RU2294247C2 - Cold rolled titanium-alloy large- and mean-diameter high-accuracy tubes production method - Google Patents

Abstract

FIELD: tube production, namely method for producing cold rolled large- and mean-diameters titanium -alloy tubes at high accuracy from conversion welded blank, possibly in cold rolling mills of given types.

SUBSTANCE: method comprises steps of making conversion hot rolled tube blank; working it for removing flaws by turning and boring; or making sheet blank, planing sheet along width; preparing sheet edges for welding; shaping sheet blank in rollers to tube blank; gas-shied welding of lengthwise edges of blank by means of consumable electrode of the same alloy; preparing welded joint for cold rolling; subjecting welded joint and basic alloy to heat treatment; rolling tubes in rolling mills during several procedures at growing elongation factor. After first rolling procedure conversion tube blank is subjected to heat treatment in inductor. After next rolling procedures it is ground or etched along outer and inner surfaces.

EFFECT: possibility for making cold rolled large- and mean-diameter titanium-alloy tubes at high accuracy of wall thickness having uniform mechanical properties from conversion tube blank instead of seamless one, lowered labor consumption for making tube blank, reduced consumption factor of titanium base alloys, decreased cost of tube production.

5 cl, 3 tbl

Description

The invention relates to pipe production, and in particular to a method for the production of cold-rolled large and medium diameter pipes of increased accuracy from titanium-based alloys from a hot-rolled pipe billet or from a welded sheet-metal finished billet, and can be used on cold rolling mills KhPT 250 and KhPT 450.

In the practice of pipe production, a method is known for the production of cold-rolled pipes of large and medium diameters (426-159) mm from titanium-based alloys from hot-rolled large-diameter pipe billets, including casting ingots with a diameter of 600-630 mm ESR, machining ingots (turning and drilling the central holes with a diameter of 100 ± 5.0 mm), heating the ingots in muffles to a ductility temperature (1140-1180) ° C, piercing on a Kosovolovoi piercing mill with a draw ratio of 1.4-1.8, rolling on a pilgrim mill with a coefficient m of hood 2.8-3.8, straightening and machining of hot-rolled pipes with removal of the outer and inner defective layers of 8-10 mm and subsequent rolling of the billets at the mills ХПТ 250 and ХПТ 450 into pipes with a wall tolerance of ± 10 to ± 12.5% depending on the wall thickness (TU 14-3-1218-83 "Hot-deformed seamless pipes turned and bored from alloy grade 14" and TI 158-Tr. TB1-64-2002 "Production of seamless hot-deformed pipes from alloy 14 according to TU 14-3-1218-83 and TU 14-3-1236-83 ").

The disadvantage of this method is the low yield (consumption rate of the metal 2.2-3.0) due to the formation of surface defects (flaws and cracks due to the alpha layer) on the hot rolled billets, the additional use of unique mechanical equipment for turning and boring long pipe billets blanks, the complexity of heating the blanks (ESR ingots) in special muffles, eliminating the possibility of ignition of blanks from titanium alloys when interacting with liquid scale and rolling of cold-rolled pipes with a tolerance of wall thickness not exceeding the increased accuracy of pipes in accordance with GOST 9941.

In the production of seamless large-diameter seamless rolled tubes, large mass ingots are used, which require a long heating time, which results in gas saturation of the surface of the ingot (occurrence of an alpha layer). In the process of cross-screw piercing and rolling on a pilgrim mill under the action of tensile and compressive stresses, flaws and cracks arise in the alfin layer, which, under the influence of water and deformation stresses that have entered them, develop deep into the body of the liners and pipes. To remove cracks from hot-rolled pipes, machining (boring and turning) to a depth of 10 mm is required, which requires additional costs for unique machine tools, and most importantly leads to induced difference in the billets and significant losses of expensive titanium alloys in the form of shavings.

In the practice of production of seamless cold-rolled pipes at HPT mills, it is recommended to reduce the outer diameter (reduction in diameter) within 26-40 mm, which increases with increasing pipe diameter (V.Ya. Osadchiy, A.S. Vavilin, V.G. Zimovets and A.P. Kolikov. “Technology and equipment for pipe production.” M.: “Internet Engineering”, 2001, p. 481). This suggests that for rolling pipes with a diameter of 159 mm (average diameter) for one roll, a billet with a diameter of not more than 200 mm is required, and for pipes with a diameter of 426 mm (large diameter) a workpiece with a diameter of not more than 470 mm.

