Low-cost 2Cr13 martensitic stainless steel and manufacturing method thereof

Abstract

The invention discloses low-cost 2Cr13 martensitic stainless steel which comprises the following chemical components in percentage by mass: 0.18-0.20% of C, 0.30-0.45% of Si, less than or equal to 0.30% of Mn, less than or equal to 0.035% of P, less than or equal to 0.030% of S, 12.50-12.70% of Cr, less than or equal to 0.60% of Ni, less than or equal to 0.020% of N and the balance of Fe and inevitable impurity elements. The nickel-chromium equivalence ratio Ni ' / Cr' is controlled to be smaller than or equal to 0.5, the chromium equivalent Cr 'is equal to% Cr + 1.5% Si, and the nickel equivalent Ni' is equal to% Ni + 30 (% C +% N) + 0.5% Mn. The method has the advantages that the production cost is reduced on the premise of ensuring the material performance, the quality defects of the casting blank are reduced, the yield of the hot-charging cogging process is improved, and high quality and low cost are both considered.

Description

Technical Field

[0001] The invention belongs to the technical field of metallurgy, and in particular relates to low-cost 2Cr13 martensitic stainless steel and a manufacturing method thereof. Background Art

[0002] CO2 corrosion is one of the main types of corrosion in oil and gas fields. In a CO2-humidified environment, the corrosion rate of steel is very high. Adding Cr can improve the corrosion resistance of steel. As the Cr content increases, the corrosion rate decreases. 13Cr martensitic stainless steel has been widely used in underground gas storage well pipes and oil casing for CO2 injection and production wells due to its good mechanical properties, excellent corrosion resistance, and high cost-effectiveness. However, the production of traditional 13Cr stainless steel still faces many challenges, especially in the smelting, continuous casting, and billeting stages, resulting in high costs and limiting its application in a wider range of industrial fields.

[0003] The production cost of traditional 2Cr13 stainless steel is relatively high, partly due to over-reliance on certain alloying elements and imprecise composition control, which leads to scrap problems. 2Cr13 martensitic stainless steel is prone to surface depression, longitudinal cracks and steel leakage during the continuous casting process, resulting in unstable ingot quality and low product qualification rate, which reduces economic benefits. Summary of the Invention

[0004] The purpose of the present invention is to solve the problems of existing 2Cr13 martensitic stainless steel such as many quality defects, poor stability and reliability, high cost and low product qualification rate, and to provide a low-cost 2Cr13 martensitic stainless steel, which reduces production costs while ensuring material properties, reduces quality defects of casting billets, improves the yield rate of hot delivery billet opening process, and takes into account both high quality and low cost.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions: A low-cost 2Cr13 martensitic stainless steel having the following chemical composition by mass: C: 0.18-0.20%, Si: 0.30-0.45%, Mn≤0.30%, P≤0.035%, S≤0.030%, Cr: 12.50-12.70%, Ni≤0.60%, N≤0.020%, with the balance being Fe and unavoidable impurity elements; and a nickel-chromium equivalent ratio (Ni' / Cr') controlled at ≤0.5, wherein chromium equivalent Cr'=%Cr+1.5%Si, and nickel equivalent Ni'=%Ni+30(%C+%N)+0.5%Mn.

