A processing method of TB8 titanium alloy pipe

Abstract

The application discloses a processing method of TB8 titanium alloy pipe, which comprises the following steps: performing one-time upsetting and elongation forging on a cast ingot at a heating temperature of 1100-1150 DEG C and a holding time t, so as to obtain a first rod material with a length-to-maximum cross section thickness ratio of not more than 2.45; performing one-time upsetting and elongation forging on the first rod material at a heating temperature of 1000-1050 DEG C and 900-950 DEG C respectively, so as to obtain a second rod material with a length-to-maximum cross section thickness ratio of not more than 2.45; performing two-time forging on the second rod material at a heating temperature of 785-845 DEG C; performing jacket extrusion on the pipe blank at a heating temperature of 760-780 DEG C, and performing surface treatment, so as to obtain an intermediate pipe material with an inner diameter of 75-85% of the outer diameter; and performing cold rolling on the intermediate pipe material, so as to obtain a finished pipe material with an inner diameter of 85-95% of the outer diameter. The process flow is short, stable and controllable, and the titanium alloy pipe material prepared has a uniform structure.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of titanium alloy material processing, and relates to a processing method of TB8 titanium alloy pipe. BACKGROUND

[0002] TB8 titanium alloy (Ti-15Mo-3Al-2.7Nb-0.2Si) is a metastable beta type super high strength titanium alloy, the alloy has excellent high temperature strength and creep resistance, good cold forming, welding, high temperature oxidation resistance and corrosion resistance, and can be used for manufacturing sheet metal parts, high temperature resistant structural parts, fasteners, pipe materials, foil materials, skins and the like, and is an ideal aerospace structural material. In view of the excellent cold working performance of the TB8 titanium alloy, the spinning technology can be used to manufacture the thin-walled rotary body structure of the engine combustion chamber shell, wind deflector, nozzle and the like, so as to meet the use requirements of high temperature resistance, oxidation resistance and hot salt and hot oil corrosion resistance.

[0003] At present, the spinning technology has become an advanced manufacturing technology for manufacturing the titanium alloy thin-walled rotary body structure, but due to the large deformation resistance of the titanium alloy and the difficulty in processing, the cost requirement is strict, and it is necessary to reasonably design the structure of the pipe material for spinning and the processing process. The traditional machining method is to cut a pipe blank on a finished bar, which leads to low material utilization, long processing cycle and high manufacturing cost; the rolling process needs to be carried out on the blank, forging, punching, machining and then rolling forming, and there are problems of many processing times, long cycle and high processing cost. Therefore, in order to overcome the above-mentioned defects, it is necessary to invent a short process and low cost processing method of TB8 titanium alloy pipe for spinning. SUMMARY

[0004] The purpose of the present application is to overcome the shortcomings of the prior art, and provide a processing method of TB8 titanium alloy pipe for spinning. The technical scheme adopted by the present application is:

[0005] Step (one): the ingot is subjected to one-time upsetting and elongating forging under the condition of heating temperature 1100℃~1150℃ and holding time t, so as to obtain a first bar with the ratio of length to maximum cross-sectional thickness not greater than 2.45.

[0006] Step (two): the first bar in step (one) is subjected to one-time upsetting and elongating forging under the condition of heating temperature 1000℃~1050℃ and 900℃~950℃ respectively, so as to obtain a second bar with the ratio of length to maximum cross-sectional thickness not greater than 2.45.

[0007] Step (three): the second bar in step (two) is subjected to two-time forging under the condition of heating temperature 785℃~845℃.

[0008] First fire forging: upsetting and elongating forging is carried out under the condition of heating temperature T1, and punching is carried out, so that a ring blank with an inner diameter of 45%~65% of its outer diameter is obtained.

[0009] Second fire forging: the ring blank is expanded under the condition of heating temperature T2, so that a pipe blank with an inner diameter of 50%~75% of its outer diameter is obtained.

