CN114635023A - Production method of martensite heat-resistant steel blank - Google Patents
Production method of martensite heat-resistant steel blank Download PDFInfo
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- CN114635023A CN114635023A CN202011482309.0A CN202011482309A CN114635023A CN 114635023 A CN114635023 A CN 114635023A CN 202011482309 A CN202011482309 A CN 202011482309A CN 114635023 A CN114635023 A CN 114635023A
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/005—Modifying the physical properties by deformation combined with, or followed by, heat treatment of ferrous alloys
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- B—PERFORMING OPERATIONS; TRANSPORTING
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- B21J5/00—Methods for forging, hammering, or pressing; Special equipment or accessories therefor
- B21J5/002—Hybrid process, e.g. forging following casting
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/008—Martensite
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Abstract
The invention relates to a production method of a martensite heat-resistant steel blank, belonging to the technical field of heat-resistant steel hot working. The production method comprises the following steps: 1) carrying out uniform heat treatment on the electroslag ingot, and designing a special stepped heating curve for reducing thermal stress; 2) forging and heating an electroslag ingot; 3) adopting an upsetting device to carry out upsetting and drawing forging more than three times; 4) annealing heat treatment; 5) and (4) quenching and tempering heat treatment. According to the production method of the martensite heat-resistant steel blank, provided by the invention, the martensite heat-resistant steel G115 blank with uniform structure, excellent performance and good welding process can be obtained through the homogenization heat treatment, the heating process, the forging process, the annealing process and the quenching and tempering heat treatment process.
Description
Technical Field
The invention belongs to the technical field of hot working, and mainly relates to a production method of a novel martensite heat-resistant steel (G115) blank.
Background
Thermal power generation is an important component of energy structures in China, and the improvement of parameters of thermal power generating units is directly related to energy conservation and emission reduction. The main parameters of the thermal power generating unit are the temperature and the pressure of steam, the current parameters of the main thermal power generating unit in China are 600 ℃ ultra-supercritical units, the installed capacity of the ultra-supercritical units is first in the global ranking, but the unit with the parameters cannot meet the high-quality requirement of China on the beautiful Chinese environment of green water hills, and the development of a new generation of high-parameter advanced ultra-supercritical unit is urgently needed. Therefore, the construction of 630 ℃ ultra-supercritical units is urgently scheduled, such as 37075of the great Tang group, and 630 ℃ ultra-supercritical demonstration power stations in cities are already approved by the national energy agency. The high requirements of the 630 ℃ ultra-supercritical unit on the material are mainly reflected in high-temperature endurance strength, stability of the structure after long-term high-temperature aging, high-temperature steam oxidation resistance and the like. In view of the fact that the performance of the existing heat-resistant steel P92 of the 600 ℃ ultra-supercritical unit can not meet the requirement of the 630 ℃ ultra-supercritical unit, under the condition, the novel martensite heat-resistant steel of 9Cr-3W-3CoVNbCuBN with higher performance is applied, the mark of the martensite heat-resistant steel is G115, the martensite heat-resistant steel is novel martensite heat-resistant steel, the design concept of composite reinforcement is adopted, the martensite heat-resistant steel has excellent high-temperature endurance strength, and the stability and the oxidation resistance of the structure after long-term high-temperature aging, and the comprehensive performance of the martensite heat-resistant steel is far better than that of P92; but the excellent performance also brings certain processing difficulty, and the traditional hot processing and heat treatment process similar to P92 can not be applied to G115 at all, so the invention provides a brand-new production method of the martensite heat-resistant steel G115 blank.
There are also related studies related to G115 in the prior art, as follows:
the Chinese patent No. CN103045962B is an invention patent of G115, mainly relates to the aspects of component design, strengthening concept, manufacturing method, performance characteristics and the like of G115, and does not relate to a production method of G115 tube blanks/forgings.
Chinese patent CN108998650A relates to a method for manufacturing a large-caliber thick-wall seamless steel tube of a G115 ultra-supercritical unit at 630 ℃, the patent only relates to a tube manufacturing process of the large-caliber thick-wall seamless steel tube of the G115, a tube blank production process is not available, northern heavy industry is also one of G115 research and development team members, and the production process of extruding and manufacturing the tube is completed on a 3.6 ten thousand ton extruder by mainly utilizing the G115 tube blank produced by BaoWltec (original BaoBt special steel).
Chinese patent CN108950148A relates to a method for improving radial structure and performance uniformity of G115 large-caliber thick-wall pipes, but does not relate to a production method of G115 pipe blanks/forgings.
Chinese patent CN106119488A relates to a forging and heating process of P91 alloy steel, does not relate to a process method related to G115 forging and heating, and has no reference value to the forging process of G115.
