Surface machining method for high-temperature alloy master alloy bar

Abstract

The invention provides a surface processing method of a high-temperature alloy mother alloy bar, which comprises the following steps: S1, dry ice cleaning pretreatment: spraying dry ice on the surface of the high-temperature alloy mother alloy bar, and cleaning the surface of the high-temperature alloy mother alloy bar; and S2, finish turning machining is conducted, specifically, lathe turning is adopted for conducting finish machining on the surface of the bar subjected to dry ice cleaning pretreatment in the step S1. According to the method, the rough turning step in the traditional turning process is creatively replaced with dry ice cleaning, the dry ice cleaning and the finish turning step are combined, an economical'dry ice and finish turning 'surface machining route is provided, and the advantages of low machining loss and high surface cleanliness can be considered at the same time.

Description

Technical Field

[0001] The invention relates to the technical field of alloy surface processing, in particular to a surface processing method for a high-temperature alloy master alloy bar. Background Art

[0002] High-temperature alloys have become the preferred material for hot-end components of modern aircraft engines and gas turbines because of their excellent comprehensive properties such as high-temperature creep resistance, fatigue resistance, oxidation resistance and heat corrosion resistance. They are composed of a large amount of strategic or rare resource metal elements such as Ni, Co, W, Cr, Ta, Mo, Ti, Hf, Zr, Re, Ru, Ce, Y, La, etc., and are a costly key metal material.

[0003] The mainstream preparation method of high-temperature alloy master alloy is the melting and casting method. The high-temperature casting process will form surface defects such as oxidation contamination layer, sand holes, surface inclusions, etc., which will reduce the surface cleanliness of the alloy. In the remelting process of the downstream parts industry, these surface defects will enter the melt as a source of contamination, seriously deteriorating the purity of the alloy and reducing the qualified rate of parts. Therefore, it is necessary to perform surface treatment on the master alloy bar to reduce the risk of these surface defects entering the interior of the alloy parts.

[0004] At present, there are five traditional methods for surface treatment of master alloy bars: lathe turning, belt / wheel grinding, shot blasting, sand blasting, and laser cleaning. Among them, turning has the best surface cleanliness, but it has problems such as large processing loss, low yield, fast tool wear, and long working hours, resulting in high processing costs. Compared with turning, grinding can reduce processing losses to a certain extent and can effectively remove surface defects such as surface oxide layer and sandstone. It has been partially applied in the industry, but studies have found that there is a problem of grinding wheel abrasive embedded in the alloy surface after grinding. A large number of surface aluminum oxide inclusions can be observed under an electron microscope, which cannot be used on some aerospace products with strict quality requirements.

[0005] Shot blasting, sand blasting, and laser cleaning are relatively efficient surface processing methods. Their processing losses are much lower than turning and grinding, and their processing efficiency is higher, but their processed surface cleanliness is poor. Shot blasting cannot completely remove the oxide layer on the surface. At the same time, the steel shots and steel grit used in shot blasting will adhere to the surface of the alloy, causing the surface composition of the alloy to change, and the alloy grade cannot be identified by the direct reading spectrometer. The surface of the alloy treated with sand blasting is matte, the alloy surface adsorbs more gas, and there is sand embedded in the alloy surface. The secondary oxidation phenomenon of the alloy surface after laser cleaning is extremely serious. Therefore, these three methods are only used in downstream parts and components, and are rarely used on master alloys.

[0006] In summary, developing a surface processing method that can take into account both low processing loss and high surface cleanliness is of great significance to improving product delivery rate and reducing costs and increasing efficiency of enterprises.

[0007] In view of this, the present invention is proposed. Summary of the invention

[0008] The purpose of the present invention is to provide a surface processing method for a high-temperature alloy master alloy bar, which innovatively replaces the rough turning step in the traditional turning process with dry ice cleaning, combines the dry ice cleaning with the fine turning step, and provides an economical "dry ice + fine turning" surface processing route, which can take into account the advantages of both low processing loss and high surface cleanliness.

[0009] In order to achieve the above object, the present invention provides the following technical solutions:

[0010] S1. Dry ice cleaning pretreatment: spray dry ice on the surface of the high-temperature alloy master alloy bar to clean its surface;

[0011] S2, finishing machining: using a lathe to finish the surface of the bar material after the dry ice cleaning pretreatment in step S1.

[0012] Preferably, in step S1, the diameter range of the dry ice particles is 0.5 to 5 mm; and / or the spray pressure of the dry ice is 0.3 to 2.0 MPa; and / or the dry ice flow rate is 0.1 to 1.0 kg / min; and / or the cleaning time is 2 to 5 min / rod.

