RU2547054C2 - Method of production of cold-rolled pipes with size vn346(40 mm from steel of grade "08-18=10t-+" for nuclear power engineering facilities - Google Patents

Abstract

FIELD: technological processes.

SUBSTANCE: invention relates to pipe rolling Cakes with size of 620×100×1750±50 mm are heated to temperature of 1260-1270°C and are pierced in a cross-rolling mill into bloom stocks with size of 620×vn.265×1985-2105 mm on a holder with diameter of 250 mm true to size along external diameter and drawing µ=1.17. Blooms are heated from cold or hot charging to temperature of 1260-1270°C and pierced - rolled true to size along the outer diameter into blooms with size of 620×vn.390×2630-2800 mm on the holder with diameter of 375 mm with drawing µ=1.33. Blooms are rolled on a TPU 8-16" with Pilger rolling mills into stock hot-rolled pipes with size 480×58×5500-5800 mm with clamping by diameter Δ=21.8% and drawing µ=2.37. Pipes are turned and bored into pig mechanically treated pipes with size of 470×47×5500-5800 mm with removal of metal on the outer surface at ≤5.0 mm, and along the inner surface at ≤6.0 mm, and roll them into pig hot-rolled mechanically treated pipes with size of 470×47×5500-5800 mm on a cold-pilgering mill 450 into commercial cold-rolled pipes with size of vn.346×40×6700-7200 mm with drawing µ=1.29 and clamping along diameter Δ=9.36%, roughness of internal and external surfaces Ra of not more than 2.5 mcm.

EFFECT: invention provides for reduced metal consumption.

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Description

The invention relates to pipe rolling production, and in particular to a method for the production of cold-rolled pipes with a size of ext. 346 × 40 mm from steel grade 08X18H10T-Sh for nuclear power facilities, and can be used in rolling limiting hot-rolled pipes with a size of 480 × 58 × 5500-5800 mm per 8-16 ″ tube-rolling installation with pilgrim mills from ESR ingots-blanks measuring 620 × 100 × 1750 ± 50 mm, followed by mechanical processing - boring and turning into conversion pipes of 470 × 47 × 5500-5800 mm in size, rolling them on the HPT 450 mill into product pipes of size ext. 3 46 × 40 × 6700-7200 mm and their acceptance for compliance with TU 14-3R-197-2001 with increased requirements for surface quality.

In pipe rolling production, a method is known for the production of commodity and conversion pipes from hardly deformed steel grades, including drilling a central hole with a diameter of 100 ± 5.0 mm in blanks and ingots of EAWs with a diameter of 380-500 mm, holding them on the grates of method furnaces at a temperature of 500-550 ° C for 70-95 minutes depending on the diameter, after which heating to a temperature of 1120-1140 ° C at a speed of 1.4-1.5 deg / min, flashing blanks and ingots of ESR into the sleeves size in size by diameter at the speed of rotation of the workers rolls 25-40 rpm on the mandrel Diameter providing pilger reduction is at least 25 mm (RF Patent №2175899, Bul. №32, 20.11.2001).

The disadvantage of this method is that it is acceptable only for the production of hot-rolled commodity and conversion pipes of medium diameter, namely pipes with a diameter of 219-325 mm, because for rolling pipes with a diameter of more than 325 mm, a workpiece with a diameter of 540-620 mm is required, which, due to the low power of the drive of the cross-helical rolling mill, cannot be sewn, and most importantly, this method does not stipulate the allowance for machining of conversion pipes for the manufacture of commodity pipes high quality ext. 346 × 40 mm in size made of corrosion-resistant steel grade 08X18H10T-Sh for nuclear facilities.

