Surface treatment method of TC4 titanium alloy bar billet

Abstract

The invention discloses a surface treatment method of a TC4 titanium alloy bar billet. According to the method, the surface defects of the TC4 titanium alloy bar billet are removed by adopting a process route of peeling, pickling and polishing, and the surface defects are exposed by adjusting the peeling speed, peeling amount, cutting fluid concentration, pickling solution preparation and pickling conditions of a centerless lathe; and finally, residual defects on the surface of the TC4 bar billet are removed through polishing, so that the surface quality of the TC4 titanium alloy intermediate billet produced through hot working such as rolling or forging is improved. According to the method, through cooperation of the working procedures of peeling, acid pickling, inspection, polishing, inspection and the like, the defects of oxide skin, cracks, wrinkles and the like on the surface of the titanium alloy can be effectively removed, meanwhile, the polishing cost of the TC4 titanium alloy bar billet can be reduced to the maximum extent, the defects on the surface of the TC4 titanium alloy are effectively removed, a TC4 titanium alloy finished product has good surface quality, and the quality of the finished product is improved. The machining cost of the TC4 titanium alloy intermediate blank is reduced to a great extent, and the yield of TC4 titanium alloy products is increased.

Description

Technical Field

[0001] The invention belongs to the technical field of titanium alloy bar blank surface treatment, and in particular relates to a TC4 titanium alloy bar blank surface treatment method. Background Art

[0002] Titanium and titanium alloys have the characteristics of high specific strength, good medium temperature performance, corrosion resistance, non-magnetic and good welding performance. They have always been one of the "backbones" of the aerospace industry and have huge market demand. However, general titanium materials will produce surface cracks, folds and other defects during processes such as rolling, wire drawing and extrusion. As an intermediate billet, the surface quality of titanium alloy bar blanks has a crucial influence on the surface quality of titanium alloy bars and wire products. Therefore, the titanium alloy intermediate billet needs to be surface treated. Although the centerless lathe can effectively remove defects such as oxide scale, cracks, wrinkles, etc. caused by rolling or forging production processes, it is difficult to find the defects remaining on the surface of the bar blank after peeling. These defects are easy to have a serious impact on the surface of titanium alloy finished bars and wires, resulting in a low yield and yield of the finished product, and increasing the cost of surface inspection of the finished product.

[0003] At present, the surface treatment of TC4 titanium alloy intermediate billet is mainly done by peeling on a centerless lathe to remove surface oxide scale, cracks, wrinkles and other defects. In order to ensure that the surface defects of TC4 titanium alloy intermediate bar billet are completely removed, one is to increase the peeling amount, and the other is to solve it by peeling + grinding. However, increasing the peeling amount leads to a serious decrease in the yield rate of TC4 titanium alloy; although the peeling + grinding method can solve the problem of the decrease in the yield rate of TC4 titanium alloy, it is difficult to find residual fine cracks on the surface of the bar billet after peeling, which leads to the continuous extension of cracks in the subsequent processing process, resulting in a decrease in the yield rate of the finished product. Summary of the invention

[0004] In view of this, the object of the present invention is to provide a surface treatment method for TC4 titanium alloy bar blanks, which adopts a process route of peeling + pickling + grinding to remove surface defects of TC4 titanium alloy bar blanks, and exposes surface defects by adjusting the peeling speed, peeling amount, cutting fluid concentration, pickling solution preparation and pickling conditions of the centerless lathe; finally, residual defects on the surface of the TC4 bar blanks are removed by grinding, thereby improving the surface quality of TC4 titanium alloy intermediate billets produced by hot processing such as rolling or forging.

[0005] To achieve the above purpose, the present invention adopts the following technical solution.