[0006] In order to further achieve the purpose of the present invention, a low-cost manufacturing method of 2Cr13 martensitic stainless steel is also provided, which comprises, in sequence, electric arc furnace / converter smelting, LF refining, VD vacuum treatment, continuous casting tundish, crystallizer vibration casting, staged cooling in the secondary cooling zone, billet cutting, staged heating in a heating furnace, high-pressure water descaling, multi-pass rolling and slow cooling in a pit, specifically as follows: (1) In the electric arc furnace smelting stage, high carbon content operation is adopted, carbon-oxygen reaction is used to achieve molten pool boiling, promote degassing and removal of inclusions, and high carbon ferrochrome and stainless steel scrap are used as the main raw materials. Among them, the Cr content of high carbon ferrochrome is ≥60% and the C content is 8%, and the Cr content of stainless steel scrap is ≥11%; (2) LF refining stage: deep desulfurization and composition fine-tuning are achieved through white slag process, and the refining time is ≥45min; (3) During the VD vacuum treatment stage, the vacuum degree should be maintained at ≤67Pa for at least 15min, ensuring that [H] in the molten steel is ≤2ppm and [O] is ≤30ppm; (4) Strictly control the superheat of the molten steel in the tundish within the range of 25~40℃, and match the corresponding casting speed system according to different superheat ranges; (5) The crystallizer vibration adopts a sinusoidal vibration mode, the vibration stroke is fixed at 7 mm, and the vibration frequency f is dynamically adjusted according to the casting speed. The calculation formula is: f = 1.3V1000 / (2*S), where S is the vibration stroke, unit is mm, and V is the casting speed of the continuous casting machine, unit is m / min; (6) The secondary cooling area is divided into zone 1 and zone 2. The water flow in each zone is allocated in proportion to the total cooling water volume. Based on the total flow Q, the water flow in zone 1 is Q1=Q*51%, and the water flow in zone 2 is Q2=Q*49%; (7) The billet with waste heat ≥ 500℃ is sent to the steel rolling heating furnace for staged heating, namely: heating to 850℃ in the heat recovery section, 850~1100℃ in the preheating section, 1100~1250℃ in the first heating section, 1240~1290℃ in the second heating section, and 1290℃ in the soaking section; (8) The blanking deformation process adopts a multi-pass small reduction design, and the total deformation is controlled within the range of 60-80%, which is completed in 5-7 passes. The first pass reduction is designed to be 15-20%, and then the subsequent passes are gradually reduced to 10-15%; (9) After rolling, the steel is put into a slow cooling pit for slow cooling treatment. The temperature of 6 points in the pit is automatically recorded every 10 minutes. The temperature entering the pit is ≥500℃. The pit cover is not allowed to be opened 36 hours after entering the pit. If the cover is opened after 36 hours, the steel can be taken out of the pit only when the temperature is below 200℃.

[0007] Furthermore, in steps (1) and (2), the tapping temperature is controlled within the range of 1580-1620°C, the tapping P is ≤ 0.025%, and the refining end temperature is controlled within the range of 1560-1580°C.

[0008] Furthermore, in step (2), the slag basicity is controlled to be CaO / SiO2=1.8~2.2, and FeO+MnO≤1.5%.

[0009] Furthermore, in step (2), the alloying sequence for fine-tuning the composition is as follows: adding FeSi to adjust Si to 0.35%, adding FeCr to adjust Cr to 12.60%, and adding Ni plate to adjust Ni to 0.55%.

[0010] Furthermore, in step (4), when the superheat of the tundish is ≤25°C, a pulling speed of 1.2 m / min is adopted; when the superheat is in the range of 25-40°C and does not include 25°C, a pulling speed of 1.1 m / min is adopted.

[0011] Furthermore, in step (5), the cooling water flow rate of the crystallizer is precisely controlled within the range of 1500-1600 L / min, with a fluctuation range of no more than ±50 L / min, the water seam flow rate of the crystallizer is controlled within the range of 6-8 m / s, and the inlet and outlet water temperature difference is controlled within the range of 4-7°C.

[0012] Furthermore, in step (6), the total flow rate of secondary cooling water is Q=KSg*p*V, wherein K is the cooling intensity, in L / kg, and S is the cross-sectional area of ​​the continuous casting billet, in m 2 , g is the acceleration due to gravity, unit is 10m / s 2 , p is the density of continuous casting billet 7800kg / m 3 , V is the casting speed of the continuous casting machine, unit is m / min.

[0013] Furthermore, in the step (8), the starting rolling temperature is set to 1100°C, and the finishing rolling temperature is set to 880°C.

[0014] Furthermore, in the step (9), the slow cooling is performed at a rate of ≤5°C / s to room temperature, and the spacing between the blanks is ≥150mm during the stack cooling.

