RU2532873C2 - PRODUCTION OF 377×14-19 mm SEAMLESS HOT-ROLLED PIPES FOR STEAM BOILERS, STEAM PIPELINES AND MANIFOLDS OF PLANTS WITH HIGH AND SUPERHIGH STEAM PARAMETERS OF "10Х9МФБ-Ш"-GRADE STEEL - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to pipe rolling. In compliance with this process hollow ESR ingots are turned and bored to hollow ingots-billets. The latter are heated to 1180-1200°C and rolled under specified conditions at PRU with Pilger mill to rerolled pipes. Hot cutting saw is used to remove process wastes in the form of Pilger heads and seed ends. The latter are straightened at six-roll straightener and subjected to heat treatment. Rerolled pipes are rolled at CPR 450 mill to commercial cold-rolled pipes to be heat treated, straightened, subjected to ultrasound control and acceptance. Hollow ingots-billets are heated to ductility temperature in continuous furnace. Note here that ingots-billets are placed on furnace grate bars in lots of 8-10 pieces in one row in 1.25-15. h at the temperature in third zone of the furnace of 1000-1050°C. Said ingots-billets are held on grate bars without turning over for 1.0-1.25 h. Ingots-billets are heated at the rate of 2.3-2.6°C a minute for 4.5-5.0 h to 1190-1200°C with uniform turning over of ingots-billets over furnace bottom from 22^nd to 6^th window in 18-20 minutes through the angle of 220-230°. Ingots-billets are held for 0.5-0.75 h with uniform turn-over from 6^th to 4^th window in 15-20 minutes through 220-230°, and turnover from 4^th window to furnace pit and discharge of ingots-billets from the furnace.

EFFECT: lower metal input, higher precision of geometrical sizes and surface quality.

2 cl, 1 tbl

Description

The invention relates to pipe production, and in particular to a method for the production of seamless pipes of 377 × 14-19 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 practice of pipe production, there is a method of manufacturing boiler pipes of large and medium diameters from forged billets of steels of grades 20, 15GS, 15XM, 12X1MF, 15X1M1F, 12X2MFSR, 10X9MFB, 12X11V2MF, 08X16H9M2, 12X18N12T, 10Kh13G12B2K2 with mechanical properties that include forging them into forgings (compaction of the structure) with a yoke of ≥2.5, machining the forgings into billets (turning with metal removal of 10-15 mm per side), drilling in the blanks of a central hole with a diameter of 100 ± 5 mm to remove the central quasi-porosity and non-metallic inclusions, heating the workpieces to a plasticity temperature, piercing the workpieces in a cross-helical rolling mill into sleeves, rolling the sleeves into pipes with a diameter of 245-550 mm on an 8-16 "pilgrim installation with a diameter tolerance of + 1.25 / -1 , 0 and wall thickness + 25 / -5% (TU 14-1-2560-78 "Forged pipe billets for boiler pipes", TU 14-3-460-2003 and TU 14-ЗР-55-2001 "Seamless steel pipes for steam boilers and pipelines "and TU 14-3-420-75" Pipes for steam boilers and pipelines from steel 15GS and 15Kh1M1F ").

The disadvantage of this method is the high energy intensity of the process associated with heating and deformation (forging) of the ingots into forgings, followed by turning and drilling of the central hole, heating the workpieces to a plasticity temperature, piercing and rolling them into pipes on pilgrim mills with a wall tolerance of + 20 / - 5%, increased consumption coefficient of the metal during the redistribution of the ingot - forging - billet - pipe and, as a result, the high cost of pipes, as well as the fact that this steel grade is included in TU 14-3R-55-2001, but the pipes are made of it until now No box was produced.

In pipe production, a method is known for manufacturing large diameter gas lift pipes from 09G2S steel ingots for the production of ESR and VDP (patent RU No. 2119395, class B21B 19/04), where the ingots are deformed in the piercing mill along the crystals, setting the ingots in the mill with the head part, and stitched with a posad in diameter by the amount

D = 2S _G (1-sinα) / S _C ,

where S _g - wall thickness of the sleeve, mm;

S _c - wall thickness of the drilled ingot ESR, mm;

α is the angle of inclination of the crystallization front to the axis of the ingot, deg.

