CN111057949A - High-nitrogen non-magnetic stainless steel with good comprehensive performance and manufacturing method thereof - Google Patents
High-nitrogen non-magnetic stainless steel with good comprehensive performance and manufacturing method thereof Download PDFInfo
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0205—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips of ferrous alloys
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C33/00—Making ferrous alloys
- C22C33/04—Making ferrous alloys by melting
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/001—Ferrous alloys, e.g. steel alloys containing N
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/58—Ferrous alloys, e.g. steel alloys containing chromium with nickel with more than 1.5% by weight of manganese
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/001—Austenite
Abstract
The invention discloses a high-nitrogen non-magnetic stainless steel with good comprehensive performance and a manufacturing method thereof, wherein the high-nitrogen non-magnetic stainless steel comprises the following chemical components in percentage by weight: c: 0.10 to 0.20%, Si 0.20 to 0.75%, Mn: 13.0-16.0%, P is less than or equal to 0.06%, S is less than or equal to 0.015%, Cr: 17.0 to 19.0%, Ni: 1.5-2.5%, N: 0.25-0.40%; the balance of Fe and inevitable impurities; and the above elements simultaneously need to satisfy the following relations: 1.60 or more Creq/NieqLess than or equal to 1.96. Then, the proper hot processing technology is combined, the material can be ensured to have better non-magnetism, the hot processing performance can be ensured, the hot rolling surface quality is good, and the generation of the high-N component system in the hot processing process of the nonmagnetic austenitic stainless steel is obviously improvedThe surface defects of mountain scale folds.
Description
Technical Field
The invention relates to a stainless steel smelting process, in particular to high-nitrogen non-magnetic stainless steel with good comprehensive performance and a manufacturing method thereof.
Background
Non-magnetic stainless steel is commonly used in the industries of electronics, instruments and meters and the like. The common nonmagnetic stainless steel is 304, 305, etc. The standard components according to ASTM a240 standard, 304 are: less than or equal to 0.07 percent of C, less than or equal to 0.75 percent of Si, less than or equal to 2.0 percent of Mn, 18.0 to 20.0 percent of Cr, 8.0 to 10.5 percent of Ni and less than or equal to 0.10 percent of N. Generally, typical components of 304 are C0.06%, Si 0.4%, Mn 1.0%, Cr 18%, Ni 8%, N0.05%. The solid solution 304 is non-magnetic, but the cold working of 304 produces a large amount of strain-induced martensite, with the martensite phase being magnetic, thus resulting in the entire strip being magnetic. The 305 stainless steel with higher Ni content (12% Ni) can keep the non-magnetic or weak magnetic characteristic under the condition of smaller cold rolling reduction, but the high Ni content increases the cost of the 305 stainless steel, and limits the popularization and application of the material.
Analyzing 304, 305 the stainless steel cold working process, the occurrence and amount of martensite transformation increase depends on the stability of the austenite phase. The martensitic transformation temperature M is generally induced by straind30/50To evaluate the stability of austenite, Md30/50The lower the value, the more stable the austenite phase and the less susceptible the material is to strain-induced martensitic transformation. Can use empirical formula Md30/50The strain-induced martensite transformation temperature of the Cu-free austenitic stainless steel is calculated by the value of = 497-42 (C% + N%) -9.2Si% -8.1Mn% -20Ni% -13.7Cr% -18.5 Mo%. M of typical composition 304d30/50A value of around 35 ℃ and M of 305d30/50The value was-45 ℃. It is clear that the austenite phase of 305 stainless steel is more stable and can maintain non-magnetic or weakly magnetic properties under cold rolling conditions.
To lowerThe material cost is low, the good non-magnetism is ensured, and a plurality of high-N non-magnetic austenitic stainless steels which replace Ni with Mn are invented. For example, chinese patent CN 101538689a discloses a non-magnetic stainless steel with high strength and toughness, which comprises the following chemical components: less than or equal to 0.04% of C, 0.35-0.65% of Si, 17.00-22.00% of Mn, less than or equal to 0.03% of P, less than or equal to 0.015% of S, 13.00-17.00% of Cr, 0.15-0.45% of Ni, 0.30-0.50% of Mo, 0.30-0.80% of N, and the balance of Fe and inevitable impurities. The component system adopts the design idea of replacing Ni with high Mn and high N, the Ni content is extremely low, and the economical efficiency is better. Md30/50The temperature is less than or equal to minus 44 ℃, the non-magnetism is better, but the low Cr and the high Mn have a certain difference from the pitting corrosion resistance of 304 even though a small amount of Mo is added.
