CN116219270A - High-strength precipitation hardening stainless steel for sensor elastomer and preparation method thereof - Google Patents
High-strength precipitation hardening stainless steel for sensor elastomer and preparation method thereof Download PDFInfo
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Abstract
The invention discloses a high-strength precipitation hardening stainless steel for a sensor elastomer and a preparation method thereof, wherein the high-strength precipitation hardening stainless steel is a new steel which is developed by reducing C, cr content, increasing Ni and N content and adding a small amount of Mo element on the basis of 17-4PH stainless steel, and has the advantages of easy processing, good corrosion resistance, high toughness, high strength and the like; according to the invention, the alloy proportion is optimized, so that the delta ferrite content is greatly reduced, and better consistency of mechanical properties in all directions is achieved; meanwhile, as vacuum consumable remelting (VAR) smelting is adopted, the content of gas impurities, particularly hydrogen and oxygen, is less, and the alloy has better toughness and hot processing performance under the condition of ensuring that the mechanical property index is not reduced.
Description
Technical Field
The invention relates to the field of metal materials, in particular to high-strength precipitation hardening stainless steel for a sensor elastomer and a preparation method thereof.
Background
The quality of the performance of the weighing sensor determines the accuracy, stability and reliability of the weighing apparatus; the weighing sensor using stainless steel as elastomer material can weld and seal metal diaphragm, has the characteristics of corrosion resistance, explosion resistance, high reliability and high stability, and can be used as a substitute of alloy steel sensors in the industries of corrosive occasions, food, chemical industry and the like.
Generally, the metal material adopted by the elastomer has excellent comprehensive performance besides strict requirements on chemical components and smelting conditions, and the material with high resistance to plastic deformation is selected as much as possible while ensuring elasticity and stress, and the purity of the material is high and the uniformity of the components is good; particular attention should be paid to the elastic modulus E of the material when selecting an elastic material, and to the influence of the elastic aftereffect and the thermo-elastic effect of the material on the sensor performance; the material composition affects the overall mechanical properties of the material, thus determining the performance of the sensor, and therefore the material selection and composition determination are critical. The common stainless steel in the weighing sensor industry at home and abroad at present mainly comprises 0Cr17Ni4Cu4Nb, 17-4PH, 630 and the like, but the stainless steel is generally produced by adopting the traditional electric furnace smelting and electric furnace and electroslag smelting methods, and has higher nonmetallic inclusion content and impurity gas content such as hydrogen, oxygen and the like, and has adverse effects on the plasticity and toughness of the material. In addition, about 10% delta ferrite exists on the martensitic matrix of the stainless steel due to the chemical composition of 17-4 PH. These delta ferrite materials have poor plasticity, can be elongated in the processing process, and can seriously affect the mechanical properties of the materials in different directions due to the continuity of the matrix tissues.
Chinese patent CN 105714063B proposes a method for preparing a 0Cr17Ni4Cu4Nb precipitation hardening stainless steel bar, which comprises vacuum melting ingot, forging cogging, extrusion deformation, etc., to produce a precipitation hardening stainless steel bar with high strength, high toughness and high corrosion resistance. However, the final product strength is more than 1500Mpa, the hardness reaches 447HBW, the strength and hardness are high, but the linearity, the repeatability and the like are poor.
Chinese patent CN 109487061B proposes a heat treatment method for martensitic precipitation-hardening stainless steel 06Cr15Ni5Cu2Ti, wherein precipitation-hardening stainless steel is treated by different solution, adjustment and aging methods to soften the steel. The toughness obtained by different heat treatment methods is relatively good, but the tensile strength is lower, the strength value is 1030-1090MPa, and the hardness is 314-317HBW respectively.
In view of the above, a new steel grade suitable for manufacturing sensor elastomers and a preparation method thereof are needed to be researched, which are easy to process, have good corrosion resistance, and have better toughness and hot workability under the condition of ensuring that the mechanical property index is not reduced.
Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to provide high-strength precipitation hardening stainless steel for a sensor elastomer and a preparation method thereof, and the high-strength precipitation hardening stainless steel which is easy to process, good in corrosion resistance and high in toughness is obtained by optimizing alloy proportion and adopting preparation processes of electric furnace smelting (EF+AOD+LF), vacuum consumable remelting, forging and heat treatment, and can be used as an elastomer material for manufacturing a weighing sensor.
In order to achieve the above purpose, the invention adopts the following technical scheme:
the first aspect of the present invention provides a high strength precipitation hardening stainless steel for a sensor elastomer comprising the following chemical components in weight percent: less than or equal to 0.03 percent of C, less than or equal to 0.01 percent of S, less than or equal to 0.02 percent of P, less than or equal to 0.80 percent of Si, and Mn:0.50 to 1.00 percent of Cr: 14.00-15.50 percent of Ni: 4.00-5.50 percent of Cu: 3.00-4.00%, mo:0.10 to 0.50 percent, less than or equal to 0.45 percent of Nb, less than or equal to 0.04 percent of N, less than or equal to 0.10 percent of Ti, less than or equal to 0.10 percent of Al, and the balance of Fe and unavoidable impurities.