[0010] Step (four): the pipe blank in step (three) is subjected to a canning extrusion under the condition of heating temperature 760℃~780℃, and surface treatment is carried out, so that an intermediate pipe material with an inner diameter of 75%~85% of its outer diameter is obtained.

[0011] Step (five): the intermediate pipe material in step (four) is subjected to cold rolling, so that a finished pipe material with an inner diameter of 85%~95% of its outer diameter is obtained.

[0012] The holding time t in step (one) satisfies: when the ingot diameter D≥200mm, t≥1500min; when the ingot diameter D<200mm, t=λ×D, and the heating coefficient λ=7.5min / mm~9.5min / mm; the upsetting is completed in two steps, wherein the deformation amount of the first step of upsetting is 15%~20%, and the deformation amount of the second step of upsetting is 15%~25%.

[0013] The upsetting in step (two) is completed in two steps, wherein the deformation amount of the first step of upsetting is 20%~25%, and the deformation amount of the second step of upsetting is 20%~30%.

[0014] The upsetting and elongating in step (three) is two-up-one-draw, and the deformation amount of the upsetting is 40%~65%; the heating temperatures T1 and T2 satisfy: T2>T1 and T2-T1≥40℃; the upsetting and elongating is two-up-one-draw, and the deformation amount of each upsetting is 40%~65%

[0015] The canning in step (four) is a double-metal canning, the outer layer is copper, and the inner layer is steel, that is, the surface of the pipe blank is first coated with steel, and then coated with copper; the surface treatment includes machining to remove surface defects, sandblasting or pickling to remove the surface oxide layer.

[0016] The number of passes of the cold rolling in step (five) is 1~4 passes, and the deformation amount of each pass of the cold rolling is 5%~10%.

[0017] Compared with the prior art, the present application has the following advantages:

[0018] (1) The present application adopts a longer heating holding time in the first β zone heating, and the main technical purpose is to allow the ingot to be subjected to sufficient homogenization treatment under the condition of a higher temperature of 1100℃~1150℃, so as to provide a good material basis for subsequent breakdown forging, which is beneficial to improve the deformation effect and reduce the forging fire times.

[0019] (2) the present application carries out "low high" two fire deformation at 785℃~845℃, first, at a lower temperature, using a large deformation to break the grain and organization, obtain sufficient recrystallization energy, then, at a higher temperature, through a large deformation, further refine the organization.

[0020] (3) the present application combines the cogging forging of titanium alloy ingot and the blank preparation (punching, expanding, etc.), completes the blank processing of the pipe material while homogenizing the ingot, compared with the traditional raw material ingot cogging forging, re-forging and drilling, the method has the advantages of less processing fire, short process, etc., simplifies the production process and improves the production efficiency.

[0021] (4) the present application uses extrusion and multi-pass cold rolling to prepare the finished pipe, compared with the traditional hot rolling and extrusion process, the prepared finished pipe has better surface quality and size precision, and solves the technical problems of large rebound and difficult processing of high-strength TB8 titanium alloy.

[0022] (4) the present application has short process flow, simple and controllable, and has good process controllability and batch production stability. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 The specific implementation process of the present application is as follows. DETAILED DESCRIPTION

[0024] The specific implementation of the present application will be further described below in combination with the drawings and using TB8 titanium alloy ingot as raw material. The main chemical composition of TB8 titanium alloy is as follows: molybdenum content 14.0%~16.0%, niobium content 2.4%~3.2%, aluminum content 2.5%~3.5%, silicon content 3.5%~4.5%, impurity elements are controlled as follows: iron ≤0.4%, carbon ≤0.05%, nitrogen ≤0.05%, hydrogen ≤0.015%, oxygen ≤0.17%, other elements ≤0.01% and total ≤0.04%, and the balance is titanium. The preparation method of the present application for high-strength titanium alloy pipe uses TB8 titanium alloy ingot as raw material blank to produce qualified TB8 titanium alloy pipe, which specifically includes the following steps:

[0025] The processing method of the present application for TB8 titanium alloy pipe uses TB8 titanium alloy ingot as raw material to produce qualified TB8 titanium alloy pipe, which specifically includes the following steps:

[0026] Step (I): the ingot is heated at a temperature of 1100-1150℃ for a holding time t, wherein, when the diameter of the ingot D≥200mm, t≥1500min, when the diameter of the ingot D<200mm, t=λ×D, the heating coefficient λ=7.5-9.5min / mm; then one heating upsetting and elongating forging is carried out, wherein, the upsetting is completed in two steps, the deformation of the first step is 15-20%, and the deformation of the second step is 15-25%, to obtain the first bar with the ratio of length to maximum cross-sectional thickness not more than 2.45.

[0027] Step (II): the first bar in step (I) is respectively subjected to one heating upsetting and elongating forging at a temperature of 1000-1050℃ and 900-950℃, wherein, the upsetting is completed in two steps, the deformation of the first step is 20-25%, and the deformation of the second step is 20-30%, to obtain the second bar with the ratio of length to maximum cross-sectional thickness not more than 2.45.

[0028] Step (III): the second bar in step (II) is subjected to two heating forgings at a temperature of 785-845℃, the first heating forging is two upsetting and one elongating forging at a temperature of T1, the deformation of each upsetting is 40-65%, followed by punching to obtain a ring blank with the inner diameter being 45-65% of the outer diameter, the second heating forging is the ring blank subjected to the expanding forging at a temperature of T2, the temperatures T1 and T2 satisfy: T2>T1 and T2-T1≥40℃, to obtain a tube blank with the inner diameter being 50-75% of the outer diameter.

[0029] Step (IV): the tube blank in step (III) is subjected to double metal cladding, the outer layer is copper and the inner layer is steel, i.e. the surface of the tube blank is first coated with steel, then coated with copper, and then subjected to cladding extrusion at a temperature of 760-780℃, after the extrusion, the surface defects are removed by machining, and the surface oxide layer is removed by sandblasting or pickling, to obtain an intermediate tube material with the inner diameter being 75-85% of the outer diameter.

[0030] Step (V): the intermediate tube material in step (IV) is subjected to cold rolling, the number of passes is 1-4, and the deformation of each pass is 5-10%, to obtain the finished tube material with the inner diameter being 85-95% of the outer diameter.

[0031] The application will be further described in detail in combination with the examples. The application lists four examples for further detailed description, but is not used to limit the application.

[0032] Example 1:

[0033] A TB8 titanium alloy ingot with a diameter of 250 mm and a length of 650 mm is selected, the surface oxide layer and defects are removed on a lathe, and after chamfering at both ends, the specific steps for preparing a TB8 titanium alloy pipe with an outer diameter of 265 mm and an inner diameter of 255 mm by adopting the method are as follows:

[0034] Step (one): the ingot is heated at a heating temperature of 1150 DEG C and kept for a time, the diameter D of the ingot is greater than or equal to 200 mm, so the heating and keeping time t is selected to be 1560 min, and then one-time upsetting and elongation forging is carried out, wherein the upsetting is completed in two steps, the deformation of the first step is 15%, and the deformation of the second step is 20%, to obtain a first rod.

[0035] Step (two): after the first rod in step (one) is polished and defects are removed, first, one-time upsetting and elongation forging is carried out at a heating temperature of 1050 DEG C, wherein the upsetting is completed in two steps, the deformation of the first step is 20%, and the deformation of the second step is 25%; after polishing and removing defects, one-time upsetting and elongation forging is carried out at a heating temperature of 950 DEG C, wherein the upsetting is completed in two steps, the deformation of the first step is 25%, and the deformation of the second step is 30%, to obtain a second rod.

