A hot rolling process for GH4169 alloy thin plates

Abstract

This invention discloses a hot rolling process for GH4169 alloy thin plates. The method includes: 1. holding the GH4169 alloy forged plate at a certain temperature and then performing a single-pass rolling; 2. holding the plate at a certain temperature and then performing a second-pass rolling; 3. holding the plate at a certain temperature and then performing a third-pass rolling; 4. surface grinding; 5. holding the plate at a certain temperature and then performing a fourth-pass rolling; 6. solution treatment and cooling; 7. pickling, polishing, and cutting to length. This invention employs a four-pass, multi-stage reversible hot rolling process. By controlling the temperature, total reduction rate, and reduction rate of each pass, the thickness accuracy of the GH4169 alloy thin plate is effectively controlled, ensuring its microstructure uniformity and performance consistency. This results in high-precision GH4169 alloy thin plates with excellent surface quality, meeting the requirements for subsequent cold rolling deformation. Furthermore, the preparation method is simple and flexible, satisfying the production needs of small batches and multiple specifications of GH4169 alloy thin plates.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of non-ferrous metal processing, and particularly relates to a hot rolling process of GH4169 alloy sheet. BACKGROUND

[0002] High-temperature alloy mainly refers to a metal material capable of working at a temperature above 600 DEG C and under certain stress conditions, and is also called heat-resistant alloy. The high-temperature alloy is a new type of metal material gradually developed in the early 1940s due to the development of aviation technology. The main feature of the high-temperature alloy is to work under certain stress conditions at a temperature above 600 DEG C. The high-temperature alloy not only has good high-temperature oxidation resistance and corrosion resistance, but also has high high-temperature strength, creep strength and endurance strength, and good fatigue resistance. These special properties of the high-temperature alloy make it an irreplaceable key material for hot end components in high-end technical fields such as modern aviation, aerospace, ships and nuclear industry. In particular, the structural components working under high-temperature conditions in the field of aerospace are most widely used, such as combustion chambers, guide vanes, turbine blades, turbine discs, casings, ring pieces and tail nozzles.

[0003] At present, the high-temperature alloy sheet with a thickness less than 4 mm is mainly prepared by cold rolling. Since the alloying degree of GH4169 alloy is high, the high-temperature alloy sheet has high strength and deformation resistance. The cold rolling deformation has high requirements for the rolling equipment capacity, and the productivity is relatively low, and the processing cost is high. Therefore, it is a good idea to obtain the GH4169 alloy sheet by hot rolling. However, in the hot working process, the structure is sensitive to temperature. If the heating system and the processing rate are not properly controlled, the structure will be coarse and cracking will occur. Therefore, it is necessary to optimize the hot rolling process of GH4169 alloy. SUMMARY

[0004] The technical problem to be solved by the application is to provide a hot rolling process of GH4169 alloy sheet in view of the shortcomings of the prior art. The process adopts four times of multi-pass reversible hot rolling. By controlling the temperature, total reduction rate and reduction rate of each pass of each heating, the thickness precision of the product GH4169 alloy sheet is effectively controlled, and the uniformity of the structure and the consistency of the performance are ensured. The GH4169 alloy sheet with high precision and good surface quality is obtained, and the problem of coarse structure and cracking caused by hot working is solved.

[0005] To solve the above technical problems, the technical scheme adopted by the application is as follows: a hot rolling process of GH4169 alloy sheet, characterized in that the method comprises the following steps:

[0006] Step one, the GH4169 alloy forged slab with thickness of 80mm-90mm and width of 300mm-400mm is kept at 1050-1080℃ for 60-90min, and then is sent to a hot rolling mill for one-pass rolling, and the surface temperature after one-pass rolling is not less than 900℃, and a one-pass plate semi-product with thickness of 30-34mm is obtained;

