1cr17ni2 stainless steel and method for manufacturing the same

Abstract

The application belongs to the technical field of metal material manufacturing, and particularly relates to a 1Cr17Ni2 stainless steel and a manufacturing method thereof. The chemical components of the 1Cr17Ni2 stainless steel include C: 0.11-0.17wt%, Si<=0.80wt%, Mn<=0.80wt%, Cr: 16-18wt%, Ni: 1.50-2.50wt%, S<=0.030wt%, P<=0.040wt%, N: 0.05-0.09wt%, C+N>=0.22wt%, and the balance of Fe and inevitable impurities. The 1Cr17Ni2 stainless steel provided by the application has a low ferrite phase content, can meet the requirement of a user that the ferrite phase content is controlled to be <=5%, and has a strong corrosion resistance when applied to a Cl ‑ environment.

Description

Technical Field

[0001] This invention belongs to the technical field of metal material manufacturing, specifically relating to a 1Cr17Ni2 stainless steel and its manufacturing method. Background Technology

[0002] 1Cr17Ni2 is a martensitic stainless steel with a good balance of strength and toughness. It has good corrosion resistance to oxidizing acids, most organic acids, and aqueous solutions of organic salts. It is generally used in the production of nitric acid and acetic acid, as well as in light industry, textiles, railways, and aviation industries for parts such as shafts, piston rods, and pumps that require both strength and corrosion resistance.

[0003] According to GB / T1220-2007, the chemical composition (%wt) of 1Cr17Ni2 steel includes: C 0.11~0.17, Si≤0.80, Mn≤0.80, Cr 16.00~18.00, Ni 1.50~2.50, S≤0.030, P≤0.040. To avoid an excessive amount of austenite phase that would reduce the mechanical properties of the steel, the Ni and Cr contents should be controlled at 2~2.5% and 16~17%, respectively. Meanwhile, the ferrite phase content is between 10~20%. The ferrite phase improves its corrosion resistance in pickling environments, which is why 1Cr17Ni2 is widely used in the production of nitric acid and acetic acid.

[0004] In this new field, the application environment is a Cl- environment, where the ferrite phase is not corrosion resistant. Therefore, reducing the ferrite phase content in the steel is of great significance. The user has proposed a requirement for 1Cr17Ni2 with a ferrite phase content of ≤5%, but the existing composition design cannot form a low-ferrite 1Cr17Ni2 material and cannot meet this requirement. Summary of the Invention

[0005] To address the aforementioned shortcomings in existing technologies, the present invention aims to provide a 1Cr17Ni2 stainless steel and its manufacturing method. The 1Cr17Ni2 stainless steel provided by this invention has a low ferrite phase content, meeting the user's requirement of controlling the ferrite phase content to ≤5%. This will facilitate its future application in Cl... - It exhibits strong corrosion resistance in various environments.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a 1Cr17Ni2 stainless steel, wherein the chemical composition of the 1Cr17Ni2 stainless steel comprises: C: 0.11-0.17wt%, Si ≤ 0.80wt%, Mn ≤ 0.80wt%, Cr: 16-18wt%, Ni: 1.50-2.50wt%, S ≤ 0.030wt%, P ≤ 0.040wt%, N: 0.05-0.09wt%, C+N ≥ 0.22wt%, and the balance being Fe and unavoidable impurities.

[0008] The 1Cr17Ni2 stainless steel provided by this invention has a low ferrite phase content, which can meet the user's requirement of controlling the ferrite phase content to ≤5%, and can be applied to Cl in the future. - It exhibits strong corrosion resistance in various environments.

[0009] In a second aspect, the present invention provides a method for manufacturing 1Cr17Ni2 stainless steel as described in the first aspect, comprising the following steps in sequence: a smelting step, an electroslag remelting step, and a forging step; wherein the smelting step comprises, in sequence, a melting treatment step, a refining treatment step, a vacuum degassing treatment step, a nitrogen-increasing step, a tapping step, and a casting step, wherein the nitrogen-increasing step comprises blowing nitrogen gas after the vacuum degassing treatment is completed, so that the nitrogen content in the molten steel is 0.05-0.09 wt%, and C+N≥0.22 wt%.

[0010] In this invention, nitrogen is used as the nitrogen source, which can reduce costs.

[0011] In the above-mentioned method for manufacturing 1Cr17Ni2 stainless steel, as a preferred embodiment, the vacuum degree (absolute pressure) in the N-addition process is 20-100 Torr (for example, it can be 20 Torr, 40 Torr, 60 Torr, 80 Torr or 100 Torr).