Preferably, in the unavoidable impurities, H content is less than or equal to 0.0001wt% and O content is less than 0.0006wt%.
Preferably, the yield strength of the high-strength precipitation hardening stainless steel for the sensor elastomer is more than or equal to 1172MPa, the hardness HB is 380-430, the delta ferrite content is less than or equal to 2%, and the grain size reaches more than 5 grades.
In a second aspect, the present invention provides a method for preparing a high strength precipitation hardening stainless steel for a sensor elastomer according to the first aspect of the present invention, comprising the steps of:
s1, raw materials are subjected to primary refining by an electric furnace, refining by an AOD furnace and refining by an LF furnace, and die casting to obtain an electrode rod;
s2, carrying out vacuum consumable remelting on the electrode rod to obtain a stainless steel cast ingot;
s3, carrying out heating treatment on the stainless steel cast ingot, and then cogging and forging to obtain a large-size bar; sawing the cooled large-sized bar into a sizing blank with the height-diameter ratio of 1.5-3.0;
s4, heating the sizing blank to 1050-1200 ℃, preserving heat for 2.5-3 hours, and forging again to obtain a sensor elastomer blank;
s5, performing heat treatment on the sensor elastomer blank to obtain the high-strength precipitation hardening stainless steel for the sensor elastomer.
Preferably, in the step S1:
in the primary smelting process of the electric furnace, the molten steel before tapping contains less than or equal to 0.02wt% of P, 13.00-15.00 wt% of Cr, 3.00-4.50 wt% of Ni and 2.50-3.50 wt% of Cu; and/or
In the primary smelting process of the electric furnace, the tapping temperature is more than 1620 ℃.
In the following examples, the tapping temperature is higher than 1620 ℃ in the primary smelting process of the electric furnace; in the AOD refining process, the tapping temperature is lower than 1700 ℃; in the refining process of the LF furnace, the ladle hanging temperature is 1500-1560 ℃; in the vacuum consumable remelting process, the gas leakage rate is less than or equal to 0.333Pa/min, the voltage is 20-26V, the current is 10-17 kA, and the melting speed is 6.0-11.7 kg/min.
Preferably, in the step S1:
in the AOD refining process, the molten steel obtained by primary refining of the electric furnace is subjected to decarburization treatment, reduction treatment and desulfurization treatment in sequence, and the molten steel components before tapping satisfy less than or equal to 0.03wt% of C and less than or equal to 0.01wt% of S; and/or
In the AOD refining process, the tapping temperature is lower than 1700 ℃.
Preferably, in the step S1:
in the refining process of the LF furnace, the molten steel components are adjusted, and the molten steel components before tapping satisfy the following conditions: less than or equal to 0.03wt% of C, less than or equal to 0.01wt% of S, less than or equal to 0.02wt% of P, less than or equal to 0.80wt% of Si, 0.50 to 1.00wt% of Mn, 14.00 to 15.50wt% of Cr, 4.00 to 5.50wt% of Ni, 3.00 to 4.00wt% of Cu, 0.10 to 0.50wt% of Mo, less than or equal to 0.45wt% of Nb, less than or equal to 0.10wt% of N, less than or equal to 0.10wt% of Ti, and less than or equal to 0.10wt% of Al; and/or
In the refining process of the LF furnace, the ladle hanging temperature is 1500-1560 ℃.
Preferably, in the step S1, in the vacuum consumable remelting process, the gas leakage rate is less than or equal to 0.333Pa/min, the voltage is 20-26V, the current is 10-17 kA, and the melting speed is 6.0-11.7 kg/min.
Preferably, in the step S3:
in the heating treatment, the heating temperature is 1150-1250, and the heat preservation time is 22-24 hours; and/or
In the cogging forging process, a rapid forging machine is utilized to forge the heated stainless steel cast ingot to obtain a middle forging stock, then the middle forging stock is returned to a furnace to be heated to 1150+/-20 ℃, the temperature is kept for 1-1.5 h, and then the large-specification bar is obtained through tapping forging; and/or
The total deformation ratio from the stainless steel ingot in the step S3 to the sensor elastomer billet in the step S4 is not less than 4.
Preferably, in the step S5, during the heat treatment, the sensor elastomer blank is heated to 1010-1070 ℃, kept for 1-5 hours, and cooled to room temperature by water or oil; then heating to 470-510 ℃, preserving heat for 4-10 h, and air cooling to room temperature.
The chemical composition design principle of the high-strength precipitation hardening stainless steel for the sensor elastomer is as follows:
carbon (C) is a interstitial solid solution element, which can significantly improve the matrix strength of steel, and which can stabilize austenite and suppress delta ferrite formation. However, the solubility of the alloy in austenite and ferrite is limited, and too high carbon content can reduce the toughness of steel, and can cause precipitation of M23C6 type carbide in the heat treatment process, so that the intergranular corrosion resistance of the steel is reduced; the carbon content in the present invention is thus controlled to be 0.03wt% or less.
