Corrosion-resistant alloy fastener material and preparation method thereof

Abstract

The invention discloses a corrosion-resistant alloy fastener material and a preparation method thereof, and belongs to the technical field of high-temperature alloy preparation. The high-temperature alloy comprises the following elements in percentage by weight: less than or equal to 0.03% of C, less than or equal to 0.2% of Si, less than or equal to 0.2% of Mn, less than or equal to 0.01% of S, 19.0%-22.0% of Cr, less than or equal to 0.015% of P, less than or equal to 0.35% of Al, 1.00%-1.60% of Ti, 7.50%-9.50% of Mo, 59.0%-63.0% of Ni, 3.00%-3.85% of Nb and the balance of Fe and inevitable impurities. According to the method, vacuum induction furnace smelting and vacuum consumable remelting are adopted to obtain a pure and uniform steel ingot, and a material with a uniform structure is obtained through optimized homogenization system, heating system, forging process, forging heating temperature and heat preservation measures in the forging process; and finally, through a double-solid-solution and double-aging heat treatment system, the structure and the performance of the obtained product exceed the range of standard requirements, and the abundant amount is sufficient. The high-temperature alloy material produced through the method is sufficient in margin, and the performance requirement of the fastener material nickel-based high-temperature alloy is met.

Description

Technical Field

[0001] The present invention relates to a corrosion-resistant high-temperature alloy, in particular to a corrosion-resistant alloy fastener material and a preparation method thereof, belonging to the technical field of alloy material preparation. Background Art

[0002] With technological advancements, nickel-based superalloys are increasingly being used, placing high demands on their performance and microstructure. Key technical requirements for nickel-based superalloys include chemical composition, mechanical properties, microstructure, and surface quality. However, challenges arise from unstable metallographic structures after heat treatment, which can lead to significant performance challenges. Consequently, overcoming these challenges in the preparation of nickel-based superalloys remains a work in progress.

[0003] Nickel-based high-temperature alloys are generally used to manufacture fasteners and shafts. Due to their unique strength and resistance to stress corrosion cracking, sulfide stress cracking, pitting, and crevice corrosion, nickel-based high-temperature alloys are often used in severely corrosive environments, such as deep sour gas wells, as well as various refineries and chemical processing industries. Furthermore, fasteners and shafts manufactured from these materials require higher strength, which places higher demands on the material's performance and structure.

[0004] At present, corrosion-resistant alloy bars are difficult to meet the strength requirements of the material, the various properties are unstable and the grain size difference is large, which cannot meet the requirements of serving in the required working environment. Therefore, the development of corrosion-resistant alloy materials for fasteners is of great significance.

[0005] However, the materials produced by the preparation methods used in existing fasteners have relatively low strength compared to the standard, and other properties are unstable, which shortens the service life of the materials and cannot meet the performance requirements of fastener materials. In addition, the structure is uneven, the mixed crystals are more serious after heat treatment, and the grain size difference is large, resulting in uneven performance of the fastener materials at the edge and center.

[0006] Therefore, how to provide a corrosion-resistant alloy fastener material and a preparation method thereof to overcome the above problems has become a technical problem that needs to be solved urgently. Summary of the Invention

[0007] The present invention addresses the aforementioned issues by providing a corrosion-resistant alloy fastener material and a method for its preparation, which can meet the requirements of use in complex working environments. The technical objective of the present invention is to provide a corrosion-resistant alloy fastener material that exhibits high strength, stable other properties, a long service life, and good structural uniformity.

[0008] In order to achieve the above object, the present invention is implemented through the following technical solutions:

[0009] The present invention first provides a method for preparing a corrosion-resistant alloy fastener material. The corrosion-resistant alloy fastener material comprises the following elemental composition, measured in weight percentage: C: ≤0.03%, Si: ≤0.2%, Mn: ≤0.2%, S: ≤0.01%, Cr: 19.0%-22.0%, P: ≤0.015%, Al: ≤0.35%, Ti: 1.00%-1.60%, Mo: 7.50%-9.50%, Ni: 59.0%-63.0%, Nb+Ta: 3.00%-3.85%, and the balance being Fe and unavoidable impurities. The method for preparing the corrosion-resistant alloy fastener material comprises the following steps:

[0010] Step A: The furnace should be loaded with nickel plate and pure iron as the bottom, metal Mo bar should be placed in the center high temperature area, and metal Cr block, metal Nb block, etc. should be placed on the top of the crucible as much as possible. After breaking the air, the furnace should be evacuated to <5Pa before loading.

