A manufacturing method for improving production efficiency of GH4169 alloy cold-drawn material

Abstract

The application discloses a manufacturing method for improving production efficiency of GH4169 alloy cold-drawing material, which cancels the bottleneck process of solid solution of cold-drawing blank by optimizing the process of hot-rolling and blooming. The specific hot-rolling and blooming process is as follows: a Φ120mm intermediate blank is heated to 1100 DEG C and kept for 2h-3h, then is rolled into 30mm-50mm square billet by using a 500 model reversible rolling mill for four times, the temperature of each time is 1100 DEG C, and the reheating and keeping time is 1h-2h; the square billet is heated to 1150 DEG C and kept for 0.5h-1h; then the square billet is rolled into Φ10mm-Φ30mm round billet by using a 200 model rolling mill for one time, the surface temperature of the rod after rolling is in the range of 980 DEG C-1050 DEG C, and the rod is forced air-cooled by a fan after rolling. The application has the following advantages: ①the grains from the center to the edge of the steel billet after hot-rolling and blooming are small and uniform; ②the hardness of the steel billet is reduced by fast air-cooling after rolling; ③the production cycle is shortened, the production efficiency is improved, and the production cost is greatly reduced.

Description

Technical Field

[0001] This invention relates to the field of cold working technology for nickel-based deformed high-temperature alloys, specifically to a manufacturing method for improving the production efficiency of GH4169 alloy cold-drawn materials. Technical Background

[0002] GH4169 alloy is an age-hardening nickel-based wrought superalloy, composed of a matrix phase γ (Ni-Fe-Cr), a metastable auxiliary strengthening phase γ′Ni3 (AlTiNb), a main strengthening phase γ″ (Ni3Nb), and a stable strengthening phase δ (Ni3Nb). Based on the compositional characteristics of GH4169 alloy, niobium, with a high content of 5.30%, is a significant component of the γ″ (Ni3Nb) strengthening phase. According to relevant literature, the peak precipitation temperature range of the main strengthening phase γ″ is 732℃~760℃, and the dissolution temperature is 870℃~950℃, while the precipitation temperature of the δ phase is 780~980℃. It begins to dissolve above 980℃, with a complete dissolution temperature of 1038℃. It is precisely because the alloy's strengthening phases are very stable at relatively high temperatures that GH4169 alloy maintains its strength at 65℃. Even at temperatures below 0℃, it retains high fatigue strength, high yield strength, and endurance and creep strength, making it primarily used in critical components such as moving blades, stationary blades, and turbine disks for aerospace engines. Cold-drawn materials also produced from GH4169 alloy possess excellent mechanical properties, high-precision dimensional control, and good surface quality, and are widely used in fastener production in the aerospace industry. Due to its high degree of alloying, GH4169 alloy exhibits high resistance to cold working deformation, resulting in a significant difference in cold-drawing deformation between high-temperature alloys and ordinary steels. The current production process for GH4169 alloy cold-drawn bars is as follows: hot-rolled GH4169 alloy steel... The billet undergoes a solution softening treatment in a furnace at 960℃ for 1 hour, followed by water cooling and polishing to remove defects. One end of the billet is then tapered. The billet surface is then treated with abrasive and saponification processes to apply a lubricant. The billet is then cold-drawn, followed by surface polishing and defect removal. The 960℃ water cooling treatment (higher than the γ″ melting temperature of 870℃~930℃) ensures that the main strengthening phase γ″ (Ni3Nb) of the GH4169 alloy is fully dissolved back into the matrix. Rapid water cooling inhibits re-precipitation during the solution cooling process, reducing the billet's hardness and resistance to cold working deformation, thus preparing it for drawing. Due to the rapid development of aerospace in recent years, there is a growing demand for high-temperature alloy cold-drawn materials. The volume has also increased exponentially. The solution softening regimes for different grades of high-temperature alloy cold-drawn steel billets vary significantly, leading to a large backlog of billets in the solution softening process. This process has become a bottleneck in cold-drawn material production, causing the solution furnace to operate under high loads for extended periods. Equipment malfunctions in the solution furnace severely restrict production efficiency, and abnormal fluctuations in furnace temperature control accuracy, along with overloading in single furnaces causing uneven heating, all seriously impact product quality. Production is difficult, inefficient, and it's hard to guarantee delivery times. Literature and patent searches have revealed no patents or literature mentioning optimizing cold-drawn material production processes to improve efficiency. Summary of the Invention

[0003] This invention discloses a manufacturing method to improve the production efficiency of GH4169 alloy cold-drawn materials. By optimizing the process control requirements of the hot rolling billet opening process, the bottleneck process in the solution treatment of cold-drawn billets can be reduced, thus solving the problem of long delivery cycle.