In pipe rolling production, a method is known for the production of commodity and conversion hot-deformed pipes of large and medium diameters from corrosion-resistant hard-deformed steel grades and alloys in pipe rolling plants with pilgrim mills, including drilling a central hole with a diameter of 100 ± 5.0 mm in ESR ingots and billets, heating them to a plasticity temperature, the first flashing of ESR ingots-blanks or forged blanks with a diameter of 460-600 mm in a cross-helical rolling mill with a hood of 1.2-1.4 at a speed the axes of rotation of the work rolls are 15-25 rpm, and the second and subsequent, if necessary, firmware rolls with a rise or landing in diameter of not more than 5.0% and a hood μ = 1.4-1.75 at a speed of rotation of the rolls 20-50 rpm, using cold or hot insert of shell blanks into the furnace, the process of flashing from capturing ingots-blanks of ESRs or blanks to being completely on the mandrel is carried out with a decrease in the number of revolutions of the work rolls from 25 to 15, the steady-state flashing process at 15-20 rpm, and at the exit of the billet blank from the rolls I increase the speed t up to 35-40 rpm, the firmware process - rolling (second firmware) from gripping the billet blank 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 rolling process at 20-25 rpm, at the exit of the sleeve from the rolls, the number of revolutions is increased to 45-50, and the tubes are rolled on a pilgrim mill with an extractor μ = 3.0-5.0 (RF Patent No. 2247612, bull. No. 7, 03/10/2005).

The disadvantage of this method is that it also does not stipulate an allowance for machining conversion pipes for the manufacture of high-quality commodity pipes with a size of ext. 346 × 40 mm from 08Kh18N10T-Sh corrosion-resistant steel for nuclear power facilities.

The closest technical solution is a method for the production of seamless hot-deformed pipes of dimensions ext. 279 × 36 and ext. 346 × 40 mm from ingots-blanks ESR of corrosion-resistant steel 08X18H10T-Sh with improved surface quality for nuclear power facilities with a bored inner and turned outer surface with roughness Ra no more than 10 microns in accordance with GOST 2789 (TU 14-158-131-2002 "Seamless hot-deformed pipes from high-quality corrosion-resistant steel").

One of the main disadvantages of this method is that in the production of this technology more than 80% of the pipes after austenization have yield strengths at + 350 ° from 12 to 18 kgf / mm ² (with the norm according to TU 14-3Р-197-2001 less than 19 kgf / mm ² ). Another disadvantage is that the allowance for machining (boring and turning) of pipes with a length of 4000 mm should be at least 10 mm per side. Thus, during machining (turning and boring) with a roughness Ra of not more than 10 μm, 134.68 to 147.52 kg of expensive metal, i.e. from 26.2 to 34.5%) (depending on the diameter and wall thickness of the pipes).

The objective of the proposed method is the production of cold-rolled pipes with a size of ext. 346 × 40 mm of high quality for nuclear facilities with mechanical properties of metal that meet the requirements of TU 14-3R-197-2001, reducing the allowance for machining (boring and turning) of hot-deformed tubes, reduction of the expenditure coefficient of the metal during the redistribution of the ingot-billet ESR is a commodity pipe of high quality according to TU 14-3R-197-2001, an increase in the length of commodity pipes, and therefore, a decrease in their cost.