The G115 martensite heat-resistant steel produced in the prior art has some problems in the aspects of tissue uniformity, tensile and impact properties, solving of microscopic defects in a welding heat affected zone and the like, cannot meet actual related enterprise standards and industrial standards, and cannot be applied to 630 ℃ ultra-supercritical demonstration power station engineering.
Disclosure of Invention
The invention aims to provide a production method of martensite heat-resistant steel G115 blank, which comprehensively solves a series of problems in large-size G115 tube blank/forge piece industrialized mass production and engineering application for the first time.
The invention is realized by the following technical scheme:
the invention provides a production method of a martensite heat-resistant steel blank, which comprises the following steps:
s1, carrying out homogenization heat treatment on the martensite heat-resistant steel electroslag ingot;
s2, forging and heating the product obtained in the step S1;
s3, forging the product obtained in the step S2 in a 6000-ton quick forging machine;
s4, annealing and heat treating the product obtained in the step S3;
and S5, carrying out quenching and tempering heat treatment on the product obtained in the step S4 to obtain the martensite heat-resistant steel blank.
Preferably, the homogenization heat treatment in step S1 specifically includes the following operations:
spraying an anti-oxidation coating on the surface of the martensite heat-resistant steel electroslag ingot, heating to 600-650 ℃ at a speed of 50-80 ℃/h, preserving heat for 5-8 h, continuing heating to 1000-1050 ℃ at a speed of 50-80 ℃/h, preserving heat for 3-5 h, continuing heating to 1200-1250 ℃ at a speed of 50-80 ℃/h, preserving heat for not less than 80h, and cooling to 700-1000 ℃ after heat preservation.
Preferably, the forging heating in step S2 specifically includes the following operations:
and (4) heating the product obtained in the step (S1) to 1140-1180 ℃ at the speed of 50-100 ℃/h, and keeping the temperature for not less than 0.5 min/mm.
Preferably, in step S3, the upper anvil and the lower anvil of the rapid forging machine are preheated until the anvil surface temperature is not lower than 500 ℃, then upset and drawn out for at least 3 times, the start forging temperature is controlled to be 1050-1100 ℃, and the finish forging temperature is controlled to be 850-900 ℃.
Preferably, in the step S3, in the upsetting process of each heating, upsetting is performed at a pressing speed of 18-20 mm/S, after upsetting is performed to 1/2 of the original height of the electroslag ingot, elongation is started at a pressing amount of 50-70 mm each time, the pressing amount is increased to 100-120 mm at a range of 10-15 mm increase of the pressing amount each time, the pressing is performed for 5-8 times, an octagon is drawn to 900-1000 mm, furnace returning heating is performed at 1140-1180 ℃, the heat preservation time is not less than 3 hours, a round product is formed after the upsetting of the last heating, and final forging is performed at 850-900 ℃.
Preferably, in step S3, in the upsetting process of each heat, upsetting is performed at a reduction speed of 18-20 mm/S, after upsetting is performed to 1/2 of the original height of the electroslag ingot, elongation is started at a reduction of 50-70 mm each time, the reduction is increased to 100-120 mm at a range of 10-15 mm increase of the reduction each time, the reduction is performed for 5-8 times, an octagon is elongated to 900-1000 mm, reheating is performed at 1140-1180 ℃, the holding time is not less than 3 hours, staggered-anvil forging is performed after the upsetting of the last heat, and final forging is performed at 850-900 ℃.
Preferably, the annealing heat treatment in step S4 specifically includes the following operations:
and (5) annealing the product obtained in the step (S3) within 2 hours after the forging is completed, controlling the annealing temperature to 750-850 ℃, controlling the annealing time to be not less than 1.5min/mm, cooling the product to be below 100 ℃ after the annealing is completed, cooling the product along with the furnace, and discharging the product from the furnace for air cooling.
Preferably, the quenching and tempering heat treatment in step S5 specifically includes the following operations:
heating the product obtained in the step S4 to 900-1000 ℃ at a speed of 50-80 ℃/h, keeping the temperature for at least 2h, then continuing heating to 1050-1090 ℃ at a speed of 50-80 ℃/h, and normalizing, wherein the normalizing time is not less than 0.6 min/mm;
and (3) heating the normalized product at the speed of 50-80 ℃/h to 760-790 ℃, and tempering for not less than 1.6 min/mm.