A known method of rolling cold-rolled pipes from titanium alloys, including the production of a sheet billet, forming a sheet billet into a tube billet, welding longitudinal edges, transverse rolling of a welded billet on a mandrel in a Kosovalkovy mill and subsequent rolling (ed. Certificate. USSR No. 499907, Cl. B 21 B 23/00, 1974).

The disadvantage of this method is that it is time-consuming due to the operation of rolling pipes on two types of rolling equipment, does not exclude the formation of defects on the outer and inner surfaces of the pipes in the form of marks on the border of fusion of the weld with the base metal, the complexity and lack of equipment for repair of the weld, as well as defects in the form of flaws of the weld due to the presence of an unremovised alfied layer from the weld. This process is acceptable only for the production of pipes from titanium alloys of small size, because There are industrial plants for the production of welded pipes of this assortment in a protective environment of argon.

A known method of rolling cold rolled tubes of titanium alloys, including the production of a sheet billet, forming a sheet billet into a tube billet, welding longitudinal edges to increase the ductility of welded joints of titanium alloys, aging is carried out in two stages, first at a temperature of 300-390 ° for 8- 16 hours, then at a temperature of 520-570 ° C for 0.5-5.0 hours, moreover, cooling from the temperature of the first stage of aging is carried out at a rate of 10-20 ° C / min, and in order to preserve the geometric dimensions of structures and In order to prevent the formation of a gas-saturated layer, heating to a temperature of 140-30 ° C below the polymorphic transformation temperature is carried out before welding (ed. certificate of the USSR No. 954498, Cl. C 22 F 1/18, Bulletin No. 32, 1982).

The disadvantage of this method of heat treatment of welded joints of titanium alloys is its complexity, the lack of data on thermal means at the HPT mills, low efficiency and the impossibility of its use in the continuous production of long pipes.

The closest in technical solution is the method of rolling cold-rolled pipes from titanium alloys, including the production of a sheet billet, preparing the sheet edges for welding, forming a sheet billet into a tube billet, welding longitudinal edges, rolling on a cylindrical mandrel in a spiral (pitch angle less than 90 °) s in increments equal to the wall thickness of the finished pipe, with a degree of deformation along the wall of 30-50% (ed. St. USSR No. 893280, class B 21 V 23/00, 1981).

The disadvantage of the above method of manufacturing a conversion tube billet for rolling cold-rolled large and medium diameters from titanium-based alloys is that it is also labor-intensive, requires large capital expenditures and does not solve the main problem, namely, the reduction of defects (stress concentrators) and their repair on the outer and inner surfaces of pipes in the form of longitudinal marks along the border of fusion of the weld with the base metal and flaw of the weld due to the alpha layer, which is removed from the pipe b of the mix is difficult and economically unfeasible.

The objective of the proposed method for the production of cold-rolled large and medium diameter pipes of increased accuracy from titanium-based alloys is to master the production of cold-rolled large and medium-diameter pipes from titanium alloys from welded or hot-rolled pig billets of larger diameter instead of a seamless hot-rolled pipe made for each size of cold-rolled pipes, manufacturing cold rolled pipes in accordance with ASTM B 862-02 and TU 14-3-158-2003, reduction or complete elimination of the alpha layer at heat treatment after the second and subsequent rifts, reduction of alloy consumption during redistribution of a welded or hot-rolled conversion billet - cold-rolled pipe and lower cost of cold-rolled pipes from titanium-based alloys.

