Forging and cold drawing method for GH696 alloy bar

Abstract

The invention relates to the technical field of high-temperature alloy forging and cold drawing, and particularly discloses a forging and cold drawing method for a GH696 alloy bar. The forging and cold drawing method of the GH696 alloy bar comprises the following steps that a GH696 alloy steel ingot is sequentially subjected to forging, hot rolling, softening annealing and cold drawing, and the GH696 alloy bar is obtained; wherein when the deformation of the cold drawing is 10%-20%, the temperature of the softening annealing is 875 DEG C-925 DEG C; when the deformation amount of cold drawing is 20%-30%, the temperature of softening annealing is 925 DEG C-975 DEG C; and when the deformation of the cold drawing is 30%-40%, the temperature of the softening annealing is 975 DEG C-1025 DEG C. By controlling different softening annealing temperatures before cold drawing corresponding to different cold drawing deformation amounts, the GH696 alloy bar with excellent comprehensive performance, low hardness and high tensile strength is prepared, and the use requirements of the GH696 alloy bar are met.

Description

Technical Field

[0001] The invention relates to the technical field of forging cold drawing of Fe-Ni-Cr based high temperature alloy, in particular to a forging cold drawing method of a GH696 alloy bar. Background Art

[0002] GH696 (also known as GH2696) alloy is a Fe-Ni-Cr based precipitation hardening deformation high temperature alloy. It is composed of Fe-Ni-Cr as the matrix to form a stable γ-phase austenite, with metal Mo element for solid solution strengthening, γ' (Ni3AlTi) as the intermetallic precipitate for aging precipitation strengthening, and contains trace B element to achieve grain boundary strengthening. The combined effect of multiple strengthening mechanisms ensures that GH696 alloy has high tensile strength, creep strength, good high temperature elastic properties and gas corrosion resistance at high temperatures. At the same time, the alloy also has good processing plasticity and can be processed into rods, plates, wires or strips of different specifications. GH696 alloy can serve for a long time below 650℃, and the short-term use temperature can reach 750℃. Due to its good comprehensive mechanical properties and corrosion resistance, it has a wide range of applications in the field of aerospace and gas turbine fasteners, such as turbine discs, compressors, fasteners, springs, working blades, turbine housings and rings.

[0003] However, there is no literature on the forging cold drawing process of GH696 alloy bars. The relevant standard requirements for GH696 alloy cold drawn bars are low hardness + high tensile strength. In daily production, the tensile strength is qualified but the hardness exceeds the standard, or the hardness is qualified but the tensile strength is low. The bars produced cannot meet the requirements of the relevant standards and the yield rate is extremely low. Summary of the invention

[0004] In view of the above problems, the present invention provides a forging cold drawing method for GH696 alloy bars. By controlling different softening annealing temperatures before cold drawing corresponding to different cold drawing deformation amounts, a GH696 alloy bar with low hardness and high tensile strength and excellent comprehensive performance is obtained to meet its use requirements.

[0005] In order to solve the above technical problems, the technical solution provided by the present invention is: A forging cold drawing method for a GH696 alloy bar comprises the following steps: The GH696 alloy steel ingot is forged, hot rolled, softened annealed and cold drawn in sequence to obtain GH696 alloy bars; wherein, When the cold-drawing deformation is 10% to 20%, the softening annealing temperature is 875°C to 925°C; When the cold-drawing deformation is 20% to 30%, the softening annealing temperature is 925° C. to 975° C.; When the deformation amount of the cold drawing is 30%-40%, the temperature of the softening annealing is 975°C-1025°C.

[0006] Compared with the prior art, the forging cold drawing method of the GH696 alloy bar provided by the present invention first processes the large-sized GH696 alloy steel ingot into a small-sized blank through forging and hot rolling processes, and then selects different softening annealing temperatures according to the deformation amount of cold drawing, so that the blank can meet the corresponding performance requirements after cold drawing under a specific deformation amount, thereby obtaining a GH696 alloy bar with low hardness and high tensile properties. The GH696 alloy bar provided by the present invention has excellent mechanical properties and high yield rate, and can meet the application requirements in the fields of aerospace and gas turbine fasteners.