The disadvantage of this method of manufacturing large diameter pipes from ingots of ESR and VDP steel grade 09G2S is the need to manufacture macro templates to determine the angle of inclination of the crystallization front to the axis of the ingot, and the piercing of the ingots with shrink (head) part forward leads to the formation of defects in the form of internal captures at the front ends of the sleeves .

In pipe production, there is also known a method for the production of large diameter boiler pipes from ESR ingots (patent RU No. 2180874, class B21B 19/04), which reduces energy costs, reduces metal consumption and, as a result, reduces the cost of boiler pipes through the use of large diameter ingots and conducting the firmware process with a posad in diameter equal to 8-16%.

The disadvantages of this method are that, due to the low power of the drive of the piercing mill of ChTPZ OJSC, it is not possible to flash ESR steel of the 10Kh9MFB-Sh grade with a diameter of 8–16% by seeding.

There is also known a method of producing seamless hot-deformed pipes of large and medium diameters in tube rolling plants with pilgrim mills for steam boilers, steam pipelines and manifolds of plants with high and supercritical parameters of steam from electroslag remelting ingots and continuously cast billets (patent RU No. 232322314, class B21B 19 / 04), which provides for the piercing of ESR and HJI3 ingots in cross-helical rolling mills with a pitch in diameter, depending on the steel grade and the total hood during redistribution of the electrical waste ingot kovogo remelting - pipe or continuously cast billet, tube, wherein the values posad diameter ingots electroslag remelting in piercing mills into helical rolling determined from the expression

Δ _i′ashp = k _i′eshp µ _i ∑,

where Δ _i′eshp are the values of the sizes according to diameter when piercing in the mills of cross-helical rolling of ESR ingots of i-steel grade,%;

µ _i ∑ = µ _pr µ _p - the total drawing coefficient when rolling pipes of the i-th size;

k _i'eshp - coefficient taking into account the size of the gang by diameter when flashing sleeves from ESR ingots of i-steel grade,%;

µ _CR - the coefficient of extraction when piercing sleeves for rolling pipes of the i-th size;

µ _p is the drawing coefficient when rolling j-sized pipes on a pilgrim mill, while the coefficients k _i′ESP for different grades vary from 24 to 40.

The disadvantage of this method is that it is very difficult to manufacture, because each pipe size requires its own ESR ingots, this method extends to the production of seamless hot-deformed pipes of large and medium diameters in tube rolling plants with pilgrim mills made of carbon steel grades and does not provide production of boiler tubes from EShP ingots of steel grade 10X9MFB-Sh.

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 pipe 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, piercing them with subsequent rolling in a cross-helical mill into shells and rolling the shells in a pilgrim mill into hot-rolled processing coarse or marketable goods 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 with rolling with the shrink end forward, pipes are rolled on the pilgrim mill with the diameter to diameter ratio 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, re-heating the billet blanks from a cold or hot seat to a ductility temperature, and flashing - rolling in the mill cross-helical rolling into sleeves with their subsequent rolling in 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, the value of which is determined from the expressions

where Δ is the value of the removed metal layer when turning hollow ingots-shells ESR, mm; Δ ₁ - the value of the removed metal layer when boring hollow ingots-shells ESR, mm; D is the outer diameter of the hollow ingots, sleeves, mm; S is the wall thickness of the hollow ingots, sleeves, mm; K = 0.3-0.4 is the coefficient for determining the magnitude of the metal layer to be removed when turning ingots-liners, large values of which relate to steels with a high content of alloying elements; K ₁ = 0.4-0.5 is the coefficient for determining the size of the metal layer to be removed during the boring of ingot shells, large values of which relate to steels with a high content of alloying elements, and the bottom of the hollow ingot shells of ESR is removed by anode-mechanical cutting, the value of which is determined from the expression

where K ₂ = 15-20 is the coefficient for determining the magnitude of the removed bottom of the ingot shells, large values, which apply to steels with a high content of alloying elements.