Chromium (Cr) is a ferrite stabilizing element which mainly improves corrosion resistance and oxidation resistance in stainless steel, and studies have shown that a minimum of 10.5wt% Cr in steel forms a stable passivation film protecting the steel from atmospheric corrosion. The corrosion resistance of the stainless steel is enhanced with the increase of Cr content; however, too high Cr content promotes the formation of harmful phases, reduces the hot workability of stainless steel, and also easily causes the occurrence of metal segregation during smelting, so that the Cr content of the present invention is controlled to 14.00-15.50 wt%.
Nickel (Ni) is an austenite stabilizing element that expands the austenite phase region, thereby ensuring that the stainless steel has good plastic deformation characteristics; the increase of the nickel content can effectively reduce the delta ferrite content; nickel improves the composition, structure and performance of the chromium oxide film, thereby improving the corrosion resistance and oxidation resistance of the stainless steel, and in addition, can significantly reduce the cold work hardening tendency of the stainless steel. However, too high a nickel content leads to an increase in production cost, and the nickel content of the present invention is controlled to be 4.00 to 5.50wt% in consideration of the total.
Copper (Cu) is a main precipitation strengthening element in stainless steel, and precipitation hardening is performed by precipitation of dispersed copper-rich phases in a martensitic matrix by solution aging heat treatment to strengthen the steel; the delta ferrite content in the steel can be reduced by properly increasing the copper content in the steel; copper is also a weaker austenite forming element; in the corrosion environment, the copper-containing steel can form a copper aggregation layer under the protection of an oxide layer, and can effectively prevent iron oxide from continuously corroding the inside of metal and prevent corrosion diffusion, so that the corrosion resistance of the steel in sulfuric acid and hydrochloric acid can be improved by adding copper into maraging stainless steel, the stress corrosion resistance of the steel can be enhanced by adding copper, and excessive copper can cause copper embrittlement during the hot working of the stainless steel. In comprehensive consideration, the copper content of the invention is controlled to be 3.00-4.00 wt%.
Molybdenum (Mo) is advantageous for strength, toughness and corrosion resistance of martensitic stainless steel. The molybdenum-rich precipitate can play a role in strengthening, can also keep the toughness of steel and plays an important role in strengthening the steel when being precipitated in the early aging stage. The existence of molybdenum can also prevent the precipitated phase from precipitating on the prior austenite grain boundary, avoid the along-grain fracture and improve the fracture toughness of the steel. In some reducing media, molybdenum also promotes the passivation of Cr. Therefore, the molybdenum can improve the corrosion resistance of the chromium-nickel stainless steel in some reducing acids such as sulfuric acid, hydrochloric acid, phosphoric acid and some organic acids, can effectively inhibit the pitting corrosion tendency of chloride ions to the steel, and improves the intergranular corrosion resistance. Since molybdenum is also an austenite forming element like nickel, molybdenum element cannot be excessively added to form residual austenite, and the molybdenum content of the present invention is controlled to be 0.10 to 0.50wt%.
Niobium (Nb) can play a role of refining grains, and can combine with carbon and nitrogen in steel to form niobium carbide and nitride, thereby reducing chromium deficiency at grain boundaries caused by precipitation of carbon and nitrogen at the grain boundaries, and improving corrosion resistance of the steel. Niobium also contributes to the improvement of the strength of the steel, in particular the high temperature strength, as it can form intermetallic phases in the steel; however, too high a niobium content in the steel will increase the delta ferrite content in the steel and reduce the strength, toughness and corrosion resistance of the steel. The niobium content of the invention is controlled below 0.45 wt%.
Silicon (Si) is mainly used as a deoxidizer during smelting, and can strengthen the matrix, improve corrosion resistance and high-temperature oxidation resistance of steel. However, too high a silicon content may cause precipitation of harmful phases, reducing the hot workability and toughness of the steel. Therefore, the silicon content of the invention is controlled below 0.80 wt%.
Manganese (Mn), which is an austenite stabilizing element that enlarges the austenite phase region, is a good deoxidizer and desulfurizing agent, and is generally contained in an amount of manganese in industrial steels. In stainless steel, manganese can replace part of nickel to stabilize austenite, so that the production cost is reduced, the nitrogen content in the steel can be improved, and the strength of the steel is ensured. However, too high a manganese content can greatly reduce the corrosion resistance, especially the pitting and intergranular corrosion resistance, of the steel. Therefore, the manganese content of the invention is controlled to be 0.50-1.00 wt%.
