Recovery method of R60705 niobium-zirconium scrap-like waste

Abstract

The invention discloses a method for recovering R60705 niobium-zirconium scrap-like waste. The method comprises the following steps: 1, collecting the R60705 niobium-zirconium scrap-like waste; 2, pretreatment; 3, pressing and welding to obtain a scrap consumable electrode; step 4, carrying out VAR primary smelting to obtain a scrap ingot; fifthly, a niobium-zirconium square strip is obtained through forging and subjected to surface treatment; 6, pressing a raw material electrode block; seventhly, the raw material electrode block and the niobium-zirconium square strip subjected to surface treatment are installed and welded to obtain the consumable electrode; and 8, VAR secondary smelting is carried out. According to the method, a large amount of R60705 niobium-zirconium scrap-shaped waste which is high in O and N element content, low in price and difficult to use is taken as a raw material, the O and N elements in the R60705 niobium-zirconium scrap-shaped waste are effectively diluted by adopting a process route of first melting, then forging and remelting, the R60705 cast ingot meeting the standard is obtained, the R60705 niobium-zirconium scrap-shaped waste is greatly utilized, the raw material cost is greatly reduced, the process route is simple and feasible, and the method is suitable for industrial production. And the method is suitable for popularization.

Description

Technical Field

[0001] The invention belongs to the technical field of rare metal material metallurgy, and in particular relates to a method for recovering R60705 niobium-zirconium chip-like waste. Background Art

[0002] R60705 is a zirconium alloy containing 2.0% to 3.0% Nb. It is a multi-purpose material suitable for chemical corrosion-resistant equipment. Its acid resistance is better than titanium and close to that of metallic tantalum. R60705 can also maintain relatively stable performance in alkaline solution and is resistant to alkali and molten alkali corrosion. Since Nb can improve the strength and plasticity of Zr metal, it has excellent plasticity and excellent mechanical properties compared to industrial pure zirconium R60702. It is used to manufacture heat exchangers, container linings, valves, blades, agitators, ducts, etc. in chemical equipment, and has a wide range of uses. However, the high price of R60705 material has hindered its wider application in more civilian chemical fields, so the low cost of R60705 material is particularly important.

[0003] Low-cost preparation technology can be achieved by adding return materials. At present, R60705 block scrap (plate edge strips, ingot risers, rod heads, etc.) is used in this field to weld R60705 consumable electrodes by bundling scraps of the same grade, and R60705 ingots are obtained after 2 to 3 VAR smelting. This process route has certain technical difficulties, which are mainly reflected in the electrode welding process. During the atmospheric plasma welding process of R60705 material, the molten pool is exposed to the air and easily absorbs nitrogen to form compounds, causing the weld to be brittle and easy to crack, making it impossible to prepare consumable electrodes. After testing, the inert gas argon is used to protect the weld after plasma welding. The inert gas argon can effectively isolate the molten pool from contact with nitrogen in the air, effectively preventing the R60705 weld from absorbing nitrogen and then cracking, and solving the problem of being unable to prepare consumable electrodes.

[0004] Blocky waste (plate edge strips, ingot risers, rod heads, etc.) are easier to prepare consumable electrodes from the perspective of morphology and structural strength. Compared with blocky waste, the chips generated during lathe turning and milling of milling machines have a filamentous and clustered morphology without strength characteristics, and this shape cannot be directly welded to consumable electrodes. In addition, the Vickers hardness of R60705 material is as high as 600HV0.05. During machining such as turning and milling, the turning and milling tools collide with the high-hardness R60705 material instantly to generate high temperatures, causing the surface of the cut chips to be severely oxidized and nitrided, and the surface of the chips is instantly oxidized and nitrided from silver-white to blue-black. Therefore, even if such chips are melted by special means, they cannot be used normally because the O and N elements exceed the standard. Based on the above reasons, R60705 niobium zirconium chip waste is difficult to recycle and reuse. my country produces a large amount of R60705 turning and milling chip waste through machining every year, which needs to be destroyed and disposed of, resulting in a huge waste of resources and a certain harm to the environment. There is currently no technical means in this field to solve this problem.