The disadvantage of this method is that it is directed to the technology of converting hollow ESR ingots into hollow ingots-blanks for the production of pipes from hard-to-form steel grades and alloys 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 a pair of steel grade 10X9MFB-Sh with a diameter of 377 mm with wall thicknesses from 14 to 19 mm.

In Russia, boiler pipes with a diameter of 377 mm with different wall thicknesses can only be produced on TPU 8-16 "with pilgrim mills and on the HPT 450 mill.

Rolling pipes with a size of 377 × 14-19 mm on TPU 8-16 "with pilgrim mills made of 10Kh9MFB-Sh steel is problematic due to the low temperature under deformation of 1180-1200 ° C. Ingot is necessary for rolling pipes with a size of 377 × 14-19 mm ESR blanks with a size of 540 × 100 × 1750 ± 50 mm, of which on the cross-helical rolling mill for flashing and rolling we get sleeves 560 × in. 390 × 3250-3440 and 560 × in. 375 × 2850-3000 mm in size or hollow sleeves billets with a size of 600 × ext. 400 × 3200 ± 50 mm, the rolling time of the pipe 377 × 14 mm from a sleeve length of 2850 mm with a wall thickness of 72.5 mm on the pilgrim mill is more than 4.5 in. Over 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 377 × 14-19 mm in size and rolling pilgrim heads made of 10Kh9MFB-Sh steel at temperatures below 850 ° C leads to increased loads on the drive of the pilgrim mill and tightening of the mandrels, which, in turn, leads to breakage of the safety bolts and spindles of the pilgrim mill, lower productivity due to the removal of mandrels due to tightening, and the 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. Rolling pipes from steel grade 10X9MFB-Sh with a D / S ratio> 25 leads to the formation of bumps on the outer surface of the pipes, i.e. to increased rejection by outer diameter. Therefore, pipes of this size are produced from hard-deformed grades of steel and alloys by the method of mechanical processing - turning and boring of thick thick-walled pipes or at HPT mills by rolling of the converted pipes into commodity ones.

The objective of the proposed method (invention) is the development of the production of seamless pipes with a diameter of 377 mm for steam boilers, steam pipelines and manifolds of installations with high and supercritical steam parameters, with wall thicknesses from 14 to 19 mm from hollow ingots-blanks of electroslag remelting with a size of 600 × ext. 400 mm steel grade 10X9MFB-Sh.

The technical result is achieved by the fact that in the known method for the production of seamless pipes 377 × 14-19 mm in size for steam boilers, steam pipelines and manifolds of installations with high and supercritical parameters of steam from steel grade 10X9MFB-Sh, including turning and boring hollow ingots of electroslag remelting into hollow ingot billets with a size of 600 × ext. 400 mm, heating ingot billets to a temperature of 1180-1200 ° C and rolling on TPU with pilgrim mills into conversion pipes of 426 × 21 and 426 × 23 mm with hoods, respectively, µ = 5.76 and µ = 5.29, compressed we have a diameter of 29% and with feeds of sleeves into the deformation zone m = 15-18 mm, a piece of technological waste - seed ends and pilgrim heads with a hot cutting saw, straightening on a six-roll straightening machine, heat treatment, rolling 450 conversion tubes of size 426 on the KhPT mill × 21 mm into commodity cold-rolled pipes with a diameter of 377 mm with a wall thickness of 14 to 16 mm, and conversion pipes of 426 × 23 mm into commodity pipes with a diameter of 377 mm with a wall thickness from 17 to 19 mm, heat treatment, dressing, ultrasonic testing and pipe acceptance, hollow ingots the preparations are heated in a methodical furnace to a temperature of plasticity, while ingots-blanks are planted on the furnace grates in batches of 8-10 pieces in a row with an interval of 1.25-1.5 hours at a temperature in the third zone of the furnace 1000-1050 ° C , exposure of ingot blanks to grates without tilting for 1.0-1.25 hours, heating of ingot blanks at a speed of 2.3-2.6 ° C per minute for 4.5-5.0 hours to a temperature of 1190 -1200 ° C with uniform pitching of ingot billets along the bottom of the furnace from the 22nd to the 6th window in 18-20 minutes at an angle of 220-230 °, holding for 0.5-0.75 hours with equal After turning from the 6th to the 4th window in 15-20 minutes at an angle of 220-230 °, the turning from the 4th window to the pit of the furnace and the delivery of billets from the furnace, heated hollow ingots after delivery from the furnace are transferred to the input side of the pilgrim mill for 1.0-1.5 minutes.