[0013] Preferably, in step S2, the feed rate used in the finish turning process is 0.05-0.5 mm; and / or, the finish turning speed is 200-400 r / min; and / or, the finish turning feed rate is 0.05-0.2 mm / r.

[0014] Preferably, the diameter of the master alloy bar is

[0015] Compared with the prior art, the technical solution of the present invention has at least the following technical effects:

[0016] (1) Compared with traditional turning, the present invention replaces the rough turning step with dry ice cleaning, which greatly reduces processing loss and labor time consumption and improves the product delivery rate.

[0017] (2) Compared with grinding wheel / belt grinding, shot blasting, sand blasting, laser cleaning, and dry ice cleaning alone, the surface cleanliness of the surface processed by the present invention is better, and the subsequent finishing step can make the final alloy surface cleanliness equal to that of traditional turning processing, and the purity level evaluated by the HB 5406-2016 slag test is high.

[0018] (3) The present invention takes into account the advantages of both low processing loss and high surface cleanliness, and is an economical method for surface processing of high-temperature alloy master alloy bars. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The drawings in the specification, which constitute a part of this application, are used to provide a further understanding of the present invention. The illustrative embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0020] in:

[0021] Figure 1 This is a macroscopic image of the surface of the alloy bar after surface processing in Example 1;

[0022] Figure 2 , 3 4 is a microscopic electron microscope image of the surface of the alloy bar after surface processing in Example 1;

[0023] Figure 5 This is a macroscopic image of the surface of the alloy bar after surface processing in Comparative Example 1;

[0024] Figure 6 , 7 8 is a microscopic electron microscope image of the surface of the alloy bar after surface processing in Comparative Example 1;

[0025] Fig. 9 This is a macroscopic image of the surface of the alloy bar after surface processing in Comparative Example 2;

[0026] Fig.10 , 11 12 is a microscopic electron microscope image of the surface of the alloy bar after surface processing in Comparative Example 2;

[0027] Fig.13 This is a macroscopic image of the surface of the alloy bar after surface processing in Comparative Example 3;

[0028] Fig.14 , 15 16 is a microscopic electron microscope image of the surface of the alloy bar after surface processing in Comparative Example 3;

[0029] Fig.17 This is a macroscopic image of the surface of the alloy bar after surface processing in Comparative Example 4;

[0030] Fig.18 , 19 20 is a microscopic electron microscope image of the surface of the alloy bar after surface processing in Comparative Example 4;

[0031] Fig.21 This is a macroscopic image of the surface of the alloy bar after surface processing in Comparative Example 5;

[0032] Fig. 22 , 23 24 is a microscopic electron microscope image of the surface of the alloy bar after surface processing in Comparative Example 5;

[0033] Fig.25 This is the liquid surface scum distribution diagram of Example 1;

[0034] Fig.26 This is the liquid surface scum distribution diagram of Comparative Example 1;

[0035] Fig. 27 This is the liquid surface scum distribution diagram of Comparative Example 2;

[0036] Fig.28 This is the liquid surface scum distribution diagram of Comparative Example 3;

[0037] Fig.29 This is the liquid surface scum distribution diagram of Comparative Example 4;

[0038] Fig.30 This is the liquid surface scum distribution diagram of Comparative Example 5. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical scheme and advantages of the present invention clearer, the technical scheme in the embodiment of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present invention. The process parameters of the following embodiments that do not specify specific conditions are usually based on conventional conditions.

[0040] The endpoints and any values ​​of the ranges disclosed in the present invention are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be regarded as specifically disclosed in the present invention.

[0041] According to a first aspect of the present invention, there is provided a surface processing method for a high temperature alloy master alloy bar, comprising the following steps:

[0042] S1. Dry ice cleaning pretreatment: spray dry ice on the surface of the high-temperature alloy master alloy bar to clean its surface;

[0043] S2, finishing machining: using a lathe to finish the surface of the bar material after the dry ice cleaning pretreatment in step S1.