[0015] Compared with the prior art, the advantages of the technical solution of the present invention are: (1) The present invention controls the nickel content to below 0.6% and precisely controls the chromium content within a narrow range, which not only ensures the basic corrosion resistance of the material but also avoids the excessive use of precious metal elements. At the same time, by controlling the nickel-chromium equivalent ratio, it effectively avoids the high concave defects commonly seen in the continuous casting process; (2) The present invention reduces production costs, reduces billet quality defects, improves the yield rate of hot delivery billet opening process, and achieves a perfect balance between performance and cost by precisely controlling chemical composition, optimizing continuous casting process parameters, and improving billet opening technology while ensuring material performance. (3) The present invention effectively avoids surface depression, longitudinal cracks and steel leakage during the continuous casting process of 2Cr13 martensitic stainless steel. Compared with the traditional process, the operation window of this method is wider and the parameter control is more precise. The continuous casting billets produced are not only of stable and reliable quality, but also have a significant improvement in the qualified rate, and the comprehensive cost per ton of product is reduced by about 8~10%. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a process flow chart of the low-cost 2Cr13 martensitic stainless steel manufacturing method of the present invention; Figure 2 This is a temperature curve diagram of the slab rolling process of the present invention; Figure 3 The performance test results of 2Cr13 martensitic stainless steel prepared in the embodiment of the present invention are as follows; Figure 4 This is a low-magnification photograph of 2Cr13 martensitic stainless steel prepared in an embodiment of the present invention. DETAILED DESCRIPTION Example

[0017] To make the present invention more clear, a low-cost 2Cr13 martensitic stainless steel and a manufacturing method thereof of the present invention are further described below. The specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0018] This embodiment provides a low-cost 2Cr13 martensitic stainless steel, whose chemical composition and mass percentage include: C: 0.18-0.20%, Si: 0.30-0.45%, Mn≤0.30%, P≤0.035%, S≤0.030%, Cr: 12.50-12.70%, Ni≤0.60%, N≤0.020%, and the balance is Fe and unavoidable impurity elements.

[0019] The key to chemical composition design lies in controlling the nickel content below 0.6% and precisely controlling the chromium content within a narrow range of 12.50% to 12.70%. This ensures the material's basic corrosion resistance while avoiding excessive use of precious metal elements. Of particular note, by controlling the nickel-chromium equivalent ratio (Ni' / Cr') to ≤ 0.5, this invention effectively avoids the high-concave defect common in continuous casting.

[0020] The nickel-chromium equivalent ratio is calculated as follows: chromium equivalent Cr' = %Cr + 1.5%Si; nickel equivalent Ni' = %Ni + 30(%C + %N) + 0.5%Mn. Numerous experiments have shown that when the nickel-chromium equivalent ratio is between 0.5 and 0.65, the steel billet exhibits high-concave defects, which are most severe when the nickel-chromium equivalent ratio is 0.55. These defects not only affect the surface quality of the rolled wire but are also the primary cause of frequent steel breakout accidents during the production of 2Cr13 in billet continuous casting machines. The present invention effectively addresses this problem by strictly controlling the Ni' / Cr' ratio to ≤0.5.

[0021] See also Figure 1 The manufacturing method of the 2Cr13 martensitic stainless steel comprises, in sequence, electric arc furnace / converter smelting, LF refining, VD vacuum treatment, continuous casting tundish, crystallizer vibration casting, segmented cooling in the secondary cooling zone, billet cutting, segmented heating in a heating furnace, high-pressure water descaling, multi-pass rolling and slow cooling in a pit, and is characterized in that: (I) Smelting process. A three-step process route employs electric arc furnace or converter smelting, combined with LF refining and VD vacuum degassing. During the electric arc furnace smelting stage, high carbon content is employed, utilizing carbon-oxygen reactions to achieve molten pool boiling, promoting degassing and removal of inclusions. During the LF refining stage, deep desulfurization and composition fine-tuning are achieved through the white slag process. During the VD vacuum treatment stage, the vacuum level is maintained at ≤67Pa for at least 15 minutes, ensuring that [H] in the molten steel is ≤2ppm and [O] is ≤30ppm. This smelting process route avoids the expensive AOD furnace refining process while ensuring molten steel purity, significantly reducing equipment investment and operating costs.