[0004] Specific technical solution of the present invention:

[0005] 1. Production process of GH4169 alloy cold-drawn material: Vacuum induction furnace melting (VI M) + vacuum arc remelting (VAR) smelting → high-temperature homogenization diffusion annealing of arc remelted steel ingots → combined billet opening with 3150-ton fast forging mill and 1800-ton radial forging mill → secondary high-temperature homogenization diffusion annealing of billet → billet opening with 500-type reversible rolling mill → billet opening with 200-type reversible rolling mill → cold drawing into finished product → standardized heat treatment and inspection results.

[0006] 2. Steelmaking process:

[0007] (1) A vacuum induction furnace (VI M) is used to melt and cast Φ340mm electrode rods. The alloy material is selected and the gas content and five harmful components of the alloy material meet the technical requirements of the plant's internal control standards. The composition control targets are set according to the technical standards: carbon: 0.25%, sulfur not more than 0.002%, phosphorus not more than 0.015%, manganese not more than 0.35%, silicon not more than 0.35%, chromium: 18.0%, molybdenum: 3.0%, niobium: 5.25%, aluminum: 0.5%, titanium: 1.0%, nickel: 53.5%, boron not more than 0.006%, and residual iron.

[0008] (2) The electrode rods were remelted in a vacuum arc remelting furnace (VAR) into Φ406mm steel ingots. The chemical composition (%) of the vacuum arc remelting steel ingots was as follows: Carbon: 0.015~0.060, Silicon: not more than 0.35, Manganese: not more than 0.35, Phosphorus: not more than 0.015, Sulfur: not more than 0.002, Nickel: 50.00~55.00, Chromium:

[0009] 17.00~21.00, Molybdenum: 2.80~3.30, Titanium: 0.75~1.15, Aluminum: 0.30~

[0010] 0.70, Niobium:

[0011] 5.00~5.50, boron not greater than 0.006%, residual iron; oxygen content in steel ingot gas less than 50×10 -6 Nitrogen content less than 100×10 -6 .

[0012] 3. High-temperature homogenization diffusion annealing:

[0013] Consumable steel ingots are subjected to high-temperature homogenization diffusion annealing treatment in a natural gas chamber furnace at 1180℃~1200℃ (1190℃ is preferred) for 40 hours. After the surface of the consumable steel ingots is machined and cleaned to meet the requirements, they are transferred to forging.

[0014] 4. Forging and blanking:

[0015] Self-consumable steel ingots are forged using a 3150-ton high-speed forging mill and an 1800-ton radial forging mill. The Φ406mm self-consumable steel ingots, after diffusion annealing, are then forged into Φ220mm intermediate billets in three passes on the 3150-ton high-speed forging mill. The first pass is heated to 1100℃, the second to 1080℃, and the third to 1050℃. Each pass is reheated in the furnace for 2-4 hours. After each pass, the surface temperature of the billet is between 850℃ and 1000℃. The hot billet is then fed into a dedicated natural gas chamber heating furnace for the 1800-ton radial forging mill, where it is heated to 1060℃ and held for 2-4 hours. The billet is then forged into Φ120mm intermediate billets on the 1800-ton radial forging mill. After the radial forging mill, the surface temperature of the billet is between 850℃ and 950℃. The billet is then air-cooled to room temperature, and the surface of the Φ120mm intermediate billet is polished and cleaned.

[0016] 5. Secondary high-temperature homogenization diffusion annealing:

[0017] The Φ120mm intermediate billet is then kept at 1180℃~1200℃ (1190℃ is preferred) for no less than 30 hours, and then cooled in the furnace to below 700℃ before being air-cooled.

[0018] 6. Hot rolling blanking:

[0019] (1) After the Φ120mm intermediate billet is heated to 1100℃ in a natural gas chamber furnace and held for 2h to 3h, it is rolled into 30mm to 50mm square steel billets in 4 passes using a 500 model reversible rolling mill. The rolling time for each pass is 3s to 5s. Each pass is reheated in the furnace at 1100℃ and held for 1h to 2h.

[0020] (2) The square steel billet is heated to 1150℃ in a natural gas chamber furnace and held for 0.5h to 1h; it is rolled into Φ10mm to Φ30mm round steel billets in one pass using a 200 type rolling mill. The surface temperature of the rolled bar is in the range of 980℃ to 1010℃, and the rolled bar is cooled by forced air cooling by a fan.