[0011] Step B, preparing an alloy according to the above element composition ratio, melting it in a vacuum induction furnace, with a furnace power of ≤1200KW, measuring the temperature after the raw materials are fully melted, and continuing to increase the temperature at the same power until the raw materials are fully melted;

[0012] Step C, adjusting the temperature of the molten steel in step B to 1440-1460° C. for refining, measuring the gas leakage rate after refining for 40 minutes, and then measuring the gas leakage rate every 10 minutes. Refining is completed when the gas leakage rate is ≤2 Pa / min and the difference between the two gas leakage rates is ≤0.2 Pa / min;

[0013] Step D: After the air leakage requirement is met, turn off the power and cool to 1420±10℃, add Al→Ti in sequence, and stir for 10-20 minutes after addition;

[0014] Step E, steel mixing: sampling and analyzing the composition, supplementing the composition, adding B-Fe, filling argon ≥10000Pa, measuring temperature T = 1420±10℃, adding Ni-Mg 5 minutes before tapping, preparing for tapping, furnace cooling for 30-40 minutes, breaking the air, demoulding and sending for annealing;

[0015] Step F: The electrode rod obtained in step E is used as an electrode, flattened and polished, and then placed in a vacuum consumable furnace for secondary remelting and purification to form a consumable ingot;

[0016] Step G: heating the consumable ingot prepared in step F to 1190° C. and keeping the temperature for 72 hours for homogenization;

[0017] Step H: heating the steel ingot from step G to 1140° C., keeping the temperature for 4 hours, forging the steel ingot by means of a press through two upsetting and two drawing processes, heating, jacketing, etc., and air cooling the steel ingot;

[0018] Step I: subject the bar forged in step H to post-forging heat treatment: 750°C × 1h + 980°C × 2h, oil cooling, then furnace cooling to 620°C at 732°C × 8h, holding for 8h, air cooling, and multiple heat treatments to obtain the desired material.

[0019] The grain size structure of the corrosion-resistant alloy material obtained by the above method of the present invention is as follows:

[0020] As a preferred solution, in step B, during the smelting process, the molten steel is melted in a 6T vacuum induction furnace, maintaining high power for full melting and removing some gases in the process.

[0021] As a preferred solution, in step C, refining is carried out after the molten steel in the 6T furnace is heated to 1450° C. The gas leakage rate must meet the refining requirements, and the refining is completed.

[0022] As a preferred solution, in step D, after the gas leakage rate requirement is met, the power is turned off and the temperature is lowered, and Al and Ti are added according to the ratio, and then stirred for 10 to 20 minutes.

[0023] As a preferred solution, in step F, the melting rate is controlled to be 3.2 kg / min-3.4 kg / min during the secondary remelting process.

[0024] As a preferred solution, in step G, the temperature for homogenization treatment is 1190° C. and the holding time is 72 h.

[0025] As a preferred solution, in step H, rapid forming and forging is performed while adopting heat preservation measures such as heating and wrapping.

[0026] As a preferred solution, in step I, the heat treatment is carried out in a 5 / 8T resistance furnace.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] (1) The present invention provides a corrosion-resistant alloy fastener material and a preparation method thereof. The obtained high-temperature alloy material has good surface quality and the center grain size after heat treatment reaches a uniform level of 6.0-6.5.

[0029] (2) The corrosion-resistant alloy fastener material obtained by the present invention has sufficient strength margin, meeting the requirements for the use of new materials. DETAILED DESCRIPTION

[0030] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0031] The corrosion-resistant alloy fastener materials in the following Examples 1-3 have the following elements, in terms of weight percentage, and their composition and proportion as shown in Table 1 below.

[0032] Table 1 Chemical composition and proportion of ingredients (wt%)

[0033] element C Cr Ni Mo Nb+Ta Al Ti Sample 1 0.03 19.0 59.0 7.50 3.0 0.35 1.0 Sample 2 0.02 20.5 61.0 8.0 3.5 0.30 1.5 Sample 3 0.015 22.0 63.0 9.50 3.85 0.28 1.6 element Mn Si S P Fe N (impurity) Mg Sample 1 0.20 0.20 0.010 0.015 margin — — Sample 2 0.15 0.16 0.003 0.007 margin — 0.035 Sample 3 0.10 0.11 0.002 0.005 margin 0.004 —