[0044] Traditional turning is mainly divided into two steps: rough turning and fine turning. Rough turning is a rough processing process, using a large-sized turning tool, the purpose of which is to remove the oxide contamination layer on the surface of the alloy, which can effectively reduce the wear of the oxide contamination layer on the fine turning tool during the fine turning process and avoid the occurrence of tool hitting and tool vibration. Since the surface of the cast alloy bar is often uneven and not a standard cylindrical shape, a larger cutting depth (>1mm) must be used to remove all the oxide layers, and the cutting speed is correspondingly reduced, which is the largest part of the processing loss; while fine turning is a fine processing process, the purpose of which is to improve the surface quality of the alloy and make the alloy surface bright, only a small-sized turning tool is needed, the cutting depth is shallow (<0.5mm), and the processing speed is fast. In addition, there is a more economical rust removal method - dry ice cleaning. The principle is that when dry ice (solid CO2) is sprayed onto the surface of an object at high speed, it will sublimate and expand 600 to 800 times in volume, similar to a tiny explosion process, forming a strong airflow, thereby removing dirt and sediments on the metal surface. Dry ice cleaning has the advantages of reducing environmental pollution, protecting the surface of the substrate, not generating high temperatures to damage the substrate, and leaving no residue. However, due to the low density of dry ice, the impact force of cleaning cannot completely remove the oxide layer on the surface of the alloy. A thin oxide film (<0.2μm) still exists on the surface after cleaning under a microscopic electron microscope. The present invention innovatively replaces the rough turning step in the traditional turning process with dry ice cleaning, combines dry ice cleaning with the fine turning step, and provides an economical "dry ice + fine turning" surface processing route. On the one hand, the present invention removes most of the oxide layer on the surface of the alloy bar through dry ice cleaning, reducing the damage of the oxide layer to the subsequent fine turning tool, which not only replaces the role of the rough turning step, but also greatly reduces processing losses and labor time consumption; on the other hand, the present invention effectively removes the residual thin oxide film through the subsequent fine turning step, so that the surface cleanliness and brightness of the final alloy product are consistent with the traditional "rough turning + fine turning" turning process.

[0045] The present invention performs bar cutting before dry ice cleaning pretreatment, cuts off defective parts at the head and tail of the bar, fixes the bar with the head and tail cut off on a platform or a tooling rack for dry ice cleaning, mounts the bar after dry ice cleaning on a lathe, and performs fine processing on the alloy surface with a small feed amount, so that the alloy surface presents a metallic luster before entering the next process.

[0046] In the above-mentioned surface processing method, as a preferred embodiment, in step S1, the diameter range of the dry ice particles is 0.5 to 5 mm; a typical but non-limiting diameter range is 0.5 mm, 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm and 5 mm and a numerical range between any two points.

[0047] Too low dry ice blasting pressure has poor effect on removing oxide scale and incomplete cleaning; while too high blasting pressure will produce strong surface work hardening effect on the surface of alloy bar, produce micro cracks on the surface, and accelerate tool wear during finishing process. Preferably, the blasting pressure of dry ice is 0.3-2.0MPa; typical but non-limiting blasting pressures are 0.3Mpa, 0.4Mpa, 0.5Mpa, 0.6Mpa, 0.7Mpa, 0.8Mpa, 0.9Mpa, 1.0Mpa, 1.1Mpa, 1.2Mpa, 1.3Mpa, 1.4Mpa, 1.5Mpa, 1.6Mpa, 1.7Mpa, 1.8Mpa, 1.9Mpa and 2.0Mpa and the range of values ​​between any two points.

[0048] Too small a dry ice flow rate will result in poor scale removal effect and incomplete cleaning; while too large a dry ice flow rate will cause unnecessary waste of dry ice particles; preferably, the dry ice flow rate is 0.1-1.0 kg / min; typical but non-limiting dry ice flow rates are 0.1 kg / min, 0.2 kg / min, 0.3 kg / min, 0.4 kg / min, 0.5 kg / min, 0.6 kg / min, 0.7 kg / min, 0.8 kg / min, 0.9 kg / min and 1.0 kg / min and a numerical range between any two points.

[0049] Too short a cleaning time will result in incomplete cleaning; too long a cleaning time will result in unnecessary waste of time; according to the conventional diameter The high-temperature alloy master alloy bar material specification is preferably used, and the cleaning time is 2 to 5 minutes per bar; typical but non-limiting cleaning times are 2 minutes per bar, 3 minutes per bar, 4 minutes per bar and 5 minutes per bar, and a numerical range between any two points.

[0050] In the above-mentioned surface processing method, as a preferred embodiment, in step S2, the finishing turning is a high-speed turning process. The high-temperature alloy master alloy bar itself has high strength. Excessive feed will cause destructive damage to the turning tool head, resulting in frequent maintenance and replacement of the tool head. At the same time, since most of the oxide scale on the surface of the bar has been effectively removed in step S1, the finishing feed does not need to be set too large. A small feed is used during the finishing. Preferably, the small feed is 0.05 to 0.5 mm. Typical but non-restrictive small feeds are 0.05 mm, 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm and 0.5 mm and the numerical range between any two points.