The technical result is achieved by the fact that in the known method for the production of cold-rolled pipes with a size of ext. 346 × 40 mm from steel grade 08Kh18N10T-Sh for nuclear power facilities, which includes heating ingots-blanks of electroslag remelting with a size of 620 × 100 × 1750 ± 50 mm in methodical furnaces up to temperature 1260-1270 ° С, piercing them in a cross-helical rolling mill into blanks 620 × ext. 265 × 1985-2105 mm in diameter on a mandrel with a diameter of 250 mm; size in outer diameter and exhaust hood μ = 1.17; heating them from cold or hot posad in methodological furnaces to temperature 1260-1270 ° С, firmware - rolling out in a cross-screw rolling mill, size to outer diameter in sleeves of size 620 × ext. 390 × 2630-2800 mm on a mandrel with a diameter of 375 mm with hood μ = 1.33, rolling of sleeves on TPU 8-16 ″ with pilgrim mills into hot-rolled chimneys of size 480 × 58 × 5500-5800 mm with a diameter reduction of Δ = 21.8% and a draft of μ = 2.37, hot-rolled chimneys are turned and bored into mechanically processed pipes 470 × 47 × 5500-5800 mm in size with removal of metal on the outer surface ≤5.0 mm, and on the inner surface <6.0 mm, and the rolling of hot-rolled mechanically processed pipes of 470 × 47 × 5500-5800 mm in size at the KhPT 450 mill into commodity cold-rolled pipes with dimensions of ext. 346 × 40 × 6700-7200 mm with a hood μ = 1.29 and compression in diameter Δ = 9.36%, ext. 346 × 40 × 6700-7200 mm with hood μ = 1.29 and compression in diameter Δ = 9.36%, roughness of the outer and inner surfaces Ra not more than 2.5 μm , trim the ends and austenization.

A comparative analysis of the proposed solution with the prototype shows that the claimed method differs from the known one in that 620 × 100 × 1750 ± 50 mm ingots-billets of electroslag remelting are used as billets, which are heated in methodological furnaces to a temperature of 1260-1270 ° C, stitched in a mill of cross-helical rolling into billet sleeves measuring 620 × ext. 265 × 1985-2105 mm on a mandrel with a diameter of 250 mm, size in outer diameter and exhaust hood μ = 1.17, they are heated from cold or hot planting in methodical furnaces to temperature 1260-1270 ° C, flashed - rolled out in a cross-rolling mill to a size in outer diameter into sleeves of size 620 × ext. 390 × 2630-2800 mm on a mandrel with a diameter of 375 mm with a hood µ = 1.33, sleeves are rolled onto TPU 8-16 ″ with pilgrim mills in hot-rolled chimneys of size 480 × 58 × 5500-5800 mm with a diameter reduction of Δ = 21.8% and a hood µ = 2.37, hot-rolled chimneys are turned and bored into mechanically processed pipes 470 × 47 × 5500-5800 mm in size with metal removal on the outer surface ≤5.0 mm, and on the inner surface 6.0 mm, and rolled hot rolled mechanically processed pipes of 470 × 47 × 5500-5800 mm in size on the KhPT 450 mill into commodity cold-rolled pipes with an extract of µ = 1.29 and a compression in diameter of Δ = 9.36%, the roughness of the outer and inner surfaces Ra not more than 2.5 microns, carry out trimming of the ends and austenization. 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 this technical field, did not reveal the signs that distinguish the claimed method from the prototype, which corresponds to patentability "inventive step".

The method was tested on TPU 8-16 ″ with Pilgrim mills of ChTPZ OJSC when rolling parcel pipes of size 445 × 58 × 5200 mm from ingot blanks EShP of size 585 × 100 × 1650 mm using existing technology and conversion tubes of size 480 × 58 × 5600 mm from ingots-blanks ESR size 620 × 100 × 1750 mm according to the proposed technology.