[0021] 7. Cold drawing process: The round steel billet is surface-polished and cleaned, and the surface roughness is tested. The surface roughness is required to be no greater than 3.2μm. One end of the billet is twisted and then treated with straw and saponification with lubricant. The billet is drawn in one pass by a 65-ton chain cold drawing machine. The cold drawing deformation is controlled between 8% and 12% according to the technical standard requirements. According to the dimensional tolerance requirements of the order, the surface is then polished and delivered to the user.

[0022] 8. Standardized heat treatment and inspection results:

[0023] (1) Standard heat treatment regime

[0024] Solution treatment: Temperature 960℃±10℃, hold at that temperature for 1 hour after homogenization, then air cool;

[0025] Aging regime: Temperature 720℃±10℃, hold for 8 hours after uniform heating, then cool to 620℃±10℃ at a rate of (50±10)℃ / h, hold for 8 hours after uniform heating, and then air cool.

[0026] (2) Mechanical properties

[0027] After being treated with standard heat treatment, the mechanical properties of cold-drawn bars should meet the requirements of Tables 1 and 2.

[0028] Table 1 Mechanical Properties

[0029]

[0030] Table 2 Durability at 650℃

[0031]

[0032] (3) High-polymorphism tissue

[0033] After being treated by the standard heat treatment process, the longitudinal average grain size of the cold-drawn bars should be greater than grade 5, and the presence of individual grade 3 grains is allowed.

[0034] The innovation of this invention is explained as follows: The GH4169 alloy consists of a matrix γ (Ni-Fe-Cr), a metastable auxiliary strengthening phase γ′-Ni3 (AlTiNb), a main strengthening phase γ″ (Ni3Nb), a stable strengthening phase δ (Ni3Nb), and carbonitrides. According to literature, the peak precipitation temperature of the main strengthening phase γ″ is 732℃~760℃, and the dissolution temperature is 870℃~950℃; the precipitation temperature of the δ phase is 780~980℃, and it begins to dissolve above 980℃. By deeply understanding the strengthening mechanism of GH4169 alloy, which has the highest production volume of cold-drawn materials, this invention increases the heating temperature of the hot-rolled billet, ensuring that the final rolling temperature is above 980℃. This temperature is higher than the precipitation temperatures of the γ″ and δ phases. Combined with forced air cooling after rolling, the billet is rapidly cooled to room temperature, suppressing the precipitation of the γ″ and δ strengthening phases in the matrix during the slow cooling process. By optimizing the hot rolling process, the hardness of cold-drawn steel billets can be reduced.

[0035] In the early stages of production, the conventional billet-making process of the 200-type rolling mill was as follows: the square billet was heated and held at 1110℃, and rolled into Φ10mm~Φ30mm round bars in one pass through the 200-type rolling mill. The final rolling temperature was measured to be in the range of 950℃~970℃. The round steel billet was naturally cooled on the cooling bed after the mill. The Brinell hardness (HBW) value of the bar was calibrated to be 217~245 at this time. The hardness value of the bar was relatively high at this time. In order to fully reduce the hardness of the billet before drawing, the round steel was heated to 980℃ in an annealing furnace and held for 1 hour before drawing, followed by water cooling treatment. The Brinell hardness (HBW) value of the bar after annealing treatment was in the range of 175~185.

[0036] The optimized billet-opening process of the 200-type rolling mill in this invention is as follows: the heating temperature of the square billet is increased to 1150℃, and then it is rolled into Φ10mm~Φ30mm round bars in one pass using the 200-type rolling mill. The final rolling temperature is measured to be in the range of 980℃~1010℃. The round steel billet is forced to cool by a fan at the back of the mill. The Brinell hardness (HBW) value of the bar is calibrated to be 188~195 at this time (see...). Figure 3 This also reduces the hardness of the cold-drawn billet, providing a hardness basis for the direct drawing of the billet.