[0022] (2) Temperature Control. The tapping temperature is controlled within the range of 1580-1620°C, and the final refining temperature is controlled between 1560-1580°C. This relatively low smelting temperature not only reduces energy consumption but also minimizes refractory loss. Furthermore, strict control of temperature fluctuations at each stage ensures uniform composition and consistent molten steel quality.

[0023] (3) Alloying Strategy: A raw material combination primarily consisting of ferrochrome and scrap steel is employed. High-carbon ferrochrome (Cr ≥ 60% and C ≈ 8%) is selected as the ferrochrome, leveraging its price advantage to reduce raw material costs. In the later stages of refining, the composition is fine-tuned by adding low-carbon ferrochrome and metallic silicon, avoiding the high costs associated with using low-carbon alloys throughout the entire refining process. This phased alloying strategy can reduce alloy costs by approximately 12-15%, while ensuring precise control of the final composition.

[0024] (4) Impurity Control. This invention places particular emphasis on limiting residual elements such as Cu, Sn, Sb, and As, requiring their total content to be ≤ 0.20%. While these residual elements have a minimal impact on cost, they can significantly affect the hot working properties of the material and the toughness of the final product. By optimizing the scrap steel ratio and using high-purity ferroalloys, effective control of these residual elements is achieved without incurring additional refining costs.

[0025] (5) Tundish superheat control. The present invention strictly controls the superheat of the molten steel in the tundish within the range of 25~40℃, and matches the corresponding pulling speed system according to different superheat ranges. Specifically, when the superheat of the tundish is ≤25℃, a higher pulling speed of 1.2m / min is adopted; when the superheat is in the range of 25~40℃ and does not include 25℃, a pulling speed of 1.1m / min is adopted. This dynamic pulling speed adjustment strategy effectively balances the contradiction between the surface quality of the ingot and production efficiency - lower superheat combined with higher pulling speed can avoid internal porosity caused by excessive growth of the solidification front; while higher superheat combined with lower pulling speed can ensure sufficient molten steel replenishment in the meniscus area, reducing surface depressions and crack defects. Compared with the traditional fixed pulling speed process, this dynamic adjustment based on superheat can increase the first-inspection pass rate of the ingot from an average of 95% to ≥99.1%.

[0026] (6) Crystallizer vibration parameters. Based on the characteristics of 2Cr13 stainless steel, a sinusoidal vibration mode is adopted, with the vibration stroke fixed at 7mm. The vibration frequency f is dynamically adjusted according to the casting speed. The calculation formula is: f = 1.3V1000 / (2*S), where S is the vibration stroke (mm) and V is the casting speed of the continuous casting machine (m / min). For example, at a casting speed of 1.1m / min, the vibration frequency is approximately 102 times / min; at a casting speed of 1.2m / min, the frequency is approximately 111 times / min. This vibration parameter design combining large amplitude and high frequency has two advantages: on the one hand, the larger amplitude increases the consumption of mold slag, which is beneficial for filling the gap between the ingot shell and the crystallizer wall and improving heat transfer uniformity; on the other hand, the higher vibration frequency promotes smooth demolding of the ingot from the crystallizer and reduces the probability of surface cracks.

[0027] (VII) Optimization of the crystallizer cooling system. The present invention precisely controls the cooling water flow rate of the crystallizer within the range of 1500~1600L / min. This flow rate range has been verified by a large number of experiments, and can ensure sufficient cooling intensity while avoiding the problem of uneven shell caused by excessive cooling. Compared with traditional processes, the cooling water flow control of the present invention is more stringent, with a fluctuation range of no more than ±50L / min, ensuring the stability of the solidification process. In addition, the flow rate of the crystallizer water seam is controlled at 6~8m / s, and the inlet and outlet water temperature difference is controlled at 4~7°C. The coordinated control of these parameters creates ideal conditions for the formation of a uniform initial shell.