Sulfur (S) is present in the steel in the form of FeS and causes hot shortness of the steel. FeS has a melting point of 1193 ℃, and a co-crystal of Fe and FeS has a melting point of only 985 ℃. The liquid Fe and FeS can be infinitely miscible, but the FeS has very small solubility in solid iron, which is only 0.015-0.020 wt%. Therefore, when the sulfur content of the steel exceeds 0.020wt%, fe-FeS is distributed in a net-like form at grain boundaries in eutectic of low melting point due to segregation during cooling solidification of the molten steel. The hot working temperature of steel is 1150-1200 deg.c, at which the eutectic at the grain boundaries has melted, causing cracking of the grain boundaries when the steel is pressed, which is the "hot embrittlement" of the steel. When the oxygen content in the steel is higher, the eutectic melting point formed by FeO and FeS is lower, only 940 ℃, and the phenomenon of thermal embrittlement of the steel is more remarkable. In addition, sulfur significantly reduces the weldability of the steel, causes high Wen Guilie, and creates many voids and porosity in the metal weld, thereby reducing the strength of the weld. When the sulfur content exceeds 0.06wt%, corrosion resistance of the steel is significantly deteriorated. Therefore, the sulfur content of the present invention is controlled to be less than 0.01 wt%.
The phosphorus (P) steel can be completely dissolved in ferrite, and the strength and hardness of the ferrite are improved. However, at room temperature, the plasticity and toughness of steel are drastically reduced, and low-temperature brittleness is generated, which is called cold embrittlement. In general, phosphorus is a harmful element in steel, mainly for precipitating brittle compounds Fe 3 P increases the brittleness of the steel, especially at low temperatures. The phosphorus content of the present invention is thus controlled below 0.02 wt%.
The nitrogen (N) acts similarly to the carbon (C), and exists in the form of interstitial atoms in the unit cell, which is more favorable for solid solution strengthening of steel due to the larger difference in atomic size. The effect of the austenite stabilizing element N on enlarging and stabilizing the austenite structure is about 25 times that of Ni, and the solid solubility content of the austenite stabilizing element N in austenite is far higher than that of ferrite. In general, in conventional stainless steel, a small amount of ferrite is present, and as the carbon content decreases, the ferrite content increases, resulting in no effectThe strength, plasticity and toughness of the stainless steel are reduced. The addition of N can suppress ferrite precipitation and compensate for the decrease in strength and toughness due to the decrease in C content. However, too high a nitrogen content tends to result in Cr during heat treatment or welding 2 N is separated out, so that the mechanical property of the stainless steel is affected, and therefore, the nitrogen content is controlled below 0.04 weight percent.
The invention has the following beneficial effects:
1. according to the high-strength precipitation hardening stainless steel for the sensor elastomer and the preparation method, the alloy proportion is optimized, and the preparation processes of electric furnace smelting (EF+AOD+LF), vacuum consumable remelting, forging and heat treatment are adopted, so that the high-strength precipitation hardening stainless steel which is easy to process, good in corrosion resistance and high in toughness is obtained, and can be used as an elastomer material for manufacturing a weighing sensor;
2. according to the invention, the content of C, cr is reduced, the content of Ni and N is increased on the basis of 17-4PH stainless steel, and a small amount of Mo element is added to develop a new steel grade, and compared with 17-4PH stainless steel, the ultra-low carbon steel-making method disclosed by the invention has the advantages that the ultra-low carbon steel-making is adopted, and the corrosion resistance is improved;
3. according to the invention, through alloy design, element proportion is optimized, delta ferrite content is greatly reduced, and better consistency of mechanical properties in all directions is achieved; meanwhile, as vacuum consumable remelting (VAR) smelting is adopted, the content of gas impurities, particularly hydrogen and oxygen, is less, and the alloy has better toughness and hot processing performance under the condition of ensuring that the mechanical property index is not reduced.
Detailed Description
In order to better understand the above technical solution of the present invention, the technical solution of the present invention is further described below with reference to examples.
The high-strength precipitation hardening stainless steel for the sensor elastomer comprises the following chemical components in percentage by weight: less than or equal to 0.03 percent of C, less than or equal to 0.01 percent of S, less than or equal to 0.02 percent of P, less than or equal to 0.80 percent of Si, and Mn:0.50 to 1.00 percent of Cr: 14.00-15.50 percent of Ni: 4.00-5.50 percent of Cu: 3.00-4.00%, mo:0.10 to 0.50 percent, less than or equal to 0.45 percent of Nb, less than or equal to 0.04 percent of N, less than or equal to 0.10 percent of Ti, less than or equal to 0.10 percent of Al, and the balance of Fe and unavoidable impurities.
Wherein the content of H in the unavoidable impurities is less than or equal to 0.0001wt% and the content of O is less than 0.0006wt%.
The yield strength of the high-strength precipitation hardening stainless steel for the sensor elastomer is more than or equal to 1172MPa, the hardness HB is 380-430, the delta ferrite content is less than or equal to 2%, and the grain size reaches more than 5 grades.