The invention has the beneficial effects that:
the invention provides a production method of G115 tube blank/forging, which is a method capable of being successfully implemented in industrial mass production, according to the G115 tube blank and the forging produced by the method, macrosegregation and microscopic bulk segregation of tungsten-rich phase of large-size tube blank and forging are effectively eliminated, the G115 tube blank and the forging with uniform structure, excellent performance and good welding process are obtained, all performance indexes of the G115 tube blank and the forging meet the requirements of novel martensite heat-resistant steel 08Cr9W3Co3VNbCuBN (G115) tube blank and section bar for Q/OAPD 2753-2017 power station of enterprises standard, after tube making and processing, the tube blank produced by the method can meet the requirements of novel martensite heat-resistant steel 08Cr9W 3VNbCuBN (G115) for Q/OAPD 2253-2017 power station of enterprises standard and the martensite heat-resistant steel tube V9W 3VNbCuBN (G115) for M00017-2017 power station, and the comprehensive evaluation of the performance of users and related CSTRE, the performance is qualified, the problem that the G115 produced by the early G115 production method has the microscopic defect of a welding heat affected zone is solved, and the method has the condition of ultra-supercritical demonstration engineering application at 630 ℃.
Drawings
Other features, objects and advantages of the invention will become more apparent upon reading of the detailed description of non-limiting embodiments with reference to the following drawings:
FIG. 1 is a schematic view of a homogenization heat treatment curve of an electroslag ingot in example 1 of the present invention;
FIG. 2 is a schematic view of a forging heating profile in example 1 of the present invention;
FIG. 3 is a graph showing the annealing heat treatment curve of the pipe billet in example 1 of the present invention;
FIG. 4 is a schematic diagram of a normalizing curve of quenching and tempering heat treatment of a forging in embodiment 4 of the invention;
FIG. 5 is a schematic diagram of a tempering curve of the quenching and tempering heat treatment of the forging in embodiment 4 of the invention;
FIG. 6 is a photograph of macrostructures in example 1 of the present invention;
FIG. 7 is a photograph of the metallographic structure in example 1 of the present invention;
FIG. 8 is a scanning electron micrograph of a feature in example 1 of the present invention.
Detailed Description
The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the invention, but are not intended to limit the invention in any way. It should be noted that variations and modifications can be made by persons skilled in the art without departing from the spirit of the invention. All falling within the scope of the invention.
A production method of martensite heat-resistant steel G115 pipe blank/forging comprises the following process flows of:
firstly, carrying out homogenization heat treatment on an electroslag ingot;
secondly, forging and heating the electroslag ingot;
thirdly, forging by a 6000-ton quick forging machine;
fourthly, annealing and heat treatment after forging;
fifthly, quenching and tempering heat treatment of the forged piece;
according to the production method of the G115 martensite heat-resistant steel tube blank/forging, the step I of the electroslag ingot homogenizing heat treatment preferably comprises the following process steps:
a. the spraying of the anti-oxidation coating has high-temperature homogenization temperature and long time, an oxidation layer with the thickness of 10mm can be caused, the yield is influenced, and after the spraying of the anti-oxidation coating, the oxidation layer can be reduced to be less than 5 mm;
b. loading the steel ingot into a furnace, and heating along with the furnace at a heating speed of 50-80 ℃/h;
c. heating to 600-650 ℃, and preserving heat for 5-8 hours to make the surface and core temperature uniform and prevent over-high thermal stress;
d. continuously heating to 1000-1050 ℃ at a heating rate of 50-80 ℃/h, and preserving heat for 3-5 hours to further uniform the surface and core temperature and prevent excessive thermal stress;
e. continuously heating to the target temperature of the homogenization heat treatment of 1200-1250 ℃ at the heating rate of 50-80 ℃/h, wherein the heat preservation time is more than or equal to 80 hours (according to the ingot types of different specifications, the heat preservation time can be prolonged but not less than 80 hours);
f. in order to ensure the uniformity and accuracy of the temperature, when each batch or new furnace is processed for the first time, a tracking thermocouple needs to be arranged, and the actual temperature of different positions of the blank and the comparison between the steel temperature and the furnace temperature are monitored;
g. after the heat preservation is finished, stopping the furnace and cooling (closing the burner and not opening the furnace door), wherein the furnace is cooled to 700-1000 ℃;
according to the production method of the G115 martensite heat-resistant steel tube blank/forging, the electroslag ingot forging and heating in the second step preferably comprises the following process steps:
a. the temperature rising speed is 50-100 ℃/h;
b. heating at 1140-1180 ℃;
c. the heat preservation time is determined according to the specification of the steel ingot (the heat preservation time is more than or equal to 0.5min/mm), and the temperature of the center of the steel ingot is ensured to be uniform;
