RU2288052C2 - Method for producing conversion tube blank for rolling cold rolled tubes of large- and mean-diameters of titanium base alloys - Google Patents

Abstract

FIELD: rolled tube production, namely method for producing conversion tube blank for rolling cold rolled tubes of large and mean diameters of titanium base alloys, possibly in roll mill with further welding of lengthwise edges in argon protective atmosphere and rolling conversion blank to cold rolled tubes.

SUBSTANCE: method comprises steps of producing sheet blank; planing sheet along its width; preparing edges of sheet for welding; forming tube blank from sheet one and welding its lengthwise edges by consumable electrode of the same kind of alloy in protective argon atmosphere; producing conversion tube blank by shaping in roll mill and then welding lengthwise edges of blank in protective argon atmosphere for rolling conversion cold rolled tube blanks to less-diameter tubes; rolling conversion tube blank to cold rolled tube of maximum diameter at relation of diameter to wall thickness D/S = 30 - 40 and rolling it (at further rerolling stages) to less diameter tubes at increasing relation D/S from 2 till 20 for each rerolling procedure. Last rerolling process is realized at relation D/S = 80 - 100. Invention provides possibility for producing large- and mean-diameter tubes of titanium base alloys according to ASTM B 862-02, reduced by 2.25 -2.8 times consumption factor of titanium base alloys.

EFFECT: possibility for lowered-cost production of high-quality tubes of large and mean diameters of titanium base alloys.

2 cl, 1 tbl

Description

The invention relates to pipe rolling production, and in particular to a method for producing a conversion billet for rolling large and medium diameter cold-rolled pipes from titanium-based alloys, and can be used on forming rollers with subsequent welding of longitudinal edges in argon protective medium and rolling the billet into cold-rolled pipes with a diameter of 159-426 mm with different wall thicknesses on the HPT 250 and HPT 450 mills.

In the practice of pipe production, there is a known method for producing a hot-rolled pipe billet for rolling cold-rolled pipes of large and medium diameters of 159-426 mm from titanium-based alloys on TPA 8-16 '' with pilgrim mills, including casting ingots with a diameter of 600-630 mm ESR, mechanical processing of ingots (turning and drilling of a central hole with a diameter of 100 mm), heating of ingots in muffles to a plasticity temperature of 1140–1180 ° C, piercing on a Kosovolova piercing mill with a drawing coefficient of 1.4–1.8, rolling on a pilgrim a mill with a drawing coefficient of 2.8-3.8, straightening and machining of hot-rolled pipes with removal of the outer and inner defective layers of 8-10 mm (TU 14-3-1218-83 "Seamless hot-deformed pipes turned and bored from alloy grade 14 "and TI 15 8-Tr. TB 1-64-2002" Production of seamless hot-deformed pipes from alloy 14 according to TU 14-3-1218-83 and TU 14-3-1236-83 ", Chelyabinsk, 2002).

The disadvantage of this method is the low yield (consumption coefficient of metal 1.8-2.5) due to the formation of surface defects (cracks due to the alpha layer), the complexity of heating billets in special muffles, eliminating the possibility of ignition of billets made of titanium alloys when interacting with liquid scale, and the use of machinery to remove the alpha layer (turning and boring of conversion pipes).

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 (formation 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, cracks arise in the alpha layer, which, under the influence of water and deformation stresses, which penetrate into 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 machine tools, and most importantly leads to significant losses of expensive titanium alloys.

In the practice of production of seamless cold-rolled pipes at HPT mills, it is recommended to reduce the outer diameter (reduction in diameter) in the range of 26-40 mm, which increases with increasing pipe diameter (V.Ya. Osadchy, A.S. Vavilin, V.G. Zimovets and A.P. Kolikov. Technology and equipment for pipe production. Moscow. "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 for the production of a conversion tube billet and rolling of 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 billet on a mandrel in a mowing mill and subsequent rolling (ed. Certificate. USSR No. USSR 499907, class B 21 B 23/00, 1974).

The disadvantage of this method is that it is laborious due to the operation of rolling pipes on two types of rolling equipment, cannot produce a conversion billet with a diameter of more than 200 mm, does not exclude the formation of defects on the outer and inner surfaces of the pipes in the form of marks along the fusion boundary a weld with the base metal, there is no equipment for repairing the weld, as well as defects in the form of flaws of the weld due to the presence of an unremoved alfied layer from the weld. This process is acceptable only for the production of pipes from titanium alloys of small size, because for this range there are industrial installations for the production of welded pipes in a protective environment of argon.

The closest to the technical solution is a method for the production of conversion pipe billets and rolling of cold-rolled pipes from titanium alloys, including the production of a sheet billet, preparing 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 °) with a step equal to the wall thickness of the finished pipe, with a degree of deformation along the wall of 30-50% (USSR Authors Certificate No. 893280, class B 21 V 23/00, 1981).