[0007] Step two, the one-pass plate semi-product obtained in step one is kept at 1050-1080℃ for 25-30min, and then is sent to a hot rolling mill for two-pass rolling, and the surface temperature after two-pass rolling is not less than 850℃, and a two-pass plate semi-product with thickness of 10-12mm is obtained;

[0008] Step three, the two-pass plate semi-product obtained in step two is kept at 1080-1100℃ for 8-10min, and then is sent to a hot rolling mill for three-pass rolling, and the surface temperature after three-pass rolling is not less than 850℃, and a three-pass plate semi-product with thickness of 4.0-5.0mm is obtained;

[0009] Step four, the three-pass plate semi-product obtained in step three is subjected to surface grinding treatment to remove surface defects such as surface cracks and indentations;

[0010] Step five, the three-pass plate semi-product subjected to surface grinding treatment in step four is kept at 1080-1100℃ for 3-5min, and then is sent to a hot rolling mill for four-pass rolling, and the surface temperature after four-pass rolling is not less than 850℃, and a four-pass plate semi-product with thickness of 2.0-3.0mm is obtained;

[0011] Step six, the four-pass plate semi-product obtained in step five is sent to a heating furnace, and is kept at 960-990℃ for 40-90min, and then is taken out and cooled; the cooling is air cooling, air blast cooling or water cooling;

[0012] Step seven, the four-pass plate semi-product after cooling in step six is subjected to pickling, polishing and cutting to a specified size, and a GH4169 alloy sheet is obtained.

[0013] This invention involves heating a GH4169 alloy forged slab and then sequentially performing single-pass rolling, double-pass rolling, and triple-pass rolling. Following surface grinding, a fourth-pass rolling process, solution treatment, pickling, polishing, and cutting to length, GH4169 alloy thin plates are obtained. In this process, by controlling the temperature of each pass, the final rolling temperature, the total reduction rate, and the reduction rate of each pass during the four-pass hot rolling, the GH4169 alloy forged slab is fully deformed, resulting in significant grain breakage, reducing surface coarseness and cracking, and creating a denser microstructure with better ductility, thus obtaining GH4169 alloy thin plates with a thickness of less than 4 mm.

[0014] The hot rolling process of the above-mentioned GH4169 alloy thin plate is characterized in that the preparation process of the GH4169 alloy forged slab in step one is as follows: GH4169 alloy ingots are obtained by a three-stage smelting process of vacuum induction melting, electroslag remelting combined with vacuum consumable remelting, and then GH4169 alloy forged slabs are obtained by high-temperature homogenization treatment and upsetting deformation 8 to 10 times.

[0015] The hot rolling process for GH4169 alloy thin plates described above is characterized in that the single-pass rolling in step one, the double-pass rolling in step two, the triple-pass rolling in step three, and the quadruple-pass rolling in step five are all multi-pass reversible rolling processes, with a total reduction rate of 50% to 70% and a reduction rate of 5% to 25% per pass. This invention, by controlling the total reduction rate and the reduction rate per pass in the quadruple-pass rolling process, ensures sufficient grain breakage and coordinated grain deformation, while avoiding obstruction of dislocation movement at grain boundaries, which is beneficial for improving ductility and resulting in a dense GH4169 alloy thin plate.

[0016] The hot rolling process of the above-mentioned GH4169 alloy sheet is characterized in that the thickness of the GH4169 alloy sheet in step seven is 2.0mm to 3.0mm, the width is 300mm to 400mm, and the thickness tolerance is controlled within ±7% of the target thickness.

[0017] The hot rolling process of the above-mentioned GH4169 alloy sheet is characterized in that the average grain size of the GH4169 alloy sheet in step seven is grade 6 to 8, and the plastic elongation is not less than 50%.

[0018] Compared with the prior art, the present invention has the following advantages:

[0019] 1. This invention uses a three-stage smelting process of "vacuum induction melting + electroslag remelting + vacuum consumable remelting" to prepare GH4169 alloy ingots, which improves the uniformity of ingot composition and reduces the content of harmful impurity elements, thus providing a foundation for the preparation of high-quality, high-performance GH4169 alloy thin plates.