Chinese patent CN 101560634a discloses a wear-resistant, corrosion-resistant, non-magnetic, high-strength stainless steel, which comprises the following chemical components: 0.06-0.12% of C, 0.30-0.60% of Si, 9.00-10.50% of Mn, less than or equal to 0.035% of P, less than or equal to 0.015% of S, 17.0-18.0% of Cr, 4.0-6.0% of Ni, 0.20-0.35% of N and the balance of Fe. The screen mesh is used for mineral processing. Material Md30/50The temperature is less than or equal to-21 ℃, and the stability of austenite is better. However, the Ni content is 4.0-6.0%, so that the comprehensive cost of the component design of the patent is relatively high.
Chinese patent CN 103266283a discloses a non-magnetic stainless steel for ore mining equipment. The chemical components are as follows: 0.11-2.0% of C, less than or equal to 0.60% of Si, 12.0-14.0% of Mn, less than or equal to 0.04% of P, less than or equal to 0.02% of S, 17.0-20.0% of Cr, 0.05-2.00% of Ni, 0.30-2.00% of N, and the balance of Fe and inevitable impurities. The material Md30/50Between-90 ℃ and-75 ℃, the stability of austenite is very good. The high Cr system has better corrosion resistance, which is equivalent to 304. Meanwhile, the low-Ni composition design ensures very strong cost competitiveness.
The patent of the high N component system nonmagnetic austenitic stainless steel fully considers the nonmagnetic property, and also relates to the properties of strength, toughness, wear resistance and the like according to different purposes of the product. However, manufacturability, in particular hot workability, is not mentioned. In fact, when the component system is used for producing and manufacturing the plate strip products, the mountain-shaped scale-fold surface defects are easy to occur in the hot working process. The mountain-shaped scale fold surface defects are recorded in a text of 'formation and analysis of mountain-shaped scale fold defects of 304 stainless steel cold-rolled sheets' on page 135 of 'the twelfth academic conference proceedings for controlling quality of steel and non-metallic inclusions' (published date: 2008, 8, 25), and the macro morphology characteristics of the mountain-shaped scale fold surface are as follows: the defects are distributed along the rolling direction and are shown as mountain-shaped peeling of the surface of the steel coil, and the generated positions are not characterized; the size is large and is usually visible to the naked eye after APH. Through energy spectrum analysis, the surface appearance of the scale-broken surface defects has obvious Fe-Cr oxide, and supposedly, the scale-broken surface defects are mainly caused by the fact that superfine cracks on the surface of a continuous casting slab are oxidized in the heating process of a heating furnace. The conclusion section discloses two schemes for improving the mountain-shaped scale fold defect of the 304 stainless steel cold-rolled sheet: 1) after the slab comes out, the slab is eliminated, for example, the casting blank is polished to reduce the number of surface fine cracks; after hot rolling and acid washing, rough rolling and coarse grinding are carried out, the scale folding defect on the surface of the white skin plate is eliminated, then cold rolling is carried out, and the surface quality of a cold-rolled finished product plate is ensured; 2) the content of S, P, O is reduced in the smelting process, and the purity of molten steel is improved, so that inclusions and slag inclusions in continuous casting billets are reduced. The scheme 1) has the problem of increasing the working procedures as a remedy for the formed mountain-shaped scale folding defects, and the scheme 2) still needs to improve the effect of improving the mountain-shaped scale folding surface defects generated in the hot working process of the high-N-component system nonmagnetic austenitic stainless steel.
Disclosure of Invention
The invention aims to provide high-nitrogen non-magnetic stainless steel with good comprehensive performance.