[0012] In the above-mentioned method for manufacturing 1Cr17Ni2 stainless steel, as a preferred embodiment, the nitrogen-increasing process further includes increasing the nitrogen content in the molten steel by adding CrN.

[0013] In the above-mentioned manufacturing method of 1Cr17Ni2 stainless steel, as a preferred embodiment, in the melting process, electric furnace steel and induction furnace steel are mixed and flushed to obtain mixed-fluff steel. The preparation method of the electric furnace steel includes: smelting the electric furnace smelting raw materials in an electric furnace, and performing dephosphorization and decarburization treatments during the smelting process to obtain electric furnace steel, with the electric furnace tapping temperature ≥1600℃; the preparation method of the induction furnace steel includes: smelting the induction furnace smelting raw materials in an induction furnace to obtain induction furnace steel, with the induction furnace tapping temperature being 1550-1650℃ (for example, 1550℃, 1570℃, 1590℃, 1610℃, or 1650℃).

[0014] In the above-mentioned method for manufacturing 1Cr17Ni2 stainless steel, as a preferred embodiment, in the refining process, the mixed molten steel is refined in an LF furnace, and during the refining process, O removal treatment, S removal treatment, and fine-tuning treatment are performed to obtain refined molten steel.

[0015] In the above-mentioned method for manufacturing 1Cr17Ni2 stainless steel, as a preferred embodiment, in the vacuum degassing process, the refined molten steel is subjected to vacuum degassing to obtain degassed molten steel, wherein the vacuum degassing time is ≥20 minutes, and degassing is performed for at least 10 minutes under a vacuum degree of less than or equal to 0.5 Torr.

[0016] In the above-mentioned manufacturing method of 1Cr17Ni2 stainless steel, as a preferred embodiment, in the steel tapping process, the molten steel after the nitrogen-increasing process is subjected to soft blowing treatment, and the steel is tapped after reaching the tapping temperature to obtain 1Cr17Ni2 stainless steel molten steel. The soft blowing time is ≥10 minutes, and the tapping temperature is 40-70℃ higher than the liquidus line of the molten steel after the nitrogen-increasing process (e.g., the liquidus line temperature is 1483℃). (For example, it can be 40℃, 50℃, 60℃ or 70℃, etc.)

[0017] In the above-mentioned manufacturing method of 1Cr17Ni2 stainless steel, as a preferred embodiment, in the casting process, the molten steel of 1Cr17Ni2 stainless steel is cast into 1Cr17Ni2 ingots.

[0018] In the above-mentioned method for manufacturing 1Cr17Ni2 stainless steel, as a preferred embodiment, in the electroslag remelting process, under the protection of argon or nitrogen, the 1Cr17Ni2 ingot is used as an electrode rod of the electroslag furnace for remelting and crystallization, and then sent to the forging process.

[0019] In the above-mentioned manufacturing method of 1Cr17Ni2 stainless steel, as a preferred embodiment, in the forging process, the crystallized steel ingot is forged into a finished product, wherein the heating temperature is 1150~1200℃ (for example, it can be 1150℃, 1170℃ or 1200℃), the initial forging temperature is ≥1000℃, and the final forging temperature is ≥800℃.

[0020] In the above-mentioned manufacturing method of 1Cr17Ni2 stainless steel, after the forging process, the manufacturing method further includes an annealing process. In the annealing process, the forged steel is air-cooled to 400℃-550℃ (for example, 400℃, 450℃, 500℃, or 550℃; if the temperature is too high, carbides will precipitate; if the temperature is too low, cracking will occur), and placed for ≤48 hours before being annealed in a furnace. The annealing process sequentially includes primary heating, primary holding, primary cooling, secondary heating, secondary holding, and secondary cooling. The primary heating is performed at a rate of ≤100℃ / h (for example, 80-100℃ / h) to heat the steel to the primary holding temperature; the primary holding temperature is 660-700℃, and the primary holding time is 5-10h (for example, 5h, 7h, or 10h); the primary cooling is... The steel is cooled to below 500℃ (e.g., 200-500℃, which can be 200℃, 300℃, 400℃, or 500℃) at a rate of ≤100℃ / h (e.g., 80-100℃ / h), and then removed from the furnace and air-cooled to room temperature; the secondary heating is heating the steel to the secondary holding temperature at a rate of ≤100℃ / h (e.g., 80-100℃ / h); the secondary holding temperature is 610-660℃, and the secondary holding time is 10-25h (e.g., 10h, 15h, 20h, or 25h); the secondary cooling is cooling the steel to below 500℃ (e.g., 200-500℃, which can be 200℃, 300℃, 400℃, or 500℃) at a rate of ≤100℃ / h (e.g., 80-100℃ / h), and then removed from the furnace and air-cooled to room temperature. The annealing process provided in this embodiment can improve the mechanical properties of 1Cr17Ni2 stainless steel.

