RU2545971C2 - MANUFACTURING METHOD OF SEAMLESS TUBES WITH SIZE OF 465×15-25 mm FOR STEAM BOILERS, STEAM LINES AND HEADERS OF PLANTS WITH HIGH AND SUPERCRITICAL STEAM PARAMETERS FROM INGOTS OF ELECTROSLAG REMELTING OF STEEL GRADE "10Х9МФБ-Ш" - Google Patents

Abstract

FIELD: technological processes.

SUBSTANCE: invention relates to tube rolling. Hollow ingots with the ratio of diameter to wall thickness of 5.0 to 5.5 are molten by means of an ESR method, which are then turned and bored into hollow cakes with the ratio of diameter to wall thickness of 5.8 to 6.6. Cakes are heated to the temperature of 1190-1200°C and rolled on TPU 8-16" unit with pilger mills into semi-finished tubes with the size of 480×30-35 mm with supplies to deformation zone m=14-16 mm and semi-finished tubes with the size of 480×38-40 mm with supplies to deformation zone m=15-17 mm. Semi-finished hot-rolled tubes are straightened, heat treated, turned and bored into marketable tubes.

EFFECT: improvement of mechanical properties and accuracy of geometrical dimensions of tubes.

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Description

The invention relates to pipe production, and in particular to a method for the production of seamless pipes of 465 × 15-25 mm in size for steam boilers, steam pipelines and collectors of plants with high and supercritical parameters of steam from hollow ingots-blanks of electroslag remelting steel grade 10X9MFB-Sh and can be used on an 8-16 ″ pipe-rolling installation with pilgrim mills.

In the pipe industry, methods are known for the production of large diameter boiler tubes from ESR ingots (patent RU No. 2180874, class B21B 19/04 and patent RU 2322314 class B21B 19/04), which reduce energy costs, reduce metal consumption and, as a result, reduce the cost of boiler pipes due to the use of large diameter ingots and the conduct of the firmware process with a diameter fit.

The disadvantages of these methods is that the firmware with a posad in diameter causes an increased load during firmware.

In pipe production, there is also known a method for the production of hot-rolled conversion and commodity pipes of large and medium diameters from hard-to-deform grades of steel and alloys in tube rolling plants with pilgrim mills (patent RU No. 2278750, class B21B 21/00), which includes turning of ESR ingots and forged billets, drilling a central hole with a diameter of 100 ± 5 mm, heating them to a plasticity temperature, flashing them with subsequent rolling in a cross-helical mill into sleeves and rolling the sleeves on a pilgrim mill in a hot-rolled front pipes or pipes with a relatively thick wall, with the first piercing of ESR ingots and forged billets in a cross-helical rolling mill with the bottom end forward, and the second piercing-rolling with the shrink end forward, the pipes are rolled on a pilgrim mill with diameter to the wall thickness D / S = 6.5-8.0 with a hood µ≤4.5.

The disadvantage of this method is that it includes heating the ESR ingots and billets to a temperature of ductility, flashing them in a cross-helical rolling mill into billet sleeves, reheating the billet blanks from a cold or hot embankment to a ductility temperature, flashing-rolling in the mill cross-helical rolling into sleeves, followed by rolling on a pilgrim mill to commodity or conversion pipes. Double heating leads to double burning of the metal, and the flashing of ESR ingots and billets into blanks, followed by rolling them into sleeves leads to a 2-fold loss in the performance of the pilgrim installation, and, consequently, to an increase in the cost of commodity and conversion pipes. This method extends to the production of seamless hot-deformed conversion and commodity pipes of large and medium diameters in tube-rolling plants with pilgrim mills from hard-to-deform grades of steel and alloys and does not provide for the production of boiler tubes from solid and hollow ingots of 10-H9MFB-Sh steel ESH.

The closest technical solution is the method of preparing billets for rolling commodity and conversion pipes of large and medium diameters from hard-to-deform grades of steel and alloys in tube rolling plants with pilgrim mills (patent RU No. 2340417, class B21B 21/00), including casting hollow ingots-sleeves electroslag remelting, turning and boring them into hollow billets with metal removal, calculated according to the proposed formula, depending on the degree of alloying of steel.

The disadvantage of this method is that it is aimed at the technology of converting hollow ESR ingots into hollow ingots-blanks for the production of pipes from hardly deformable steel and alloy grades and does not solve the technological issues of the production of seamless pipes for steam boilers, steam pipelines and collectors of installations with high and supercritical parameters from steel grade 10X9MFB-Sh with a diameter of 465 mm with wall thicknesses from 15 to 25 mm.