The high strength precipitation hardening stainless steel for sensor elastomer prepared as described above is specifically prepared by:
s1, raw materials are subjected to primary refining by an electric furnace, refining by an AOD furnace and refining by an LF furnace, and die casting to obtain an electrode rod;
the specific process is as follows: adopting scrap steel, pig iron and the like with lower five-harmful elements (Pb, sn, as, sb, bi) as raw materials, and primary smelting by an electric furnace to obtain molten steel with low phosphorus and low five-harmful elements, wherein before tapping, the molten steel comprises the following components: less than or equal to 0.02wt% of P, 13.00-15.00 wt% of Cr, 3.00-4.50 wt% of Ni, 2.50-3.50 wt% of Cu, and tapping temperature of over 1620 ℃; then transferring the molten steel obtained by primary smelting in an electric furnace into an AOD furnace for refining, firstly carrying out decarburization treatment, and carrying out reduction treatment and desulfurization treatment after decarburization treatment, wherein the molten steel components before tapping are as follows: c is less than or equal to 0.03wt percent, S is less than or equal to 0.01wt percent, and the tapping temperature is lower than 1700 ℃; transferring the molten steel obtained by AOD refining to an LF furnace for refining, and adjusting the chemical components of the molten steel to ensure that the components of the molten steel before tapping meet the following conditions: less than or equal to 0.03wt% of C, less than or equal to 0.01wt% of S, less than or equal to 0.02wt% of P, less than or equal to 0.80wt% of Si, and Mn:0.50 to 1.00 weight percent of Cr:14.00 to 15.50 weight percent of Ni:4.00 to 5.50 weight percent of Cu:3.00 to 4.00 weight percent of Mo:0.10 to 0.50 weight percent, less than or equal to 0.45 weight percent of Nb, less than or equal to 0.10 weight percent of N, less than or equal to 0.10 weight percent of Ti, less than or equal to 0.10 weight percent of Al; and pouring the molten steel into an ingot mould to obtain the electrode rod, wherein the temperature of the ladle is 1500-1560 ℃.
S2, carrying out vacuum consumable remelting on the electrode rod to obtain a stainless steel cast ingot;
the specific process is as follows: putting the electrode rod obtained in the step S1 into a vacuum consumable furnace, and performing vacuum consumable remelting smelting to obtain a stainless steel cast ingot required by high-strength precipitation hardening stainless steel for the chemical components and the sensor elastomer; wherein in the vacuum consumable remelting process, the air leakage rate is less than or equal to 0.333Pa/min, the voltage is 20-26V, the current is 10-17 kA, and the melting speed is 6.0-11.7 kg/min.
S3, carrying out heating treatment on the stainless steel cast ingot, and then cogging and forging to obtain a large-size bar; sawing the cooled large-sized bar into a sizing blank with the height-diameter ratio of 1.5-3.0;
the specific process is as follows: heating a stainless steel cast ingot to 1150-1250 ℃, preserving heat for 22-24 hours, and then utilizing a rapid forging machine to perform cogging forging to obtain a middle forging stock, wherein in the cogging forging process, the cogging forging temperature is more than or equal to 1000 ℃, and the final forging temperature is more than or equal to 850 ℃; then the intermediate forging stock is returned to the furnace and heated to 1150+/-20 ℃, the temperature is kept for 1-1.5 hours, and the bar is discharged from the furnace and forged after being heated to obtain a large-specification bar, wherein the dimension of the large-specification bar is forged according to the requirement of a finished product sensor; and after the large-size bar is cooled, sawing the bar into fixed-length blanks with different lengths according to the requirements of a finished sensor, wherein the height-diameter ratio of the fixed-length blanks is 1.5-3.0.
S4, heating the sizing blank to 1050-1200 ℃, preserving heat for 2.5-3 hours, and forging again to obtain a sensor elastomer blank;
the specific process is as follows: heating the sizing blank to 1050-1200 ℃, preserving heat for 2.5-3 h, discharging from a furnace for re-forging, upsetting to obtain a sensor elastomer blank, wherein in the re-forging process, the forging temperature is more than or equal to 1000 ℃, and the final forging temperature is more than or equal to 850 ℃; wherein the total deformation ratio from the stainless steel ingot in step S3 to the sensor elastomer billet in step S4 is not less than 4.
S5, performing heat treatment on the sensor elastomer blank to obtain the high-strength precipitation hardening stainless steel for the sensor elastomer.
The specific process is as follows: heating the sensor elastomer blank to 1010-1070 ℃, preserving heat for 1-5 h according to the diameter and thickness of the sensor elastomer blank, and cooling the sensor elastomer blank to room temperature by water or oil; and then heating to 470-510 ℃, preserving heat for 4-10 hours according to the diameter and thickness of the sensor elastomer blank, and air-cooling to room temperature to finally obtain the high-strength precipitation hardening stainless steel for the sensor elastomer.