[0034] Example 1

[0035] A method for preparing a corrosion-resistant alloy fastener material, taking sample 1 (see Table 1) as an example, the specific steps are as follows:

[0036] Step A: Loading the furnace requires nickel plates and pure iron as the bottom, metal Mo bars in the center high temperature area, and metal Cr blocks and metal Nb as much as possible on the top of the crucible. After breaking the air, the furnace needs to be evacuated to 5Pa before loading;

[0037] Step B: preparing an alloy according to the above elemental composition ratio, melting it in a 6T vacuum induction furnace with a power of 1200KW, measuring the temperature after the raw materials are fully melted, and continuing to increase the temperature at the same power until the raw materials are fully melted;

[0038] Step C, adjusting the temperature of the molten steel in the 6T furnace in step A to 1440° C. for refining, measuring the gas leakage rate after refining for 40 minutes, and then measuring the gas leakage rate every 10 minutes. If the gas leakage rate is ≤2 Pa / min and the difference between the two gas leakage rates is ≤0.2 Pa / min, the refining is completed;

[0039] Step D: After the air leakage requirement is met, the power is turned off and the temperature is lowered to 1420°C. Al→Ti are added in sequence and stirred for 10 minutes after addition.

[0040] Step E, steel mixing: sampling and analyzing the composition, supplementing the composition, adding B-Fe, filling argon 10000Pa, measuring the temperature T = 1420 ± 10 ° C, adding Ni-Mg 5 minutes before tapping, preparing for tapping, furnace cooling for 30 minutes, breaking the air, demoulding and sending for annealing;

[0041] Step F: The electrode rod obtained in step E is used as an electrode, flattened and polished, and then placed in a vacuum consumable furnace for secondary remelting and purification to form a consumable ingot;

[0042] Step G: heating the consumable ingot prepared in step F to 1190° C. and keeping the temperature for 72 hours for homogenization;

[0043] Step H: heating the steel ingot from step G to 1140° C., keeping the temperature for 4 hours, forging the steel ingot by means of a press through two upsetting and two drawing processes, heating, jacketing, etc., and air cooling the steel ingot;

[0044] Step I: subject the bar forged in step H to post-forging heat treatment: the specific heat treatment process is: 750°C × 1h + 980°C × 2h, oil cooling, then continuing to furnace cooling to 620°C at 732°C × 8h, holding for 8h, air cooling, and other multiple heat treatments to obtain the desired material.

[0045] Example 2

[0046] A method for preparing a corrosion-resistant alloy fastener material, taking sample 2 (see Table 1) as an example, the specific steps are as follows:

[0047] Step A: The nickel plate (pure iron) should be placed at the bottom of the furnace, J-Mo should be placed in the central high temperature area, and J-Cr, J-Nb, etc. should be placed on the top of the crucible as much as possible. After breaking the air, the furnace should be evacuated to 4.5Pa before loading;

[0048] Step B: prepare the alloy according to the above element composition ratio, and melt it in a 6T vacuum induction furnace with a power of 1150KW. After the raw materials are fully melted, measure the temperature and continue to increase the temperature at the same power until they are fully melted.

[0049] Step C, adjusting the temperature of the molten steel in the 6T furnace in step A to 1460° C. for refining, measuring the gas leakage rate after refining for 40 minutes, and then measuring the gas leakage rate every 10 minutes. If the gas leakage rate is ≤2 Pa / min and the difference between the two gas leakage rates is ≤0.2 Pa / min, the refining is completed;

[0050] Step D: After the air leakage requirement is met, the power is turned off and the temperature is lowered to 1410°C. Al→Ti are added in sequence and stirred for 20 minutes after addition.

[0051] Step E, steel mixing: sampling and analyzing the composition, supplementing the composition, adding B-Fe, filling argon 10100Pa, measuring temperature T = 1430 ° C, adding Ni-Mg 5 minutes before tapping, preparing for tapping, furnace cooling for 40 minutes, breaking the air, demoulding and sending for annealing;

[0052] Step F: The electrode rod obtained in step E is used as an electrode, flattened and polished, and then placed in a vacuum consumable furnace for secondary remelting and purification to form a consumable ingot;

[0053] Step G: heating the consumable ingot prepared in step F to 1190° C. and keeping the temperature for 72 hours for homogenization;

[0054] Step H: heating the steel ingot from step G to 1140° C., keeping the temperature for 4 hours, forging the steel ingot by means of a press through two upsetting and two drawing processes, heating, jacketing, etc., and air cooling the steel ingot;

[0055] Step I: subject the bar forged in step H to post-forging heat treatment: the specific heat treatment process is: 750°C × 1h + 980°C × 2h, oil cooling, then continuing to furnace cooling to 620°C at 732°C × 8h, holding for 8h, air cooling, and other multiple heat treatments to obtain the desired material.