Boiler pipes with a diameter of 465 mm with different wall thicknesses in Russia can be produced only on TPU 8-16 ″ with pilgrim mills. Rolling pipes of 465 × 15-25 mm in size on TPU 8-16 ″ with pilgrim mills is problematic due to the low temperature of 10Kh9MFB-Sh steel under a deformation of 1180-1200 ° C. For rolling pipes with a size of 465 × 15-25 mm, ESR ingots-blanks with a size of 620 × 100 × 1750 ± 50 mm are required, of which on a cross-helical rolling mill for piercing and rolling we get sleeves with a size of 620 × ext. 465 × 3700-3900 mm or hollow billet blanks measuring 640 × in. 440 × 3200 ± 50 and 640 × in. 420 × 3200 ± 50, mm. On the existing piercing mill of ChTPZ OJSC it is possible to get a sleeve no longer than 3600 mm, and to put a sleeve no longer than 3500 mm into the pilgrim mill. The rolling time of a pipe measuring 465 × 15 mm from a sleeve 3,500 mm long with a wall thickness of 77.5 mm on a pilgrim mill is more than 4.0 minutes. During this period of time, the sleeve tube cools below 800 ° C (at a recommended minimum of 850 ° C at the end of rolling). Rolling pipes of 465 × 15-25 mm in size and rolling pilgrim heads made of 10Kh9MFB-Sh steel at temperatures below 850 ° C leads to increased loads on the pilgrim mill drive and tightening mandrels, which in turn leads to breakage of the safety bolts and spindles of the pilgrim mill , reduced productivity due to the removal of mandrels due to puffs, replacement of safety bolts and spindles. To avoid tightening the mandrels, it is necessary to roll pipes on mandrels with a taper of 5-6 mm instead of the existing taper of 1.0 mm, and this will lead to a longitudinal difference, i.e. to increased rejection of pipes by wall thickness.

The objective of the proposed method (invention) is the development of the production of seamless pipes with a diameter of 465 mm with wall thicknesses from 15 to 25 mm for steam boilers, steam pipelines and manifolds of plants with high and supercritical steam parameters, from hollow ingots-blanks of electroslag remelting from 10Kh9MFB-Sh steel , with increased accuracy of geometric dimensions and surface quality.

The technical result is achieved in that in a method for the production of seamless pipes of 465 × 15-25 mm in size for steam boilers, steam pipelines and manifolds of plants with high and supercritical parameters of steam from electroslag remelting ingots of steel grade 10X9MFB-Sh, including electroslag remelting of hollow ingots with a ratio diameter and wall thickness from 5.0 to 5.5, turning and boring them into hollow ingots-blanks with a ratio of diameter and wall thickness from 5.8 to 6.6, heating to a temperature of 1190-1200 ° C, rolling is carried out at TPU 8-16 ′ ′ with drank with rim mills into conversion pipes with dimensions of 480 × 30 × 10300-10700 mm and 480 × 35 × 8700-9000 mm with feeds to the deformation zone m = 14-16 mm and with hoods µ = 3.92 and µ = 3.40, respectively into conversion pipes with dimensions of 480 × 38 × 8300-8650 mm and 480 × 40 × 8200-8500 mm with feeds to the deformation zone m = 15-17 mm and with hoods µ = 3.28 and µ = 3.25, respectively, then cut technological waste with a hot cutting saw, rule on a six-roll straightening machine, heat treat, grind and bore it into commodity pipes, conduct ultrasonic inspection and acceptance.

Comparative analysis with the prototype shows that the claimed method for the production of seamless pipes of 465 × 15-25 mm in size for steam boilers, steam pipelines and manifolds of installations with high and supercritical parameters of steam from 10Kh9MFB-Sh steel is characterized in that electroslag remelting of hollow ingots with the ratio of diameter and wall thickness from 5.0 to 5.5, turning and boring them into hollow ingots-blanks with a ratio of diameter and wall thickness from 5.8 to 6.6, which are heated to a temperature of 1190-1200 ° C, rolling on TPU 8 -16 ″ with pilgrim mills into conversion pipes with dimensions of 480 × 30 × 10300-10700 mm and 480 × 35 × 8700-9000 mm with feeds into the deformation zone m = 14-16 mm (large values for a larger wall thickness) and with hoods µ = 3.92 and µ = 3.40, respectively, into conversion pipes with dimensions of 480 × 38 × 8300-8650 mm and 480 × 40 × 8200-8500 mm with feeds into the deformation zone m = 15-17 mm (large values for larger wall thickness) and with hoods µ = 3.28 and µ = 3.25, respectively, then process waste is cut off with a hot cutting saw, straightened on a six-roll straightening machine, heat treated, machined and bored into commodity pipes, conduct ultrasonic inspection and acceptance. 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 condition "inventive step".

The proposed method for the production of seamless pipes of 465 × 15-25 mm in size for steam boilers, steam pipelines and manifolds of plants with high and supercritical parameters of steam from electroslag remelting ingots of 10Kh9MFB-Sh steel was implemented in the production of 465 × 18-21 mm pipes at ChTPZ OJSC .