[0006] A surface treatment method for a TC4 titanium alloy bar blank comprises the following steps:

[0007] (1) TC4 titanium alloy bar peeling

[0008] The surface of the rolled or forged bar is peeled, the double-sided peeling amount is 2 to 4 mm, the peeling speed is 0.1 to 0.3 m / min, and the cutting fluid concentration is 1% to 10%;

[0009] (2) Pickling of TC4 titanium alloy bars

[0010] Using a pickling solution to pickle the TC4 titanium alloy bar blank obtained in step (1);

[0011] (4) TC4 titanium alloy billet inspection

[0012] Inspect the surface of the pickled TC4 titanium alloy bar obtained in step (2) and mark the defect locations;

[0013] (4) TC4 titanium alloy bar grinding

[0014] According to the position and size of the defects marked in step (3), select a hand-held grinder or a rocker arm grinder to grind the defects of the rod blank clean;

[0015] (5) TC4 titanium alloy billet re-inspection

[0016] The surface of the TC4 titanium alloy bar blank that has been polished in step (4) is re-inspected, and the defects found in the re-inspection are polished and repaired again.

[0017] Furthermore, the pickling solution is a mixture of hydrofluoric acid solution and nitric acid solution, wherein, by volume percentage, HF:HNO3:H2O=3%~5%:15%~35%:60%~82%.

[0018] Furthermore, in step (2), the pickling time is 5 to 15 minutes, and the pickling temperature is room temperature.

[0019] Furthermore, the method further comprises washing the rod blank with a water gun after pickling in step (2) so that there is no residual pickling solution on the surface of the rod blank and no H attached to the surface of the rod blank. + .

[0020] Furthermore, in step (3), a lighting lamp is used to inspect the surface of each of the pickled TC4 titanium alloy rods obtained in step (2) and mark the defects exposed by pickling.

[0021] Furthermore, in step (4), a handheld grinder is used to grind the rod blanks with fewer surface defects, shallower depth and smaller area; and a rocker arm grinder is used to grind the rod blanks with more surface defects, deeper depth and larger area.

[0022] Furthermore, in step (4), the deep pits on the surface of the rod blank are polished to achieve a smooth transition, with a depth-to-width ratio of 1 / 8 to 1 / 10.

[0023] Furthermore, in step (5), a lighting lamp is used to perform a surface inspection on the rod blank that has been polished in step (4), and the defects that have not been polished clean are marked, and then the defects that have not been polished clean are polished clean using a handheld grinder.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] The present invention provides a surface treatment process for a TC4 titanium alloy bar blank. Through the cooperation of peeling, pickling, inspection, grinding, testing and other processes, not only can the oxide scale, cracks, wrinkles and other defects on the surface of the titanium alloy be effectively removed, but also the grinding cost of the TC4 titanium alloy bar blank can be reduced to the maximum extent, the surface defects of the TC4 titanium alloy can be effectively removed, so that the TC4 titanium alloy finished product has good surface quality, the processing cost of the TC4 titanium alloy intermediate blank is greatly reduced, and the yield rate of the TC4 titanium alloy product is improved.

[0026] The finished product rates of TC4 titanium alloy wires, coils and other products obtained by the surface treatment method of the TC4 titanium alloy bar blank of the present invention are all greater than 80%, the yields are all greater than 98%, and the cost of the finished product inspection process is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the description of the prior art. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0028] Figure 1 It is a schematic diagram of the process flow of the surface treatment method of TC4 titanium alloy bar blank of the present invention;

[0029] Figure 2 The surface quality of the TC4 titanium alloy bar blank obtained by processing in Example 1 of the present invention;

[0030] Figure 3 The surface quality of the TC4 titanium alloy bar blank after peeling provided in Example 1 of the present invention;

[0031] Figure 4 The surface quality of the TC4 titanium alloy bar blank after pickling provided in Example 1 of the present invention;

[0032] Figure 5 The surface quality of the TC4 titanium alloy bar blank after grinding provided in Example 1 of the present invention. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the following will be clearly and completely described in conjunction with the embodiments of the present invention. The described embodiments are only part of the embodiments of the present invention, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] The invention provides a surface treatment method for a TC4 titanium alloy bar blank. Figure 1 The process flow chart of the treatment method is shown in FIG. , and the method comprises the following steps:

[0035] (1) TC4 titanium alloy bar peeling

[0036] The surface of the rolled or forged bar is peeled, the double-sided peeling amount is 2 to 4 mm, the peeling speed is 0.1 to 0.3 m / min, and the cutting fluid concentration is 1% to 10%;

[0037] (2) Pickling of TC4 titanium alloy bars

[0038] The TC4 titanium alloy bar blank obtained in step (1) is pickled using a pickling solution; the pickling time is 5 to 15 minutes and the pickling temperature is room temperature.

[0039] Preferably, the pickling solution is a mixture of hydrofluoric acid solution and nitric acid solution, wherein, by volume percentage, HF:HNO3:H2O=3%~5%:15%~35%:60%~82%.

[0040] Preferably, the method further comprises flushing the rod blank with a water gun after pickling in step (2) so that there is no residual pickling solution and H attached to the surface of the rod blank. + .

[0041] (3) TC4 titanium alloy billet inspection

[0042] The surface of the pickled TC4 titanium alloy bar blank obtained in step (2) is inspected and the defect positions are marked; further, a lighting lamp is used to inspect the surface of each of the pickled TC4 titanium alloy bar blanks obtained in step (2) and the defects exposed by pickling are marked.

[0043] (4) TC4 titanium alloy bar grinding

[0044] According to the position and size of the defects marked in step (3), select a hand-held grinder or a rocker arm grinder to grind the defects of the rod blank clean;

[0045] (5) TC4 titanium alloy billet re-inspection

[0046] The surface of the TC4 titanium alloy bar blank that has been polished in step (4) is re-inspected, and the defects found in the re-inspection are polished and repaired again. Furthermore, the bar blank with a small number of surface defects, a shallow depth, and a small area is polished with a handheld grinder; the bar blank with a large number of surface defects, a deep depth, and a large area is polished with a rocker arm grinder. For the deep pits on the surface of the bar blank, a smooth transition is performed during polishing, and the depth-to-width ratio is 1 / 8 to 1 / 10.

[0047] Furthermore, a lighting lamp is used to perform a surface inspection on the rod blank that has been polished in step (4), and the defects that have not been polished clean are marked, and then the defects that have not been polished clean are polished clean using a handheld polisher.

[0048] Example 1

[0049] A TC4 titanium alloy bar with a size of Φ100mm was selected. After rolling, a layer of oxide scale would form on the surface. The centerless lathe was used with a double-sided peeling amount of 3mm, a peeling speed of 0.2m / min, and a cutting fluid concentration of 5%. The Φ100mm titanium alloy bar was machined and peeled to remove the oxide scale on the surface of the bar.

[0050] The pickling solution was prepared with 3% vol-HF, 15 vol-% HNO3 and 82 vol-% H2O. The pickling time was 10 min. The peeled bar was pickled until the metal luster was reached and the fine cracks, wrinkles and other defects remaining on the surface of the bar were completely exposed. After pickling, the bar was immediately rinsed to remove the pickling solution and H2O remaining on the surface of the bar. + Remove cleanly.

[0051] The pickled rods are inspected one by one using a lighting lamp, and defects such as cracks, wrinkles, pits, etc. on the surface of the rods are marked.

[0052] Handheld grinders are used to grind the rods with fewer surface defects, shallower depth and smaller area; rocker grinders are used to grind the rods with more surface defects, deeper depth and larger area. Deep pits on the surface of the rods need to be smoothly transitioned during grinding to ensure a depth-to-width ratio of 1 / 9.

[0053] Use lighting to recheck the polished bar billets one by one and mark the defects that are not polished cleanly. The unpolished bar billets are polished with a hand-held grinder until there are no defects on the surface of the bar billets, ensuring that the defects of the intermediate billets will not extend to the finished products and the product yield rate is guaranteed. Figure 2 The surface quality of the TC4 titanium alloy bar blank obtained by the treatment in this embodiment is shown in FIG.