according to the production method of the G115 martensite heat-resistant steel tube blank/forging, preferably, the forging of the 6000-ton quick forging machine in the third step comprises the following technological processes:
a. preheating an upper anvil and a lower anvil, adopting scrap steel heated to be more than 800 ℃, closely adhering the upper anvil and the lower anvil, preheating for more than or equal to 20 minutes, and ensuring that the surface temperature of the anvil is more than or equal to 500 ℃;
b. the open forging temperature is 1050-1100 ℃, and the finish forging temperature is 850-900 ℃;
c. first, upsetting is carried out on 6000-ton quick forging machines to 1/2 of the original height of an electroslag ingot by a special upsetting device (Bao steel special steel patent No. CN107552699A, a manufacturing method of a large-sized upsetting device); the specially-made upsetting device is a disc-shaped device with a handle, the thickness of the specially-made upsetting device is 500-700 mm, the weight of the specially-made upsetting device is about 20 tons, the upper surface and the lower surface of a steel ingot can be ensured to be flat during upsetting, the stress is uniform (the upsetting of 13.5 tons of steel ingots can be completed at one time without moving the steel ingot), and the defects of bending, inclination and the like do not occur;
d. the upsetting reduction speed is 15-25 mm/s;
e. drawing to form an octagonal ingot with the diameter close to that of the electroslag ingot, wherein the length of the octagonal ingot is 1.8-2.5 times of the length of the upset ingot, and if the diameter of the electroslag ingot is phi 1000, drawing to form the octagonal ingot with the diameter of 980 mm;
f. the tube blank/forging piece needs to be repeatedly upset and drawn out for more than three times so as to fully break large tungsten-rich phase and eliminate the microscopic defect of the welding heat affected zone;
g. the temperature of each time of remelting is 1140-1180 ℃, and the heat preservation time is more than or equal to 3 hours (the specific time is determined according to the specification of the intermediate blank);
h. the tube blank is thrown to be round to the specification of a finished product, and the dimensional tolerance is (-10mm, +20 mm);
i. forging the forged piece into a specified shape according to the design specification of a drawing after the forged piece needs upsetting and drawing, and forging the unilateral step-shaped forged piece by adopting a staggered anvil forging mode;
j. and finally, the material is rolled into a round material by fire, the deformation is small, and the finish forging temperature can be widened to 850 ℃.
According to the production method of the G115 martensite heat-resistant steel tube blank/forging, the annealing heat treatment after forging in the fourth step preferably comprises the following process steps:
a. after the forging is finished, the forging furnace is driven into and out of the furnace within 2 hours;
b. the annealing temperature is 750-780 ℃;
c. the heat preservation time is determined according to the size of the ingot (the annealing time is determined according to the speed of not less than 1.5 min/mm);
d. and after the heat preservation is finished, cooling the furnace to be below 100 ℃ (closing the burner, not opening the furnace door, cooling along with the furnace), discharging the furnace and air cooling.
According to the production method of the G115 martensite heat-resistant steel tube blank/forging, the quenching and tempering heat treatment of the forging in the step e preferably comprises the following process steps:
a. the modulation heat treatment of the forge piece comprises two procedures of normalizing and tempering;
b. normalizing at a heating rate of 50-80 ℃/h, heating to 900-1000 ℃, keeping the temperature for more than or equal to 2 hours, then continuously heating to a normalizing target temperature of 1050-1090 ℃ at a heating rate of 50-80 ℃/h, keeping the temperature for a certain time according to the maximum cross section of the workpiece (normalizing time is determined according to the speed of not less than 0.6 min/mm), and discharging and air-cooling;
the tempering temperature rise speed is 50-80 ℃/h, the temperature is raised to the tempering target temperature of 760-790 ℃, the tempering time is determined according to the maximum section of the workpiece (the tempering time is determined according to the speed of not less than 1.6 min/mm), and the workpiece is discharged and then cooled in air.
Example 1
Adopting an electroslag ingot with phi of 1200, firstly uniformly spraying an anti-oxidation coating on the surface, airing, then charging, charging and heating according to a homogenization heat treatment curve shown in figure 1, heating to 640-660 ℃ at a heating rate of 60-70 ℃/h, preserving heat for 6 hours, heating to 990-1010 ℃ at a heating rate of 70-80 ℃/h, preserving heat for 4 hours, heating to 1230-1250 ℃ at a heating rate of 70-80 ℃/h, preserving heat for 90 hours, cooling to 800 ℃ in the furnace, and not discharging.
After 12 hours at 800 ℃ the temperature was raised and the heating was carried out according to the forging heating curve shown in FIG. 2. The temperature is increased to 1160 +/-10 ℃ at the speed of 80-90 ℃/h, the temperature is kept for 10 hours, and the steel plate is taken out of the furnace to be forged by a first fire.