[0021] In the above-mentioned manufacturing method of 1Cr17Ni2 stainless steel, as a preferred embodiment, before the smelting process, the manufacturing method further includes a batching process. In the batching process, according to the composition of the 1Cr17Ni2 stainless steel, blast furnace iron and alloy raw materials are prepared and batched. The alloy raw materials include at least one of chromium, nickel plate, ferromanganese, ferrosilicon, manganese nitride, and chromium nitride. The chromium is low-carbon ferrochrome or micro-carbon ferrochrome.

[0022] In the above-mentioned manufacturing method of 1Cr17Ni2 stainless steel, as a preferred embodiment, the alloy raw material further includes at least one of 1Cr17Ni2 recycled material, 13Cr recycled material, and 304 recycled material.

[0023] Compared with the prior art, the beneficial effects of the present invention include at least one of the following:

[0024] (1) The 1Cr17Ni2 stainless steel provided by this invention has a low ferrite phase content, which can meet the user's requirement of controlling the ferrite phase content to ≤5%, and can be applied to Cl in the future. - It exhibits strong corrosion resistance in various environments.

[0025] (2) The 1Cr17Ni2 stainless steel provided by the present invention has higher tensile strength under the same heat treatment regime. Attached Figure Description

[0026] Figure 1 This is a flowchart of the annealing process provided in Embodiment 1 of the present invention.

[0027] Figure 2 This is a microstructure diagram of the 1Cr17Ni2 stainless steel provided in Embodiment 1 of the present invention.

[0028] Figure 3 This is a microstructure diagram of the 1Cr17Ni2 stainless steel provided in Embodiment 2 of the present invention.

[0029] Figure 4 This is a microstructure diagram of 1Cr17Ni2 stainless steel provided in Comparative Example 1 of the present invention.

[0030] Figure 5 This is a microstructure diagram of 1Cr17Ni2 stainless steel provided in Comparative Example 2 of the present invention. Detailed Implementation

[0031] The following embodiments further illustrate the content of this application in detail. The scope of protection of this application includes, but is not limited to, the following embodiments. The following embodiments are only used to illustrate the advantages and effects of the technical solution of this application and do not constitute a limitation on the scope of protection of this application. Equivalent substitutions made by those skilled in the art based on this application are all within the scope of protection of this application.

[0032] Unless otherwise defined, the technical terms used in the following embodiments have the same meanings as commonly understood by those skilled in the art. Unless otherwise specified, the experimental reagents used in the following embodiments are conventional biochemical reagents; the amounts of experimental reagents used are, unless otherwise specified, the amounts used in conventional experimental operations; and the experimental methods used are, unless otherwise specified, conventional methods.

[0033] To further understand the present invention, the following detailed description of a 1Cr17Ni2 stainless steel and its manufacturing method provided by the present invention is provided in conjunction with embodiments. The scope of protection of the present invention is not limited by the following embodiments.

[0034] Example 1

[0035] The final chemical composition (wt%) of the 1Cr17Ni2 stainless steel provided in this embodiment is as follows:

[0036]

[0037] The balance is Fe and unavoidable impurities.

[0038] The manufacturing method of 1Cr17Ni2 stainless steel provided in this embodiment includes the following steps in sequence:

[0039] S1. Batching process: Batching is carried out according to the composition of the 1Cr17Ni2 stainless steel; the raw materials include blast furnace iron and alloy raw materials, and the alloy raw materials include micro-carbon ferrochrome, nickel plate, medium-carbon ferromanganese, ferrosilicon and 1Cr17Ni2 recycled material.

[0040] S2. Smelting Process: The smelting process sequentially includes a melting treatment process, a refining treatment process, a vacuum degassing treatment process, a nitrogen-increasing process, a tapping process, and a casting process; wherein...

[0041] Melting process: blast furnace molten iron is smelted in an electric furnace, and dephosphorization and decarboxylation are performed during the smelting process to obtain electric furnace steel. The tapping temperature of the electric furnace is 1620℃. Alloy raw materials are smelted in an induction furnace to obtain induction furnace steel. The tapping temperature of the induction furnace is controlled at 1600℃. The induction furnace is used for alloying and improving the steel yield. The electric furnace steel and induction furnace steel are mixed and blended at a mass ratio of 1:1 to obtain blended steel.