The specified technical result is achieved by the fact that in the known method for the production of cold rolled pipes of large and medium diameters of increased accuracy on the wall of titanium-based alloys, including the manufacture of a hot-rolled pre-formed billet or a converted billet from a welded billet, rolling of pipes from the obtained tube-made billets into cold rolling mills to produce cold-rolled tube blanks of maximum diameter with a ratio of diameter to pipe wall thickness D / S = 30-40 with subsequent rolls of cold-rolled pipe billets into pipes of smaller diameter for several rolls with an increasing hood, and before and after the first roll, the pipe conversion billet is heat treated in the inductor, and after subsequent rolls, it is ground or etched on the outer and inner surfaces, after each subsequent rolling, the pipe billets are subjected to heat treatment in the inductor without forming an alfin layer, heat treatment in the inductor is performed according to the mode: in the inductor at a temperature of 580-700 ° C, then in the inductor of a thermostat at a temperature of 750 ± 50 ° C with cooling in air, while with a wall thickness> 10 mm the speed of the pipes is 0.2-0.4 m / min, with a wall thickness of 6 , 0-8.0 mm - 0.3-0.5 m / min, and with a wall thickness of 1.5-5.0 mm - 0.5-0.8 m / min, the manufacture of a hot-rolled pipe billet includes rolling ESR ingots to produce a hot-rolled tube billet, its machining in the form of turning and boring to remove defects and an alfin layer, and the manufacture of a converted tube billet from a welded sheet billets includes the production of sheet billets, gouging the width of the sheet, preparing the edges of the sheet for welding, forming the sheet billets on rollers into a tube billet, welding longitudinal edges in argon with a consumable electrode of the same alloy grade, preparing the weld for cold rolling, and heat treating the welded compound and base alloy.

The essence of the method lies in the fact that in order to reduce the consumption of the alloy, the complexity of the production of cold rolled pipes of large and medium diameters from titanium-based alloys with tighter tolerances on the wall, replace seamless conversion pipes with welded pipes, reduce pipe defects due to defects in the welded joint in the form of flaws from the alpha layer and the production of pipes that meet the requirements of ASTM B 862-02 and TU 14-158-135-2003, the manufacture of a hot-rolled pre-formed billet or a converted billet from a welded sheet billet, pipe rolling from the obtained pipe conversion billets on cold pipe rolling mills to produce cold-rolled pipe billets of maximum diameter with a ratio of diameter to pipe wall thickness D / S = 30-40 with subsequent rolling of cold-rolled pipe billets into pipes of smaller diameter for several rolls with an increasing hood, moreover, before and after the first roll, the pipe conversion billet is heat treated in the inductor, and after subsequent rolls, it is ground or etched along the outer and inner surfaces, after each of the subsequent rolling, the conversion pipe billets are subjected to heat treatment in an inductor without forming an alpha layer, heat treatment in an inductor is carried out according to the regime: in an inductor at a temperature of 580-700 ° C, then in an induction thermostat at a temperature of 750 ± 50 ° C with air cooling, while with a wall thickness> 10 mm the speed of the pipes is 0.2-0.4 m / min, with a wall thickness of 6.0-8.0 mm - 0.3-0.5 m / min, and with a wall thickness of 1 , 5-5.0 mm - 0.5-0.8 m / min, the manufacture of hot-rolled pipe billet includes rolling ESR ingots to obtain a hot-rolled tube billet, machining it in the form of turning and boring to remove defects and an alpha layer, and the manufacture of a converted tube billet from a welded sheet billet includes the production of a billet, gouging the width of the sheet, preparing the edges of the sheet for welding, forming the sheet billet rollers into a tube billet, welding of longitudinal edges in argon protective medium with a consumable electrode of the same alloy grade, preparation of the weld for cold rolling, heat treatment welded joint and base alloy. Thus, these differences allow us to conclude that the criterion of "inventive step" is met.