[0028] (8) The secondary cooling system adopts precise control by zoning. The secondary cooling area is divided into two areas, namely area 1 and area 2. The water flow in each area is allocated in proportion to the total cooling water volume. The specific calculation method is: the total flow of secondary cooling water Q = KSg*p*V, where K is the cooling intensity (L / kg), S is the cross-sectional area of ​​the continuous casting billet (m²), and g is the acceleration of gravity (10m / s 2 ), p is the density of continuous casting billet (7800kg / m 3 ), V is the casting speed of the continuous casting machine (m / min). Based on the total flow Q, the water flow in zone 1 Q1 = Q*51%, and the water flow in zone 2 Q2 = Q*49%. For 150×150mm 2 For a typical billet, the total water volume for secondary cooling is approximately 42.5~46.3L / min, with 21.7~23.6L / min for zone 1 and 20.8~22.7L / min for zone 2. This proportional distribution ensures uniform cooling of the billet in the brittle temperature zone of 700~900℃, effectively reducing temperature stress and the resulting internal cracks. (IX) Segmented heating. The billet with residual heat ≥ 500°C is heated to the steel rolling heating furnace for heating. In view of the characteristics of 2Cr13 martensitic stainless steel, the present invention adopts a segmented heating strategy: see Figure 2 The heat recovery section heats the steel to 850°C, the preheating section maintains a temperature of 850-1100°C, the first heating section maintains a temperature of 1100-1250°C, the second heating section maintains a temperature of 1240-1290°C, and the soaking section maintains a temperature of 1290°C. This temperature curve design fully considers the phase transformation characteristics and thermal conductivity of 2Cr13. The lower preheating temperature avoids cracks caused by thermal stress, while the moderate heating section temperature ensures uniform heating of the steel billet. Compared with traditional processes, the maximum heating temperature of this invention is reduced by approximately 20°C, which not only reduces energy consumption and gas consumption by approximately 12%, but also significantly reduces the amount of iron oxide scale generated, reducing oxidation loss from 1.2% to below 0.8%.

[0029] (10) The cogging deformation process utilizes multiple passes with small reductions. The total deformation is controlled within the range of 60-80%, completed in 5-7 passes. The first-pass reduction is designed to be 15-20%, with subsequent passes gradually decreasing to 10-15%. This deformation distribution facilitates the breakdown of coarse as-cast structures while avoiding edge cracks caused by excessive deformation in a single pass. Compared to traditional high-reduction processes, this multi-pass, small-reduction process, while increasing the number of rolling passes, significantly improves the internal quality of the material, reduces defects such as cracks, and increases the overall yield by 3-5 percentage points.

[0030] (11) After rolling, the steel is placed in a slow cooling pit for slow cooling treatment. The temperature at 6 points in the pit is automatically recorded every 10 minutes. The pit temperature must be ≥500℃. The pit cover is not allowed to be opened for 36 hours after entering the pit. The cover can be opened after 36 hours. The steel can only be taken out of the pit when the steel temperature is below 200℃.

[0031] In addition to the aforementioned low-temperature heating and efficient descaling technologies, the rolling line of this invention utilizes an AC variable-frequency motor, which saves 15-20% energy compared to traditional DC motors. The heating furnace employs regenerative combustion technology, increasing thermal efficiency to over 65%. A waste heat recovery system reduces exhaust gas temperatures to below 150°C, with the recovered heat used to preheat combustion air or meet other factory heating needs. These comprehensive measures reduce the total energy consumption of the billet opening process from the traditional approximately 180 kWh / t to 145 kWh / t, a reduction of 19.4%, significantly reducing production costs.

[0032] In this embodiment, during electric arc furnace smelting: Raw material ratio: high carbon ferrochrome (Cr60%, C8%) 120kg / t; stainless steel scrap (Cr≥11%) 850kg / t; ordinary carbon steel scrap 30kg / t; Key points of operation: Melt clear C control ≥0.25%; tapping temperature 1600±10℃; tapping P ≤0.025%.