[0042] Refining process: The mixed molten steel is refined in an LF furnace, and during the refining process, O removal, S removal and fine-tuning are performed to obtain refined molten steel;

[0043] Vacuum degassing process: The refined molten steel is subjected to vacuum degassing to obtain degassed molten steel. The total vacuum degassing time is 26 minutes, of which 14 minutes are required to reduce the pressure from atmospheric pressure to 0.5 Torr, and 12 minutes are required to degas under a vacuum of 0.5 Torr.

[0044] Nitrogen addition process: Before the vacuum process ends, adjust the vacuum level to 80 Torr and blow nitrogen into the bottom of the degassed molten steel for 10 minutes. After the vacuum process ends, switch the stirring gas to Ar. At this point, check that the N content in the molten steel is 0.085% and the C content is 0.15%, and the C+N ratio is 0.235%, which meets the composition design requirements.

[0045] Steel tapping process: The molten steel after the N-addition process is subjected to soft blowing treatment for 12 minutes. After reaching the tapping temperature, the steel is tapped to obtain 1Cr17Ni2 stainless steel. The tapping temperature is 51°C higher than the liquidus line of 1483°C, which is 1534°C.

[0046] Casting process (mold casting): The molten steel of the 1Cr17Ni2 stainless steel is cast into a 2.5t ingot shape, and the required electroslag base of the same steel grade is cast at the same time.

[0047] S3. Electroslag remelting process: Using a 2.5t gas-supported electroslag remelting furnace, under nitrogen protection, the 1Cr17Ni2 cast rod is used as the electrode rod of the electroslag furnace for remelting and crystallization, and then sent to the forging process.

[0048] S4. Forging process: The crystallized steel ingot is forged into a finished product. The forging process is carried out by using a 20MN press to open the billet to a 320mm octagonal billet, and then transferring it to a 16MN diameter forging machine to form a 210mm (section diameter) circle. The forging heating temperature is 1180℃, the initial forging temperature is 1020℃, and the final forging temperature is 860℃.

[0049] S5. Annealing process: The forged steel is air-cooled to 420℃, placed at 420℃ for 5 hours, and then annealed in a furnace. The annealing process is as follows: Figure 1 As shown, the annealing process sequentially includes a first heating, a first holding, a first cooling, a second heating, a second holding, and a second cooling. The first heating involves heating the steel to the first holding temperature at a rate of 100℃ / h; the first holding temperature is 690℃, and the first holding time is 10 hours. The first cooling involves cooling the steel to 300℃ at a rate of 100℃ / h, followed by air cooling to room temperature. The second heating involves heating the steel to the second holding temperature at a rate of 100℃ / h; the second holding temperature is 650℃, and the second holding time is 25 hours. The second cooling involves cooling the steel to 500℃ at a rate of 100℃ / h, followed by air cooling to room temperature.

[0050] S6. Finally, the final composition is inspected, the steel is machined to a 200mm circle, the ends and the surface of the steel are finished, flaw detection is performed, and the product is packaged and put into storage to obtain the finished 1Cr17Ni2 stainless steel.

[0051] Example 2

[0052] The final chemical composition (wt%) of the 1Cr17Ni2 stainless steel provided in this embodiment is as follows:

[0053] C N C+N Si Mn Cr Ni S P 0.16 0.0810 0.241 0.26 0.71 16.24 2.33 0.015 0.001

[0054] The balance is Fe and unavoidable impurities.

[0055] The manufacturing method of 1Cr17Ni2 stainless steel provided in this embodiment includes the following steps in sequence:

[0056] S1. Batching process: Batching is carried out according to the composition of the 1Cr17Ni2 stainless steel; the raw materials include blast furnace iron and alloy raw materials, and the alloy raw materials include micro-carbon ferrochrome, nickel plate, medium-carbon ferromanganese, ferrosilicon and 1Cr17Ni2 recycled material.

[0057] S2. Smelting Process: The smelting process sequentially includes a melting treatment process, a refining treatment process, a vacuum degassing treatment process, a nitrogen-increasing process, a tapping process, and a casting process; wherein...

[0058] Melting process: blast furnace molten iron is smelted in an electric furnace, and dephosphorization and decarboxylation are performed during the smelting process to obtain electric furnace steel. The tapping temperature of the electric furnace is 1620℃. Alloy raw materials are smelted in an induction furnace to obtain induction furnace steel. The tapping temperature of the induction furnace is controlled at 1600℃. The induction furnace is used for alloying and improving the steel yield. The electric furnace steel and induction furnace steel are mixed and blended at a mass ratio of 1:1 to obtain blended steel.