The technical scheme for realizing the first purpose of the invention is as follows: a high-nitrogen non-magnetic stainless steel with good comprehensive performance comprises the following chemical components in percentage by weight: c: 0.10 to 0.20%, Si 0.20 to 0.75%, Mn: 13.0-16.0%, P is less than or equal to 0.06%, S is less than or equal to 0.015%, Cr: 17.0 to 19.0%, Ni: 1.5-2.5%, N: 0.25-0.40%; the balance of Fe and inevitable impurities; and the above elements simultaneously need to satisfy the following relations: 1.60 or more Creq/NieqLess than or equal to 1.96, wherein, Creq=Cr%+1.37Mo%+1.5Si%，Nieq=Ni%+0.31Mn%+22C%+14.2N%。
Further, the strain-induced martensitic transformation temperature point of the high-nitrogen non-magnetic stainless steel
Md30/50The value of 497-462(C% + N%) -9.2Si% -8.1Mn% -20Ni% -13.7Cr% -18.5Mo% < 110 ℃. The high-nitrogen non-magnetic stainless steel is ensured not to generate a magnetic martensite phase after cold forming or deformation, and has better cold-processing non-magnetic characteristic.
Furthermore, the pitting corrosion resistance equivalent PREN = Cr% +3.3Mo% +20C% +20N% -0.5Mn% -0.25 Ni%. gtoreq.18.1, so as to ensure that the pitting corrosion resistance of the material is equal to or better than 304.
The design principle of each chemical element of the high-nitrogen non-magnetic stainless steel is as follows:
carbon, which is an element that strongly forms, stabilizes and expands the austenite region, may substitute nickel to some extent, promotes austenite formation, stabilizes the austenite structure, and significantly reduces Md30/50At a temperature of 0.1% C per addition of Md30/50The temperature is reduced by 46 ℃, and the formation of a magnetic martensite phase in a strain process is effectively inhibited. However, when the carbon content is too high, the plasticity of the stainless steel is lowered and the corrosion resistance of the stainless steel is not good. In addition, the chromium-rich carbides formed also reduce the impact toughness of the steel. Too low a carbon content will increase the difficulty and cost of the preparation process. Therefore, the carbon content in the steel is designed to be 0.10-0.20%.
Silicon, is an element commonly contained in steel smelting. Silicon is a ferrite forming and stabilizing element. Silicon is used for deoxidation in the smelting process, and meanwhile, the silicon can improve the high-temperature strength of a ferrite phase, so that the general stainless steel contains more than 0.2 percent of silicon. However, if the silicon content is too high, the solubility of nitrogen is lowered and the precipitation of intermetallic phases is accelerated. Therefore, the silicon content in the steel is designed to be 0.2-0.75%.
Manganese, which is a relatively weak austenite-forming element, is a strong austenite structure-stabilizing element in stainless steel and can improve the solubility of nitrogen in steel. In the low-nickel high-nitrogen austenitic stainless steel, manganese and elements such as carbon, nitrogen and the like in the steel generate composite action to partially replace nickel, ensure that the stainless steel is an austenite structure at room temperature, and simultaneously can obviously reduce M of the stainless steeld30/50The temperature value of (2). However, too high manganese affects the corrosion resistance of stainless steel, so M is controlled in the steel of the present inventionThe content of n is 13.0-16.0%.
Chromium, the most important element for obtaining corrosion resistance of steel. The minimum chromium content to achieve corrosion resistance is typically 12%. Because chromium is an element for obviously enhancing the corrosion resistance, the chromium content in the steel is controlled to be more than 17.0 percent in order to ensure good corrosion resistance. However, chromium is a main ferrite forming element, and excessively high chromium causes a ferrite phase in the material and cannot ensure that completely nonmagnetic austenite is obtained at room temperature, so that a correspondingly higher nickel equivalent is required to be matched with the ferrite phase to ensure that a room-temperature austenite structure is obtained. Therefore, the content of chromium in the steel is controlled to be 17.0-19.0%.
Nickel is a strong austenite forming and stabilizing element, but the nickel is expensive, and the Ni is controlled to be 1.5-2.5% so as to ensure that the material has better economy. While ensuring the austenitic structure of the steel at room temperature.