[0005] Therefore, there is an urgent need for a recycling method for R60705 niobium zirconium chip waste, which can eliminate the problem of high O and N element content, and recycle the chips and remelt them into R60705 ingots that meet national standards. This not only saves resources, but also greatly reduces the cost of R60705 ingot raw materials, making it more widely used. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a method for recycling R60705 niobium zirconium chip waste in view of the above-mentioned deficiencies of the prior art. The method uses a large amount of R60705 niobium zirconium chip waste with high O and N content, low price and difficult to use as raw materials, and mixes the ingredients after accurate calculation according to the target product composition. The R60705 niobium zirconium chip waste is first smelted and forged, and then smelted with other raw materials to effectively dilute the O and N elements in the R60705 niobium zirconium chip waste, and obtain R60705 ingots that meet the standards, thereby solving the problem that the R60705 niobium zirconium chip waste cannot be used normally due to excessive O and N elements in it.

[0007] In order to solve the above technical problems, the technical solution adopted by the present invention is: a method for recycling R60705 niobium zirconium chip-like waste, characterized in that the method comprises the following steps:

[0008] Step 1: Collect the chip-like waste generated during the machining process of R60705 niobium-zirconium products, including turning and milling, and classify and store them;

[0009] Step 2: Pre-treat the R60705 niobium-zirconium chip waste classified and stored in step 1 by crushing, removing oil, removing saponification liquid, ultrasonic cleaning and dust-free drying;

[0010] Step 3, pressing the R60705 niobium zirconium scrap pretreated in step 2 to obtain a scrap electrode block, and then welding to obtain a scrap consumable electrode;

[0011] Step 4: Perform VAR primary smelting on the chip consumable electrode obtained in step 3 to obtain a chip ingot;

[0012] Step 5: Forging the scrap ingot obtained in step 4 to obtain niobium-zirconium square bars and performing surface treatment;

[0013] Step 6: Select the raw materials of zirconium sponge, niobium powder and ZrO2 according to the designed composition of the target product R60705 ingot and calculate the addition amount, and then press the zirconium sponge, niobium powder and ZrO2 into raw material electrode blocks;

[0014] Step 7: welding the raw material electrode block obtained in step 6 and the niobium-zirconium square bar surface-treated in step 5 to obtain a consumable electrode;

[0015] Step 8: subject the consumable electrode obtained in step 7 to secondary VAR smelting to obtain R60705 ingot.

[0016] The present invention uses R60705 niobium zirconium product machining process including turning and milling surface generated by chip-like waste (such as Figure 1 As shown in the figure, R60705 niobium zirconium scraps are used as raw materials. The surface of the R60705 niobium zirconium scraps is severely oxidized and nitrided during the machining process, and turns blue-black. In this regard, the present invention adopts a process route of first melting → re-forging → re-melting. First, the R60705 niobium zirconium scraps are pressed into scrap electrode blocks separately, and then welded into scrap consumable electrodes for VAR primary melting to obtain scrap ingots. Then, the scrap ingots are forged into niobium zirconium square bars (such as Figure 2 As shown), however, high temperature forging causes a milky white oxide layer to form on the surface of the niobium zirconium square bar, so the niobium zirconium square bar is surface treated to remove the oxide layer (as shown Figure 3 As shown), and then welded into a consumable electrode (as shown Figure 4 The R60705 niobium zirconium scrap is effectively diluted with O and N elements in the R60705 niobium zirconium scrap, and an R60705 ingot meeting the ASTM B551 / B551M-12 standard is smelted.

[0017] The above-mentioned method for recycling R60705 niobium zirconium chip-like waste is characterized in that the degreasing in step 2 is carried out using a metal cleaning agent, and the degreasing temperature is 60°C ± 5°C, the soaking time is 20 minutes, and the dust-free drying is carried out without contacting the ground. The present invention uses a metal cleaning agent for degreasing to fully dissolve the oil on the surface of the R60705 niobium zirconium chip-like waste, and avoids the volatilization of the metal cleaning agent to cause a decrease in concentration; at the same time, the dust-free drying of the present invention is carried out without contacting the ground to prevent the mixing of sand and impurities. In addition, since the R60705 material is an active metal, the R60705 niobium zirconium chip-like waste is very easy to catch fire during the crushing process, so a wet crushing method is used for crushing.