[0059] Refining process: The mixed molten steel is refined in an LF furnace, and during the refining process, O removal, S removal and fine-tuning are performed to obtain refined molten steel;

[0060] Vacuum degassing process: The refined molten steel is subjected to vacuum degassing to obtain degassed molten steel. The total vacuum degassing time is 26 minutes, of which 14 minutes are required to reduce the pressure from atmospheric pressure to 0.5 Torr, and 12 minutes are required to degas under a vacuum of 0.5 Torr.

[0061] Nitrogen addition process: Before the vacuum process ends, adjust the vacuum level to 80 Torr and blow nitrogen into the bottom of the degassed molten steel for 8 minutes. After the vacuum process ends, switch the stirring gas to Ar. At this point, check that the N content in the molten steel is 0.081% and the C content is 0.16%, and the C+N ratio is 0.241%, which meets the composition design requirements.

[0062] Steel tapping process: The molten steel after the N-addition process is subjected to soft blowing treatment for 12 minutes to obtain 1Cr17Ni2 stainless steel. After reaching the tapping temperature, the steel is tapped. The tapping temperature is 51°C higher than the liquidus line of 1483°C, which is 1534°C.

[0063] Casting process (mold casting): The molten steel of the 1Cr17Ni2 stainless steel is cast into a 2.5t ingot shape, and the required electroslag base of the same steel grade is cast at the same time.

[0064] S3. Electroslag remelting process: Using a 2.5t gas-supported electroslag remelting furnace, under nitrogen protection, the 1Cr17Ni2 cast rod is used as the electrode rod of the electroslag furnace for remelting and crystallization, and then sent to the forging process.

[0065] S4. Forging process: The crystallized steel ingot is forged into a finished product. The forging process is carried out by using a 20MN press to open the billet to a 320mm octagonal billet, and then transferring it to a 16MN diameter forging machine to form a 210mm round product. The forging heating temperature is 1180℃, the initial forging temperature is 1020℃, and the final forging temperature is 860℃.

[0066] S5. Annealing process: The forged steel is air-cooled to 420℃, placed at 420℃ for 5 hours, and then annealed in a furnace. The annealing process is as follows: Figure 1 As shown, the annealing process sequentially includes primary heating, primary holding, primary cooling, secondary heating, secondary holding, and secondary cooling. The primary heating involves heating the steel to the primary holding temperature at a rate of 100℃ / h; the primary holding temperature is 690℃, and the primary holding time is 10 hours. The primary cooling involves cooling the steel to 300℃ at a rate of 100℃ / h, followed by air cooling to room temperature. The secondary heating involves heating the billet to the secondary holding temperature at a rate of 100℃ / h; the secondary holding temperature is 650℃, and the secondary holding time is 25 hours. The secondary cooling involves cooling the steel to 500℃ at a rate of 100℃ / h, followed by air cooling to room temperature.

[0067] S6. Finally, the final composition is inspected, the steel is machined to a 200mm circle, the ends and the surface of the steel are finished, flaw detection is performed, and the product is packaged and put into storage to obtain the finished 1Cr17Ni2 stainless steel.

[0068] Comparative Example 1

[0069] The final chemical composition (wt%) of the 1Cr17Ni2 stainless steel provided in this comparative example is as follows:

[0070] C N C+N Si Mn Cr Ni S P 0.13 0.023 0.153 0.37 0.62 16.69 2.17 0.016 0.002

[0071] The balance is Fe and unavoidable impurities.

[0072] The manufacturing method of 1Cr17Ni2 stainless steel provided in this comparative example includes the following steps in sequence:

[0073] S1. Batching process: Batching is carried out according to the composition of the 1Cr17Ni2 stainless steel; the raw materials include blast furnace iron and alloy raw materials, and the alloy raw materials include micro-carbon ferrochrome, nickel plate, medium-carbon ferromanganese, ferrosilicon and 1Cr17Ni2 recycled material.

[0074] S2. Smelting Process: The smelting process sequentially includes a melting treatment process, a refining treatment process, a vacuum degassing treatment process, a tapping process, and a casting process; wherein...

[0075] Melting process: blast furnace molten iron is smelted in an electric furnace, and dephosphorization and decarboxylation are performed during the smelting process to obtain electric furnace steel. The tapping temperature of the electric furnace is 1620℃. Alloy raw materials are smelted in an induction furnace to obtain induction furnace steel. The tapping temperature of the induction furnace is controlled at 1600℃. The induction furnace is used for alloying and improving the steel yield. The electric furnace steel and induction furnace steel are mixed and blended at a mass ratio of 1:1 to obtain blended steel.