[0054] The surface of the TC4 titanium alloy bar after peeling treated by the process route of this example is as follows Figure 3 As shown in the figure, there are no obvious defects such as oxide scale and black pits on the surface of the bar billet after peeling; after pickling the bar billet after peeling, fine cracks on the surface of the bar billet are exposed as shown in the figure. Figure 4 As shown, pickling exposes small defects on the surface of the rod blank, and then grinding can ensure that the surface of the rod blank is free of any defects, which can meet the finished product rate and yield of TC4 titanium alloy rods and wires to the greatest extent.

[0055] Example 2

[0056] A TC4 titanium alloy billet with a size of Φ165mm was selected. After rolling, a layer of oxide scale would form on the surface. The centerless lathe had a double-sided peeling amount of 2mm, a peeling speed of 0.1m / min, and a cutting fluid concentration of 1%. The Φ165mm titanium alloy billet was machined and peeled to remove the oxide scale on the billet surface.

[0057] The pickling solution was prepared with 4 vol-% HF, 25 vol-% HNO3 and 71 vol-% H2O. The pickling time was 15 min. The peeled bar was pickled until the metal luster was reached and the fine cracks, wrinkles and other defects remaining on the surface of the bar were completely exposed. After pickling, the bar was immediately rinsed to remove the pickling solution and H2O remaining on the surface of the bar. + Remove cleanly.

[0058] The pickled rods are inspected one by one using a lighting lamp, and defects such as cracks, wrinkles, pits, etc. on the surface of the rods are marked.

[0059] Handheld grinders are used to grind the rods with fewer surface defects, shallower depth and smaller area; rocker grinders are used to grind the rods with more surface defects, deeper depth and larger area. Deep pits on the surface of the rods need to be smoothly transitioned during grinding to ensure a depth-to-width ratio of 1 / 8.

[0060] Use lighting to recheck the polished bar billets one by one and mark the defects that are not polished cleanly. The unpolished bar billets are polished with a hand-held grinder until there are no defects on the surface of the bar billets, ensuring that the defects of the intermediate billets will not extend to the finished products and the product yield rate is guaranteed.

[0061] Example 3

[0062] A TC4 titanium alloy bar with a size of Φ45mm was selected. After rolling, a layer of oxide scale would form on the surface. The centerless lathe had a double-sided peeling amount of 4mm, a peeling speed of 0.3m / min, and a cutting fluid concentration of 10%. The Φ45mm titanium alloy bar was machined and peeled to remove the oxide scale on the surface of the bar.

[0063] The pickling solution was prepared with 5% HF, 35% HNO3 and 60% H2O. The pickling time was 5 minutes. The peeled bar was pickled until the metal luster was reached, and the fine cracks, wrinkles and other defects remaining on the surface of the bar were completely exposed. After pickling, the bar was immediately rinsed to remove the pickling solution and H2O remaining on the surface of the bar. + Remove cleanly.

[0064] The pickled rods are inspected one by one using a lighting lamp, and defects such as cracks, wrinkles, pits, etc. on the surface of the rods are marked.

[0065] Handheld grinders are used to grind the rods with fewer surface defects, shallower depth and smaller area; rocker grinders are used to grind the rods with more surface defects, deeper depth and larger area. Deep pits on the surface of the rods need to be smoothly transitioned during grinding to ensure a depth-to-width ratio of 1 / 8.

[0066] Use lighting to recheck the polished bar billets one by one and mark the defects that are not polished cleanly. The unpolished bar billets are polished with a hand-held grinder until there are no defects on the surface of the bar billets, ensuring that the defects of the intermediate billets will not extend to the finished products and the product yield rate is guaranteed.