[0007] Preferably, the GH696 alloy steel ingot comprises the following chemical components by mass content: Ni 21.0%~25.0%, Cr10.0%~12.5%, Ti 2.6%~3.2%, Mo 1.0%~1.6%, Al≤0.8%, Si≤0.6%, Mn≤0.6%, B≤0.2%, P≤0.2%, S≤0.1%, C≤0.1%, and the balance is Fe and unavoidable impurities.

[0008] Preferably, the forging cold drawing method of the GH696 alloy bar specifically comprises the following steps: S1, vacuum induction smelting and casting of GH696 alloy raw materials to obtain electrode rods; S2, performing vacuum consumable remelting on the electrode rod to obtain a GH696 alloy steel ingot; S3, forging the GH696 alloy steel ingot to obtain a first blank; S4, hot rolling the first blank once to obtain a second blank; S5, performing a second hot rolling on the second blank to obtain a third blank; S6, performing softening annealing and cold drawing on the third blank to obtain a fourth blank; S7, heat treating the fourth blank to obtain a GH696 alloy rod.

[0009] For example, in S1, after pouring and cooling, polishing is also included.

[0010] Further preferably, in S1, the diameter of the electrode rod is 220 mm to 280 mm.

[0011] Further preferably, in S2, the diameter of the GH696 alloy steel ingot is 280 mm to 330 mm.

[0012] The present invention has no special requirements on the specific process parameters of vacuum induction smelting and vacuum consumable remelting, and the conventional parameter range in the field can be adopted.

[0013] Preferably, the heating temperature of the forging is 1060°C to 1100°C, and the holding time is 2h to 3h.

[0014] Preferably, the forging is performed with 3 to 5 firings.

[0015] Further preferably, in S3, the deformation amount of the 1st to 2nd forging fire is 35% to 45%, and the deformation amount of the 3rd to 5th forging fire is 55% to 65%.

[0016] Further preferably, the initial forging temperature of the forging is ≥950°C, and the final forging temperature of the forging is ≥850°C.

[0017] For example, in S3, after the forging is completed, air cooling to room temperature is also included.

[0018] Further preferably, in S3, the diameter of the first blank is 140 mm to 160 mm.

[0019] Further preferably, in S4, the heating temperature of the primary hot rolling is 1070° C. to 1090° C., and the holding time is 1 h to 1.5 h.

[0020] More preferably, in S4, the primary hot rolling is performed in a one-pass multi-pass manner.

[0021] More preferably, in S4, the starting temperature of the first hot rolling is ≥920°C, and the finishing temperature of the first hot rolling is ≥850°C.

[0022] For example, in S4, after the hot rolling is completed, air cooling to room temperature is also included.

[0023] Further preferably, in S4, the side length of the second blank is 40 mm to 55 mm.

[0024] Further preferably, in S5, the heating temperature of the secondary hot rolling is 1060° C. to 1080° C., and the holding time is 0.5 h to 1 h.

[0025] More preferably, in S5, the secondary hot rolling is performed in a one-fire-multiple-pass manner.

[0026] More preferably, in S5, the starting temperature of the secondary hot rolling is ≥920°C, and the finishing temperature of the secondary hot rolling is ≥850°C.

[0027] For example, in S5, after the secondary hot rolling is completed, air cooling to room temperature is also included.

[0028] Further preferably, in S5, the diameter of the third blank is 10 mm to 20 mm.

[0029] Preferably, the holding time of the softening annealing is 50 min to 70 min.

[0030] Preferably, the cooling method of the softening annealing is water cooling.