[0076] Refining process: The mixed molten steel is refined in an LF furnace, and during the refining process, O removal, S removal and fine-tuning are performed to obtain refined molten steel;

[0077] Vacuum degassing process: The refined molten steel is subjected to vacuum degassing to obtain degassed molten steel. The total vacuum degassing time is 26 minutes, of which 14 minutes are required to reduce the pressure from atmospheric pressure to 0.5 Torr, and 12 minutes are required to degas under a vacuum of 0.5 Torr.

[0078] The steel tapping process involves soft blowing the degassed molten steel for 10 minutes until the tapping temperature is reached, resulting in molten steel for 1Cr17Ni2 stainless steel. The tapping temperature is 51°C above the liquidus line of 1483°C, specifically 1534°C.

[0079] Casting process (mold casting): The molten steel of the 1Cr17Ni2 stainless steel is cast into a 2.5t ingot shape, and the required electroslag base of the same steel grade is cast at the same time.

[0080] S3. Electroslag remelting process: Using a 2.5t gas-supported electroslag remelting furnace, under nitrogen protection, the 1Cr17Ni2 cast rod is used as the electrode rod of the electroslag furnace for remelting and crystallization, and then sent to the forging process.

[0081] S4. Forging process: The crystallized steel ingot is forged into a finished product. The forging process is carried out by using a 20MN press to open the billet to a 320mm octagonal billet, and then transferring it to a 16MN diameter forging machine to form a 210mm (section diameter) circle. The forging heating temperature is 1180℃, the initial forging temperature is 1020℃, and the final forging temperature is 860℃.

[0082] S5. Annealing Process: The forged steel is air-cooled to 420℃, placed at 420℃ for 5 hours, and then annealed in a furnace. The annealing process includes, in sequence, primary heating, primary holding, primary cooling, secondary heating, secondary holding, and secondary cooling. The primary heating is to heat the steel to the primary holding temperature at a rate of 100℃ / h; the primary holding temperature is 690℃, and the primary holding time is 10 hours; the primary cooling is to cool the steel to 300℃ at a rate of 100℃ / h, and then air-cool it to room temperature; the secondary heating is to heat the steel to the secondary holding temperature at a rate of 100℃ / h; the secondary holding temperature is 650℃, and the secondary holding time is 25 hours; the secondary cooling is to cool the steel to 500℃ at a rate of 100℃ / h, and then air-cool it to room temperature.

[0083] S6. Finally, the final composition is inspected, the steel is machined to a 200mm circle, the ends and the surface of the steel are finished, flaw detection is performed, and the product is packaged and put into storage to obtain the finished 1Cr17Ni2 stainless steel.

[0084] Comparative Example 2

[0085] The final chemical composition (wt%) of the 1Cr17Ni2 stainless steel provided in this comparative example is as follows:

[0086] C N C+N Si Mn Cr Ni S P 0.13 0.021 0.151 0.34 0.67 16.54 2.22 0.018 0.001

[0087] The balance is Fe and unavoidable impurities.

[0088] The manufacturing method of 1Cr17Ni2 stainless steel provided in this comparative example includes the following steps in sequence:

[0089] S1. Batching process: Batching is carried out according to the composition of the 1Cr17Ni2 stainless steel; the raw materials include blast furnace iron and alloy raw materials, and the alloy raw materials include micro-carbon ferrochrome, nickel plate, medium-carbon ferromanganese, ferrosilicon and 1Cr17Ni2 recycled material.

[0090] S2. Smelting Process: The smelting process sequentially includes a melting treatment process, a refining treatment process, a vacuum degassing treatment process, a tapping process, and a casting process; wherein...

[0091] Melting process: blast furnace molten iron is smelted in an electric furnace, and dephosphorization and decarboxylation are performed during the smelting process to obtain electric furnace steel. The tapping temperature of the electric furnace is 1620℃. Alloy raw materials are smelted in an induction furnace to obtain induction furnace steel. The tapping temperature of the induction furnace is controlled at 1600℃. The induction furnace is used for alloying and improving the steel yield. The electric furnace steel and induction furnace steel are mixed and blended at a mass ratio of 1:1 to obtain blended steel.

[0092] Refining process: The mixed molten steel is refined in an LF furnace, and during the refining process, O removal, S removal and fine-tuning are performed to obtain refined molten steel;

[0093] Vacuum degassing process: The refined molten steel is subjected to vacuum degassing to obtain degassed molten steel. The total vacuum degassing time is 26 minutes, of which 14 minutes are required to reduce the pressure from atmospheric pressure to 0.5 Torr, and 12 minutes are required to degas under a vacuum of 0.5 Torr.