Comparative analysis with the prototype shows that the inventive method for the production of seamless pipes 377 × 14-19 mm in size for steam boilers, steam pipelines and manifolds of plants with high and supercritical parameters of steam from 10Kh9MFB-Sh steel is characterized in that hollow ingots are heated in a methodical the furnace to the temperature of plasticity, while the ingots are blanked on the furnace grates in batches of 8-10 pieces in a row with an interval of 1.25-1.5 hours at a temperature in the third zone of the furnace 1000-1050 ° C, the ingots are aged blanks on the grate without a rim for 1.0-1.25 hours, heating the ingot blanks at a speed of 2.3-2.6 ° C per minute for 4.5-5.0 hours to a temperature of 1190-1200 ° C uniform tilting of ingot billets along the bottom of the furnace from the 22nd to the 6th window after 18-20 minutes at an angle of 220-230 °, holding for 0.5-0.75 hours with a uniform tilting from 6th to 4- the e-window in 15-20 minutes at an angle of 220-230 °, the tilting from the 4th window to the pit of the furnace and the delivery of billets from the furnace, the heated hollow ingots-billets, after being dispensed from the furnace, are transferred to the entrance side of the pilgrim mill for 1.0- 1.5 minutes. 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 "inventive step".

Commodity pipes 377 × 20 in size and 426 × 23 mm in size were rolled from 10Kh9MFB-Sh steel at 8-16 "TPU with pilgrim mills from hollow ingot blanks EShB measuring 600 × ext. 400 × 3200 ± 50 mm. For comparison, the data the dimensions of the pipes were rolled according to the classical scheme, that is, from ingot blanks of 565 × 100 × 1750 ± 50 mm in size, Conversion pipes of 426 × 23 mm in size were rolled on the KhPT 450 mill to 377 × 18 mm in commodity ones. conversion pipes 426 × 23 mm in size and commodity pipes 377 × 20 mm in size from ingot blanks and hollow ingot blanks ESR steel 10Kh9MFB-Sh arches on TPU 8-16 "with pilgrim mills and rolling red coarse grades of 426 × 23 mm in commodity pipes 377 × 18 mm in size at the KhPT 450 mill of ChTPZ OJSC and the results of commissioning are shown in Table 1. Table 1 shows that for the production of conversion pipes 426 × 23 mm in size according to the proposed technology, 5 hollow ESH ingots-blanks with a size of 600 × ext. 400 × 3200 ± 50 mm supplied by ZMZ were used. ESW hollow ingot blanks with a size of 600 × ext. 400 × 2200 ± 50 mm were heated and rolled at 8-16 "TPU into 426 × 23 mm pig tubes in accordance with the claims. Hollow ingot blanks for rolling pig tubes were planted into a methodical furnace, and heated to a temperature of 1180-1200 ° C. Hollow ingots-billets with a total mass of 19.790 tons were rolled on a pilgrim mill into conversion tubes of 426 × 23 × 14200-14700 mm in size with a hood µ = 5.29, compression in diameter Δ = 28.3% and feeds into the deformation zone 16-18 mm Technological were cut from the pipes on the hot cutting saw the waste was pilgrim heads and seed ends.The pipes were straightened on a six-roll straightening machine, heat-treated, cut into two parts of equal length and sent to roll on the KhPT 450 mill to 377 × 18 mm in commodity size. pipes with a size of 377 × 18 × 9300-9700 mm, which were accepted with a tolerance of ± 1.0% in diameter and + 15 / -5.0 on the wall with a total weight of 15.913 tons. The metal consumption coefficient for pipes of this batch was 1.244. For comparison, this pipe size was rolled according to the classical scheme from drilled EBP ingots-blanks measuring 565 × 100 × 1750 ± 50 mm with double heating, firmware, firmware - rolling, rolling on a pilgrim mill and subsequent rolling on the HPT 450 mill. Metal consumption coefficient amounted to 1,295.