[0067] In view of the above-mentioned TC4 titanium alloy intermediate bar surface quality problem, we successfully solved the above problem through the process of peeling + pickling + grinding. The oxide scale on the surface of the rolled or forged intermediate bar is removed by the centerless lathe, and then the TC4 titanium alloy intermediate bar is washed to a metallic luster by pickling, and the defects remaining on the surface of the intermediate bar after peeling are exposed, and then the surface defects of the intermediate bar are removed by grinding.

[0068] Through the bar surface treatment technology route of peeling + pickling + grinding, the TC4 titanium alloy coil and wire product yield rate produced by the peeling and peeling + grinding process routes is about 75%, and the yield rate is about 95%. Using the peeling + pickling + grinding bar surface treatment process, the TC4 titanium alloy finished product yield rate is greater than 80%, and the yield rate is greater than 98%.

[0069] It should be noted that the above-described embodiments are only preferred embodiments of the present invention. For those skilled in the art, without departing from the principles of the present invention, the present invention may be modified, improved and replaced with equivalents, and these modifications, improvements and equivalent replacements are also considered to fall within the scope of protection of the claims of the present invention.

Claims

1. A surface treatment method for TC4 titanium alloy bar blank, characterized in that: The steps include: (1) TC4 titanium alloy bar peeling The surface of the rolled or forged bar is peeled, the double-sided peeling amount is 2 to 4 mm, the peeling speed is 0.1 to 0.3 m / min, and the cutting fluid concentration is 1% to 10%; (2) Pickling of TC4 titanium alloy bars Using a pickling solution to pickle the TC4 titanium alloy bar blank obtained in step (1); (3) TC4 titanium alloy billet inspection Inspect the surface of the pickled TC4 titanium alloy bar obtained in step (2) and mark the defect locations; (4) TC4 titanium alloy bar grinding According to the position and size of the defects marked in step (3), select a hand-held grinder or a rocker arm grinder to grind the defects of the rod blank clean; (5) TC4 titanium alloy billet re-inspection The surface of the TC4 titanium alloy bar blank that has been polished in step (4) is re-inspected, and the defects found in the re-inspection are polished and repaired again.

2. The surface treatment method of TC4 titanium alloy bar blank according to claim 1, characterized in that: The pickling solution is a mixture of hydrofluoric acid solution and nitric acid solution, wherein by volume percentage, HF:HNO3:H2O=3%-5%:15%-35%:60%-82%.

3. The surface treatment method of TC4 titanium alloy bar blank according to claim 1, characterized in that: In step (2), the pickling time is 5 to 15 minutes, and the pickling temperature is room temperature.

4. The surface treatment method of TC4 titanium alloy bar blank according to claim 1, characterized in that: The process further includes washing the rod blank with a water gun after pickling in step (2) so that no pickling solution or H attached to the surface of the rod blank remains on the surface of the rod blank. + .

5. The surface treatment method of TC4 titanium alloy bar blank according to claim 1, characterized in that: In step (3), a lighting lamp is used to inspect the surface of each of the pickled TC4 titanium alloy rods obtained in step (2) and mark the defects exposed by pickling.

6. The surface treatment method of TC4 titanium alloy bar blank according to claim 1, characterized in that: In step (4), a hand-held grinder is used to grind the rod blanks with fewer surface defects, shallower depth and smaller area; and a rocker arm grinder is used to grind the rod blanks with more surface defects, deeper depth and larger area.

7. The surface treatment method of TC4 titanium alloy bar blank according to claim 1, characterized in that: In step (4), the deep pits on the surface of the rod blank are polished to achieve a smooth transition, with a depth-to-width ratio of 1 / 8 to 1 / 10.

8. The surface treatment method of TC4 titanium alloy bar blank according to claim 1, characterized in that: In step (5), the surface of the rod blank polished in step (4) is inspected by using an illumination lamp, and the defects that have not been polished clean are marked, and then the defects that have not been polished clean are polished clean by using a handheld polisher.

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