[0094] The steel tapping process involves soft blowing the degassed molten steel for 10 minutes to obtain 1Cr17Ni2 stainless steel. The steel is then tapped after reaching the tapping temperature, which is 60°C above the liquidus line of 1483°C, specifically 1543°C.

[0095] Casting process (mold casting): The molten steel of the 1Cr17Ni2 stainless steel is cast into a 2.5t ingot shape, and the required electroslag base of the same steel grade is cast at the same time.

[0096] S3. Electroslag remelting process: Using a 2.5t gas-supported electroslag remelting furnace, under nitrogen protection, the 1Cr17Ni2 cast rod is used as the electrode rod of the electroslag furnace for remelting and crystallization, and then sent to the forging process.

[0097] S4. Forging process: The crystallized steel ingot is forged into a finished product. The forging process is carried out by using a 20MN press to open the billet to a 320mm octagonal billet, and then transferring it to a 16MN diameter forging machine to form a 210mm (section diameter) circle. The forging heating temperature is 1180℃, the initial forging temperature is 1020℃, and the final forging temperature is 860℃.

[0098] S5. Annealing Process: The forged steel is air-cooled to 500℃, placed at 500℃ for 5 hours, and then annealed in a furnace. The annealing process includes, in sequence, primary heating, primary holding, primary cooling, secondary heating, secondary holding, and secondary cooling. The primary heating is performed at a rate of 90℃ / h to heat the steel to the primary holding temperature; the primary holding temperature is 690℃, and the primary holding time is 10 hours; the primary cooling is performed at a rate of 90℃ / h to cool the steel to 300℃, and then it is removed from the furnace and air-cooled to room temperature; the secondary heating is performed at a rate of 90℃ / h to heat the steel to the secondary holding temperature; the secondary holding temperature is 650℃, and the secondary holding time is 25 hours; the secondary cooling is performed at a rate of 90℃ / h to cool the steel to 500℃, and then it is removed from the furnace and air-cooled to room temperature.

[0099] S6. Finally, the final composition is inspected, the steel is machined to a 200mm circle, the ends and the surface of the steel are finished, flaw detection is performed, and the product is packaged and put into storage to obtain the finished 1Cr17Ni2 stainless steel.

[0100] Performance testing

[0101] The mechanical properties and ferrite content of the 1Cr17Ni2 stainless steel provided in the examples and comparative examples were tested, and the results are shown in Table 1.

[0102] Mechanical property testing: The heat treatment process is: quenching + tempering; a 25mm blank is taken from 1 / 2 radius, quenched at 1040℃ for 30min, then oil-cooled to room temperature, and then tempered at 300℃ for 1h, and air-cooled to finish; tensile property testing is carried out according to GB / T228 standard, and impact property testing is carried out according to GB / T229 standard.

[0103] Ferrite content testing: performed according to ASTM E562 standard.

[0104] Table 1

[0105]

[0106] As can be seen from Table 1, the ferrite phase content in the 1Cr17Ni2 stainless steel provided by the embodiments of the present invention is relatively low, which can meet the user's requirement of controlling the ferrite phase content to ≤5%.

[0107] Figure 2 This is a microstructure diagram of the 1Cr17Ni2 stainless steel provided in Embodiment 1 of the present invention. Figure 3 This is a microstructure diagram of the 1Cr17Ni2 stainless steel provided in Embodiment 2 of the present invention. Figure 4 This is a microstructure diagram of the 1Cr17Ni2 stainless steel provided in Comparative Example 1 of the present invention. Figure 5 This is a microstructure diagram of the 1Cr17Ni2 stainless steel provided in Comparative Example 2 of the present invention. Figures 2-5 It can be seen that the ferrite content in the 1Cr17Ni2 stainless steel provided in Examples 1 and 2 is lower than that in the 1Cr17Ni2 stainless steel provided in Comparative Examples 1 and 2.