The disadvantage of the above method for the production of a conversion pipe billet for rolling cold-rolled pipes from titanium-based alloys is that it can be distributed only for rolling pipes of small diameter, because There are no longitudinal welding mills with a diameter of more than 200 mm in Russia, especially for the production of titanium titanium tubes in an argon protective environment. This method is time-consuming, 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 boundary of fusion of the weld with the base metal and the flaw of the welded joint for the alpha layer, which is difficult and economically inexpedient to remove from pipes of small diameter.

The objective of the proposed method for the production of a conversion pipe billet for rolling cold-rolled large and medium diameter pipes from titanium-based alloys is the production of a conversion pipe billet using existing methods without additional capital investments and the construction of plants for their production, the manufacture of a conversion billet of large diameter of relatively short lengths, on which effectively repair welds and remove the alpha layer using existing methods (grinding oh) and use them instead of seamless ones, which means to significantly reduce the expenditure coefficient of the metal during redistribution: the conversion pipe billet is a cold-rolled pipe with a diameter of 159-426 mm.

The technical result is achieved by the fact that in the known method for the production of a conversion pipe billet for rolling cold-rolled large and medium diameter pipes from titanium-based alloys, including the production of a sheet billet, gouging the width of the sheet, preparing the sheet edges for welding, forming the sheet billet into a pipe billet, and welding of longitudinal edges by a consumable electrode of the same alloy grade in an argon protective medium; a conversion pipe billet is made by molding on rollers with subsequent longitudinal welding edges in argon protective medium for rolling cold-rolled tubes of maximum diameter, followed by rolling of cold rolled tubes-blanks into tubes of smaller diameter, and the redacting tube stock is rolled into a cold-rolled tube of maximum diameter with a ratio D / S = 30-40, which during subsequent rolling rolled into pipes of smaller diameter with an increase in the D / S ratio from 2 to 20 for each roll, and the last roll is made with the ratio D / S = 80-100.

The essence of the method lies in the fact that to reduce the consumption of the alloy and the complexity of the production of cold-rolled large and medium diameter pipes from titanium-based alloys, 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 pipe production, meeting the requirements of ASTM B 862-02 and TU 14-158-135-2003, a conversion pipe billet is made by molding on rollers with subsequent welding of longitudinal edges in argon protective medium for rolling cold-rolled pipes of the maximum diameter, with subsequent rolling of the cold rolled steel billets into smaller pipes, and the billet rolled into a cold rolled maximum diameter pipe with a ratio of D / S = 30-40, which during subsequent rolling is rolled into smaller pipes with an increase in the D / S from 2 to 20 for each roll, and the last roll is produced with a ratio of D / S = 80-100. Thus, the claimed method meets the criterion of "novelty."

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 allows us to conclude that the criterion of "significant differences".

The method has been tested and implemented on the KhPT 250 and KhPT 450 mills of ChTPZ OJSC when rolling cold-rolled pipes of size 426 × 12-377 × 10-325 × 8-273 × 6-219 × 4.5-180 × 3.0-159 × 2.0 mm from a converted welded tube billet and machined (turned and bored) hot-rolled billets of 470 × 14.5 mm in size from VT 1-0 alloy. A conversion welded billet with a size of 470 × 14.5 × 4500 mm was manufactured at ZAO Zavod PSK, Novosibirsk. Sheets were formed into tube blanks on rollers with a gap of 4.0 mm. The longitudinal edges were welded using a consumable electrode made of VT1-0 alloy in a protective argon medium. The conversion machined billet with a size of 470 × 14.5 × 4500 mm was made from a hot-rolled billet with a size of 485 × 30 × 4500 mm, rolled from a 630 × 100 × 1700 mm ESP ingot at a PTA 8-16 "with Pilgrim mills of ChTPZ OJSC The billets were rolled on cold rolling mills of ChTPZ OJSC. Data on the rolling of cold-rolled large and medium diameter pipes at KhPT 250 and KhPT 450 mills of ChTPZ OJSC from welded and mechanically processed hot-rolled billets of VT 1-0 alloy according to the existing and proposed technologies are given in table The table shows that the welded straight-seam and seamless billets according to the proposed and existing 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 D / S ratios of 35.5; 37.7; 40.6; 45.5; 48.7; 60.0 and 79.5 and reductions (reduction) according to the diameter, respectively, 44; 49; 52; 52; 54; 39 and 21 mm, which is fully consistent with the claims. Pipes of all sizes, rolled according to the proposed technology, according to geometric dimensions and mechanical properties, met the requirements of ASTM B 862-02 and TU 14-158-135-2003. The expenditure coefficient of metal for redistribution ranged from 1.015 to 1.042, and the total expenditure coefficient for pipes of medium (final) diameter measuring 159 × 2.0 mm from the welded billet to the pipe amounted to 1.195 (data in the brackets of the table). According to the existing technology, rolling of pipes of this series was carried out from a seamless machined (turned and bored) billet of 470 × 14.5 × 4500 mm in size, made from a pipe billet of 485 × 30 × 4500 mm in size. Since in Russia there are no mills for longitudinal welding of pipes with a diameter of 377, 325 and 265 mm, and even more so for the production of welded pipes from titanium-based alloys in an argon protective environment, a seamless hot-rolled billet of size 485 was adopted for the production of cold-rolled pipes of this size range × 30 × 4500 mm. According to the existing technology, the expenditure coefficient of metal for hire ranged from 1.017 to 1.042, and taking into account the machining of hot-rolled pipes and the expenditure coefficient when rolling pipes on a 8-16 '' TPA with pilgrim mills, respectively, from 2.343 to 2.768 (data in table brackets), when the coefficient of metal consumption when rolling pipes on TPA 8-16 '' 1.125, and during machining 1.999. Thus, when rolling pipes with a size of 159 × 2.0 mm according to the proposed technology from a converted welded pipe billet for seven rolls, the total consumption coefficient of VT 1-0 alloy was 1.195, and according to the existing technology when rolling from hot-rolled machined billets, the total consumption coefficient of alloy VT1-0 was 2.768, i.e. a decrease in the consumption coefficient by 2.32 times was obtained when obtaining high-quality pipes in geometric dimensions and mechanical properties and a loss in productivity of mills ≈ 2 times. Since the cost of titanium-based alloys is much higher than the cost of a mill-hour, it is economically feasible to go along the path of saving alloys due to loss of productivity of mills, especially when the mills of KhPT 250 and KhPT 450 are not fully loaded.