[0031] Preferably, when the cold-drawing deformation is 10% to 20%, the softening annealing temperature is 880° C. to 920° C.; When the cold-drawing deformation is 20% to 30%, the softening annealing temperature is 930° C. to 970° C.; When the deformation amount of the cold drawing is 30%-40%, the temperature of the softening annealing is 980°C-1020°C.

[0032] For example, in S6, after the softening annealing is completed, peeling and polishing are also included to remove surface defects.

[0033] Further preferably, in S6, the diameter of the fourth blank is 6 mm to 17.5 mm, more preferably 6.5 mm to 15 mm.

[0034] Further preferably, in S7, the heat treatment step comprises: After keeping at 980℃~1200℃ for 1.8h~2.2h, water cool to room temperature; then keep at 740℃~760℃ for 14h~18h, air cool to room temperature; finally keep at 640℃~660℃ for 14h~18h, air cool to room temperature.

[0035] For example, in S7, after the heat treatment is completed, polishing finishing is also included. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0037] Unless otherwise specified, the contents in the present invention are all weight contents.

[0038] Example 1 This embodiment provides a forging cold drawing method for a GH696 alloy bar, comprising the following steps: S1, put the GH696 alloy raw material into a vacuum smelting furnace, perform vacuum induction smelting, pour, cool and then polish to obtain a Φ250mm electrode rod.

[0039] S2, placing the electrode rod into a vacuum consumable furnace for vacuum consumable remelting to obtain a GH696 alloy steel ingot of Φ305 mm.

[0040] GH696 alloy steel ingot includes the following chemical components by mass: Ni 23.0%, Cr 11.5%, Ti 2.9%, Mo1.3%, Al 0.6%, Si 0.4%, Mn 0.4%, B 0.1%, P 0.02%, S 0.01%, C 0.05%, and the balance is Fe and unavoidable impurities.

[0041] S3, put the GH696 alloy steel ingot into a heating furnace at 1080℃, keep it warm for 2.5h, and then perform 4-time forging (drawing). After the second time, a 210mm×210mm square billet is obtained, that is, the deformation amount from the first to the second time is 39.6%; after the fourth time, a Φ150mm round billet is obtained, that is, the deformation amount from the third to the fourth time is 59.9%. After forging, air cool to room temperature to obtain the first billet.

[0042] S4, placing the first blank into a heating furnace at 1080°C, keeping it warm for 1.5 hours, and then performing a hot rolling (1 fire and multiple passes), and air cooling to room temperature to obtain a second blank of 48mm×48mm.

[0043] S5, put the second billet into a heating furnace at 1070°C, keep it warm for 0.8h, and then carry out secondary hot rolling (1 fire and multiple passes), and air cool it to room temperature to obtain a third billet of Φ10mm.

[0044] S6, the third blank is placed in a heating furnace at 880°C for softening annealing, kept at this temperature for 60 minutes, cooled to room temperature with water, peeled and polished to Φ9.2mm, and then cold drawn. The deformation amount of cold drawing is 12.6%, and a fourth blank of Φ8.6mm is obtained.

[0045] S7, heat-treating the fourth blank, keeping it at 1000°C for 2 hours, and then cooling it to room temperature with water; then keeping it at 750°C for 16 hours, and then air-cooling it to room temperature; finally keeping it at 650°C for 16 hours, and then air-cooling it to room temperature, and polishing and finishing it to obtain a Φ8.5mm GH696 alloy bar.

[0046] Example 2 This embodiment provides a forging cold drawing method for a GH696 alloy bar, comprising the following steps: S1, put the GH696 alloy raw material into a vacuum smelting furnace, perform vacuum induction smelting, pour, cool and then polish to obtain a Φ250mm electrode rod.

[0047] S2, placing the electrode rod into a vacuum consumable furnace for vacuum consumable remelting to obtain a GH696 alloy steel ingot of Φ305 mm.