[0051] Since most of the scale on the surface of the bar has been effectively removed in step S1, the finishing speed can be set higher to improve the processing efficiency. Preferably, the speed is 200-400r / min, and typical but non-limiting speeds are 200r / min, 250r / min, 300r / min and 400r / min and the range of values ​​between any two points.

[0052] In order to obtain better flatness of the master alloy bar, the finishing feed should be set smaller, but too small a feed will also reduce the processing efficiency. Preferably, the feed is 0.05-0.2 mm / r, and typical but non-limiting speeds are 0.05 mm / r, 0.10 mm / r and 0.20 mm / r and any range between two points.

[0053] The present invention will be described in detail below in conjunction with the accompanying drawings and embodiments of the present invention. Each example is provided by way of explanation of the present invention and does not limit the present invention. In fact, it will be clear to those skilled in the art that modifications and variations may be made in the present invention without departing from the scope or spirit of the present invention. For example, a feature shown or described as a part of an embodiment may be used in another embodiment to produce yet another embodiment. Therefore, it is desired that the present invention includes such modifications and variations within the scope of the appended claims and their equivalents.

[0054] Example 1

[0055] This embodiment adopts the present invention to perform surface processing on a K418 alloy round bar with a diameter of 80 mm, and the specific operations are as follows:

[0056] (1) Before surface processing, the bar is cut to remove the defective parts at the head and tail of the bar.

[0057] (2) Dry ice cleaning pretreatment: Place the cut rod on the ground and use a handheld dry ice cleaning machine to clean its surface with dry ice. Use 2-3 mm dry ice particles, set the spray pressure to 0.4 MPa, set the dry ice flow rate to 0.4 kg / min, and the cleaning time is about 2 min / rod.

[0058] (3) Finishing machining: The bar material after dry ice cleaning is mounted on a lathe, and the surface of the bar material is directly finished by using a feed amount of 0.3 mm, a rotation speed of 200 r / min, and a feed rate of 0.1 mm / r.

[0059] (4) After surface processing, visually inspect the surface of the bar, use a handheld grinder to grind away any residual defects, and finally wipe the surface of the bar with alcohol, weigh and record it, and package it for storage.

[0060] Comparative Example 1

[0061] Comparative Example 1 The K418 alloy round bars of the same batch as Example 1 were surface processed by conventional turning, and the specific operations were as follows:

[0062] (1) Before surface processing, the bar is cut to remove the defective parts at the head and tail of the bar.

[0063] (2) Rough turning: After cutting the head and tail, install the bar on the lathe, use a large-size turning tool to rough-machine the bar surface, set the feed amount to 1mm, the speed to 80r / min, and the feed rate to 0.5mm / r to remove most of the black skin on the surface.

[0064] (3) Finishing machining: After rough turning, replace the small-sized turning tool and use a feed amount of 0.3 mm, a rotation speed of 200 r / min and a feed rate of 0.1 mm / r to finish the surface of the bar.

[0065] (4) After surface processing, visually inspect the surface of the bar, use a handheld grinder to grind away any residual defects, and finally wipe the surface of the bar with alcohol, weigh and record it, and package it for storage.

[0066] Comparative Example 2

[0067] Comparative Example 2: Dry ice cleaning was used to perform surface processing on the K418 alloy round bars of the same batch as Example 1. The specific operation was as follows:

[0068] (1) Before surface processing, the bar is cut to remove the defective parts at the head and tail of the bar.

[0069] (2) Dry ice cleaning: Place the cut rod on the ground and use a handheld dry ice cleaning machine to clean its surface with dry ice. Use 2-3 mm dry ice particles, set the spray pressure to 0.4 MPa, set the dry ice flow rate to 0.4 kg / min, and the cleaning time is about 2 min / rod.

[0070] (3) After surface processing, visually inspect the surface of the bar, use a handheld grinder to grind away any residual defects, and finally wipe the surface of the bar with alcohol, weigh and record it, and package it for storage.

[0071] Comparative Example 3

[0072] Comparative Example 3: The K418 alloy round bars of the same batch as Example 1 were surface processed by laser cleaning. The specific operation is as follows:

[0073] (1) Before surface processing, the bar is cut to remove the defective parts at the head and tail of the bar.

[0074] (2) Laser cleaning: Place the bar material after cutting on the ground and use a handheld laser to clean its surface. The cleaning mode is dry method, the light source type is set to Gaussian light, the pulse frequency is set to 3000kHz, and the laser power is set to 800W.

[0075] (3) After surface processing, visually inspect the surface of the bar, use a handheld grinder to grind away any residual defects, and finally wipe the surface of the bar with alcohol, weigh and record it, and package it for storage.