[0020] 2. This invention employs four-pass reversible hot rolling. By controlling the temperature, total reduction rate, and reduction rate of each pass during rolling, the thickness accuracy of the GH4169 alloy sheet is effectively controlled, and its microstructure uniformity and performance consistency are ensured, resulting in a GH4169 alloy sheet with high precision and good surface quality.

[0021] 3. During the rolling process of this invention, the surface temperature of the slab after each hot rolling is strictly controlled. When the temperature is lower than the final rolling temperature or micro-cracks appear on the edge, it should be reheated in time to ensure that the slab deforms uniformly and obtains GH4169 alloy thin plate with good thickness accuracy and surface quality.

[0022] 4. The thickness tolerance of the GH4169 alloy sheet prepared by this invention is controlled within ±7% of the target thickness, the average grain size is grade 6 to 8, and the plastic elongation is not less than 50%, which fully meets the requirements for subsequent cold rolling deformation.

[0023] 5. The preparation method of the present invention is simple and flexible, meeting the production needs of small batches and multiple specifications of GH4169 alloy thin plates.

[0024] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0025] Figure 1 This is a microstructure diagram of the GH4169 alloy thin plate prepared in Example 1 of the present invention.

[0026] Figure 2 This is a microstructure diagram of the GH4169 alloy thin plate prepared in Example 2 of the present invention.

[0027] Figure 3 This is a microstructure image of the GH4169 alloy thin plate prepared in Example 3 of the present invention. Detailed Implementation

[0028] Example 1

[0029] This embodiment includes the following steps:

[0030] Step 1: Hold the GH4169 alloy forged slab with a thickness of 85mm and a width of 300mm at 1050℃ for 90min, and then send it into a hot rolling mill for one-time rolling. After the one-time rolling is completed, the surface temperature is 909℃, and a one-time plate semi-finished product with a thickness of 32mm is obtained.

[0031] The preparation process of the GH4169 alloy forged slab is as follows: GH4169 alloy ingots are obtained by a three-stage smelting process of vacuum induction melting, electroslag remelting and vacuum consumable remelting, and then GH4169 alloy slabs are obtained by high temperature homogenization treatment and upsetting deformation in 9 heats.

[0032] The single-pass rolling is a 7-pass reversible rolling, and the total reduction rate of the 7-pass reversible rolling is 62.4%, with the reduction rates of each pass being 10.6%, 10.5%, 11.8%, 13.3%, 15.4%, 15.9%, and 13.5%, respectively.

[0033] Step 2: Hold the semi-finished sheet material obtained in Step 1 at 1050℃ for 30 minutes, and then send it into a hot rolling mill for a second rolling process. After the second rolling process, the surface temperature is 884℃, resulting in a semi-finished sheet material with a thickness of 10mm.

[0034] The two-pass rolling is a 6-pass reversible rolling, and the total reduction rate of the 6-pass reversible rolling is 65.6%, with the reduction rates of each pass being 15.6%, 18.5%, 18.2%, 16.7%, 13.3%, and 15.4% respectively.

[0035] Step 3: Hold the secondary sheet metal semi-finished product obtained in Step 2 at 1080℃ for 8 minutes, and then send it into a hot rolling mill for three-stage rolling. After the three-stage rolling is completed, the surface temperature is 867℃, and a tertiary sheet metal semi-finished product with a thickness of 4.5mm is obtained.

[0036] The three-pass rolling is a four-pass reversible rolling, and the total reduction rate of the four-pass reversible rolling is 59.1%, with the reduction rates of each pass being 18.2%, 22.2%, 21.4%, and 18.2%, respectively.

[0037] Step 4: Perform surface grinding on the three semi-finished boards obtained in Step 3 to remove surface defects such as surface cracks and indentations.

