Production process of novel economic martensitic stainless steel 1Cr13Ni2 with high low-temperature toughness

Abstract

The invention relates to the technical field of martensitic stainless steel, in particular to a production process of novel economic martensitic stainless steel 1Cr13Ni2 with high low-temperature toughness, which comprises the following steps: S1, material component design and smelting: selecting a proper material, treating the material, and smelting the material to obtain a material component; then the treated materials are poured into a smelting furnace to be smelted, a catalyst is added during smelting, and the raw materials are prepared into steel ingots; s2, cogging and preheating are conducted, specifically, the steel ingot is placed in a heating furnace to be heated and preheated, in the preheating process, a forging machine is operated to be started, the steel ingot is forged, and after forging is finished, the steel ingot is taken out and cooled to a certain temperature; according to the component improvement technology, on the basis of AISI 410 stainless steel, the Ni content is increased, delta-ferrite formation is inhibited, the tempered inverted austenite content is increased, the high strength of the AISI 410 stainless steel is achieved, the good low-temperature toughness is achieved, and the material has the stable and good low-temperature impact performance.

Description

Technical Field

[0001] The present invention relates to the technical field of martensitic stainless steel, and particularly relates to a production process of a new type of martensitic stainless steel 1Cr13Ni2 with economical high and low temperature toughness. Background Art

[0002] Due to its special martensitic structure, martensitic stainless steel can obtain a martensitic structure with a high dislocation density through a heat treatment process of quenching + tempering, improving strength, hardness, plasticity and toughness. At the same time, its corrosion resistance and weldability make it widely used in fields such as aviation, automobile manufacturing, cutting tools, medical devices, and petroleum. Martensitic stainless steel can be divided into martensitic chromium stainless steel and martensitic chromium-nickel stainless steel according to alloying elements. At present, the typical martensitic chromium stainless steel AISI410 (1Cr13) has been widely used in the petroleum field, such as components like valves and pumps. However, due to its limitation of low temperature brittleness, it affects its application in subarctic and arctic climate regions such as Canada and Russia. Very few domestic-made AISI410 stainless steels can meet the requirements of grade L (-46 °C, 27 J) and have stable quality. A large number of literatures show that δ-ferrite in AISI410 stainless steel is the key factor reducing the low temperature impact of the material, resulting in unstable low temperature impact performance of the material at -46 °C. Another common type of martensitic stainless steel F6NM (04Cr13Ni5Mo) contains a large amount of elements such as Cr, Ni, and Mo, which improves the δ-ferrite in the structure. The impact absorption work at -46 °C can reach more than 80 J. At the same time, it has high strength, high hardness and good corrosion resistance, and is an ideal material in the field of mechanical manufacturing. However, the high production cost limits its wide use.

[0003] In order to improve the low temperature toughness of martensitic stainless steel and develop an economical and high-performance Cr13 martensitic stainless steel, the present invention has developed a new type of martensitic stainless steel 1Cr13Ni2 on the basis of AISI 410 material. By increasing the Ni content, it has both the high strength of AISI 410 stainless steel and good low temperature toughness. Summary of the Invention

[0004] The purpose of the present invention is to provide a production process of a new type of martensitic stainless steel 1Cr13Ni2 with economical high and low temperature toughness to solve the above deficiencies in the prior art.

[0005] In order to achieve the above purpose, the present invention provides the following technical solutions:

[0006] δ-ferrite is a phase rich in W, Mo, Cr, and V and poor in Mn. To reduce the content of δ-ferrite in the AISI 410 microstructure, the content of the strong austenitizing element Ni is increased by 1.40 - 2.50% to inhibit the formation of δ-ferrite. To further confirm, the Creq and Nieq of the chemical compositions of AISI 410 and the improved 1Cr13Ni2 steel are calculated using formulas (1) and (2), and combined with the Schaeffler microstructure diagram. The results show that the ferrite content in AISI 410 is approximately 5 - 10%, and the ferrite content in 1Cr13Ni2 is approximately 0%.