[0033] In this embodiment, during LF refining: Slag system control: basicity CaO / SiO2=1.8-2.2; FeO+MnO≤1.5%; Alloying sequence: 1) Add FeSi to adjust Si to 0.35%; 2) Add FeCr to adjust Cr to 12.60%; 3) Add Ni plate to adjust Ni to 0.55%; Refining time ≥45min.

[0034] In this embodiment, during the VD vacuum treatment, the following conditions were met: vacuum degree ≤ 67 Pa and maintained for 18 min; soft argon blowing time ≥ 15 min; and final [H] ≤ 1.5 ppm, [O] ≤ 25 ppm.

[0035] In this embodiment, during continuous casting: Crystallizer water volume: 1550L / min (±20); Vibration frequency: 107 times / min (pulling speed 1.15m / min) Secondary cooling water volume: 0.45L / kg (51% in zone 1, 49% in zone 2).

[0036] In this embodiment, during the slab rolling, the starting rolling temperature is 1100° C., the finishing rolling temperature is 880° C., and the total deformation is 65%.

[0037] In the embodiment, the slow cooling is performed at a cooling rate of ≤5℃ / s to room temperature, and the billet spacing is ≥150mm.

[0038] The tensile strength, yield strength, elongation, hardness and other test structures of the 2Cr13 martensitic stainless steel prepared by the method of the embodiment are shown in Table 1. Figure 3 The macroscopic photograph is shown in Figure 2. Figure 4 It can be seen that the 2Cr13 martensitic stainless steel of the application can reduce the production cost, reduce the casting billet quality defects, improve the product quality, improve the yield of the hot sending cogging process, and balance the high performance and low cost under the premise of ensuring the material performance.

[0039] In addition to the above embodiments, the application can have other implementation manners. Any technical solution formed by equivalent replacement or equivalent transformation falls within the protection scope required by the application.

Claims

1. A low-cost 2Cr13 martensitic stainless steel, characterized by: The chemical composition and mass percentage of the steel include: C: 0.18-0.20%, Si: 0.30-0.45%, Mn≤0.30%, P≤0.035%, S≤0.030%, Cr: 12.50-12.70%, Ni≤0.60%, N≤0.020%, and the balance is Fe and unavoidable impurity elements; and the nickel-chromium equivalent ratio Ni' / Cr' is controlled at a level of ≤0.5, wherein the chromium equivalent Cr'=%Cr+1.5%Si, and the nickel equivalent Ni'=%Ni+30(%C+%N)+0.5%Mn.