[0108] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method of manufacturing 1Cr17Ni2 stainless steel, characterized by, The manufacturing method sequentially comprises a smelting process, an electroslag remelting process and a forging process; wherein the smelting process sequentially comprises a melting treatment process, a refining treatment process, a vacuum degassing treatment process, an N-increasing process, a tapping process and a casting forming process, the N-increasing process comprises blowing nitrogen after the vacuum degassing treatment is completed, so that the nitrogen content in the molten steel is 0.081-0.09wt%, C+N≥0.22wt%; The chemical composition of the 1Cr17Ni2 stainless steel comprises: C: 0.11-0.17wt%, Si≤0.80wt%, Mn≤0.80wt%, Cr: 16-18wt%, Ni: 1.50-2.50wt%, S≤0.030wt%, P≤0.040wt%, N: 0.081-0.09wt%, C+N≥0.22wt%, and the balance is Fe and inevitable impurities; After the forging process, the manufacturing method further comprises an annealing process, in which the forged steel material is air-cooled to 400-550℃ and placed for ≤48 hours before being put into the furnace for annealing, the annealing process sequentially comprises first heating, first holding, first cooling, second heating, second holding, and second cooling, the first heating is to heat the steel material to the first holding temperature at a speed of ≤100℃ / h; the first holding temperature is 660-700℃, and the first holding time is 5-10h; the first cooling is to cool the steel material to below 500℃ at a speed of ≤100℃ / h, and then the furnace is discharged for air cooling to room temperature; the second heating is to heat the steel material to the second holding temperature at a speed of ≤100℃ / h; the second holding temperature is 610-660℃, and the second holding time is 10-25h; the second cooling is to cool the steel material to below 500℃ at a speed of ≤100℃ / h, and then the furnace is discharged for air cooling to room temperature.

2. The method of producing 1Cr17Ni2 stainless steel according to claim 1, characterized by, In the N-increasing process, the vacuum degree is 20-100 Torr; And / or, in the N-increasing process, further comprising increasing the nitrogen content in the molten steel by adding CrN; And / or, in the melting treatment process, the molten steel of the electric furnace and the molten steel of the induction furnace are mixed and treated to obtain mixed molten steel, wherein the preparation method of the molten steel of the electric furnace comprises: smelting the smelting raw materials of the electric furnace in the electric furnace, and performing P-removing treatment and C-removing treatment during smelting to obtain the molten steel of the electric furnace, and the tapping temperature of the electric furnace is ≥1600℃; the preparation method of the molten steel of the induction furnace comprises: smelting the smelting raw materials of the induction furnace in the induction furnace to obtain the molten steel of the induction furnace, and the tapping temperature of the induction furnace is 1550-1650℃.

3. The method of producing 1Cr17Ni2 stainless steel according to claim 2, characterized by, In the refining treatment process, the mixed molten steel is refined in the LF furnace, and O-removing treatment, S-removing treatment and fine adjustment treatment are performed during the refining process to obtain refined molten steel; And / or, in the vacuum degassing treatment process, the refined molten steel is subjected to vacuum degassing treatment to obtain degassed molten steel, wherein the vacuum degassing time is ≥20 minutes, and the degassing is performed at a vacuum degree of ≤0.5 Torr for at least 10 minutes; And / or, in the tapping process, the molten steel treated by the N-increasing process is subjected to soft blowing treatment, and the molten steel of 1Cr17Ni2 stainless steel is obtained after the molten steel reaches the tapping temperature, wherein the soft blowing time is greater than or equal to 10 minutes, and the tapping temperature is 40-70℃ higher than the liquidus of the molten steel treated by the N-increasing process.

4. The method of producing 1Cr17Ni2 stainless steel according to claim 3, characterized by, In the pouring forming process, the molten steel of 1Cr17Ni2 stainless steel is poured into 1Cr17Ni2 ingot.

5. The method of producing 1Cr17Ni2 stainless steel according to claim 4, characterized by, In the electric slag remelting process, the 1Cr17Ni2 ingot is used as an electrode rod of an electric slag furnace, and is subjected to remelting and crystallization under the protection of argon or nitrogen, and then is red sent to the forging process.

6. The method of producing 1Cr17Ni2 stainless steel according to claim 5, characterized by, In the forging process, the crystallized ingot is forged into a material, wherein the heating temperature is 1150-1200℃, the open-die forging temperature is greater than or equal to 1000℃, and the finish-die forging temperature is greater than or equal to 800℃.

7. The method of producing 1Cr17Ni2 stainless steel according to claim 1, characterized by, Before the melting process, the manufacturing method further comprises a batching process, in which, according to the composition of the 1Cr17Ni2 stainless steel, blast furnace molten iron and alloy raw materials are prepared for batching, wherein the alloy raw materials include at least one of chromium, nickel plate, manganese iron, silicon iron, manganese nitride and chromium nitride, and the chromium is low-carbon chromium iron or micro-carbon chromium iron.

8. The method of producing 1Cr17Ni2 stainless steel according to claim 7, characterized by, The alloy raw materials further include at least one of 1Cr17Ni2 return material, 13Cr return material and 304 return material.

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