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

The method was tested on the KhPT 250 and KhPT 450 mills of ChTPZ OJSC during the rolling of cold-rolled pipes of sizes 426 × 12, 377 × 10 and 325 × 8 mm from VT1-0 alloy. According to the existing technology, the production of pipes of this assortment is made from hot-rolled steel tubes of 470 × 14.5 × 4500, 426 × 12 × 5400 and 377 × 10 × 6000 mm in size, obtained after machining (turning and boring) of hot-rolled pipe billets with a size of 485 × 35 × 9100, 445 × 32 × 10800 and 395 × 30 × 12100 mm. Rolling hot-rolled chimneys were carried out at the Pilgrim mill 8-16 of OAO "ChTPZ" from ingots of 630 × 100 × 1750 and 600 × 100 × 1750 mm ESPs. According to the proposed technology, cold-rolled pipes of 426 × 12 mm in size are produced from mechanically processed conversion tubes billets with a size of 470 × 14.5 × 4500 mm, followed by rolling into smaller pipes. Data on the rolling of cold-rolled large and medium-diameter pipes at the KhPT250 and KhPT450 mills from the hot-rolled billets of VT1-0 alloy according to the existing and proposed technologies are shown in Table 1. It can be seen from the table that for the production of cold-rolled pipes 426 × 12, 377 × 10 and 325 × 8 mm in size from VT1-0 alloy according to GOST 9941 and ASTM B 862-02, 5 ingots were set into production according to the existing technology ESR of 630 × 100 × 1750 mm in size and 10 ingots of ESR of 600 × 100 × 1750 mm in size supplied by VSMPO-AVISMA Corporation OJSC. Five ingots of 630 × 100 × 1750 mm in size were heated to ductility temperature and sewn into the shells by oblique rolling. size 650 × 440 ext. × 2950 mm and rolled in a pilgrim mill into pig tubes of 485 × 35 × 9100 mm in size, which were cut in length into two equal parts, turned and bored into pig tubes of 470 × 14.5 × 4500 mm. 12.068 tons of ESR ingots were set into production, of which, after mechanical processing, 4.237 tons of converting pipes of 470 × 14.5 × 4500 mm in size were obtained, which were rolled at the HPT 450 mill into 426 × 12 × 5680 mm pipes. The weight of cold-rolled pipes was 4.023 tons. The total expenditure coefficient of the alloy from ingots to pipes with a size of 426 × 12 mm for this batch was 3,000. Five 600 × 100 × 1750 ingots were heated to ductility temperature and sewn in an oblique rolling mill into 620 × 415 cn shells. × 2890 mm and rolled on a pilgrim mill into 445 × 32 × 10800 mm conversion pipes, which were cut into two equal parts in length, turned and bored into conversion pipes of 426 × 12 × 5400 mm. Pipes of 426 × 12 × 5400 mm in size were rolled at HPT 450 into commodity pipes of 377 × 10 × 6950 mm. 10.917 tons of VT1-0 alloy ingots were set into production, of which, after machining, 3.824 tons of conversion pipes were obtained with a size of 426 × 12 mm. Converting pipes of 426 × 12 × 5400 mm in size were rolled at the KhPT 450 mill into commodity pipes of 377 × 10 mm in size. The total expenditure coefficient from ingots to pipes measuring 377 × 10 mm was 3.003. For the production of 325 × 8 mm commercial tubes from VT1-0 alloy according to the existing technology, 5 ESR ingots 600 × 100 × 1750 mm in size were set into production, which were heated to the ductility temperature, sewn into a 600 × 365 sleeve in an oblique rolling mill ext. × 2700 mm and rolled into conversion pipes measuring 395 × 30 × 12100 mm. The pipes were cut in length into two equal parts, turned and bored to a size of 377 × 10 × 6000 mm. The weight of the conversion pipes amounted to 3.139 tons. Pipes 377 × 10 × 6000 mm in size at the KhPT 450 mill were rolled into commodity pipes in accordance with GOST 9941 with a size of 325 × 8 × 8280 mm. The weight of the goods pipes amounted to 2.933 tons, and the total expenditure coefficient of the metal from the ingot to the goods pipe amounted to 3.649. According to the proposed technology, 15 ESR ingots 630 × 100 × 1750 mm in size with a total weight of 36,204 tons were set into production, which were rolled into pig tubes of 485 × 35 × 9100 mm in size, cut into two equal parts in length, and then turned and bored to size 470 × 14.5 × 4500 mm. The total weight of the conversion pipes amounted to 12.711 tons. All pipes were rolled to a size of 426 × 12 × 5680 mm, of which 10 pipes were commissioned, and 20 pipes were rolled into pipes of 377 × 10 × 7680 mm. Of these pipes, 10 were delivered to commercial pipes, and 10 were rolled into pipes of 325 × 8 × 11120 mm in size. The weight of commodity pipes measuring 426 × 12 × 5680 mm was 4.023 tons, and the expenditure coefficient of the metal from the ingot to the commodity pipe was 3,000. The weight of commodity pipes measuring 377 × 10 × 7680 mm amounted to 4.018 tons, and the expenditure coefficient of the metal, respectively, 3.004. The weight of commodity pipes measuring 325 × 8 × 11 120 mm was 4.020 tons, and the expenditure coefficient of the metal was 3.002. Thus, when rolling commodity pipes with a size of 325 × 8 mm according to the proposed technology from hot rolled pipes, the consumption coefficient decreased by 646 kg per ton. When redistributed into pipes of a smaller diameter, the expenditure coefficient of the metal will decrease more intensively.