The high strength precipitation hardening stainless steel for sensor elastomers of the present invention and the method of making the same are further described below in connection with specific examples. In the following examples 1-3, an electric furnace (EF+AOD+LF) +vacuum consumable remelting (VAR) smelting process is adopted, wherein the tapping temperature is higher than 1620 ℃ in the primary smelting process of the electric furnace; in the AOD refining process, the tapping temperature is lower than 1700 ℃; in the refining process of the LF furnace, the ladle hanging temperature is 1500-1560 ℃; in the vacuum consumable remelting process, the gas leakage rate is less than or equal to 0.333Pa/min, the voltage is 20-26V, the current is 10-17 kA, and the melting speed is 6.0-11.7 kg/min.
Example 1
The preparation process of the high strength precipitation hardening stainless steel for the sensor elastomer in this example is as follows:
(1) Adopting scrap steel, pig iron and the like with lower five harmful elements (Pb, sn, as, sb, bi) as raw materials, and obtaining a stainless steel ingot with the diameter of phi 610mm by adopting an electric furnace (EF+AOD+LF) +vacuum consumable remelting (VAR) smelting process, wherein the chemical composition of the stainless steel ingot is shown in table 1;
(2) Heating the obtained stainless steel cast ingot to 1200+/-20 ℃, preserving heat for 24 hours, performing cogging forging on a 4000-ton quick forging machine, wherein the forging temperature is 1010+/-10 ℃, and the final forging temperature is 860+/-10 ℃, so as to finally obtain a 650mm octagonal intermediate forging stock;
(3) Returning the 650mm octagonal intermediate forging stock to a furnace to heat to 1150+/-20 ℃, preserving heat for 1-1.5 h, forging on a 4000 ton quick forging machine, wherein the forging temperature is 1010+/-10 ℃ and the final forging temperature is 860+/-10 ℃, and finally obtaining large-specification bars with phi 430 mm;
(4) Air-cooling the phi 430mm forged bar to room temperature, and then sawing a sizing blank with the length of 780 mm;
(5) And heating the sizing blank with the diameter of phi 430mm to 1150 ℃, preserving heat for 3 hours, and then discharging, upsetting and forging to obtain the sensor elastomer blank with the diameter of phi 980 multiplied by 150 mm.
(6) And heating the sensor elastomer blank to 1040+/-10 ℃, preserving heat for 3 hours, cooling the oil to room temperature, then heating to 470-510 ℃, preserving heat for 10 hours, and cooling the oil to room temperature to finally obtain the high-strength precipitation hardening stainless steel for the sensor elastomer.
(7) The high strength precipitation hardening stainless steel for the sensor elastomer was subjected to mechanical properties and delta ferrite content measurement, and the results are shown in table 2.
Example 2
The preparation process of the high strength precipitation hardening stainless steel for the sensor elastomer in this example is as follows:
(1) Adopting scrap steel, pig iron and the like with lower five harmful elements (Pb, sn, as, sb, bi) as raw materials, and obtaining a stainless steel ingot with the diameter of phi 610mm by adopting an electric furnace (EF+AOD+LF) +vacuum consumable remelting (VAR) smelting process, wherein the chemical composition of the stainless steel ingot is shown in table 1;
(2) Heating the obtained stainless steel cast ingot to 1170+/-20 ℃, preserving heat for 24 hours, performing cogging forging on a 4000-ton quick forging machine, wherein the cogging temperature is 1020+/-10 ℃ and the final forging temperature is 870+/-10 ℃, and finally obtaining a 650mm octagonal intermediate forging stock;
(3) Returning the 650mm octagonal intermediate forging stock to a furnace to heat to 1150+/-20 ℃, preserving heat for 1-1.5 h, forging on a 4000 ton quick forging machine, wherein the forging temperature is 1020+/-10 ℃ and the final forging temperature is 870+/-10 ℃, and finally obtaining a large-specification bar with the diameter of 415 mm;
(4) Air-cooling the phi 415mm forged bar to room temperature, and sawing a sizing blank with the length of 750 mm;
(5) And heating the sizing blank with the diameter of phi 415mm to 1150 ℃ for 3 hours, and then discharging, upsetting and forging to obtain the sensor elastomer blank with the diameter of phi 920 multiplied by 150 mm.
(6) And heating the sensor elastomer blank to 1020+/-10 ℃, preserving heat for 3 hours, cooling the oil to room temperature, then heating to 470-510 ℃, preserving heat for 10 hours, and cooling the oil to room temperature to finally obtain the high-strength precipitation hardening stainless steel for the sensor elastomer.
(7) The high strength precipitation hardening stainless steel for the sensor elastomer was subjected to mechanical properties and delta ferrite content measurement, and the results are shown in table 2.