[0036] Step (three): after the second rod in step (two) is polished and defects are removed, first, two-up-one-down forging is carried out at a heating temperature T1 of 785 DEG C for the first time, the deformation of the first upsetting is 60%, the deformation of the second upsetting is 60%, and punching is carried out to obtain a ring blank with an outer diameter of 405 mm and an inner diameter of 200 mm; then, under the condition of a heating temperature T2 of 830 DEG C, the diameter expansion forging is carried out on a ring rolling mill for the second time, to obtain a pipe blank with an outer diameter of 430 mm and an inner diameter of 253 mm.

[0037] Step (four): the pipe blank in step (three) is first coated with steel on the surface, and then coated with copper, and then the sleeve extrusion is carried out at a heating temperature of 765 DEG C, after the extrusion, the surface defects are removed by machining, and the surface oxide layer is removed by sandblasting, to obtain an intermediate pipe material with an outer diameter of 330 mm and an inner diameter of 250 mm.

[0038] Step (five): the intermediate pipe material in step (four) is cold-rolled for 3 passes, and the deformation of each pass is 10%, 5% and 5% in turn, and after straightening, finishing and polishing, the finished pipe material with an outer diameter of 265 mm and an inner diameter of 255 mm is obtained.

[0039] Example 2:

[0040] A TB8 titanium alloy ingot with a diameter of 320 mm and a length of 750 mm is selected, the surface oxide layer and defects are removed on a lathe, and after chamfering at both ends, the specific steps for preparing a TB8 titanium alloy pipe with an outer diameter of 355 mm and an inner diameter of 335 mm by adopting the method are as follows:

[0041] Step (one): the ingot is heated at a heating temperature of 1145℃ for a holding time, the diameter D of the ingot is greater than or equal to 200mm, and the heating holding time t is 1600min, and then one fire upsetting and elongation forging is carried out, wherein the upsetting is completed in two steps, the deformation of the first step is 20%, and the deformation of the second step is 25%, to obtain the first bar.

[0042] Step (two): after the first bar in step (one) is polished and the defects are removed, first, one fire upsetting and elongation forging is carried out at a heating temperature of 1035℃, wherein the upsetting is completed in two steps, the deformation of the first step is 20%, and the deformation of the second step is 25%; after polishing and removing the defects, one fire upsetting and elongation forging is carried out at a heating temperature of 910℃, wherein the upsetting is completed in two steps, the deformation of the first step is 25%, and the deformation of the second step is 30%, to obtain the second bar.

[0043] Step (three): after the second bar in step (two) is polished and the defects are removed, first, two upsetting and one elongation forging is carried out in the first fire at a heating temperature of T1=790℃, the deformation of the first upsetting is 40%, and the deformation of the second upsetting is 45%, and a ring blank with an outer diameter of 435mm and an inner diameter of 230mm is punched; then, the diameter expansion forging is carried out in the second fire on the ring rolling machine at a heating temperature of T2=835℃, to obtain a pipe blank with an outer diameter of 455mm and an inner diameter of 333mm.

[0044] Step (four): the pipe blank in step (three) is first coated with steel on the surface, and then coated with copper, and then the package extrusion is carried out at a heating temperature of 770℃, and after the extrusion, the surface defects are removed by machining and the surface oxide layer is removed by sandblasting, to obtain an intermediate pipe material with an outer diameter of 440mm and an inner diameter of 330mm.

[0045] Step (five): the intermediate pipe material in step (four) is cold-rolled in four passes, and the deformation of each pass is 5%, 5%, 5% and 5% in turn, and after straightening, finishing and polishing, the finished pipe material with an outer diameter of 355mm and an inner diameter of 335mm is obtained.

[0046] Example 3:

[0047] A TB8 titanium alloy ingot with a diameter of 180mm and a length of 440mm is selected, the surface oxide layer and defects are removed on a lathe, and after chamfering both ends, the specific steps for preparing a TB8 titanium alloy pipe material with an outer diameter of 210mm and an inner diameter of 190mm by using the present application are as follows:

[0048] Step (one): the ingot is heated at a heating temperature of 1100℃ for a holding time of t=7.5min / mm*180mm=1350min, and then is subjected to one-time upsetting and elongation forging, wherein the upsetting is completed in two steps, the deformation of the first step of upsetting is 15%, and the deformation of the second step of upsetting is 15%, to obtain a first bar.