[0056] Example 3

[0057] A method for preparing a corrosion-resistant alloy fastener material, taking sample 3 (see Table 1) as an example, the specific steps are as follows:

[0058] Step A: Loading the furnace requires nickel plates and pure iron as the bottom, metal Mo bars in the center high temperature area, and metal Cr blocks and metal Nb as much as possible on the top of the crucible. After breaking the air, the furnace needs to be evacuated to 4.2Pa before loading;

[0059] Step B: prepare the alloy according to the above element composition ratio, and melt it in a 6T vacuum induction furnace with a power of 1100KW. After the raw materials are fully melted, measure the temperature and continue to increase the temperature at the same power until they are fully melted.

[0060] Step C: Adjust the temperature of the molten steel in the 6T furnace in step A to 1450°C for refining. Measure the leakage rate after refining for 40 minutes, and then measure the leakage rate every 10 minutes. Refining is completed when the leakage rate is ≤2Pa / min and the difference between the two leakage rates is ≤0.2Pa / min.

[0061] Step D: After the air leakage requirement is met, the power is turned off and the temperature is lowered to 1430°C. Al→Ti are added in sequence and stirred for 15 minutes after addition.

[0062] Step E, steel mixing: sampling and analyzing the composition, supplementing the composition, adding B-Fe, filling argon 10500Pa, measuring temperature T = 1410 ° C, adding Ni-Mg 5 minutes before tapping, preparing for tapping, furnace cooling for 35 minutes, breaking the air, demoulding and sending for annealing;

[0063] Step F: The electrode rod obtained in step E is used as an electrode, flattened and polished, and then placed in a vacuum consumable furnace for secondary remelting and purification to form a consumable ingot;

[0064] Step G: heating the consumable ingot prepared in step F to 1190° C. and keeping the temperature for 72 hours for homogenization;

[0065] Step H: heating the steel ingot from step G to 1140° C., keeping the temperature for 4 hours, forging the steel ingot by means of a press through two upsetting and two drawing processes, heating, jacketing, etc., and air cooling the steel ingot;

[0066] Step I: subject the bar forged in step H to post-forging heat treatment: the specific heat treatment process is: 750°C × 1h + 980°C × 2h, oil cooling, then continuing to furnace cooling to 620°C at 732°C × 8h, holding for 8h, air cooling, and other multiple heat treatments to obtain the desired material.

[0067] Comparative Example 1

[0068] According to the method of Example 1, the process parameters in step I are replaced as follows: the specific process of heat treatment is: 1038°C×2h, oil cooling, then continuing at 732°C×8h, furnace cooling to 620°C, keeping warm for 8h, and air cooling. After multiple heat treatments, the desired material is obtained.

[0069] Comparative Example 2

[0070] According to the method of Example 1, the process parameters in step I are replaced as follows: the specific process of heat treatment is: 750°C×1h+980°C×2h, oil cooling, then continuing with 720°C×8h, air cooling; 620°C×20h, air cooling, and multiple heat treatments to obtain the desired material.

[0071] Comparative Example 3

[0072] According to the method of Example 2, the process parameters in step I are replaced as follows: the specific process of heat treatment is: 1038°C×1h, air cooling, followed by 720°C×8h, air cooling, 620°C×20h, air cooling, and other multiple heat treatments to obtain the desired material.

[0073] Comparative Example 4

[0074] According to the method of Example 2, the process parameters in step I are replaced as follows: the specific process of heat treatment is: solution treatment: 980°C×2h, oil cooling, followed by 720°C×8h, air cooling; 620°C×20h, air cooling, and other multiple heat treatments to obtain the desired material.

[0075] Test Example 1

[0076] The properties of the bars obtained in Examples 1-3 and Comparative Examples 1-4 were tested. The test contents included: the grain size of the bar edge and center, and the performance gap of the bars (15 samples were tested and the average grain size and performance indicators of the samples were calculated). The test results are shown in Table 2 below:

[0077] Table 2 Sample performance test results

[0078]

[0079]

[0080] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims, not the foregoing description, and all variations within the meaning and range of equivalents of the claims are intended to be encompassed therein. Any reference in a claim should not be construed as limiting the claim to which it relates.