[0018] The above-mentioned method for recycling R60705 niobium zirconium chip-like waste is characterized in that, during the welding described in step three, plasma reinforcement welding of the chip electrode block is adopted outside the furnace. Since the chip electrode block is pressed from R60705 niobium zirconium chip-like waste, its strength is limited, especially the edges are relatively loose, so plasma reinforcement welding outside the furnace is adopted to improve the strength of the chip electrode block and ensure the smooth progress of the welding process; at the same time, plasma reinforcement welding outside the furnace has an argon protection effect on rare metals. After the molten pool on the surface of the rare metal is opened, the plasma welding can blow in inert gas argon. Argon effectively isolates the molten pool of the rare metal weld from reacting with the O and N elements in the atmosphere, reducing oxidation and nitridation, and ensuring the quality of the chip consumable electrode.

[0019] The above-mentioned method for recycling R60705 niobium zirconium chip-like waste is characterized in that the VAR primary smelting in step 4 is carried out in a crucible with a diameter of φ500mm. Since the R60705 niobium zirconium chip-like waste undergoes oxidation and nitridation to varying degrees during the machining process, the present invention shapes the R60705 niobium zirconium chip-like waste through VAR primary smelting and converts it into chip ingots for subsequent welding and smelting with niobium zirconium square bars.

[0020] The above-mentioned method for recycling R60705 niobium zirconium chip-like waste is characterized in that in step 4, the chip ingot is analyzed for chemical elements including Nb, O, Fe, N and other impurity elements. By analyzing the chemical element content of the chip ingot, the actual content of elements such as Nb, O, Fe, and N is determined as a basis for subsequent batching and pressing of raw material electrode blocks.

[0021] The above-mentioned method for recycling R60705 niobium zirconium chip-like waste is characterized in that the width×thickness×length of the niobium zirconium square bar in step 5 is 380mm×200mm×3500mm, and the niobium zirconium square bar is subjected to surface treatment such as machining and chamfering of side edges. Figure 2As shown in the figure, the surface of the niobium zirconium square bar obtained by forging the chip ingot is covered with a milky white compound oxide layer. Chemical methods such as alkali washing (NaOH) and hydrofluoric acid washing (HF) cannot remove the compound. Therefore, machining is used to remove the milky white compound formed on the surface after forging.

[0022] The above-mentioned method for recycling R60705 niobium-zirconium chip-like waste is characterized in that the designed composition of the target product R60705 ingot in step six is ​​Zr-2.489Nb-0.145O, and sponge zirconium, FNB-3 niobium powder and ZrO2 are selected as raw materials.

[0023] The above-mentioned method for recycling R60705 niobium zirconium chip-like waste is characterized in that the raw material electrode block is spot welded on the top of the niobium zirconium square bar during the group welding in step 7. For safety considerations in actual operation, the niobium zirconium square bar has a regular shape after milling, and it is relatively stable and not easy to shake when placed at the bottom. The raw material electrode block is placed on the top of it for welding, and it is also stable and not easy to shake. The edges are more closely cut, ensuring the smooth progress of subsequent smelting.

[0024] The above-mentioned method for recycling R60705 niobium-zirconium chip-like waste is characterized in that the number of VAR secondary smelting in step eight is 4 times, and the diameters of the ingot specifications in the VAR secondary smelting are: primary ingot φ560mm, secondary ingot φ640mm, tertiary ingot φ720mm, and finished ingot φ820mm.

[0025] The above-mentioned method for recycling R60705 niobium-zirconium chip-like waste is characterized in that in step eight, three points of the upper, middle and lower points of the R60705 ingot are used to take hydroxide blocks and chip samples for chemical element analysis.

[0026] Compared with the prior art, the present invention has the following advantages:

[0027] 1. The present invention uses R60705 niobium zirconium chip waste with high content of O and N elements as raw materials, adopts a melting → re-forging → re-melting process route, effectively dilutes the O and N elements in the R60705 niobium zirconium chip waste, controls the chemical composition of each element, obtains R60705 ingots that meet the standard ASTM B551 / B551M-12, realizes large-scale utilization of R60705 niobium zirconium chip waste, and solves the problem that R60705 niobium zirconium chip waste cannot be used normally due to excessive O and N elements in it.