[0037] Compared with the prior art, the present invention has the following advantages:

[0038] ① The steel billet after hot rolling has fine and uniform grains from the core to the edge (grain size meets the standard requirement of being greater than grade 5) (see...) Figure 1 ); ② Increasing the hot-rolled billet heating temperature ensures that the microstructure of the rolled bar fully completes dynamic recrystallization, and rapid post-rolling air cooling suppresses the precipitation of γ″(Ni3Nb), reducing the hardness of the billet (see Figure 2 ) Eliminating the solution softening process of GH4169 alloy cold-drawn steel billets improved production efficiency; ③ Through the optimization of the GH4169 alloy rolling process, not only was the bottleneck problem restricting the production of the cold-drawn solution softening process solved, but also the production capacity of cold-drawn materials was released, production costs were significantly reduced, and the production cycle was shortened. Attached Figure Description

[0039] Figure 1 Images of the grain structure morphology at the edge of a hot-rolled steel billet;

[0040] Figure 2 Image of the grain structure morphology at the center of a hot-rolled steel billet;

[0041] Figure 3 Comparison chart of room temperature Brinell hardness values ​​of steel billets controlled by optimized hot rolling process. Detailed Implementation

[0042] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0043] Examples 1 through 3 were all produced using the same process:

[0044] 1. Vacuum induction furnace melting (VI M) + vacuum arc remelting (VAR) smelting → high-temperature homogenization diffusion annealing of arc remelting ingots → combined billet making with 3150-ton fast forging mill and 1800-ton radial forging mill → secondary high-temperature homogenization diffusion annealing of billet → billet making with 500-type reversible rolling mill → billet making with 200-type reversible rolling mill → cold drawing into finished products → standardized heat treatment and inspection results.

[0045] 2. A Φ340mm electrode rod is melted and cast in a vacuum induction furnace (VI M). After the electrode rod surface is polished and cleaned to meet the requirements, it is remelted in a vacuum arc remelting furnace (VAR) into a Φ406mm steel ingot, ensuring that the oxygen content of the steel ingot is less than 50×10⁻⁶. -6 Nitrogen content less than 100×10 -6 After the surface of the consumable steel ingot is machined and cleaned to meet the requirements, it is transferred to the forging process. The chemical composition is shown in Table 3.

[0046] Table 3 Chemical composition of vacuum self-consumable steel ingots

[0047]

[0048] 3. The self-consumable steel ingot is heated to 1190℃ in a natural gas chamber furnace and held for 40 hours. A high-temperature homogenization diffusion annealing treatment is then performed to eliminate as-cast component segregation and harmful precipitates.

[0049] 4. The self-consumable steel ingot is forged using a 3150-ton high-speed forging mill and an 1800-ton radial forging mill. The 3150-ton high-speed forging mill is forged into an intermediate billet of Φ220mm in three passes. The heating temperature for the first pass is 1100℃, the second pass is 1080℃, and the third pass is 1050℃. Each pass is reheated in the furnace for 2 to 4 hours. After forging, the hot billet is sent to a natural gas-fired heating furnace for the 1800-ton radial forging mill. The Φ220mm billet is heated to 1060℃ in a natural gas chamber furnace and held for 2 to 4 hours. Then, it is forged into a Φ120mm billet by the 1800-ton radial forging mill. After the surface of the Φ120mm billet is polished and cleaned to meet the requirements, it is transferred to the rolling process.

[0050] 5. The Φ120mm billet is loaded into a high-temperature diffusion annealing natural gas chamber furnace and heated to 1190℃ for 30 hours. After furnace cooling to below 700℃, it is removed from the furnace and air-cooled. This second high-temperature homogenization diffusion annealing treatment further homogenizes the composition.

[0051] 6. Hot rolling blanking:

[0052] (1) After secondary high-temperature homogenization and diffusion, the Φ120mm intermediate billet is heated to 1100℃ in a natural gas chamber furnace and held for 2h to 3h. Then, it is rolled into steel billets in 4 passes using a 500 model reversible rolling mill. Each pass is reheated in the furnace for 1h to 2h. Specifications of Examples 1 to 3: Example 1 (30mm×30mm square), Example 2 (40mm×40mm square), Example 3 (50mm×50mm square).

[0053] (2) After the square steel billet is held at 1150℃ for 0.5 hours in a natural gas chamber furnace, it is rolled into a round steel billet using a 200-type reversible rolling mill. The rolled round steel billets are then laid out on a cooling bed and forced to cool using a high-power fan. After cooling to room temperature, the round steel billets are transferred to the cold drawing process. Specifications for each example: Example 1: Φ13mm, Example 2: Φ19mm, Example 3: Φ25mm.

[0054] 7. Cold drawing process: After receiving the round steel billet, no solution softening treatment is performed. After straightening, the round steel billet undergoes surface polishing and scratch removal. The surface roughness of the billet is no greater than 3.2μm. One end of the billet is tipped, and the surface is then treated with a curing and saponification process, followed by lubrication. The round steel billet is drawn into finished products in one pass using a 65-ton chain cold drawing machine. Example 1: Φ11mm, Example 2: Φ17mm, Example 3: Φ22.5mm.