Example 3
The preparation process of the high strength precipitation hardening stainless steel for the sensor elastomer in this example is as follows:
(1) Adopting scrap steel, pig iron and the like with lower five harmful elements (Pb, sn, as, sb, bi) as raw materials, and obtaining a stainless steel ingot with the diameter of phi 610mm by adopting an electric furnace (EF+AOD+LF) +vacuum consumable remelting (VAR) smelting process, wherein the chemical composition of the stainless steel ingot is shown in table 1;
(2) Heating the obtained stainless steel cast ingot to 1230+/-20 ℃, preserving heat for 24 hours, performing cogging forging on a 4000-ton quick forging machine, wherein the forging temperature is 1100+/-10 ℃, and the final forging temperature is 880+/-10 ℃, so as to finally obtain a 650mm octagonal intermediate forging stock;
(3) Returning the 650mm octagonal intermediate forging stock to a furnace to heat to 1150+/-20 ℃, preserving heat for 1-1.5 h, forging on a 4000 ton quick forging machine, wherein the forging temperature is 1100+/-10 ℃ and the final forging temperature is 880+/-10 ℃, and finally obtaining large-specification bars with phi 325 mm;
(4) Air-cooling the phi 325mm forged bar to room temperature, and then sawing a sizing blank with the length of 580 mm;
(5) And heating the fixed-length blank with the diameter of phi 325mm to 1150 ℃, preserving heat for 3 hours, and then discharging, upsetting and forging to obtain the sensor elastomer blank with the diameter of phi 660 multiplied by 140 mm.
(6) And heating the sensor elastomer blank to 1058+/-10 ℃, preserving heat for 3 hours, cooling the oil to room temperature, then heating to 470-510 ℃, preserving heat for 10 hours, and cooling the oil to room temperature to finally obtain the high-strength precipitation hardening stainless steel for the sensor elastomer.
(7) The high strength precipitation hardening stainless steel for the sensor elastomer was subjected to mechanical properties and delta ferrite content measurement, and the results are shown in table 2.
TABLE 1 chemical composition (wt) of the alloys of the present invention and 17-4PH
| C | S | P | Si | Mn | Ni | Cr | Cu | |
| Example 1 | 0.02 | 0.001 | 0.013 | 0.64 | 0.52 | 5.05 | 14.75 | 3.3 |
| Example 2 | 0.02 | 0.001 | 0.014 | 0.45 | 0.46 | 5 | 14.95 | 3.55 |
| Example 3 | 0.03 | 0.001 | 0.015 | 0.5 | 0.48 | 5.1 | 15.02 | 3.11 |
| 17-4PH | 0.06 | 0.022 | 0.031 | 0.82 | 0.87 | 3.89 | 17.2 | 3.68 |
| Mo | Nb | N | Ti | Al | H | O | ||
| Example 1 | 0.15 | 0.25 | 0.021 | 0.03 | 0.05 | 0.0001 | 0.0005 | |
| Example 2 | 0.12 | 0.27 | 0.025 | 0.02 | 0.06 | 0.0001 | 0.0006 | |
| Example 3 | 0.2 | 0.32 | 0.03 | 0.03 | 0.05 | 0.0001 | 0.0005 | |
| 17-4PH | 0.02 | 0.23 | 0.028 | 0.01 | 0.023 | 0.0005 | 0.0018 |
TABLE 2 mechanical Properties of the alloys of the invention and 17-4PH
As can be seen from the combination of tables 1 and 2, the high-strength precipitation hardening stainless steel for the sensor elastomer prepared by the invention has low carbon content and good corrosion resistance through electric furnace (EF+AOD+LF) +vacuum consumable remelting (VAR) smelting, and the content of gas impurities, particularly hydrogen and oxygen, is less; compared with the traditional 17-4PH alloy, the high-strength precipitation hardening stainless steel for the sensor elastomer has obviously reduced high-temperature ferrite content, better toughness and hot workability under the condition that indexes of mechanical property indexes such as strength are not reduced, and the elasticity, linearity, impact flying and the like of the high-strength precipitation hardening stainless steel for the sensor elastomer can meet the use requirements of the sensor elastomer.
It will be appreciated by persons skilled in the art that the above embodiments are provided for illustration only and not for limitation of the invention, and that changes and modifications to the above described embodiments are intended to be within the scope of the appended claims.
Claims (10)
1. A high strength precipitation hardening stainless steel for a sensor elastomer comprising the following chemical components in weight percent: less than or equal to 0.03 percent of C, less than or equal to 0.01 percent of S, less than or equal to 0.02 percent of P, less than or equal to 0.80 percent of Si, and Mn:0.50 to 1.00 percent of Cr: 14.00-15.50 percent of Ni: 4.00-5.50 percent of Cu: 3.00-4.00%, mo:0.10 to 0.50 percent, less than or equal to 0.45 percent of Nb, less than or equal to 0.04 percent of N, less than or equal to 0.10 percent of Ti, less than or equal to 0.10 percent of Al, and the balance of Fe and unavoidable impurities.
2. The high strength precipitation hardening stainless steel for sensor elastomer according to claim 1, wherein the unavoidable impurities have a H content of 0.0001wt% or less and an O content of 0.0006wt%.
3. The high-strength precipitation-hardenable stainless steel for a sensor elastomer according to claim 1, wherein the high-strength precipitation-hardenable stainless steel for a sensor elastomer has a yield strength of 1172MPa or more, a hardness HB of 380 to 430, a delta ferrite content of 2% or less, and a grain size of 5 or more.