Before discharging and forging, the upper anvil and the lower anvil of a 6000-ton quick forging machine are preheated for 20 minutes by using scrap steel with the temperature of 900 ℃, and the temperature of the anvil surface is measured to be 550 ℃ after preheating is finished. The first hot upsetting is carried out by adopting a specially-made upsetting device (Chinese patent CN107552699A, a manufacturing method of a large-sized upsetting device) in a 6000-ton quick forging machine, upsetting is carried out to 1/2 of the original height of an electroslag ingot, the upsetting pressing speed is 18-20 mm/s, the measured temperature at the beginning of upsetting is 1080 ℃ (the real steel temperature measured after an oxide skin falls off), after the upsetting is finished, drawing is started, the started pressing amount is controlled to be 50-70 mm each time, then the pressing amount is gradually increased to 100-120 mm, the drawing length is 1000mm octagonal, and the length is 2.2 m. The finish forging temperature is 900 ℃. And returning to the furnace for heating, keeping the temperature at 1150-1170 ℃, and keeping the temperature for 3 hours.
The second fire adopts the same process as the first fire, upsetting is carried out to 1/2 with the original height, the octagon is drawn out to 1000mm, and the finish forging temperature is 900 ℃. And (4) returning and heating, keeping the temperature at 1150-1170 ℃ for 3 hours, discharging and forging for the third fire.
And upsetting to 1/2 with the original height by a third fire, drawing to an octagonal shape of 920mm, and then rounding to a tube blank with phi 900(-10mm, +20 mm). The finish forging temperature is 850 ℃.
Annealing in a furnace after 1.5 hours after forging, heating according to an annealing heat treatment curve shown in figure 3, keeping the annealing temperature at 760-780 ℃, keeping the temperature for 25 hours, cooling in a furnace to 100 ℃, sharing for 50 hours, discharging from the furnace and air cooling.
The low power test results of the tube blank are shown in table 1, the inclusions are shown in table 2, and the grain size is shown in table 3. Fig. 6, 7, 8. FIG. 6 is a macroscopic photograph of the tube blank, which shows that the tube blank has a uniform and dense macroscopic structure, and no center segregation, ingot segregation, point segregation and other visual defects; FIG. 7 is a 100-fold metallographic structure photograph of a tube blank, which shows that the tube blank has a typical tempered martensite structure, a prior austenite grain size of 3.5-4.5 grade, and a uniform microstructure; FIG. 8 is a scanning electron microscope secondary electron morphology photograph of the tube blank, showing no obvious precipitated phase aggregation and uniform structure.
Example 2
Adopting an electroslag ingot with the diameter of phi 1000, uniformly spraying an anti-oxidation coating on the surface, airing, charging, carrying out homogenization heat treatment, heating to 640-660 ℃ at a heating rate of 70-80 ℃/h, keeping the temperature for 5 hours, heating to 1010-1030 ℃ at a heating rate of 70-80 ℃/h, keeping the temperature for 3 hours, heating to 1220-1240 ℃ at a heating rate of 70-80 ℃/h, keeping the temperature for 85 hours, cooling the furnace to 900 ℃, and not discharging.
After preserving heat at 900 ℃ for 10 hours, heating up to 1150-1170 ℃ at a heating rate of 90-100 ℃/h, preserving heat for 9 hours, and discharging and forging the first fire.
Before discharging and forging, the upper anvil and the lower anvil of a 6000-ton quick forging machine are preheated for 20 minutes by using scrap steel with the temperature of 900 ℃, and the temperature of the anvil surface is measured to be 560 ℃ after preheating is finished. The first hot upsetting is carried out by adopting a special upsetting device (Chinese patent CN107552699A, a manufacturing method of a large-sized upsetting device) in a 6000-ton quick forging machine, upsetting is carried out to 1/2 of the original height of an electroslag ingot, the upsetting reduction speed is 20-22 mm/s, the measured temperature at the beginning of upsetting is 1070 ℃ (the real steel temperature measured after an oxide skin falls), after upsetting is finished, drawing is started, the started drawing is controlled to be 50-70 mm each time, then the drawing is gradually increased to 100-120 mm, the drawing is carried out to 900mm octagonal, and the length is 2.3 m. The finish forging temperature is 900 ℃. And returning to the furnace for heating, keeping the temperature at 1150-1170 ℃, and keeping the temperature for 3 hours.
The second fire adopts the same process as the first fire, upsetting is carried out to 1/2 with the original height, the octagon is drawn out to 900mm, and the finish forging temperature is 900 ℃. And (4) returning to the furnace, heating, keeping the temperature at 1160 +/-10 ℃ for 3 hours, discharging from the furnace, and forging by a third fire.
And upsetting to 1/2 with the original height by a third fire, drawing out to 900mm octagonal, and then rounding to a phi 850(-10mm, +20mm) tube blank. The finish forging temperature is 850 ℃.