Pipes with a size of 465 × 15-25 mm are made from hollow ingots of electroslag remelting, hollow ingots are grinded and bored into hollow ingots-blanks of sizes 640 × in. 440 × 3200 ± 50, 640 × in. 430 × 3200 ± 50 and 640 × in. 420 × 3200 ± 50 mm, which are heated to a temperature of 1190-1200 ° C. The hollow ingot blanks with a size of 640 × ext. 440 × 3200 ± 50 are rolled on 8-16 ″ TPU with pilgrim mills into the conversion pipes of 480 × 30 × 10300-10700 and 480 × 35 × 8700-9000, the hollow ingot with the size 640 × ext. 430 × 3200 ± 50 mm is rolled into conversion pipes of size 480 × 38 × 8300-8650, and hollow ingots-blanks of size 640 × ext. 420 × 3200 ± 50 mm are rolled into conversion pipes of size 480 × 40 × 8200- 8500 mm with hoods, respectively, µ = 3.92, µ = 3.40, µ = 3.28 and µ = 3.25, with a diameter reduction of 25.0%. The supply of sleeves to the deformation zone during the rolling of pipes of size 480 × 30-35 mm is m = 14-16 mm, and when rolling pipes of size 480 × 38-40 mm, m = 15-17 mm. Process wastes are cut off with a hot cutting saw, straightened on a six-roll straightening machine, heat treated, repaired if necessary and re-straightened on a six-straighted straightening machine with a measurement of the total pipe curvature of not more than 5.0 mm. Then the pipes are transferred to the section for processing forgings and pipes for special purposes and cut into two pipes of equal length. Converted pipes of size 480 × 30 × 5150-5350 mm are grinded and bored into marketable goods of size 465 × 15-18 × 5150-5350 mm, conversion tubes of 480 × 35 × 4350-4500 mm are turned and bored into commodity pipes of 465 × 18 -21 × 6000-6500 mm, conversion pipe size 480 × 38 × 4150-4325 mm grind and bore into commodity size 465 × 21-23 × 4150-4325, and conversion pipe size 480 × 40 × 4100-4250 mm grind and bore into commodity pipes measuring 465 × 23-25 × 4100-4250 mm.

The pipes were adopted in accordance with TU 14-3R-55-2001 “Seamless steel pipes for steam boilers and pipelines” with a tolerance of + 20 / -5%, with a tolerance of ± 1.0% in diameter and + 15 / in wall thickness -5.0%.

Thus, the use of the proposed method will allow for the first time in Russia to produce seamless pipes with a size of 465 × 15-25 mm from hollow ingots of 10 × 9MFB-Sh steel ESRs for steam boilers, steam pipelines and manifolds of installations with high and supercritical steam parameters with geometric pipe sizes exceeding the values of these indicators given in TU 14-3R-55-2001, and also will significantly reduce energy costs by eliminating the heating of ingots-blanks ESR for firmware, exceptions from the process roshivki ingots, blanks in-liner blank, piercing-rolling sleeves blanks in the sleeve, to stabilize the supply amount of the hollow ingots, blanks in the hearth pilger deformation due to their smaller curvature, and hence reduce the cost of boiler tubes of steel 10H9MFB-III.

Claims (1)

Method for the production of seamless pipes with a size of 465 × 15-25 mm for steam boilers, steam pipelines and manifolds of plants with high and supercritical parameters of steam from 10Kh9MFB-Sh steel, including electroslag remelting of hollow ingots with a diameter and wall thickness ratio of 5.0 to 5 , 5, turning and boring them into hollow ingots-blanks with a ratio of diameter and wall thickness of 5.8 to 6.6, heating to a temperature of 1190-1200 ° C, rolling at TPU 8-16 '' with pilgrim mills into conversion pipes sizes 480 × 30 × 10300-10700 mm and 480 × 35 × 8700-9000 mm with feeds into the deformation zone m = 14-16 mm and with hoods μ = 3.92 and μ = 3.40, respectively, and into conversion pipes with sizes of 480 × 38 × 8300-8650 mm and 480 × 40 × 8200-8500 mm with feeds to the center deformations m = 15-17 mm and with hoods µ = 3.28 and µ = 3.25, respectively, a piece of technological waste with a hot cutting saw, straightening on a six-roll straightening machine, heat treatment, turning and boring of conversion pipes of 480 × 30 mm in size pipes with dimensions of 465 × 15-18 mm, conversion pipes of size 480 × 35 mm into commodity pipes of sizes 465 × 18-21 mm, conversion pipes of size 480 × 38 mm into commodity pipes with dimensions of 465 × 21-23 mm, and conversion pipes of size 480 × 40 mm into commodity pipes measuring 465 × 23-25 mm, ultrasonic inspection and acceptance of commodity pipes.