[0049] Step (two): after the first bar in step (one) is polished to remove defects, first one-time upsetting and elongation forging is performed at a heating temperature of 1030℃, wherein the upsetting is completed in two steps, the deformation of the first step of upsetting is 22%, and the deformation of the second step of upsetting is 23%; after polishing to remove defects, one-time upsetting and elongation forging is further performed at a heating temperature of 905℃, wherein the upsetting is completed in two steps, the deformation of the first step of upsetting is 23%, and the deformation of the second step of upsetting is 28%, to obtain a second bar.

[0050] Step (three): after the second bar in step (two) is polished to remove defects, first-time two-up-one-down forging is performed at a heating temperature of T1=795℃, the deformation of the first upsetting is 45%, the deformation of the second upsetting is 55%, and punching is performed to obtain a ring blank with an outer diameter of 270mm and an inner diameter of 175mm; then, second-time expanding forging is performed on a ring rolling mill at a heating temperature of T2=845℃, to obtain a pipe blank with an outer diameter of 285mm and an inner diameter of 188mm.

[0051] Step (four): the pipe blank in step (three) is first coated with steel and then coated with copper, and then is subjected to pack extrusion at a heating temperature of 760℃, and after extrusion, surface defects are removed by machining and the surface oxide layer is removed by sandblasting, to obtain an intermediate pipe material with an outer diameter of 235mm and an inner diameter of 185mm.

[0052] Step (five): the intermediate pipe material in step (four) is subjected to two passes of cold rolling, and the deformation of each pass of cold rolling is 10% and 5% respectively, and after straightening, finishing and polishing, a finished pipe material with an outer diameter of 210mm and an inner diameter of 190mm is obtained.

[0053] Example 4:

[0054] A TB8 titanium alloy ingot with a diameter of 280mm and a length of 680mm is selected, the surface oxide layer and defects are removed on a lathe, and after chamfering both ends, the specific steps for preparing a TB8 titanium alloy pipe material with an outer diameter of 385mm and an inner diameter of 340mm by using the application are as follows:

[0055] Step (one): the ingot is heated at a heating temperature of 1140℃ for a holding time of t=1580 min, and then is subjected to one-time upsetting and elongation forging, wherein the upsetting is completed in two steps, the deformation of the first step is 16%, and the deformation of the second step is 18%, to obtain the first bar.

[0056] Step (two): after the first bar in step (one) is polished to remove defects, it is first subjected to one-time upsetting and elongation forging at a heating temperature of 1025℃, wherein the upsetting is completed in two steps, the deformation of the first step is 21%, and the deformation of the second step is 24%; after polishing to remove defects, it is subjected to one-time upsetting and elongation forging at a heating temperature of 920℃, wherein the upsetting is completed in two steps, the deformation of the first step is 26%, and the deformation of the second step is 29%, to obtain the second bar.

[0057] Step (three): after the second bar in step (two) is polished to remove defects, it is first subjected to two-up-one-down forging in the first heating at a temperature of T1=788℃, the deformation of the first upsetting is 50%, and the deformation of the second upsetting is 60%, to obtain a ring blank with an outer diameter of 455mm and an inner diameter of 280mm; then, the ring blank is subjected to diameter expansion forging in the second heating at a temperature of T2=844℃ on a ring rolling mill, to obtain a pipe blank with an outer diameter of 470mm and an inner diameter of 338mm.

[0058] Step (four): the pipe blank in step (three) is first coated with steel, and then coated with copper, and then is subjected to pack extrusion at a heating temperature of 780℃, and after extrusion, the surface defects are removed by machining, and the surface oxide layer is removed by sandblasting, to obtain an intermediate pipe material with an outer diameter of 430mm and an inner diameter of 335mm.