The data on the rolling of cold-rolled large and medium-diameter pipes at the KhPT 250 and KhPT 450 mills from the welded and machined hot-rolled billets from VT 1-0 alloy according to the existing and proposed technologies are shown in Table 2. 470 × 14.5 × welded billet 4500 mm was manufactured at JSC "Zavod PSK", Novosibirsk. Sheets were formed into tube blanks on rollers with a gap of 4.0 mm. Welding of the longitudinal edges was carried out by a consumable electrode made of VT 1-0 alloy in a protective argon medium. Converted machined billets of 470 × 14.5 × 4500, 426 × 12 × 5400 and 377 × 10 × 6000 mm in size were made of hot-rolled billets of sizes 485 × 30 × 9100, 445 × 32 × 10800 and 395 × 30 × 12100 mm, rolled from an ESR ingot 630 × 100 × 1750 and 600 × 100 × 1750 mm in size at PTA 8-16 "with pilgrim mills of ChTPZ OJSC. Billets were rolled at cold rolling mills of ChTPZ OJSC. Table 2 shows that welded straight-seam billets according to the proposed technologies were successively rolled into cold-rolled pipes of size 426 × 12 - 377 × 10 - 325 × 8 - 273 × 6 - 219 × 4.5 - 180 × 3.0 and 159 × 2.0 mm with hoods from responsiblely 1.33; 1.36; 1.45; 1.58; 1.66; 1.82 and 1.69, i.e. the hood coefficients increased from roll to roll, and the hot-rolled conversion billets of 470 × 14.5 × 4500, 426 × 12 × 5400 and 377 × 10 × 6000 mm were rolled according to existing technology into cold-rolled pipes of sizes 426 × 12 × 5680, 377 × 10 × 6950 and 325 × 8 × 8280 mm, respectively. 76.5 meters of pipes measuring 159 × 2.0 mm were obtained from the experimental welded billets of 470 × 14.5 × 4500 mm in size. The expenditure coefficient of the metal in the rolls ranged from 1.019 to 1.042, and the total from the initial billet to the final pipe was 1.195. Of the machined seamless hot-rolled pipes, the consumption coefficient of the alloy on the rolls ranged from 1,050 to 1,059, i.e. they are on the same level. The expenditure coefficient of the VT1-0 alloy during rolling of pipes according to the existing technology from the ESR ingot to the final pipe was from 3,000 to 3,648. Thus, when rolling pipes from welded billets according to the proposed technology, we obtained a decrease in the consumption coefficient of VT1-0 alloy by 2.88-3.32 times, depending on the assortment. According to the proposed technology, pipes with a size of 426 × 12 mm after heat treatment in order to remove defects and an alpha layer from the surface of the weld and the body of the pipe were etched for 15-20 minutes in a nitrogen-fluorine solution. Then, after each subsequent route (roll), the billets, both according to the proposed and existing technologies, were subjected to heat treatment in the inductor without forming an alfin layer according to the regime: temperature in the inductor - 580-700 ° C, temperature in the inductor of the thermostat - 750 ± 50 ° C, air cooling, pipe speed with a wall thickness> 10 mm - 0.2-0.4 m / min, with a wall thickness of 6.0-8.0 mm - 0.3-0.5 m / min and with a wall thickness of 1.5-5.0 mm - 0.5-0.8 m / min. After each route, wall thicknesses were measured and the following values were determined: nominal, maximum and minimum wall thickness, absolute and relative difference, wall thickness spread and tolerance wall thickness. The actual dimensions and deviations of the wall thicknesses of pipes converted from welded (proposed technology) and machined processing billets are shown in table 3. The table shows that the tolerance field for the wall thickness of pipes (the main quality indicator), rolled according to the proposed technology, depending on the geometric dimensions (from 426 × 12 to 159 × 1.5 mm) it gradually increases from 2.4 to 9.5%, and their values relative to GOST 9941 are much smaller. When rolling pipes of this series according to existing technology, the tolerance field decreases from 16.5 to 13.2%. This is explained by the fact that when rolling pipes with a size of 426 × 12 mm from a machined (turned and bored) billet, which, due to the induced difference in the machining, has a significantly larger initial difference compared to the rolled sheet. As the transitions, the difference decreases to a wall of 6.0 mm, and then with the thinning of the pipe wall less than 5.0 mm, the absolute difference decreases, and the relative begins to increase.