[0055] The cold drawing deformation processes for each embodiment are as follows:

[0056] Example 1

[0057] Cold drawing deformation process: Φ13mm billet → straightening → billet polishing to Φ12.2mm (dimensional tolerance controlled at ±0.05mm) → tipping treatment of one end of billet → surface treatment of billet by strawing and saponification → cold drawing to Φ11.5mm (cold drawing deformation amount 11.14%) → fine grinding to Φ11mm.

[0058] Example 2

[0059] Cold drawing deformation process: Φ19mm billet → straightening → billet polishing to Φ18.3mm (dimensional tolerance controlled at ±0.05mm) → tipping treatment of one end of billet → surface treatment of billet by strawing and saponification → cold drawing to Φ17.3mm (cold drawing deformation amount 10.6%) → fine grinding to Φ17mm.

[0060] Example 3

[0061] Cold drawing deformation process: Φ25mm billet → straightening → billet polishing to Φ24.3mm (dimensional tolerance controlled at ±0.05mm) → tipping treatment of one end of billet → surface treatment of billet by strawing and saponification → cold drawing to Φ23.0mm (cold drawing deformation amount 10.4%) → fine grinding to Φ22.5mm.

[0062] 8. Standardized heat treatment (electric heating furnace)

[0063] Mechanical property test specimens were subjected to the following heat treatments: solution treatment at 960℃±10℃, followed by holding at that temperature for 1 hour and then air cooling; aging treatment at 720℃±10℃, followed by holding at that temperature for 8 hours, then cooling to 620℃±10℃ at a rate of (50±10)℃ / h, followed by holding at that temperature for 8 hours and then air cooling. For all heat treatment processes, the specimens were loaded into the furnace after it reached the set temperature, and the holding time was started after all thermometers in the electric heating furnace had returned to the set temperature.

[0064] 9. Performance test results of GH4169 high-temperature alloy cold-drawn bars:

[0065] Three batches with specifications of Φ11mm, Φ17mm and Φ22.5mm were selected from multiple production batches. Their room temperature mechanical properties are shown in Table 4, and their high temperature mechanical properties at 650℃ are shown in Table 5.

[0066] Table 4 shows the test results of the room temperature mechanical properties of GH4169 high-temperature alloy.

[0067]

[0068] Table 5 shows the test results of the mechanical properties of GH4169 high-temperature alloy at 650℃.

[0069]

[0070] As can be seen from the mechanical property test results in Tables 4 and 5, the GH4169 alloy cold-drawn material produced by this invention using an optimized rolling and billet-opening process, eliminating the pre-cold-drawing solution softening step, meets the technical standard requirements and has a large performance margin. Figure 1 , Figure 2 It can be seen that by controlling the amount of deformation during rolling and increasing the rolling temperature and post-rolling cooling rate, the longitudinal edge grain structure and the central grain structure of the bar are both fully dynamically recrystallized equiaxed grains, and the grains are fine and uniform, with an average grain size of grade 8 to 9, which meets the technical standard requirement of being finer than grade 5.

Claims

1. A manufacturing method for improving the production efficiency of GH4169 alloy cold-drawn materials, characterized in that, The manufacturing process is as follows: Vacuum Induction Furnace Melting (VIM) + Vacuum Arsenic Remelting (VAR) → High-Temperature Homogenization Diffusion Annealing of Arsenic Steel Ingots → Combined Billet Making with 3150-ton Fast Forging Mill and 1800-ton Radial Forging Mill → Secondary High-Temperature Homogenization Diffusion Annealing of Billet → Billet Making with 500-type Reversible Rolling Mill → Billet Making with 200-type Reversible Rolling Mill → Cold Drawing into Finished Products → Standardized Heat Treatment and Inspection Results; The 500 model reversible rolling mill billet preparation: Φ120mm intermediate billet is heated to 1100℃ in a natural gas chamber furnace and held for 2h to 3h. Then, it is rolled into 30mm to 50mm square steel billet in 4 passes using the 500 model reversible rolling mill. Each pass takes 3s to 5s. Each pass is reheated in the furnace at 1100℃ and held for 1h to 2h. The 200-type reversible rolling mill is used for billet preparation: 30mm to 50mm square steel billets are heated to 1150℃ in a natural gas chamber furnace and held for 0.5h to 1h. The billets are then prepared using the 200-type reversible rolling mill and rolled into Φ10mm to Φ30mm round steel billets in one pass. The surface temperature of the rolled bars is in the range of 980℃ to 1050℃, and the bars are cooled by forced air cooling after rolling.

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