[0048] GH696 alloy steel ingot includes the following chemical components by mass: Ni 22.0%, Cr 11.0%, Ti 2.8%, Mo1.4%, Al 0.7%, Si 0.5%, Mn 0.4%, B 0.1%, P 0.02%, S 0.01%, C 0.04%, and the balance is Fe and unavoidable impurities.

[0049] S3, put the GH696 alloy steel ingot into a heating furnace at 1090℃, keep it warm for 2.5h, and then perform 3-time forging (drawing). After the second time, a 205mm×205mm square billet is obtained, that is, the deformation amount of the first to second times is 43.3%; after the third time, a Φ150mm round billet is obtained, that is, the deformation amount of the third time is 57.9%. After forging, air cool to room temperature to obtain the first billet.

[0050] S4, placing the first billet into a heating furnace at 1080°C, keeping it warm for 1.2 hours, and then performing a hot rolling (1 fire and multiple passes), and air cooling to room temperature to obtain a second billet of 48mm×48mm.

[0051] S5, put the second billet into a heating furnace at 1070℃, keep it warm for 1h, and then carry out secondary hot rolling (1 fire and multiple passes), and air cool it to room temperature to obtain a third billet of Φ10mm.

[0052] S6, the third blank is placed in a heating furnace at 1100°C for softening annealing, kept at this temperature for 60 minutes, cooled to room temperature with water, peeled and polished to Φ9.2mm, and then cold drawn. The deformation of the cold drawing is 37.0%, and a fourth blank of Φ7.3mm is obtained.

[0053] S7, heat-treating the fourth blank, keeping it at 1000°C for 2 hours, and then cooling it to room temperature with water; then keeping it at 750°C for 16 hours, and then air-cooling it to room temperature; finally keeping it at 645°C for 16 hours, and then air-cooling it to room temperature, and polishing and finishing to obtain a Φ7.2mm GH696 alloy bar.

[0054] Example 3 This embodiment provides a forging cold drawing method for a GH696 alloy bar, comprising the following steps: S1, put the GH696 alloy raw material into a vacuum smelting furnace, perform vacuum induction smelting, pour, cool and then polish to obtain a Φ250mm electrode rod.

[0055] S2, placing the electrode rod into a vacuum consumable furnace for vacuum consumable remelting to obtain a GH696 alloy steel ingot of Φ305 mm.

[0056] GH696 alloy steel ingot includes the following chemical components by mass: Ni 21.0%, Cr 12.5%, Ti 3.2%, Mo1.0%, Al 0.6%, Si 0.5%, Mn 0.4%, B 0.1%, P 0.02%, S 0.01%, C 0.05%, and the balance is Fe and unavoidable impurities.

[0057] S3, put the GH696 alloy steel ingot into a heating furnace at 1060℃, keep it warm for 3h, and then perform 4-time forging (drawing). After the second time, a 210mm×210mm square billet is obtained, that is, the deformation amount from the first to the second time is 39.6%; after the fourth time, a Φ145mm round billet is obtained, that is, the deformation amount from the third to the fourth time is 62.6%. After forging, air cool to room temperature to obtain the first billet.

[0058] S4, placing the first blank into a heating furnace at 1070°C, keeping it warm for 1.5 hours, and then performing a hot rolling (1 fire and multiple passes), and air cooling to room temperature to obtain a second blank of 50mm×50mm.

[0059] S5, put the second billet into a heating furnace at 1060°C, keep it warm for 1h, and then carry out secondary hot rolling (1 fire and multiple passes), and air cool it to room temperature to obtain a third billet of Φ15mm.

[0060] S6, the third blank is placed in a heating furnace at 950°C for softening annealing, kept at this temperature for 52 minutes, and then water-cooled to room temperature. After peeling and polishing to Φ14mm, it is cold-drawn with a deformation of 25.3% to obtain a fourth blank of Φ12.1mm.

[0061] S7, heat-treating the fourth blank, keeping it at 980°C for 2.2h, and then cooling it to room temperature with water; then keeping it at 740°C for 18h, and then air-cooling it to room temperature; finally keeping it at 640°C for 18h, and then air-cooling it to room temperature, and polishing and finishing to obtain a Φ12.0mm GH696 alloy bar.