Conversion pipes 445 × 58 × 5200 mm in size were bored and turned in workshop No. 1 into commodity pipes with a size of ext. 346 × 40 × 5200 mm, with a roughness of the outer and inner surfaces Ra of not more than 10 μm, from which the drums were taken, samples were made and mechanical tests were performed. The pipes passed the ultrasonic inspection. Out of 3 pipes with a size of ext. 346 × 40 mm, one pipe, which was delivered for its intended purpose, passed the yield strength tests at a temperature of + 350 ° C after austenization, and two pipes were accepted as conditionally suitable. The expenditure coefficient of the metal was 1.811. According to the proposed technology, the conversion pipes of size 480 × 58 × 5600 mm were bored and turned into conversion machined pipes of size 470 × 47 × 5600 mm. On one pipe, unreduced blackness was removed by grinding with abrasive wheels. Converted hot-rolled machined pipes with a size of 470 × 47 × 5600 mm were rolled at the KhPT 450 mill into commercial cold-rolled pipes with a dimension of ext. 346 × 40 × 6900 mm with a roughness of the outer and inner surfaces Ra of no more than 2.5 μm. Drums were taken from three pipes, samples were made and mechanical tests were carried out. The pipes passed the ultrasonic inspection. Two pipes with a size of ext. 346 × 40 mm were adopted according to TU 14-3R-197-2001 for their intended purpose for nuclear facilities, and one as conditionally suitable, because did not pass the yield strength test at a temperature of + 350 ° C after austenization. This pipe has been commissioned for another purpose. The expenditure coefficient of the metal in the pipes of this batch was 1.538. A pipe with a size of ext. 346 × 40 mm, which did not pass the yield strength test at a temperature of + 350 ° C after austenization, was rolled on a KPT 450 mill into a pipe with a size of ext. 279 × 36 × 9000 mm, passed all tests and passed for its intended purpose NUCLEAR POWER STATION.

Data on the production of cold-rolled pipes with a size of ext. 345 × 40 mm from 08Kh18N10T-Sh steel for nuclear facilities according to the existing and proposed technologies is shown in Table 1. It can be seen from the table that the yield for its intended purpose when rolling pipes for nuclear power plants using existing technology amounted to 33.3%, and according to the proposed technology from the first presentation 66.7%. After rolling the pipe with a size of ext. 346 × 40 mm into a pipe with a size of ext. 279 × 36 mm, the yield was 100%. The expenditure coefficient of the metal when rolling pipes ext. 346 × 40 mm in size by the proposed technology is reduced by 273 kg. According to the proposed technology, when rolling pipes ext. 346 × 40 mm in size, the average increase in pipe length was 1.41 times, and the roughness of the outer and inner surfaces was reduced by more than 4.0 times.

Using the proposed method for the production of cold-rolled pipes of size 346 × 40 mm in high quality from steel grade 08Kh18N10T-Sh for nuclear power facilities will reduce the cost of expensive metal, increase the yield of pipes for nuclear power plants from the first presentation, reduce the roughness of the outer and inner surfaces, increase their length and, therefore, reduce the cost of pipes and reduce the number of welding joints when installing pipelines at nuclear power plants.

Claims (1)

Method for the production of cold-rolled pipes ext. 346 × 40 mm in size from steel grade 08Kh18N10T-Sh for nuclear power facilities, including heating ingots-blanks of electroslag remelting of 620 × 100 × 1750 ± 50 mm in method furnaces to a temperature of 1260-1270 ° C, firmware them in a mill of cross-helical rolling into billet sleeves measuring 620 × ext. 265 × 1985-2105 mm on a mandrel with a diameter of 250 mm; size in outer diameter and exhaust hood µ = 1.17; heating them from cold or hot planting in methodological furnaces to a temperature of 1260-1270 ° C, firmware - rolling across the mill across on-screw rolling size to size on outer diameter into sleeves of size 620 × ext. 390 × 2630-2800 mm on a mandrel with a diameter of 375 mm with a hood µ = 1.33, rolling of sleeves on TPU 8-16 ″ with pilgrim mills in hot-rolled pipes with a size of 480 × 58 × 5500-5800 mm with compression in diameter Δ = 21.8% and a hood µ = 2.37, turning and boring of converted hot-rolled pipes into converted machined pipes with a size of 470 × 47 × 5500-5800 mm with removal metal on the outer surface ≤5.0 mm, and on the inner surface ≤6.0 mm, and rolling hot rolling mechanically about worked pipes of 470 × 47 × 5500-5800 mm in size at the KhPT 450 mill into commodity cold-rolled pipes of ext. 346 × 40 × 6700-7200 mm in size with a hood µ = 1.29 and compression in diameter Δ = 9.36%, roughness outer and inner surfaces Ra of not more than 2.5 μm, carry out trimming of the ends and austenization.