And (3) annealing in a furnace after 1.5 hours after forging, wherein the annealing temperature is 750-770 ℃, the heat preservation time is 22 hours, the furnace is cooled to 100 ℃, the sharing time is 47 hours, and the steel plate is discharged from the furnace and cooled in air.
The low power test results of the tube blank are shown in table 1, the inclusions are shown in table 2, and the grain size is shown in table 3.
Example 3
Adopting an electroslag ingot with the diameter of phi 900, uniformly spraying an anti-oxidation coating on the surface, airing, charging, carrying out homogenization heat treatment, heating to 640-660 ℃ at a heating rate of 70-80 ℃/h, keeping the temperature for 5 hours, heating to 1010-1030 ℃ at a heating rate of 70-80 ℃/h, keeping the temperature for 3 hours, heating to 1210-1230 ℃ at a heating rate of 70-80 ℃/h, keeping the temperature for 80 hours, cooling the furnace to 900 ℃, and not discharging.
And after preserving heat at 900 ℃ for 8 hours, starting heating up at the heating rate of 90-100 ℃/h to 1160-1180 ℃, preserving heat for 8 hours, and discharging from the furnace to forge a first fire.
Before discharging and forging, the upper anvil and the lower anvil of a 6000-ton quick forging machine are preheated for 20 minutes by using scrap steel with the temperature of 900 ℃, and the temperature of the anvil surface is measured to be 550 ℃ after preheating is finished. The first hot upsetting is carried out by adopting a special upsetting device (Chinese patent CN107552699A, a manufacturing method of a large-sized upsetting device) in a 6000-ton quick forging machine, upsetting is carried out to 1/2 of the original height of an electroslag ingot, the upsetting reduction speed is 22-24 mm/s, the measured temperature at the beginning of upsetting is 1080 ℃ (the real steel temperature measured after an oxide skin falls off), after the upsetting is finished, drawing is started, the started drawing is controlled to be 50-70 mm each time, then the drawing is gradually increased to 100-120 mm, the drawing is carried out to 900mm octagonal, and the length is 2.0 m. The finish forging temperature is 900 ℃. And (4) returning to the furnace for heating, keeping the temperature of 1160-1180 ℃, and keeping the temperature for 3 hours.
The second fire adopts the same process as the first fire, upsetting is carried out to 1/2 with the original height, the octagon is drawn out to 900mm, and the finish forging temperature is 900 ℃. And (4) returning to the furnace for heating, preserving heat for 3 hours at the temperature of 1160-1180 ℃, discharging from the furnace and forging on a third fire.
And upsetting to 1/2 with the original height by a third fire, drawing out to an octagonal shape of 850mm, and then rounding to a phi 820(-10mm, +20mm) tube blank. The finish forging temperature is 850 ℃.
Annealing in a furnace at the annealing temperature of 750 +/-10 ℃ for 21 hours after 1.5 hours after forging, cooling in the furnace to 100 ℃ for 46 hours in total, and discharging and air cooling.
The low power test results of the tube blank are shown in table 1, the inclusions are shown in table 2, and the grain size is shown in table 3.
Example 4
Firstly, uniformly spraying an anti-oxidation coating on the surface of an electroslag ingot with the diameter phi of 1000, airing, then charging, carrying out homogenization heat treatment, heating to 640-660 ℃ at the heating rate of 70-80 ℃/h, preserving heat for 5 hours, heating to 1010-1030 ℃ at the heating rate of 70-80 ℃/h, preserving heat for 3 hours, heating to 1220-1240 ℃ at the heating rate of 70-80 ℃/h, preserving heat for 85 hours, cooling the furnace to 900 ℃, and not discharging.
After preserving heat at 900 ℃ for 10 hours, heating up to 1150-1170 ℃ at a heating rate of 90-100 ℃/h, preserving heat for 9 hours, and discharging and forging the first fire.
Before discharging and forging, the upper anvil and the lower anvil of a 6000-ton quick forging machine are preheated for 20 minutes by using scrap steel with the temperature of 900 ℃, and the temperature of the anvil surface is measured to be 570 ℃ after the preheating is finished. The first hot upsetting is carried out by adopting a special upsetting device (Chinese patent CN107552699A, a manufacturing method of a large-scale upsetting device) in a 6000-ton quick forging machine, upsetting is carried out to 1/2 of the original height of an electroslag ingot, the upsetting reduction speed is 20-22 mm/s, the measured temperature at the beginning of upsetting is 1100 ℃ (the real steel temperature measured after an oxide skin falls), after the upsetting is finished, drawing is started, the started drawing is controlled to be 50-70 mm each time, then the drawing is gradually increased to 100-120 mm, the drawing is carried out to 900mm octagonal, and the length is 2.3 m. The finish forging temperature is 900 ℃. And returning to the furnace for heating, keeping the temperature at 1150-1170 ℃, and keeping the temperature for 3 hours.
