deburring, cleaning and purging hexagonal blanks, editing presses of hexagonal blanks with a curvature of more than 3.0 mm, checking after editing the turnkey size curvature, checking the hexagonal blanks for passability with caliber, editing if necessary, checking the geometric dimensions of six faceted workpieces, stripping sections of hexagonal workpieces having dimensions beyond the plus maximum dimensions for wall thickness and turnkey size with subsequent acceptance, clarification, testing of metal templates of hexagonal workpieces for mechanical properties with subsequent acceptance, marking and packaging of hexagonal workpieces, in this case, the workpieces after boring, turning and correction of defects of the outer surface with wall thicknesses at the correction points of less than 5.0 mm are assigned to the following operations of the technological process including the degreasing of the workpieces, and then correcting the defective places by electric arc surfacing under a flux layer or in a protective argon atmosphere with a boron steel electrode, followed by grinding of the repair areas to the specified wall thickness, smoothly interfacing with the hexagonal planes and performing heat treatment with all subsequent operations on the technological process. 2. The method according to claim 1, characterized in that a wire with a mass fraction of boron content exceeding the content in the hexagonal workpiece by the amount of burnout during welding is used as an electrode when correcting defective places by electric arc welding in argon medium; in electric arc surfacing using flux or electrode coating with the introduction of ferroboron in them. 3. The method according to claim 1, characterized in that the correction of defective places by surfacing is performed to a depth Δ≤0,45 * S _nom. , where S _nom. - nominal wall thickness of the hexagonal workpiece, mm.