Thus, the use of the proposed method for the production of a conversion pipe billet for rolling cold-rolled large and medium diameters from titanium-based alloys will allow the production of high-quality pipes in accordance with ASTM B 862-02 and TU 14-158-135-2003 from a welded conversion pipe billet, made for rolling pipes of maximum diameter, instead of a seamless conversion billet, significantly reduce the complexity of manufacturing a conversion billet, reduce the expenditure coefficient of titanium alloys in 2.25-2.8 times during redistribution: a welded conversion billet for rolling cold-rolled pipes of larger diameter - cold-rolled pipe of the size range from maximum to medium, and therefore, significantly reduce the cost of cold-rolled pipes of this size range from titanium-based alloys.

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 Type and dimensions of the conversion workpiece (mm) Pipe dimensions (mm) D / S ratio Diameter Compression (mm) Pipe length after trimming ends (mm) Consumption. coefficients metal Type and dimensions of the conversion workpiece (mm) Pipe dimensions (mm) Rel. D / s Diameter Compression (mm) Pipe length after trimming ends (mm) Consumption. coefficients metal Welded longitudinal seam 470 × 14.5 × 4500 426 × 12 35.5 44 5750 1,042 Seamless machined 470 × 14.5 × 4500 from a pipe billet with a size of 485 × 30 × 4500 426 × 12 35.5 44 5800 1,042 (2,343) 377 × 10 37.7 49 7600 1,025 (1,068) 377 × 10 37.7 49 7650 1,025 (2,402) 325 × 8 40.6 52 10700 1,029 (1,099) 325 × 8 40.6 40 10600 1,039 (2,496) 273 × 6 45.5 52 16700 (8350 × 2) 1.016 (1.117) 273 × 6 45.5 42 16600 (8300 × 2) 1,022 (2,551) 219 × 4.5 48.7 54 13600
13600 1.019 (1.138) 219 × 4.5 48.7 31 13500 13500 1,027 (2,619) 180 × 3.0 60.0 39 12,200 × 2 12,200 × 2 1.015 (1.155) 180 × 3.0 60.0 39 12250 × 2 12100 × 2 1.017 (2.664) 159 × 2.0 79.5 21 10000 × 8 + 7300 × 4 1,035 (1,195) 159 × 2.0 79.5 21 10000 × 8 + 7200 × 4 1,039 (2,768) Note: in brackets are given the expenditure coefficients of the metal, taking into account the sequence of redistribution (rolling) from larger to smaller diameters (the proposed technology), and according to the existing technology, taking into account the expenditure coefficient when regrinding (1,999) and when rolling on a TPA 8-16 '' with pilgrim camps (1,125).

Claims (2)

1. Method for the production of a conversion tube billet for rolling cold-rolled large and medium diameters from titanium-based alloys, including the production of a sheet billet, gouging the sheet in width, preparing sheet edges for welding, forming a sheet billet into a tube billet, and welding longitudinal edges with a consumable electrode alloy grades in the argon protective medium, characterized in that the molding is carried out by forming on rollers with subsequent welding of the longitudinal edges, rolling into red cold rolled tr slab billets with a maximum diameter and rolls of converted cold-rolled pipe billets into pipes of a smaller diameter. 2. The method according to claim 1, characterized in that the conversion pipe billet is rolled into a cold-rolled pipe of maximum diameter with a ratio of diameter to wall thickness of the pipe D / S = 30-40, which is rolled into pipes of smaller diameter during subsequent rolls with increasing ratio D / S from 2 to 20 for each roll, and the last roll is performed with the ratio D / S = 80-100.