[0038] Step 5: After surface grinding in Step 4, the semi-finished sheet material is kept at 1080℃ for 5 minutes, and then sent to a hot rolling mill for four-stage rolling. After the four-stage rolling, the surface temperature is 858℃, and a semi-finished sheet material with a thickness of 2.0mm is obtained.

[0039] The four-pass rolling is a five-pass reversible rolling, and the total reduction rate of the five-pass reversible rolling is 55.6%, with the reduction rates of each pass being 22.2%, 20.0%, 14.3%, 8.3%, and 9.1%, respectively.

[0040] Step 6: The four-stage semi-finished board obtained in Step 5 is sent into a heating furnace and kept at 960℃ for 60 minutes, then removed from the furnace and air-cooled.

[0041] Step 7: After the air-cooling process in Step 6, the four semi-finished plates are pickled, polished, and cut to length to obtain GH4169 alloy thin plates with a thickness of 2.0 mm and a width of 300 mm.

[0042] Testing revealed that the thickness tolerance of the GH4169 alloy sheet prepared in this embodiment was ±0.1 mm, only ±5% of the product thickness. The surface was smooth and flat, free from defects such as scars, flaking, oxide scale, and pitting. Furthermore, the microstructure was uniform, with an average grain size of grade 7. Figure 1 As shown in Table 1, the room temperature properties of the GH4169 alloy sheet are as follows.

[0043] Table 1

[0044]

[0045] Example 2

[0046] This embodiment includes the following steps:

[0047] Step 1: Hold the GH4169 alloy forged slab with a thickness of 90mm and a width of 400mm at 1080℃ for 70min, and then send it into a hot rolling mill for one-time rolling. After the one-time rolling, the surface temperature is 918℃, and a one-time plate semi-finished product with a thickness of 34mm is obtained.

[0048] The preparation process of the GH4169 alloy forged slab is as follows: GH4169 alloy ingots are obtained by a three-stage smelting process of vacuum induction melting, electroslag remelting and vacuum consumable remelting, and then GH4169 alloy slabs are obtained by high temperature homogenization treatment and upsetting deformation in 8 heats.

[0049] The single-pass rolling is a 9-pass reversible rolling, and the total reduction rate of the 9-pass reversible rolling is 62.2%, with the reduction rates of each pass being 6.7%, 8.3%, 10.4%, 10.1%, 12.9%, 13.0%, 12.7%, 9.8%, and 8.1% respectively.

[0050] Step 2: Hold the semi-finished sheet material obtained in Step 1 at 1080℃ for 30 minutes, and then send it into a hot rolling mill for a second rolling process. After the second rolling process, the surface temperature is 892℃, resulting in a semi-finished sheet material with a thickness of 12mm.

[0051] The two-pass reversible rolling is an 8-pass reversible rolling process, and the total reduction rate of the 8-pass reversible rolling is 64.7%, with the reduction rates of each pass being 11.8%, 15.0%, 15.7%, 14.0%, 13.5%, 9.4%, 10.3%, and 7.7%, respectively.

[0052] Step 3: Hold the secondary sheet metal semi-finished product obtained in Step 2 at 1100℃ for 10 minutes, and then send it into a hot rolling mill for three-stage rolling. After the three-stage rolling is completed, the surface temperature is 874℃, and a tertiary sheet metal semi-finished product with a thickness of 5.0mm is obtained.

[0053] The three-pass rolling process is a 5-pass reversible rolling process, and the total reduction rate of the 5-pass reversible rolling process is 58.3%, with the reduction rates of each pass being 20.8%, 23.2%, 17.8%, 10.0%, and 7.4%, respectively.

[0054] Step 4: Perform surface grinding on the three semi-finished boards obtained in Step 3 to remove surface defects such as surface cracks and indentations.

[0055] Step 5: After surface grinding in Step 4, the semi-finished sheet material is kept at 1100℃ for 5 minutes, and then sent to a hot rolling mill for four-stage rolling. After the four-stage rolling, the surface temperature is 861℃, and a semi-finished sheet material with a thickness of 3.0mm is obtained.