[0062] Example 4 This embodiment provides a forging cold drawing method for a GH696 alloy bar, comprising the following steps: S1, put the GH696 alloy raw material into a vacuum smelting furnace, perform vacuum induction smelting, pour, cool and then polish to obtain a Φ250mm electrode rod.

[0063] S2, placing the electrode rod into a vacuum consumable furnace for vacuum consumable remelting to obtain a GH696 alloy steel ingot of Φ305 mm.

[0064] GH696 alloy steel ingot includes the following chemical components by mass: Ni 25.0%, Cr 10.0%, Ti 2.6%, Mo1.6%, Al 0.7%, Si 0.6%, Mn 0.5%, B 0.15%, P 0.02%, S 0.01%, C 0.03%, and the balance is Fe and unavoidable impurities.

[0065] S3, put the GH696 alloy steel ingot into a heating furnace at 1100℃, keep it warm for 2h, and then perform 5-time forging (drawing). After the second time, a 217mm×217mm square billet is obtained, that is, the deformation amount from the first to the second time is 35.5%; after the fifth time, a Φ160mm round billet is obtained, that is, the deformation amount from the third to the fifth time is 57.3%. After forging, air cool to room temperature to obtain the first billet.

[0066] S4, put the first billet into a heating furnace at 1090°C, keep it warm for 1h, perform a hot rolling (1 fire and multiple passes), and air cool it to room temperature to obtain a second billet of 55mm×55mm.

[0067] S5, placing the second billet into a heating furnace at 1080°C, keeping it warm for 0.5h, and then performing secondary hot rolling (1 fire and multiple passes), air cooling to room temperature to obtain a third billet of Φ20mm.

[0068] S6, the third blank is placed in a heating furnace at 915°C for softening annealing, kept at this temperature for 70 minutes, and then water-cooled to room temperature. After peeling and polishing to Φ19mm, it is cold-drawn with a cold-drawing deformation of 18.0%, and a fourth blank of Φ17.2mm is obtained.

[0069] S7, heat-treating the fourth blank, keeping it at 1200°C for 1.8h, and then cooling it to room temperature with water; then keeping it at 760°C for 14h, and then air-cooling it to room temperature; finally keeping it at 660°C for 14h, and then air-cooling it to room temperature, and polishing and finishing to obtain a Φ17.0mm GH696 alloy bar.

[0070] Comparative Example 1 This comparative example provides a forging cold drawing method for a GH696 alloy bar, which is similar to Example 1, except that: in S6, the temperature of the softening annealing (heating furnace) is 950° C. The remaining conditions are the same as those in Example 1 and will not be described in detail.

[0071] Comparative Example 2 This comparative example provides a forging cold drawing method for a GH696 alloy bar, which is similar to Example 2, except that: in S6, the temperature of the softening annealing (heating furnace) is 900° C. The remaining conditions are the same as those in Example 2 and will not be described in detail.

[0072] Comparative Example 3 This comparative example provides a forging cold drawing method for a GH696 alloy bar, which is similar to Example 3, except that: in S6, the temperature of the softening annealing (heating furnace) is 1000° C. The remaining conditions are the same as those in Example 3 and will not be described in detail.

[0073] Comparative Example 4 This comparative example provides a forging cold drawing method for a GH696 alloy bar, which is similar to Example 4, except that: in S6, the temperature of the softening annealing (heating furnace) is 1000° C. The remaining conditions are the same as those in Example 4 and will not be described in detail.

[0074] Verification test The mechanical properties of the GH696 alloy bars (head and tail) provided in Examples 1 to 4 and Comparative Examples 1 to 4 were tested with reference to the ZHSD / JT-22-0025 / 0 technical protocol. The test results are shown in Table 1.