2. A method for producing low-cost 2Cr13 martensitic stainless steel according to claim 1, comprising, in sequence, electric arc furnace / converter smelting, LF refining, VD vacuum treatment, continuous casting tundish, crystallizer vibration casting, staged cooling in a secondary cooling zone, billet cutting, staged heating in a heating furnace, high-pressure water descaling, multi-pass rolling, and slow cooling in a pit, wherein: (1) In the electric arc furnace smelting stage, high carbon operation is adopted, with high carbon ferrochrome and stainless steel scrap as the main raw materials. Among them, the Cr content of high carbon ferrochrome is ≥60%, the C content is 8%, and the Cr content of stainless steel scrap is ≥11%; (2) LF refining stage: deep desulfurization and composition fine-tuning are achieved through white slag process, and the refining time is ≥45min; (3) During the VD vacuum treatment stage, the vacuum degree should be maintained at ≤67Pa for at least 15min, ensuring that [H] in the molten steel is ≤2ppm and [O] is ≤30ppm; (4) Strictly control the superheat of the molten steel in the tundish within the range of 25~40℃, and match the corresponding casting speed system according to different superheat ranges; (5) The crystallizer vibration adopts a sinusoidal vibration mode, the vibration stroke is fixed at 7 mm, and the vibration frequency f is dynamically adjusted according to the casting speed. The calculation formula is: f = 1.3V1000 / (2*S), where S is the vibration stroke, unit is mm, and V is the casting speed of the continuous casting machine, unit is m / min; (6) The secondary cooling area is divided into zone 1 and zone 2. The water flow in each zone is allocated in proportion to the total cooling water volume. Based on the total flow Q, the water flow in zone 1 is Q1=Q*51%, and the water flow in zone 2 is Q2=Q*49%; (7) The billet with waste heat ≥ 500℃ is sent to the steel rolling heating furnace for staged heating, namely: heating to 850℃ in the heat recovery section, 850~1100℃ in the preheating section, 1100~1250℃ in the first heating section, 1240~1290℃ in the second heating section, and 1290℃ in the soaking section; (8) The blanking deformation process adopts a multi-pass small reduction design, and the total deformation is controlled within the range of 60-80%, which is completed in 5-7 passes. The first pass reduction is designed to be 15-20%, and then the subsequent passes are gradually reduced to 10-15%; (9) After rolling, the steel is put into a slow cooling pit for slow cooling treatment. The temperature of 6 points in the pit is automatically recorded every 10 minutes. The temperature entering the pit is ≥500℃. The pit cover is not allowed to be opened 36 hours after entering the pit. If the cover is opened after 36 hours, the steel can be taken out of the pit only when the temperature is below 200℃.

3. The method for manufacturing low-cost 2Cr13 martensitic stainless steel according to claim 2, characterized in that: In the steps (1) and (2), the tapping temperature is controlled within the range of 1580-1620°C, the tapping P is ≤ 0.025%, and the refining end temperature is controlled within the range of 1560-1580°C.

4. The method for manufacturing low-cost 2Cr13 martensitic stainless steel according to claim 2, characterized in that: In the step (2), the slag basicity is controlled to be CaO / SiO2=1.8~2.2, and FeO+MnO≤1.5%.

5. The method for manufacturing low-cost 2Cr13 martensitic stainless steel according to claim 2, characterized in that: In the step (2), the alloying sequence for fine-tuning the composition is as follows: adding FeSi to adjust Si to 0.35%, adding FeCr to adjust Cr to 12.60%, and adding Ni plate to adjust Ni to 0.55%.

6. The method for manufacturing low-cost 2Cr13 martensitic stainless steel according to claim 2, characterized in that: In the step (4), when the superheat degree of the tundish is ≤25°C, a pulling speed of 1.2 m / min is adopted; when the superheat degree is in the range of 25-40°C and does not include 25°C, a pulling speed of 1.1 m / min is adopted.

7. The method for manufacturing low-cost 2Cr13 martensitic stainless steel according to claim 2, characterized in that: In the step (5), the cooling water flow rate of the crystallizer is precisely controlled within the range of 1500-1600 L / min, with a fluctuation range of no more than ±50 L / min, the water seam flow rate of the crystallizer is controlled within the range of 6-8 m / s, and the inlet and outlet water temperature difference is controlled within the range of 4-7°C.

8. The method for manufacturing low-cost 2Cr13 martensitic stainless steel according to claim 2, characterized in that: In the step (6), the total flow rate of the secondary cooling water is Q=KSg*p*V, wherein K is the cooling intensity, in L / kg, and S is the cross-sectional area of ​​the continuous casting billet, in m 2 , g is the acceleration due to gravity, unit is 10m / s 2 , p is the density of continuous casting billet 7800kg / m 3 , V is the casting speed of the continuous casting machine, unit is m / min.

9. The method for manufacturing low-cost 2Cr13 martensitic stainless steel according to claim 2, characterized in that: In the step (8), the starting rolling temperature is set to 1100°C and the finishing rolling temperature is set to 880°C.

10. The method for manufacturing low-cost 2Cr13 martensitic stainless steel according to claim 2, characterized in that: In the step (9), the slow cooling is performed at a rate of ≤5°C / s to room temperature, and the spacing between the blanks is ≥150mm during the stack cooling.

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