[0007] Cr eq = %Cr + %Mo + 1.5%Si + 0.5%Nb + 2%Ti (1)

[0008] Ni eq = %Ni + 30%C + 0.5%Mn (2)

[0009] A production process for a new type of martensitic stainless steel 1Cr13Ni2 with high and low temperature toughness and economy includes the following steps:

[0010] Step S1. Material composition design and smelting: Select suitable materials, process the materials, and then pour the processed materials into the internal part of the smelting furnace for smelting, and add a catalyst during smelting to prepare the raw materials into ingots;

[0011] Step S2. Ingot heating and preheating: Place the ingot in a heating furnace to heat and preheat the ingot. During the preheating process, start the forging machine to forge the ingot. After forging, take out the ingot and cool it to a certain temperature to obtain a billet;

[0012] Step S3. Forging: After the billet cooling is completed, place the billet in the heating furnace again for heating and forging, and ensure the temperature during forging;

[0013] Step S4. Nondestructive testing: After forging is completed, take out the forged part for cooling. After cooling to room temperature, detect the forged part through nondestructive testing technology;

[0014] Step S5. Heat treatment: Put the detected forged part back into the heating furnace for quenching and tempering treatments, and after the heat treatment is completed, cool it to room temperature;

[0015] Step S6. Secondary nondestructive testing: Conduct secondary testing on the heat-treated forged part through nondestructive testing technology to determine whether there are damages inside the forged part.

[0016] Further, the material components selected in step S1 are as follows: C: 0.10 - 0.15%, Si: ≤1.00%, Mn: ≤1.00%, P: ≤0.025%, S: ≤0.025%, Cr: 11.50 - 13.50%, Mo: 0.15 - 0.35%, Ni: 1.40 - 2.50%, and the remaining elements are Fe and other residual elements. The Ni content in the ingot in step S1 needs to be strictly controlled.

[0017] Further, when preheating the bloom, the preheating temperature of the ingot is 1000 - 1200 °C, and the preheating time is 30 - 45 min.

[0018] Further, the temperature control during forging in step S3 is as follows: charging temperature ≤300 °C, heating rate ≤100 °C / h, heating temperature 1200 °C, initial forging temperature 1140 °C, and final forging temperature ≥850 °C.

[0019] Further, the forging in step S3 specifically includes the following processes:

[0020] The first heat: upsetting, forging ratio > 1.6, reheating and holding for not less than 2 h;

[0021] The second heat: drawing out, forging ratio > 1.6, reheating and holding for not less than 2 h;

[0022] The third heat: drawing out and rolling into a round shape, forging ratio > 1.6, air cooling.

[0023] Further, during the forging in step S3, transverse upsetting is carried out, and the forging ratio is greater than 1.6.

[0024] Further, after the forging in step S3 is completed, annealing should be carried out in a timely manner to relieve the forging stress.

[0025] Further, during quenching in step S5, the heating rate of the quenching temperature ≤200 °C / h. After heating to 950 - 1025 °C and holding for ≥5 h, water cooling is used for quenching.

[0026] Further, there are two temperings in step S5, and specifically as follows:

[0027] The first tempering: the heating rate of the temperature ≤250 °C / h, heating to 650 - 780 °C, holding for ≥10 h, and then water cooling;

[0028] The second tempering: the temperature is 15 °C lower than the first time, holding for ≥10 h, and then water cooling.

[0029] Further, the cooling method for heat treatment in step S5 is all water cooling, and the time for transferring the sample from the furnace to the quenching tank does not exceed 60 s.

[0030] In the above technical solution, the production process of a new type of economical martensitic stainless steel 1Cr13Ni2 with high and low temperature toughness provided by the present invention has the following beneficial effects:

[0031] (1) The present invention provides a composition improvement process. By increasing the Ni content, the formation of δ-ferrite is inhibited, and the content of reverse austenite after tempering is increased, so that it has both the high strength of AISI410 stainless steel and good low temperature toughness, and the material has stable and good low temperature impact performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required in the embodiments. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those of ordinary skill in the art, other drawings can also be obtained based on these drawings.

[0033] Figure 1 It is a three-dimensional structure diagram provided for an embodiment of the production process of a new type of economical martensitic stainless steel 1Cr13Ni2 with high and low temperature toughness of the present invention.

[0034] Figure 2 It is a heat treatment process diagram provided for an embodiment of the production process of a new type of economical martensitic stainless steel 1Cr13Ni2 with high and low temperature toughness of the present invention.

[0035] Figure 3 It is a 100X metallographic structure diagram after heat treatment of Example 1 provided for an embodiment of the production process of a new type of economical martensitic stainless steel 1Cr13Ni2 with high and low temperature toughness of the present invention.