Thus, the use of the proposed method will allow for the first time in Russia to produce seamless pipes with a size of 377 × 14-19 mm from hollow ingots of EHP steel grade 10X9MFB-Sh for steam boilers, steam pipelines and manifolds of installations with high and supercritical steam parameters with mechanical properties of the metal and geometric pipe sizes exceeding the values of these indicators given in TU 14-ЗР-55-2001, which will significantly reduce energy costs by eliminating the heating of ESR ingots-blanks for flashing and flashing y - rolling for exclusion from the treatment process EEPROM ingot billets in-liner blank. to produce high-quality commodity and conversion pipes at TPU 8-16 "with pilgrim mills of ChTPZ OJSC for the subsequent conversion of conversion pipes into commodity pipes by rolling them at the KhPT 450 mill, to exclude mechanical processing-turning and boring of conversion pipes into commodity ones with a size of 377 × from the technological process 14-19 mm, and consequently, significantly reduce metal consumption during their production, reduce metal consumption during the redistribution of hollow ingots-blanks ESR into commodity pipes, increase the productivity of TPU 8-16 "with pilgrim mills, and the investigator but to reduce the cost of boiler tubes of steel grade 10H9MFB-W.

Table continuation

Claims (2)

1. Method for the production of seamless pipes 377 × 14-19 mm in size for steam boilers, steam pipelines and manifolds of plants with high and supercritical steam parameters made of 10Kh9MFB-Sh steel, including turning and boring hollow ingots of electroslag remelting into hollow ingots-blanks of 600 × ext. 400 mm, heating the hollow ingot blanks to a temperature of 1180-1200 ° C and rolling on TPU with pilgrim mills into conversion tubes of 426 × 21 and 426 × 23 mm in size with hoods µ = 5.76 and µ = 5.29, respectively , compression by diameter of 29% and with feeds of sleeves into the deformation zone m = 15-18 mm, for the segment of technological waste - seed ends and pilgrim heads with a hot cutting saw, straightening on a six-roll straightening machine, heat treatment, rolling at the KhPT mill 450 conversion pipes 426 × 21 mm in size into commodity cold-rolled pipes with a diameter of 377 mm with wall thickness from 14 to 16 mm, and conversion pipe size 426 × 23 mm into commodity pipes with a diameter of 377 mm with wall thickness from 17 to 19 mm, heat treatment, dressing, ultrasonic inspection and pipe acceptance, characterized in that the hollow ingots are billets heated in method of the furnace to plasticity temperature, while ingots-blanks are planted on the furnace grates in batches of 8-10 pieces in a row with an interval of 1.25-1.5 hours at a temperature in the third zone of the furnace 1000-1050 ° C, the ingots are aged of preparations on the grate without a rim for 1.0-1.25 hours, heating of the ingot blanks at a speed of 2.3-2.6 ° C per minute for 4.5-5.0 hours to a temperature of 1190-1200 ° C with uniform pitching of ingot blanks along the hearth of the furnace from the 22nd to 6th window after 18-20 minutes at an angle of 220-230 °, exposure for 0.5-0.75 hours with uniform pitching from the 6th to 4th a window in 15-20 minutes at an angle of 220-230 °, a tilting from the 4th window into the pit of the furnace and delivery of blanks from the furnace.       2. The method according to claim 1, characterized in that the heated hollow ingots-blanks, after being dispensed from the furnace, are transferred to the input side of the pilgrim mill for 1.0-1.5 minutes.