[0076] Comparative Example 4

[0077] Comparative Example 4: The K418 alloy round bars of the same batch as Example 1 were surface processed by sandblasting. The specific operation is as follows:

[0078] (1) Before surface processing, the bar is cut to remove the defective parts at the head and tail of the bar.

[0079] (2) Sand blasting: Fix the rod material after cutting the head and tail on the sand blasting table, and use a handheld sand blasting machine to blast the surface of the rod material. The sand blasting mode is dry spraying, and the sand blasting abrasive is quartz sand. The sand blasting pressure is 0.5MPa.

[0080] (3) After surface processing, visually inspect the surface of the bar, use a handheld grinder to grind away any residual defects, and finally wipe the surface of the bar with alcohol, weigh and record it, and package it for storage.

[0081] Comparative Example 5

[0082] Comparative Example 5: The K418 alloy round bars of the same batch as Example 1 were surface processed by shot blasting. The specific operation is as follows:

[0083] (1) Before surface processing, the bar is cut to remove the defective parts at the head and tail of the bar.

[0084] (2) Shot blasting: Place the cut rods into a drum shot blasting machine for shot blasting. Use No. 45 steel shot as the shot. The rod loading capacity for each shot blasting is 250 kg. The shot blasting time is 30 min. The shot blasting amount is 160 kg / min. The shot blasting speed is 60 m / s.

[0085] (3) After surface processing, visually inspect the surface of the bar, use a handheld grinder to grind away any residual defects, and finally wipe the surface of the bar with alcohol, weigh and record it, and package it for storage.

[0086] The surface cleanliness of the rods after surface processing in Example 1 and Comparative Examples 1-5, the purity grade evaluated by the scum test according to HB 5406-2016, the statistical processing loss, and the working time consumption are compared respectively. The specific data are shown in Table 1 and Table 2.

[0087] Table 1 (Surface cleanliness)

[0088] sample Physical ingot surface Microscopic electron microscope surface Example 1 Macro surface finish (see Figure 1 ) No impurities on the microscopic surface (see Figure 2 , 3 、4) Comparative Example 1 Macro surface finish (see Figure 5 ) No impurities on the microscopic surface (see Figure 6 , 7 、8) Comparative Example 2 Macro surface matte (see Fig. 9 ) The presence of unremoved oxide scale on the microscopic surface (see Fig.10 , 11 、12) Comparative Example 3 Macroscopic surface brightness (see Fig.13 ) Remelting and secondary oxidation phenomenon occurs on the microscopic surface (see Fig.14 , 15 、16) Comparative Example 4 Macro surface matte (see Fig.17 ) Microscopic surface embedded in quartz sand (see Fig.18 , 19 、20) Comparative Example 5 Macroscopic surface brightness (see Fig.21 ) Iron-containing impurities attached to the microscopic surface (see Fig. 22 , 23 ,twenty four)

[0089] Table 2 (Purity level, statistical processing loss, and working hours)

[0090]

[0091]

[0092] It can be seen from the data in Table 1 and Table 2 that, compared with Comparative Example 1 of the conventional turning process, Example 1 of the present invention reduces 69% of processing loss and 38% of man-hour consumption while ensuring that the surface cleanliness is not reduced, thereby improving economic benefits. Compared with other surface treatment methods such as sandblasting, shot blasting, laser cleaning, and dry ice cleaning, Example 1 of the present invention has significantly better surface cleanliness, and has significantly less scum after inspection according to HB 5406-2016, and has a higher purity level.

[0093] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A surface processing method for a high-temperature alloy master alloy bar, characterized in that: The following steps are involved: S1. Dry ice cleaning pretreatment: spray dry ice on the surface of the high-temperature alloy master alloy bar to clean its surface; S2, finishing machining: using a lathe to finish the surface of the bar material after the dry ice cleaning pretreatment in step S1.

2. The surface processing method according to claim 1, characterized in that: In step S1, the diameter of the dry ice particles ranges from 0.5 to 5 mm; And / or, the spraying pressure of the dry ice is 0.3-2.0 MPa; And / or, the dry ice flow rate is 0.1-1.0 kg / min; And / or, the cleaning time is 2 to 5 minutes per rod.

3. The surface processing method according to claim 1, characterized in that: In step S2, the feed rate used in the fine turning process is 0.05-0.5 mm; And / or, the finishing speed is 200-400 r / min; And / or, the finishing feed rate is 0.05-0.2 mm / r.

4. The surface processing method according to any one of claims 1 to 3, characterized in that: The diameter of the master alloy rod is φ50-φ100.

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