[0056] The four-pass rolling is a three-pass reversible rolling, and the total reduction rate of the three-pass reversible rolling is 40.0%, with the reduction rates of each pass being 20.0%, 15.0%, and 11.8% respectively.

[0057] Step 6: The four-stage semi-finished board obtained in Step 5 is sent into a heating furnace and held at 990℃ for 90 minutes, then removed from the furnace and air-cooled.

[0058] Step 7: After air cooling in Step 6, the four semi-finished plates are pickled, polished, and cut to length to obtain GH4169 alloy thin plates with a thickness of 3.0mm and a width of 400mm.

[0059] Testing revealed that the thickness tolerance of the GH4169 alloy sheet prepared in this embodiment was ±0.2 mm, only ±7% of the product thickness. The surface was smooth and flat, free from defects such as scars, flaking, oxide scale, and pitting. Furthermore, the microstructure was uniform, with an average grain size of grade 6. Figure 2 As shown in Table 2, the room temperature properties of the GH4169 alloy sheet are as follows.

[0060] Table 2

[0061]

[0062] Example 3

[0063] This embodiment includes the following steps:

[0064] Step 1: Hold the GH4169 alloy forged slab with a thickness of 80mm and a width of 350mm at 1080℃ for 60min, and then send it into a hot rolling mill for one-pass rolling. After the one-pass rolling, the surface temperature is 906℃, and a 30mm thick plate semi-finished product is obtained.

[0065] The preparation process of the GH4169 alloy forged slab is as follows: GH4169 alloy ingots are obtained by a three-stage smelting process of vacuum induction melting, electroslag remelting and vacuum consumable remelting, and then GH4169 alloy slabs are obtained by high temperature homogenization treatment and 10 upsetting and drawing deformations.

[0066] The single-pass rolling is an 8-pass reversible rolling, and the total reduction rate of the 8-pass reversible rolling is 62.4%, with the reduction rates of each pass being 10.0%, 11.1%, 12.5%, 14.3%, 12.5%, 11.9%, 10.8%, and 9.1% respectively.

[0067] Step 2: Hold the semi-finished sheet material obtained in Step 1 at 1080℃ for 25 minutes, and then send it into a hot rolling mill for a second rolling process. After the second rolling process, the surface temperature is 880℃, resulting in a semi-finished sheet material with a thickness of 10mm.

[0068] The two-pass rolling is a 7-pass reversible rolling, and the total reduction rate of the 7-pass reversible rolling is 66.7%, with the reduction rates of each pass being 13.3%, 17.3%, 18.6%, 17.1%, 13.8%, 12.0%, and 9.1% respectively.

[0069] Step 3: Hold the secondary sheet material semi-finished product obtained in Step 2 at 1100℃ for 8 minutes, and then send it into a hot rolling mill for three-stage rolling. After the three-stage rolling is completed, the surface temperature is 863℃, and a tertiary sheet material semi-finished product with a thickness of 4.0mm is obtained.

[0070] The three-pass rolling is a 5-pass reversible rolling, and the total reduction rate of the 5-pass reversible rolling is 60.0%, with the reduction rates of each pass being 20.0%, 23.8%, 18.0%, 12.0%, and 9.1%, respectively.

[0071] Step 4: Perform surface grinding on the three semi-finished boards obtained in Step 3 to remove surface defects such as surface cracks and indentations.

[0072] Step 5: After surface grinding in Step 4, the semi-finished sheet material is kept at 1100℃ for 3 minutes, and then sent to a hot rolling mill for four-stage rolling. After the four-stage rolling, the surface temperature is 855℃, and a semi-finished sheet material with a thickness of 2.0mm is obtained.

[0073] The four-pass rolling is a five-pass reversible rolling, and the total reduction rate of the five-pass reversible rolling is 50.0%, with the reduction rates of each pass being 24.0%, 21.1%, 16.7%, 12.0%, and 9.1%, respectively.