[0028] 2. The present invention adopts low-cost R60705 niobium zirconium chip-like waste to partially replace the raw material sponge zirconium and Nb powder to prepare R60705 ingots, effectively utilizing the R60705 niobium zirconium chip-like waste that is difficult to recycle, saving the raw material sponge zirconium and Nb powder, greatly reducing the raw material cost, and facilitating the application of R60705 ingots in more fields.

[0029] 3. The method of recycling and remelting R60705 niobium zirconium chip waste of the present invention fills the gap in this field. The obtained R60705 ingot meets the standard ASTM B551 / B551M-12 and downstream deep processing technology and performance requirements, and the process route is simple and feasible, easy to mass produce, suitable for promotion, and has huge potential economic benefits.

[0030] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a physical picture of the R60705 niobium-zirconium chip-like waste in the present invention.

[0032] Figure 2 This is a physical picture of the niobium-zirconium square bar of the present invention.

[0033] Figure 3 This is a physical picture of the niobium-zirconium square bar after surface treatment in the present invention.

[0034] Figure 4 This is a physical picture of the consumable electrode in the present invention. DETAILED DESCRIPTION

[0035] Example 1

[0036] This embodiment includes the following steps:

[0037] Step 1: Collect the scraps generated during the machining process of R60705 niobium-zirconium products, including turning and milling, and classify and store them. It is strictly forbidden to mix other metals and foreign matter;

[0038] Step 2: The R60705 niobium zirconium chip waste classified and stored in step 1 is pre-treated by crushing, degreasing, removing saponification liquid, ultrasonic cleaning and dust-free drying; the length of the R60705 niobium zirconium chip waste after crushing is 20mm-50mm, the degreasing is carried out by a metal cleaning agent, and the degreasing temperature is 60℃±5℃, the immersion time is 20min, and the dust-free drying is carried out without contacting the ground;

[0039] Step 3: Press the R60705 niobium-zirconium scraps pretreated in step 2 to obtain a scrap electrode block, and then weld to obtain a scrap consumable electrode with a diameter of less than 420 mm and a length of 4180 mm. During welding, the scrap electrode block is reinforced by plasma outside the furnace. The welding method is: 2×11 sections are welded together, with a total of 2 primary electrodes, all welded in the furnace, and a weld is superimposed on both sides of each transverse seam. The superimposed width is one third of the original weld. When welding in a vacuum plasma welding box, the furnace electrode is single-sidedly root-welded to ensure strength.

[0040] Step 4: Use a crucible with a diameter of φ500 mm to perform VAR primary melting on the consumable electrode obtained in step 3: the vacuum degree before melting shall not exceed 5×10 0 Pa, the leakage rate before melting does not exceed 0.9Pa / min; the setting value of the melting current in the stable stage is 12.0kA~13.0kA, and the allowable range of melting current fluctuation is 10.0kA~16.0kA; the setting value of the arc stabilization current in the stable stage is 10.0A, and the allowable range of arc stabilization current fluctuation in the stable stage is the setting value±5A, the arc stabilization stirring reversing frequency in the stable stage is 10 seconds / time, the arc voltage setting value in the stable stage is 31.0V~38.0V, and the allowable range of arc voltage fluctuation is 29.0V~40.0V, and the maximum vacuum degree in the stable stage does not exceed 35Pa, and a chip ingot is obtained;

[0041] The chemical elements of the chip ingots including Nb, O, Fe, N and other impurity elements (%) were analyzed, and the results are shown in Table 1;

[0042] Table 1

[0043]

[0044] The standard ASTM B551 / B551M-12 requires: Nb 2.0% to 3.0%, O < 0.18%, N < 0.025%, C < 0.05%, and the content of other single impurity elements < 0.1%. From Table 1, it can be seen that the O and N elements in the chip ingot are higher than the standard range, especially the Nb element is on the lower limit;

[0045] Step 5: Forging the scrap ingot obtained in step 4 to obtain a niobium zirconium square bar with a width × thickness × length of 380 mm × 200 mm × 3500 mm, and performing surface treatments such as machining and chamfering of the side edges on the niobium zirconium square bar;

[0046] Step 6: Select raw materials of zirconium sponge, FNB-3 niobium powder and ZrO2 according to the design composition Zr-2.48Nb-0.145O of ​​the target product R60705 ingot and calculate the addition amount, and then use an 8000T hydraulic press to press the zirconium sponge, niobium powder and ZrO2 into raw material electrode blocks with a width × thickness × length of 380 mm × 380 mm × 125 mm, as shown in Table 2 below;