Thus, the use of the proposed method for the production of cold-rolled pipes of large and medium diameters from titanium-based alloys, using the technology in accordance with the claims, will make it possible to produce pipes of increased accuracy in wall thickness with equal mechanical properties in accordance with ASTM B 862-02 and TU 14 -158-135-2003 from a welded billets made for rolling pipes of maximum diameter, instead of a seamless billets, significantly reduce the complexity of manufacturing the billets of the finished workpiece, reduce the expenditure coefficient of titanium alloys by 2.8-3.3 times, and therefore, reduce the cost of their production.

Data on the rolling of cold-rolled large and medium-diameter pipes at the KhPT250 and KhPT450 mills of ChTPZ OJSC from hot-rolled billets of VT1-0 alloy according to the existing and proposed technologies Table 1 No. p / p Existing technology Proposed technology    ESW blank size (mm) Count gulp. (PC.) The weight of the gulp. (tons) The size is hot. pipes (mm) Mechanical size arr. pipes (mm) Weight before. pipes (tons) Cold Rolled Pipe Size (mm) Weight of tubes after CPT The general r / c metal. The size of the fur. arr. blanks (mm) HC size before. gulp. (mm) Size HC tubes (mm) Weight HC tubes (t.) Total metal cutting one 630 × 100 × 1750 5 12,068 485 × 35 × 9100 470 × 14.5 × 4500 4,237 426 × 12 × 5680 4,023 3,000 470 × 14.5 × 4500 - 426 × 12 × 5680 4,023 3,000 2 600 × 100 × 1750 5 10,917 445 × 32 × 10800 426 × 12 × 5400 3,824 377 × 10 × 6950 3,636 3,003 - 426 × 12 × 5680 377 × 10 × 7680 4,018 3,004 3 600 × 100 × 1750 5 10,917 395 × 30 × 12100 377 × 10 × 6000 3,139 325 × 8 × 8280 2,993 3,648 - 377 × 10 × 7680 325 × 8 × 11120 4,020 3,002

table 2 Data on the rolling of cold-rolled large and medium-diameter pipes at the KhPT 250 and KhPT 450 mills of ChTPZ OJSC from the conversion billets of VT1-0 alloy according to the existing and proposed technologies Proposed technology Existing technology Dimensions of Welded Conversion Workpiece (mm) Pipe dimensions (mm) Coef. hoods (μ) Diameter Compression (mm) Pipe length after trimming ends (mm) Consumption. coefficients metal The sizes of the hot conversion are hot. mechanical machined workpiece (mm) Pipe dimensions (mm) Coef. hoods (μ) Crimped by dia. (mm) Pipe length after trimming ends (mm) Consumption. coefficients metal one 2 3 four 5 6 7 8 9 10 eleven 12 470 × 14.5 × 4500 426 × 12 1.33 44 5750 1,042 470 × 14.5 × 4500 426 × 12 × 5680 1.33 44 5680

377 × 10 1.36 49 7600

426 × 12 × 5400 377 × 10 × 6950 1.36 49 6950

325 × 8 1.45 52 10700

377 × 10 × 6000 325 × 8 × 8280 1.45 52 8280

273 × 6 1,58 52 16700

- - - - - - 8350 × 2 219 × 4.5 1.66 54 13600

- - - - - - 13600 180 × 3.0 1.82 39 12,200 × 2

- - - - - - 12,200 × 2 159 × 2.0 1,69 21 6375 × 12

- - - - - ^- (76500) Notes: 1. In column 6, when rolling pipes according to the proposed technology, the numerators show the expenditure coefficients of the VT1-0 alloy when rolling from size to size, and the denominators show the expenditure coefficients taking into account the sequence of redistribution from a larger diameter to a smaller one. 2. In column 12, when rolling pipes according to the existing technology, the numerators show the expenditure coefficients of the VT1-0 alloy when rolling from size to size, and the denominators show the expenditure coefficients taking into account the machining of the hot-rolled pipes into the conversion and the expenditure coefficient of the metal during hot conversion to PTA with pilgrim camps (technological waste).