[0081] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementations that can be understood by those skilled in the art.

Claims

1. A method for preparing a corrosion-resistant alloy fastener material, characterized in that: The corrosion-resistant alloy fastener material comprises the following elements by weight percentage: C: ≤0.03%, Si: ≤0.2%, Mn: ≤0.2%, S: ≤0.01%, Cr: 19.0%-22.0%, P: ≤0.015%, Al: ≤0.35%, Ti: 1.00%-1.60%, Mo: 7.50%-9.50%, Ni: 59.0%-63.0%, Nb+Ta: 3.00%-3.85%, the balance is Fe and unavoidable impurities; The method for preparing the corrosion-resistant alloy fastener material comprises the following steps: Step A: When charging the furnace, place nickel plate and pure iron at the bottom, put J-Mo in the central high temperature area, and put J-Cr and J-Nb on the top of the crucible. After breaking the air, close the furnace and evacuate to <5Pa before charging; Step B, preparing the alloy according to the above element composition ratio, using a vacuum induction furnace for smelting, the vacuum induction furnace power is ≤1200KW, and measuring the temperature after the raw materials are fully melted; Step C, adjusting the temperature of the molten steel in the furnace of step B to 1440-1460° C. for refining, measuring the gas leakage rate after refining for 40 minutes, and then measuring the gas leakage rate every 10 minutes. Refining is completed when the gas leakage rate is ≤2 Pa / min and the difference between the two gas leakage rates is ≤0.2 Pa / min; Step D: After the air leakage requirement is met, the power is turned off and the temperature is lowered to 1420±10°C, and Al and Ti are added in sequence; Step E, steel mixing: sampling and analyzing the composition, supplementing the composition, adding B-Fe, filling with argon ≥10000Pa, measuring the temperature T = 1420±10℃, adding Ni-Mg 5 minutes before tapping, preparing for tapping, cooling the furnace for 30-40 minutes, breaking the air, demoulding and sending for annealing to prepare the electrode rod; Step F: The electrode rod obtained in step E is used as an electrode, flattened and polished, and then placed in a vacuum consumable furnace for secondary remelting and purification to form a consumable ingot; Step G, homogenizing the consumable ingot prepared in step F; Step H: heating the steel ingot from step G to 1140° C., keeping the temperature for 4 hours, forging it into a bar by using a press through two upsetting and two drawing processes, and air cooling; Step I: The bar forged in step H is subjected to post-forging heat treatment. The specific process of the heat treatment is: 750°C × 1h + 980°C × 2h, oil cooling, then furnace cooling to 620°C at 732°C × 8h, keeping warm for 8h, and air cooling. After the above multiple heat treatments, the desired material is obtained.

2. The preparation method according to claim 1, wherein: In step B, the molten steel is melted in a 6T vacuum induction furnace during the melting process.

3. The preparation method according to claim 1, wherein: In step C, refining is carried out after the molten steel in the 6T furnace is heated to 1450°C. The refining time in the vacuum induction furnace is determined according to the leakage rate.

4. The preparation method according to claim 1, wherein: In step D, stir for 10 to 20 minutes after adding Al and Ti.

5. The preparation method according to claim 1, wherein: In step F, the melting rate is controlled to be 3.2 kg / min-3.4 kg / min during the secondary remelting process.

6. The preparation method according to claim 1, wherein: In step G, the temperature for homogenization treatment is 1190° C. and the holding time is 72 h.

7. The preparation method according to claim 1, wherein: In step H, rapid forming forging is performed while adopting heat preservation measures such as heating and wrapping.

8. The preparation method according to claim 1, wherein: In step I, heat treatment is carried out in a 5 / 8T resistance furnace.

9. The corrosion-resistant alloy fastener material obtained by the preparation method according to any one of claims 1 to 8.

10. The corrosion-resistant alloy fastener material according to claim 9, characterized in that: The corrosion-resistant alloy fastener material is composed of the following elements by weight: C: 0.02%, Si: 0.16%, Mn: 0.1%, S: 0.002%, Cr: 20.5%, P: 0.007%, Al: 0.30%, Ti: 1.5%, Mo: 8.0%, Ni: 61.0%, Nb+Ta: 3.5%, and the balance is Fe and unavoidable impurities.

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