[0059] Step (five): the intermediate pipe material in step (four) is subjected to two-pass cold rolling, and the deformation of each pass is 10% and 5% respectively, and after straightening, finishing and polishing, the finished pipe material with an outer diameter of 365mm and an inner diameter of 340mm is obtained.

[0060] The above is only a preferred embodiment of the present application, and does not limit the present application in any way. Any simple modification, change and equivalent change made according to the technical essence of the present application all fall within the protection scope of the technical solution of the present application.

Claims

1. A method of processing a TB8 titanium alloy tube, characterized by, The method comprises the following steps: Step (I): the ingot is subjected to one-time upsetting and elongating forging under the condition of a heating temperature of 1100-1150 DEG C and a holding time t, to obtain a first bar with a length to maximum cross-sectional thickness ratio of not more than 2.45; Step (II): the first bar in step (I) is subjected to one-time upsetting and elongating forging under the condition of a heating temperature of 1000-1050 DEG C and 900-950 DEG C respectively, to obtain a second bar with a length to maximum cross-sectional thickness ratio of not more than 2.45; Step (III): the second bar in step (II) is subjected to two-time forging under the condition of a heating temperature of 785-845 DEG C: First-time forging: the upsetting and elongating forging and punching are performed under the condition of a heating temperature T1, to obtain a ring blank with an inner diameter of 45-65% of the outer diameter; Second-time forging: the ring blank is subjected to diameter expanding forging under the condition of a heating temperature T2, to obtain a tube blank with an inner diameter of 50-75% of the outer diameter; Step (IV): the tube blank in step (III) is subjected to jacket extrusion under the condition of a heating temperature of 760-780 DEG C, and surface treatment is performed to obtain an intermediate tube with an inner diameter of 75-85% of the outer diameter; Step (V): the intermediate tube in step (IV) is subjected to cold rolling, to obtain a finished tube with an inner diameter of 85-95% of the outer diameter.

2. The method of claim 1, wherein the TB8 titanium alloy pipe is a pipe having a diameter of 50 mm or more. The holding time t in step (I) satisfies: when the ingot diameter D is not less than 200 mm, t is not less than 1500 min; when the ingot diameter D is less than 200 mm, t = λ×D, and the heating coefficient λ is 7.5-9.5 min / mm.

3. The method of claim 1, wherein the TB8 titanium alloy pipe is a pipe having a diameter of 50 mm or more. The upsetting in step (I) is completed in two steps, wherein the deformation amount of the first step is 15-20%, and the deformation amount of the second step is 15-25%.

4. The method of claim 1, wherein the TB8 titanium alloy pipe is a pipe having a diameter of 200 mm or more. The upsetting in step (II) is completed in two steps, wherein the deformation amount of the first step is 20-25%, and the deformation amount of the second step is 20-30%.

5. The method of claim 1, wherein the TB8 titanium alloy pipe is a pipe having a diameter of 200 mm or more. The heating temperatures T1 and T2 in step (III) satisfy: T2>T1 and T2-T1≥40 DEG C.

6. The method of claim 1, wherein the TB8 titanium alloy pipe is a pipe having a diameter of 200 mm or more. The upsetting and elongating in step (III) is two-up-one-down, and the deformation amount of each upsetting is 40-65%.

7. The method of claim 1, wherein the TB8 titanium alloy pipe is a pipe having a diameter of 200 mm or more. The jacket in step (IV) is a double-metal jacket, the outer layer is copper, and the inner layer is steel, that is, the surface of the tube blank is first coated with steel, and then coated with copper.

8. The method of claim 1, wherein the TB8 titanium alloy pipe is a pipe having a diameter of 200 mm or more. The surface treatment in step (IV) comprises machining to remove surface defects, sandblasting or pickling to remove surface oxide layers.

9. The method of claim 1, wherein the TB8 titanium alloy pipe is a pipe having a diameter of 200 mm or more. The cold rolling in step (V) is 1-4 passes, and the deformation amount of each pass is 5-10%.

Images