Table 3 Actual dimensions and wall thickness deviations of pipes of large and medium diameters, rolled at the KhPT 250 and KhPT 450 mills from the conversion workpieces of VT1-0 alloy according to the existing and proposed technologies Type of technology Values of pipe wall thickness (mm) Proposed technology 426 × 12 377 × 10 325 × 8 273 × 6 219 × 4.5 180 × 3 159 × 2.0 S max 12.37 10.69 8.42 6.24 4.25 3.34 2.25 S min 12.08 10.30 8.12 6.0 4.07 3.16 2.05 S nom 12,20 10.5 8.20 6.10 4.10 3.20 2.10 ΔS 0.29 0.39 0.30 0.24 0.18 0.18 0.20 Scatter S (%) + 1.4 / -1.0 + 1.8 / -1.9 + 2.7 / -1.0 + 2.3 / -1.6 + 3.7 / -0.7 + 4.3 / -1.2 + 7.1 / -2.4 Tolerance Field (%) 2,4 3,7 3,7 3.9 4.4 5.5 9.5 Existing technology S max 12.5 11,4 8.8 - - - - S min 10.6 9.7 7.7 - - - - S nom 11.5 10.5 8.2 - - - - ΔS 1.9 1.7 1,1 - - - - Scatter S (%) + 8.7 / -7.8 + 8.6 / -7.6 + 7.3 / -6.1 - - - - Tolerance Field (%) 16.5 16,2 13,4 - - - - Tolerance field according to GOST 9941 - ± 10 (20.0) ± 10 (20.0) ± 10 (20.0) + 12.5 / -10.0 (22.5) + 12.5 / -10.0 (22.5) ± 12.5 (25.0) ± 12.5 (25.0) ASTM B 862-02 Approval Field - ± 12.5 (25.0) ± 12.5 (25.0) ± 12.5 (25.0) ± 12.5 (25.0) ± 12.5 (25.0) ± 12.5 (25.0) ± 12.5 (25.0)

Claims (5)

1. A method for the production of cold-rolled large and medium diameter pipes of increased accuracy along the wall of titanium-based alloys, including the manufacture of a hot-rolled pre-formed billet or a pre-made billet from a welded billet, rolling of pipes from the obtained tube-made billets on cold-rolled pipe mills to produce cold-rolled pipe billets of maximum diameter with a ratio of diameter to wall thickness of the pipe D / S = 30-40 with subsequent rolls of cold-rolled pipe billets into pipes of a smaller diameter for several rolls with an increasing hood, and before and after the first roll, the pipe conversion billet is heat treated in the inductor, and after subsequent rolls, it is ground or etched on the outer and inner surfaces. 2. The method according to claim 1, characterized in that after each subsequent rolling the conversion tube blanks are subjected to heat treatment in an inductor without forming an alpha layer. 3. The method according to claim 2, characterized in that the heat treatment in the inductor is carried out in the inductor at a temperature of 580-700 ° C, then in the thermostat inductor at a temperature of (750 ± 50) ° С air-cooled while with a wall thickness> 10 mm the speed of the pipes is 0.2-0.4 m / min, with a wall thickness of 6.0-8.0 mm - 0.3-0.5 m / min, with a wall thickness of 1.5-5.0 mm - 0.5-0.8 m / min. 4. The method according to claim 1, characterized in that the manufacture of a hot-rolled tubular billet includes rolling ESR ingots to produce a hot-rolled tubular billet, its machining in the form of turning and boring to remove defects and the alpha layer. 5. The method according to claim 1, characterized in that the manufacture of a converted pipe billet from a welded sheet billet includes the production of a sheet billet, gouging the sheet in width, preparing the sheet edges for welding, forming a sheet billet on rollers into a billet, welding longitudinal edges in a protective argon medium with a consumable electrode of the same grade of alloy, preparation of the weld for cold rolling, heat treatment of the welded joint and the main alloy.