The second fire adopts the same process as the first fire, upsetting is carried out to 1/2 with the original height, the octagon is drawn out to 900mm, and the finish forging temperature is 900 ℃. And (4) returning and heating, keeping the temperature at 1150-1170 ℃ for 3 hours, discharging and forging for the third fire.
And upsetting to 1/2 of the original height by a third fire, drawing out to 900mm octagonal, and performing finish forging at the temperature of 900 ℃. And (4) returning and heating, keeping the temperature at 1150-1170 ℃ for 3 hours, discharging and forging for a fourth fire.
The fourth fire was further drawn out and forged to a slab having a thickness of 700mm and a width of 1100mm at a finish forging temperature of 900 ℃. And (4) returning and heating, keeping the temperature at 1150-1170 ℃ for 3 hours, discharging and forging for the fifth fire.
And forging the single-side stepped forge piece by adopting a staggered anvil forging mode in the fifth fire. The finish forging temperature is 870 ℃.
Annealing in a furnace feeding and discharging manner 1.5 hours after the forging is finished, keeping the annealing temperature at 770 +/-10 ℃, keeping the temperature for 18 hours, cooling the furnace to 100 ℃, sharing the time for 44 hours, discharging the furnace and air cooling.
And (3) carrying out normalizing heat treatment according to a normalizing curve of quenching and tempering heat treatment of the forging shown in the figure 4, wherein the heating rate is 60-70 ℃/h, heating to 940-960 ℃, keeping the temperature for 2 hours, heating to 1070-1090 ℃ at the heating rate of 70-80 ℃/h, keeping the temperature for 7 hours, and discharging and air cooling to room temperature.
And (3) carrying out tempering heat treatment according to the tempering curve of the quenching and tempering heat treatment of the forge piece shown in the figure 5, wherein the temperature rise speed is 60-70 ℃/h, the temperature is raised to 760-780 ℃, the temperature is kept for 19 hours, and the forge piece is taken out of the furnace and cooled to the room temperature in an air cooling mode.
The macroscopic test results of the forgings are shown in table 1, the inclusions are shown in table 2, the grain sizes are shown in table 3, and the mechanical properties are shown in table 4.
TABLE 1 results of the low power test of the examples
| Generally loose | Center porosity | Segregation of ingot form | Point segregation | Other defects visible to the eye | |
| Example 1 | 0.5 | 0 | 0 | 0 | 0 |
| Example 2 | 0.5 | 0 | 0 | 0 | 0 |
| Example 3 | 0.5 | 0 | 0 | 0 | 0 |
| Example 4 | 0.5 | 0 | 0 | 0 | 0 |
TABLE 2 inclusions of examples
TABLE 3 grain size of the examples
TABLE 4 mechanical Properties of forgings of examples 4
It should be noted that the above examples are only for illustrating the technical solutions of the present invention and are not limited. Although the present invention has been described in detail with reference to the preferred embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the scope of the present invention as set forth in the claims below.
Claims (8)
1. A method for producing a martensitic heat-resistant steel blank, characterized by comprising the steps of:
s1, carrying out homogenization heat treatment on the martensite heat-resistant steel electroslag ingot;
s2, forging and heating the product obtained in the step S1;
s3, forging the product obtained in the step S2 in a 6000-ton quick forging machine;
s4, annealing and heat treating the product obtained in the step S3;
and S5, carrying out quenching and tempering heat treatment on the product obtained in the step S4 to obtain the martensite heat-resistant steel blank.
2. The method for producing a martensitic heat-resistant steel blank as claimed in claim 1, wherein said homogenization heat treatment in step S1 specifically comprises the following operations:
spraying an anti-oxidation coating on the surface of the martensite heat-resistant steel electroslag ingot, heating to 600-650 ℃ at a speed of 50-80 ℃/h, preserving heat for 5-8 h, continuing heating to 1000-1050 ℃ at a speed of 50-80 ℃/h, preserving heat for 3-5 h, continuing heating to 1200-1250 ℃ at a speed of 50-80 ℃/h, preserving heat for not less than 80h, and cooling to 700-1000 ℃ after heat preservation.
3. The method for producing a martensitic heat-resistant steel blank as claimed in claim 1, wherein said forging heat in step S2 specifically includes the operations of:
and heating the product obtained in the step S1 to 1140-1180 ℃ at the speed of 50-100 ℃/h, wherein the heat preservation time is not less than 0.5 min/mm.
4. The method for producing a martensitic heat-resistant steel blank as claimed in claim 1, wherein in step S3, the upper and lower anvils of the rapid forging machine are preheated to an anvil surface temperature of not less than 500 ℃, then are upset and drawn out for at least 3 cycles, and the start forging temperature is controlled to 1050 to 1100 ℃ and the finish forging temperature is controlled to 850 to 900 ℃.