[0047] Table 2

[0048]

[0049] Step 7: Weld the raw material electrode block obtained in step 6 and the niobium zirconium square bar after surface treatment in step 5 by spot welding, and spot weld the raw material electrode block on the niobium zirconium square bar to obtain a consumable electrode, and the O and N elements are diluted along the axial direction of the consumable electrode;

[0050] Step 8: The consumable electrode obtained in step 7 is subjected to 4 VAR secondary smeltings, and the corresponding ingot diameters are: primary ingot φ560mm, secondary ingot φ640mm, tertiary ingot φ720mm, and finished ingot φ820mm. The specific process parameters are shown in Table 3 below, and the finished ingot is R60705 ingot;

[0051] Table 3

[0052]

[0053]

[0054] Hydrogen blocks and chip samples were taken from the top, middle and bottom of the R60705 ingot for chemical element analysis. The chemical composition element content was tested according to the requirements of chemical composition in ASTM B551 / B551M-12. The results are shown in Table 4 below:

[0055] Table 4

[0056]

[0057] As can be seen from Table 5, the O, N, and Nb element compositions and contents in the R60705 ingot prepared from R60705 niobium zirconium chip-like waste in this embodiment meet the requirements of ASTM B551 / B551M-12, and are close to the target value: Zr-2.48Nb-0.145O, which is suitable for product production.

[0058] Example 2

[0059] This embodiment includes the following steps:

[0060] Steps 1 to 4 are the same as those in Example 1;

[0061] The chip ingot prepared in step 4 was analyzed for chemical elements including Nb, O, Fe, N and other impurity element contents (%), and the results are shown in Table 5;

[0062] Table 5

[0063]

[0064] The standard ASTM B551 / B551M-12 requires: Nb 2.0% to 3.0%, O < 0.18%, N < 0.025%, C < 0.05%, and the content of other single impurity elements < 0.1%. From Table 1, it can be seen that the O and N elements in the chip ingot are higher than the standard range, especially the Nb element is on the lower limit;

[0065] Step 5: Forging the scrap ingot obtained in step 4 to obtain a niobium zirconium square bar with a width × thickness × length of 380 mm × 200 mm × 3500 mm, and performing surface treatments such as machining and chamfering of the side edges on the niobium zirconium square bar;

[0066] Step 6: Select raw materials of zirconium sponge, FNB-3 niobium powder and ZrO2 according to the design composition Zr-2.48Nb-0.145O of ​​the target product R60705 ingot and calculate the addition amount, and then use an 8000T hydraulic press to press the zirconium sponge, niobium powder and ZrO2 into raw material electrode blocks with a width × thickness × length of 380 mm × 380 mm × 125 mm, as shown in Table 6 below;

[0067] Table 6

[0068]

[0069] Step 7: Weld the raw material electrode block obtained in step 6 and the niobium zirconium square bar after surface treatment in step 5 by spot welding, and spot weld the raw material electrode block on the niobium zirconium square bar to obtain a consumable electrode, and the O and N elements are diluted along the axial direction of the consumable electrode;

[0070] Step 8: The consumable electrode obtained in step 7 is subjected to 4 VAR secondary smelting, and the corresponding ingot diameters are: primary ingot φ560mm, secondary ingot φ640mm, tertiary ingot φ720mm, and finished ingot φ820mm. The specific process parameters are shown in Table 7 below, and the finished ingot is R60705 ingot;

[0071] Table 7

[0072]

[0073]

[0074] Hydrogen blocks and chip samples were taken from the top, middle and bottom of the R60705 ingot for chemical element analysis. The chemical composition element content was tested according to the requirements of chemical composition in ASTM B551 / B551M-12. The results are shown in Table 8 below:

[0075] Table 8

[0076]

[0077] As can be seen from Table 8, the O, N, and Nb element compositions and contents in the R60705 ingot prepared from R60705 niobium-zirconium chip-like waste in this embodiment all meet the requirements of ASTM B551 / B551M-12 and are suitable for product production.