[0074] Step 6: The four-stage semi-finished board obtained in Step 5 is sent into a heating furnace and kept at 960℃ for 40 minutes, then removed from the furnace and water-cooled.

[0075] Step 7: After water cooling in Step 6, the four semi-finished plates are pickled, polished, and cut to length to obtain GH4169 alloy thin plates with a thickness of 2.0 mm and a width of 350 mm.

[0076] Testing revealed that the thickness tolerance of the GH4169 alloy sheet prepared in this embodiment was ±0.12 mm, only ±6% of the product thickness. The surface was smooth and flat, free from defects such as scars, flaking, oxide scale, and pitting. Furthermore, the microstructure was uniform, with an average grain size of grade 8. Figure 3 As shown in Table 3, the room temperature properties of the GH4169 alloy sheet are as follows.

[0077] Table 3

[0078]

[0079] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any way. Any simple modifications, alterations, and equivalent changes made to the above embodiments based on the inventive essence shall still fall within the protection scope of the present invention.

Claims

1. A hot rolling process for a GH4169 alloy sheet, characterized in that, The method comprises the following steps: Step one, the GH4169 alloy forged slab with a thickness of 80mm~90mm and a width of 300mm~400mm is kept at 1050℃~1080℃ for 60min~90min, and then is sent to a hot rolling mill for one-pass rolling, and the surface temperature after one-pass rolling is not lower than 900℃, thereby obtaining a one-pass plate semi-product with a thickness of 30mm~34mm; Step two, the one-pass plate semi-product obtained in step one is kept at 1050℃~1080℃ for 25min~30min, and then is sent to a hot rolling mill for two-pass rolling, and the surface temperature after two-pass rolling is not lower than 850℃, thereby obtaining a two-pass plate semi-product with a thickness of 10mm~12mm; Step three, the two-pass plate semi-product obtained in step two is kept at 1080℃~1100℃ for 8min~10min, and then is sent to a hot rolling mill for three-pass rolling, and the surface temperature after three-pass rolling is not lower than 850℃, thereby obtaining a three-pass plate semi-product with a thickness of 4.0mm~5.0mm; Step four, the three-pass plate semi-product obtained in step three is subjected to surface grinding treatment to remove surface defects such as surface cracks and indentations; Step five, the three-pass plate semi-product subjected to surface grinding treatment in step four is kept at 1080℃~1100℃ for 3min~5min, and then is sent to a hot rolling mill for four-pass rolling, and the surface temperature after four-pass rolling is not lower than 850℃, thereby obtaining a four-pass plate semi-product with a thickness of 2.0mm~3.0mm; The one-pass rolling in step one, the two-pass rolling in step two, the three-pass rolling in step three and the four-pass rolling in step five are all multi-pass reversible rolling, and the total reduction rate of the multi-pass reversible rolling is 50%~70%, and the reduction rate of each pass is 5%~25%; Step six, the four-pass plate semi-product obtained in step five is sent to a heating furnace, kept at 960℃~990℃ for 40min~90min, and then is taken out and cooled; the cooling is air cooling, air cooling or water cooling; Step seven, the four-pass plate semi-product after cooling in step six is subjected to pickling, polishing and cutting to size, thereby obtaining a GH4169 alloy thin plate; the thickness of the GH4169 alloy thin plate is 2.0mm~3.0mm, the width is 300mm~400mm, and the thickness tolerance is controlled within ±7% of the target thickness; the average grain size of the GH4169 alloy thin plate is 6~8, and the plastic elongation is not lower than 50%.

2. The process for hot rolling of GH4169 alloy sheet according to claim 1, wherein, The preparation process of the GH4169 alloy forged slab in step one is as follows: a GH4169 alloy ingot is smelted by adopting a vacuum induction smelting, electroslag remelting and vacuum consumable remelting combined triple smelting process, and then is subjected to high-temperature homogenization treatment and 8~10-pass upsetting and drawing deformation, thereby obtaining a GH4169 alloy forged slab.

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