5. The method for producing a martensitic heat-resistant steel blank as claimed in claim 4, wherein in step S3, upsetting is performed at a reduction speed of 18-20 mm/S during each hot upsetting, after upsetting is performed to 1/2 of the original height of the electroslag ingot, elongation drawing is started at a reduction of 50-70 mm each time, the elongation is increased to 100-120 mm at a range of 10-15 mm increase of the reduction each time, the elongation is performed for 5-8 times until octagonal elongation is 900-1000 mm, reheating is performed at 1140-1180 ℃, the holding time is not less than 3 hours, and finally the round product is formed after the final hot upsetting, and final forging is performed at 850-900 ℃.
6. The method for producing a martensitic heat-resistant steel blank as claimed in claim 4, wherein in step S3, upsetting is performed at a reduction speed of 18-20 mm/S during each hot upsetting, after upsetting is performed to 1/2 of the original height of the electroslag ingot, elongation drawing is started at a reduction of 50-70 mm each time, the reduction is increased to 100-120 mm at a range of 10-15 mm increase of the reduction each time, the reduction is performed for 5-8 times, the elongation is performed to 900-1000 mm octagonal, reheating is performed at 1140-1180 ℃, the holding time is not less than 3 hours, staggered forging is performed after the last hot upsetting, and finish forging is performed at 850-900 ℃.
7. A method for producing a martensitic heat-resistant steel blank as claimed in claim 1, characterized in that said annealing heat treatment in step S4 specifically comprises the following operations:
and (5) annealing the product obtained in the step (S3) within 2 hours after the forging is completed, controlling the annealing temperature to 750-850 ℃, controlling the annealing time to be not less than 1.5min/mm, cooling the product to be below 100 ℃ after the annealing is completed, cooling the product along with the furnace, and discharging the product from the furnace for air cooling.
8. The method for producing a martensitic heat-resistant steel blank as claimed in claim 1, wherein said quenching and tempering heat treatment in step S5 specifically comprises the following operations:
heating the product obtained in the step S4 to 900-1000 ℃ at a speed of 50-80 ℃/h, keeping the temperature for at least 2h, then continuing heating to 1050-1090 ℃ at a speed of 50-80 ℃/h, and normalizing, wherein the normalizing time is not less than 0.6 min/mm;
and (3) heating the normalized product at the speed of 50-80 ℃/h to 760-790 ℃, and tempering for not less than 1.6 min/mm.
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| CN116949260A (en) * | 2023-09-20 | 2023-10-27 | 成都先进金属材料产业技术研究院股份有限公司 | Steel ingot for P91 seamless steel tube and thermal deformation method thereof |
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| WO2004087979A1 (en) * | 2003-03-31 | 2004-10-14 | National Institute For Materials Science | Welded joint of tempered martensite based heat-resistant steel |
| CN101545076A (en) * | 2008-03-25 | 2009-09-30 | 宝山钢铁股份有限公司 | Martensite refractory stainless steel and manufacturing method thereof |
| WO2017206552A1 (en) * | 2016-06-03 | 2017-12-07 | 上海新闵（东台）重型锻造有限公司 | Monoblock forging of nuclear power steam generator housing and method for molding same by forging |
| CN109112408A (en) * | 2018-09-25 | 2019-01-01 | 成都先进金属材料产业技术研究院有限公司 | The manufacturing method of the heat-resisting steel forgings of big specification P92 |
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| WO2004087979A1 (en) * | 2003-03-31 | 2004-10-14 | National Institute For Materials Science | Welded joint of tempered martensite based heat-resistant steel |
| CN101545076A (en) * | 2008-03-25 | 2009-09-30 | 宝山钢铁股份有限公司 | Martensite refractory stainless steel and manufacturing method thereof |
| WO2017206552A1 (en) * | 2016-06-03 | 2017-12-07 | 上海新闵（东台）重型锻造有限公司 | Monoblock forging of nuclear power steam generator housing and method for molding same by forging |
| CN109112408A (en) * | 2018-09-25 | 2019-01-01 | 成都先进金属材料产业技术研究院有限公司 | The manufacturing method of the heat-resisting steel forgings of big specification P92 |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN116949260A (en) * | 2023-09-20 | 2023-10-27 | 成都先进金属材料产业技术研究院股份有限公司 | Steel ingot for P91 seamless steel tube and thermal deformation method thereof |
| CN116949260B (en) * | 2023-09-20 | 2023-12-19 | 成都先进金属材料产业技术研究院股份有限公司 | Steel ingot for P91 seamless steel tube and thermal deformation method thereof |
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