[0036] Figure 4 It is a 100X metallographic structure diagram after heat treatment of Example 2 provided for an embodiment of the production process of a new type of economical martensitic stainless steel 1Cr13Ni2 with high and low temperature toughness of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0037] In order to enable those skilled in the art to better understand the technical solutions of the present invention, the following will further introduce the present invention in detail with reference to the drawings.

[0038] As Figures 1-4 shown, the production process of a new type of economical martensitic stainless steel 1Cr13Ni2 with high and low temperature toughness provided by the embodiment of the present invention includes the following steps:

[0039] Step S1. Material composition design and smelting: Select appropriate materials, crush and grind the materials. The material composition is as follows: C: 0.10 - 0.15%, Si: ≤1.00%, Mn: ≤1.00%, P: ≤0.025%, S: ≤0.025%, Cr: 11.50 - 13.50%, Mo: 0.15 - 0.35%, Ni: 1.40 - 2.50%, and the remaining elements are Fe and other residual elements. The Ni content in the ingot needs to be strictly controlled. Then pour the processed materials into the smelting furnace for smelting, and add a catalyst during smelting to prepare the raw materials into an ingot;

[0040] Step S2. Billet preheating: Place the ingot in a heating furnace for heating and preheating. During preheating, the preheating temperature of the ingot is 1000 - 1200°C, and the preheating time is 30 - 45 min. During the preheating process, start the forging machine to forge the ingot. After forging, take out the ingot and cool it to a certain temperature to obtain a billet;

[0041] Step S3. Forging: After the billet is cooled, put the billet into the heating furnace again for heating. The temperature control during forging is as follows: charging temperature ≤300°C, heating rate ≤100°C / h, heating temperature 1200°C, starting forging temperature 1140°C, finishing forging temperature ≥850°C, and then carry out forging. Ensure the temperature during forging. The forging specifically includes the following processes:

[0042] The first fire: Upsetting, forging ratio > 1.6, reheating and holding for not less than 2 h;

[0043] The second fire: Drawing out, forging ratio > 1.6, reheating and holding for not less than 2 h;

[0044] The third fire: Drawing out and rolling into a round shape, forging ratio > 1.6, air cooling;

[0045] During forging, upset transversely and the forging ratio is greater than 1.6. After forging, it is necessary to anneal in time to relieve the forging stress and clean the oxide scale generated during forging in time to avoid forming folds and reducing corrosion resistance;

[0046] Step S4. Nondestructive testing: After forging, take out the forged part for cooling. After cooling to room temperature, detect the forged part through nondestructive testing technology;

[0047] Step S5. Heat treatment: Put the detected forged part back into the heating furnace for quenching and tempering. During quenching, the heating rate of the quenching temperature ≤200°C / h, heat up to 950 - 1025°C, hold for a minimum of 5 h, and then quench by water cooling; There are two tempering processes, and the details are as follows:

[0048] The first tempering: The temperature rising rate ≤ 250 °C / h, heat up to 650 - 780 °C, after holding for ≥ 10 h, water cooling;

[0049] The second tempering: The temperature is 15 °C lower than the first time, after holding for ≥ 10 h, water cooling and after the heat treatment is completed, cool to room temperature;

[0050] The cooling method of the heat treatment is all water cooling, and the time for the sample to be transferred from the furnace to the quenching tank does not exceed 60 s;

[0051] Step S6. Secondary non-destructive testing: Use non-destructive testing technology to conduct secondary testing on the heat-treated forgings to determine whether there are damages inside the forgings.

[0052] Example 1

[0053] Select a 1Cr13Ni2 electroslag ingot added with 1.6% Ni. According to the calculations of formulas (1) and (2), Cr eq and Ni eq are 12.84 and 6.19 respectively. According to the Schaeffler structure diagram calculation, the δ-ferrite is about 0%.

[0054] Cr eq = %Cr + %Mo + 1.5%Si + 0.5%Nb + 2%Ti (1)

[0055] Ni eq = %Ni + 30%C + 0.5%Mn (2)

[0056] S1 Steel billet selection: The material composition meets: C: 0.10 - 0.15%, Si: ≤ 1.00%, Mn: ≤ 1.00%, P: ≤ 0.025%, S: ≤ 0.025%, Cr: 11.50 - 13.50%, Mo: 0.15 - 0.35%, Ni: 1.6%, and the remaining elements are Fe and other residual elements;