[0078] Comparing Example 1 with Example 2, it can be seen that both Example 1 and Example 2 of the present invention can prepare R60705 niobium zirconium chip waste into R60705 ingots that meet the current use standards, wherein Example 2 uses a larger ingot with a diameter of φ820mm, so the ingredients are adjusted compared to Example 1, the amount of R60705 niobium zirconium chip waste input at a single time is larger, and the input amount of raw material ZrO2 is reduced to 0, the single input amount is about 47% more than that of Example 1, and the recovery efficiency is higher and the cost is lower than that of Example 1. Therefore, the preparation method of the present invention uses R60705 niobium zirconium chip waste as raw material to prepare low-cost R60705 ingots without affecting the composition and performance.

[0079] The above is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent change made to the above embodiment according to the technical essence of the invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A method for recycling R60705 niobium zirconium chip waste, characterized in that: The method comprises the following steps: Step 1: Collect the chip-like waste generated during the machining process of R60705 niobium-zirconium products, including turning and milling, and classify and store them; Step 2: Pre-treat the R60705 niobium-zirconium chip waste classified and stored in step 1 by crushing, removing oil, removing saponification liquid, ultrasonic cleaning and dust-free drying; Step 3, pressing the R60705 niobium zirconium scrap pretreated in step 2 to obtain a scrap electrode block, and then welding to obtain a scrap consumable electrode; Step 4: Perform VAR primary smelting on the chip consumable electrode obtained in step 3 to obtain a chip ingot; Step 5: Forging the scrap ingot obtained in step 4 to obtain niobium-zirconium square bars and performing surface treatment; Step 6: Select the raw materials of zirconium sponge, niobium powder and ZrO2 according to the designed composition of the target product R60705 ingot and calculate the addition amount, and then press the zirconium sponge, niobium powder and ZrO2 into raw material electrode blocks; Step 7: welding the raw material electrode block obtained in step 6 and the niobium-zirconium square bar surface-treated in step 5 to obtain a consumable electrode; Step 8: subject the consumable electrode obtained in step 7 to secondary VAR smelting to obtain R60705 ingot.

2. The method for recycling R60705 niobium-zirconium chip waste according to claim 1, characterized in that: The degreasing in step 2 is performed using a metal cleaning agent, and the degreasing temperature is 60°C ± 5°C, the soaking time is 20 minutes, and the dust-free drying is performed without contacting the ground.

3. The method for recycling R60705 niobium-zirconium chip waste according to claim 1, characterized in that: During the welding described in step 3, plasma outside the furnace is used to reinforce the welding chip electrode block.

4. The method for recycling R60705 niobium-zirconium chip waste according to claim 1, characterized in that: The VAR primary smelting in step 4 is carried out in a crucible with a diameter of φ500 mm.

5. The method for recycling R60705 niobium-zirconium chip waste according to claim 1, characterized in that: In step 4, the chemical elements of the chip ingot are analyzed, including the contents of Nb, O, Fe, N and other impurity elements.

6. The method for recycling R60705 niobium-zirconium chip waste according to claim 1, characterized in that: The width×thickness×length of the niobium zirconium square bar in step 5 is 380mm×200mm×3500mm, and the niobium zirconium square bar is subjected to surface treatments such as machining and chamfering of side edges.

7. The method for recycling R60705 niobium-zirconium chip waste according to claim 1, characterized in that: The designed composition of the target product R60705 ingot in step six is ​​Zr-2.489Nb-0.145O, and sponge zirconium, FNB-3 niobium powder and ZrO2 are selected as raw materials.

8. The method for recycling R60705 niobium-zirconium chip waste according to claim 1, characterized in that: During the assembly welding described in step seven, the raw material electrode block is spot welded on top of the niobium zirconium square bar.

9. The method for recycling R60705 niobium-zirconium chip waste according to claim 1, characterized in that: The number of VAR secondary smelting in step eight is 4 times, and the diameters of the ingots in the VAR secondary smelting are: primary ingot φ560mm, secondary ingot φ640mm, tertiary ingot φ720mm, and finished ingot φ820mm.

10. The method for recycling R60705 niobium-zirconium chip waste according to claim 1, characterized in that: In step eight, the R60705 ingot is subjected to the upper, middle and lower points to take hydrogen and oxygen blocks and chip samples for chemical element analysis.

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