[0075] Table 1 Mechanical properties test results of GH696 alloy bars of the embodiment and comparative example

[0076] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modification, equivalent substitution or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A forging cold drawing method for GH696 alloy bars, characterized in that: The following steps are involved: The GH696 alloy steel ingot is forged, hot rolled, softened annealed and cold drawn in sequence to obtain GH696 alloy bars; wherein, When the cold-drawing deformation is 10% to 20%, the softening annealing temperature is 875°C to 925°C; When the cold-drawing deformation is 20% to 30%, the softening annealing temperature is 925° C. to 975° C.; When the deformation amount of the cold drawing is 30%-40%, the temperature of the softening annealing is 975°C-1025°C.

2. The forging cold drawing method of GH696 alloy bar according to claim 1, characterized in that: The forging cold drawing method of the GH696 alloy bar specifically comprises the following steps: S1, vacuum induction smelting and casting of GH696 alloy raw materials to obtain electrode rods; S2, performing vacuum consumable remelting on the electrode rod to obtain a GH696 alloy steel ingot; S3, forging the GH696 alloy steel ingot to obtain a first blank; S4, hot rolling the first blank once to obtain a second blank; S5, performing a second hot rolling on the second blank to obtain a third blank; S6, performing softening annealing and cold drawing on the third blank to obtain a fourth blank; S7, heat treating the fourth blank to obtain a GH696 alloy rod.

3. The forging cold drawing method of GH696 alloy bar according to claim 1 or 2, characterized in that: The holding time of the softening annealing is 50 min to 70 min, and the cooling method of the softening annealing is water cooling.

4. The forging cold drawing method of GH696 alloy bar according to claim 1 or 2, characterized in that: The GH696 alloy steel ingot includes the following chemical components by mass content: Ni 21.0%~25.0%, Cr 10.0%~12.5%, Ti 2.6%~3.2%, Mo 1.0%~1.6%, Al≤0.8%, Si≤0.6%, Mn≤0.6%, B≤0.2%, P≤0.2%, S≤0.1%, C≤0.1%, and the balance is Fe and unavoidable impurities.

5. The forging cold drawing method of GH696 alloy bar according to claim 1 or 2, characterized in that: The diameter of the GH696 alloy steel ingot is 280 mm to 330 mm; The heating temperature of the forging is 1060°C to 1100°C, and the holding time is 2h to 3h; The forging is performed using 3 to 5 firings.

6. The forging cold drawing method of GH696 alloy bar according to claim 5, characterized in that: The deformation amount of the 1st to 2nd forging is 35% to 45%, and the deformation amount of the 3rd to 5th forging is 55% to 65%.

7. The forging cold drawing method of GH696 alloy bar according to claim 2, characterized in that: In S3, the diameter of the first blank is 140 mm to 160 mm; In S4, the side length of the second blank is 40 mm to 55 mm; In S5, the diameter of the third blank is 10 mm to 20 mm; In S6, the diameter of the fourth blank is 6 mm to 17.5 mm.

8. The forging cold drawing method of GH696 alloy bar according to claim 2, characterized in that: In S4, the heating temperature of the first hot rolling is 1070°C to 1090°C, and the holding time is 1h to 1.5h; In S4, the primary hot rolling is performed in a one-pass multi-pass manner.

9. The forging cold drawing method of GH696 alloy bar according to claim 2, characterized in that: In S5, the heating temperature of the secondary hot rolling is 1060°C to 1080°C, and the holding time is 0.5h to 1h; In S5, the secondary hot rolling is performed in a one-pass multi-pass manner.

10. The forging cold drawing method of GH696 alloy bar according to claim 2, characterized in that: In S7, the heat treatment step includes: After keeping at 980℃~1200℃ for 1.8h~2.2h, water cool to room temperature; then keep at 740℃~760℃ for 14h~18h, air cool to room temperature; finally keep at 640℃~660℃ for 14h~18h, air cool to room temperature.

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