4. A method of producing a high strength precipitation hardening stainless steel for a sensor elastomer as claimed in any one of claims 1 to 3, comprising the steps of:
s1, raw materials are subjected to primary refining by an electric furnace, refining by an AOD furnace and refining by an LF furnace, and die casting to obtain an electrode rod;
s2, carrying out vacuum consumable remelting on the electrode rod to obtain a stainless steel cast ingot;
s3, carrying out heating treatment on the stainless steel cast ingot, and then cogging and forging to obtain a large-size bar; sawing the cooled large-sized bar into a sizing blank with the height-diameter ratio of 1.5-3.0;
s4, heating the sizing blank to 1050-1200 ℃, preserving heat for 2.5-3 hours, and forging again to obtain a sensor elastomer blank;
s5, performing heat treatment on the sensor elastomer blank to obtain the high-strength precipitation hardening stainless steel for the sensor elastomer.
5. The method for producing a high-strength precipitation-hardened stainless steel for a sensor elastomer according to claim 4, wherein in said step S1:
in the primary smelting process of the electric furnace, the molten steel before tapping contains less than or equal to 0.02wt% of P, 13.00-15.00 wt% of Cr, 3.00-4.50 wt% of Ni and 2.50-3.50 wt% of Cu; and/or
In the primary smelting process of the electric furnace, the tapping temperature is more than 1620 ℃.
In the following examples, the tapping temperature is higher than 1620 ℃ in the primary smelting process of the electric furnace; in the AOD refining process, the tapping temperature is lower than 1700 ℃; in the refining process of the LF furnace, the ladle hanging temperature is 1500-1560 ℃; in the vacuum consumable remelting process, the gas leakage rate is less than or equal to 0.333Pa/min, the voltage is 20-26V, the current is 10-17 kA, and the melting speed is 6.0-11.7 kg/min.
6. The method for producing a high-strength precipitation-hardened stainless steel for a sensor elastomer according to claim 4, wherein in said step S1:
in the AOD refining process, the molten steel obtained by primary refining of the electric furnace is subjected to decarburization treatment, reduction treatment and desulfurization treatment in sequence, and the molten steel components before tapping satisfy less than or equal to 0.03wt% of C and less than or equal to 0.01wt% of S; and/or
In the AOD refining process, the tapping temperature is lower than 1700 ℃.
7. The method for producing a high-strength precipitation-hardened stainless steel for a sensor elastomer according to claim 4, wherein in said step S1:
in the refining process of the LF furnace, the molten steel components are adjusted, and the molten steel components before tapping satisfy the following conditions: less than or equal to 0.03wt% of C, less than or equal to 0.01wt% of S, less than or equal to 0.02wt% of P, less than or equal to 0.80wt% of Si, 0.50 to 1.00wt% of Mn, 14.00 to 15.50wt% of Cr, 4.00 to 5.50wt% of Ni, 3.00 to 4.00wt% of Cu, 0.10 to 0.50wt% of Mo, less than or equal to 0.45wt% of Nb, less than or equal to 0.10wt% of N, less than or equal to 0.10wt% of Ti, and less than or equal to 0.10wt% of Al; and/or
In the refining process of the LF furnace, the ladle hanging temperature is 1500-1560 ℃.
8. The method for producing high-strength precipitation-hardened stainless steel for sensor elastomers according to claim 4, wherein in said step S1, the gas leakage rate is 0.333Pa/min or less, the voltage is 20 to 26V, the current is 10 to 17kA, and the melting rate is 6.0 to 11.7kg/min in the vacuum consumable remelting process.
9. The method for producing a high-strength precipitation-hardened stainless steel for a sensor elastomer according to claim 4, wherein in step S3:
in the heating treatment, the heating temperature is 1150-1250, and the heat preservation time is 22-24 hours; and/or
In the cogging forging process, a rapid forging machine is utilized to forge the heated stainless steel cast ingot to obtain a middle forging stock, then the middle forging stock is returned to a furnace to be heated to 1150+/-20 ℃, the temperature is kept for 1-1.5 h, and then the large-specification bar is obtained through tapping forging; and/or
The total deformation ratio from the stainless steel ingot in the step S3 to the sensor elastomer billet in the step S4 is not less than 4.
10. The method for producing a high-strength precipitation-hardened stainless steel for a sensor elastomer according to claim 4, wherein in the step S5, the sensor elastomer blank is heated to 1010 to 1070 ℃ and kept at a temperature for 1 to 5 hours during the heat treatment, and is cooled by water or oil to room temperature; then heating to 470-510 ℃, preserving heat for 4-10 h, and air cooling to room temperature.
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| CN117551838B (en) * | 2024-01-11 | 2024-04-23 | 成都先进金属材料产业技术研究院股份有限公司 | Control method for low-magnification pocking defects of large-specification martensitic stainless steel forging |
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