[0057] S2 Billet opening

[0058] S3 Forging: Place the billet in a heating furnace, the furnace loading temperature ≤ 300 °C, the heating rate ≤ 100 °C / h, the heating temperature is 1200 °C, the starting forging temperature is 1140 °C, the final forging temperature ≥ 850 °C. Preheat the tooling such as the anvil before forging to avoid cracks caused by large temperature differences; The forging ratio ≥ 1.6 to ensure a dense structure after forging, break the coarse grains, refine the grains, and improve the mechanical properties;

[0059] S4 Non-destructive testing

[0060] S5 Heat treatment: Quench by heating to 950 - 1025°C at a rate of ≤200°C / h, hold for ≥5 h, then water-cool; For the first tempering, heat to 650 - 780°C at a rate of ≤250°C / h, hold for ≥10 h, then water-cool; The temperature of the second tempering is 15°C lower than the first, hold for ≥10 h, then water-cool.

[0061] S6 Non-destructive testing

[0062] Before forging, it is necessary to inspect the composition of the raw materials to avoid the presence of δ-ferrite; During forging, it is necessary to control the forging ratio of each heating to ≥1.6; Remove the scale generated during forging in a timely manner to prevent the formation of folds and reduce corrosion resistance. In addition, water-cooling is used for all heat treatment cooling methods, and the time for transferring the sample from the furnace to the quenching tank does not exceed 60 s. The specific implementation is as Figure 1 shown in the heat treatment process diagram of the embodiment. The metallographic structure of Example 1 after heat treatment is as Figure 2 shown. There is no δ-ferrite in the structure, which is consistent with the calculation results. The as-forged sample of Example 1 after heat treatment is subjected to room temperature tensile testing and -46°C Charpy impact testing, and the results are shown in Table 1.

[0063] Table 1 Performance test data of the QTC sample of Example 1

[0064]

[0065] Example 2

[0066] Select a 1Cr13Ni2 electroslag ingot added with 2% Ni. According to the calculations of formulas (1) and (2), Cr eq and Ni eq are 12.84 and 6.59 respectively. According to the Schaeffler diagram calculation, the δ-ferrite is approximately 0%.

[0067] Cr eq = %Cr + %Mo + 1.5%Si + 0.5%Nb + 2%Ti (1)

[0068] Ni eq = %Ni + 30%C + 0.5%Mn (2)

[0069] S1 Steel billet selection: The material composition meets: C: 0.10 - 0.15%, Si: ≤1.00%, Mn: ≤1.00%, P: ≤0.025%, S: ≤0.025%, Cr: 11.50 - 13.50%, Mo: 0.15 - 0.35%, Ni: 2.0%, and the remaining elements are Fe and other residual elements;

[0070] S2 Blooming

[0071] S3 Forging: Place the ingot in a heating furnace. The furnace loading temperature ≤ 300°C, the heating rate ≤ 100°C / h, the heating temperature 1200°C, the starting forging temperature 1140°C, the final forging temperature ≥ 850°C. Preheat tooling such as anvil seats before forging to avoid cracks caused by large temperature differences; the forging ratio ≥ 1.6 to ensure a dense structure after forging, break up coarse grains, refine the grains, and improve mechanical properties;

[0072] S4 Non-destructive testing

[0073] S5 Heat treatment: Quench by heating to 950 - 1025°C at a rate ≤ 200°C / h, hold for ≥ 5 h, then water-cool; for the first tempering, heat to 650 - 780°C at a rate ≤ 250°C / h, hold for ≥ 10 h, then water-cool; the temperature of the second tempering is 15°C lower than the first, hold for ≥ 10 h, then water-cool.

[0074] S6 Non-destructive testing

[0075] Among them, it is necessary to inspect the composition of the raw materials before forging to avoid the existence of δ-ferrite; during forging, it is necessary to control the forging ratio of each heat ≥ 1.6; promptly clean the scale generated during forging to prevent the formation of folds and reduce corrosion resistance. In addition, the cooling method for heat treatment is all water-cooling, and the time for the sample to be transferred from the furnace to the quenching tank does not exceed 60 s. The specific implementation is as shown in the heat treatment process diagram of the Figure 1 embodiment. The metallographic structure of Example 2 after heat treatment is as shown in Figure 3 the figure. There is no δ-ferrite in the structure, which is consistent with the calculation results. Conduct a room-temperature tensile test and a -46°C Charpy impact test on the test block of Example 2 after heat treatment. The results are shown in Table 2.

[0076] Table 2 Performance test data of the QTC test block of Example 2

[0077]

[0078]

[0079] Only some exemplary embodiments of the present invention are described by way of illustration above. Undoubtedly, for those of ordinary skill in the art, without departing from the spirit and scope of the present invention, the described embodiments can be modified in various different ways. Therefore, the above drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A new type of economical high and low temperature toughness martensitic stainless steel 1Cr13Ni2 production process, characterized in that: The following steps are involved: Step S1. Material composition design and smelting: Select appropriate materials, process the materials, pour the processed materials into a smelting furnace for smelting, add catalysts during smelting, and prepare the raw materials into steel ingots; Step S2. Preheating the billet: placing the steel ingot in a heating furnace for heating, preheating the steel ingot, and during the preheating process, operating the forging machine to start the steel ingot forging, and after the forging is completed, taking out the steel ingot and cooling it to a certain temperature to obtain a billet; Step S3. Forging: After the blank is cooled, the blank is placed in a heating furnace for heating again and forging is performed, and the temperature is maintained during forging; Step S4. Nondestructive testing: After forging is completed, the forged piece is taken out for cooling. After cooling to room temperature, the forged piece is tested by nondestructive testing technology; Step S5. Heat treatment: the forged piece after inspection is put back into the heating furnace for quenching and tempering, and after the heat treatment is completed, it is cooled to room temperature; Step S6. Secondary nondestructive testing: Perform secondary testing on the heat-treated forgings using nondestructive testing technology to determine whether there is any damage inside the forgings.

2. The production process of a new type of economical high and low temperature toughness martensitic stainless steel 1Cr13Ni2 according to claim 1 is characterized by: The material composition selected in step S1 is as follows: C: 0.10-0.15%, Si: ≤1.00%, Mn: ≤1.00%, P: ≤0.025%, S: ≤0.025%, Cr: 11.50-13.50%, Mo: 0.15-0.35%, Ni: 1.40-2.50%, and the remaining elements are Fe and other residual elements. The Ni content of the steel ingot in step S1 needs to be strictly controlled.

3. The production process of a new type of economical high and low temperature toughness martensitic stainless steel 1Cr13Ni2 according to claim 1 is characterized in that: The preheating temperature of the steel ingot during the preheating of the blank is 1000-1200°C, and the preheating time is 30-45 minutes.

4. The production process of a new type of economical high and low temperature toughness martensitic stainless steel 1Cr13Ni2 according to claim 1 is characterized in that: The temperature control during forging in step S3 is as follows: furnace charging temperature ≤300°C, heating rate ≤100°C / h, heating temperature 1200°C, initial forging temperature 1140°C, and final forging temperature ≥850°C.

5. The production process of a new type of economical high and low temperature toughness martensitic stainless steel 1Cr13Ni2 according to claim 1 is characterized in that: The forging in step S3 specifically includes the following steps: First fire: roughing, forging ratio>1.6, remelting and heat preservation for not less than 2h; Second fire: drawing, forging ratio>1.6, remelting and heat preservation for not less than 2h; The third fire: stretch and round, forging ratio>1.6, air cooling.

6. The production process of a new type of economical high and low temperature toughness martensitic stainless steel 1Cr13Ni2 according to claim 1 is characterized in that: In the step S3, the forging process is transversely upsetting, and the forging ratio is greater than 1.

6.

7. The production process of a new type of economical high and low temperature toughness martensitic stainless steel 1Cr13Ni2 according to claim 1 is characterized in that: After the forging in step S3 is completed, timely annealing is required to relieve the forging stress.

8. The production process of a new type of economical high and low temperature toughness martensitic stainless steel 1Cr13Ni2 according to claim 1 is characterized in that: During quenching in step S5, the quenching temperature is increased at a rate of ≤200°C / h to 950-1025°C, and after the temperature is kept at a temperature for ≥5h, water cooling is used for quenching.

9. The production process of a new type of economical high and low temperature toughness martensitic stainless steel 1Cr13Ni2 according to claim 1 is characterized in that: There are two tempering steps in step S5, and the details are as follows: First tempering: temperature rise rate ≤250℃ / h, temperature rise to 650-780℃, keep temperature for ≥10h, then water cool; Second tempering: The temperature is 15℃ lower than the first tempering. After keeping warm for ≥10h, cool with water.

10. The production process of a new type of economical high and low temperature toughness martensitic stainless steel 1Cr13Ni2 according to claim 3, characterized in that: The cooling method of the heat treatment in step S5 is water cooling, and the time for transferring the sample from the furnace to the quenching tank does not exceed 60s.

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