Nitrogen, which is a strong austenite forming element. Nitrogen is a key factor for forming and stabilizing an austenite phase in the nitrogen-containing nickel-saving austenitic stainless steel, and every 0.1 percent of nitrogen is added, so that M can be addedd30/50The temperature is reduced by 46 ℃, the formation of a magnetic martensite phase in the strain process is effectively inhibited, and the effect of reducing the martensite phase in the strain process is similar to that of carbon. More advantageously, nitrogen has a higher solid solubility in austenite and, unlike carbon which tends to precipitate as carbides, nitrides do not generally precipitate in the austenite phase. Meanwhile, the addition of nitrogen is beneficial to improving the strength and the corrosion resistance of the steel. However, if the nitrogen content is too high, the difficulty of smelting and hot working will be increased, and especially, the increase of the nitrogen content will cause severe hot rolling edge cracking, which makes it difficult to produce on the existing production line. Therefore, the nitrogen content in the steel is controlled to be 0.25-0.40%.
Phosphorus: less than or equal to 0.06 percent, and phosphorus is regarded as a harmful element in stainless steel, and the lower the content of phosphorus should be controlled, the better.
Sulfur: s is less than or equal to 0.015 percent, and sulfur is also regarded as a harmful element in stainless steel. In particular, in the present invention, the manganese content in the steel is high, and the sulfur content needs to be strictly controlled, the lower the content, the better.
The balance being Fe and unavoidable impurities.
In the component design process, the following principles are followed:
first, it is known that Ni, Mn, N, C, etc. are austenite forming elements, Cr, Mo, Si, etc. are ferrite forming elements, and δ ferrite belongs to a ferromagnetic phase, and therefore should be controlled as a harmful additive in nonmagnetic stainless steel. Therefore, the nickel-saving economical nonmagnetic austenitic stainless steel recorded in the literature at present adopts the high-Mn and high-N component design to ensure the nonmagnetic property of the original state of the material and the austenite stability in the cold working process, so that no or little delta ferrite is generated in the solidification process of the material. The inventor researches and discovers that the high-Mn and high-N component design is easy to generate a full austenite solidification mode, so that hot cracks are generated in the solidification process of a casting blank, and surface defects such as 'mountain scale fracture' appear in the subsequent hot working process. While the austenitic stainless steel has a solidification mode of the component system and Creq/NieqThe equivalence ratio is of great concern, specifically, Creq/NieqThe larger the equivalence ratio, the greater the tendency for the delta ferrite to precipitate in the solidification process. The inventors adopted Creq=Cr%+1.37Mo%+1.5Si%，Nieq= Ni% +0.31Mn% +22C% +14.2N%, Cr of non-magnetic steel of three patents in the background art was calculated separatelyeq/NieqAll with an equivalent ratio lower than 1.55, in particular from CN 103266283A, Creq/NieqLess than or equal to 1.4. The inventor of the invention breaks through the traditional design thought of the components of the nonmagnetic austenitic stainless steel, adds Mo in zero, and controls Cr to be more than or equal to 1.60eq/NieqLess than or equal to 1.96, and a small amount of delta ferrite is generated in a solidified casting blank structure instead of a full austenite solidification mode, so that the subsequent hot workability of the material is improved, the surface defects of 'mountain scale fold' type generated in the hot working process of the material are obviously improved, the 'scale fold' type defects on the surface of the strip steel are fewer or none, the redundant delta ferrite phase is reduced after the hot working, and the non-magnetism of a solid solution product is ensured.
Second, Md30/50The lower the Md30 value, the less the martensite is induced during cold working deformation, the smaller the degree of cold hardening, and the more favorable the magnetic properties of the product are stabilized. The invention adjusts Cr, Ni, Mn and the likeThe content of elements, especially C and N elements, contributes to the material having a lower Md30/50The temperature is higher, so that the austenite phase of the material is more stable, and the nonmagnetic austenite phase can be maintained after strain such as cold rolling, and the magnetic martensite phase is not generated.
Further, Cr, Mo and N improve the pitting corrosion resistance, and C also plays a role provided that elements such as C, N are sufficiently dissolved in solid solution, while Mn and Ni are disadvantageous to the pitting corrosion resistance, especially Mn. Firstly, the Cr content is ensured to be more than or equal to 17.0 percent, the N content is ensured to be more than or equal to 0.25 percent, and the Mn content is controlled to be less than or equal to 16.0 percent. N promotes the enrichment of Cr in the passive film, improves the passivation capability of steel, and simultaneously, N can improve the PH value of the micro-area. Mn is an important element for improving the solid solubility of N, so that the content of Mn cannot be too low, and the Mn is limited to be more than or equal to 13.0 percent. The contents of N, Ni and Mn are comprehensively adjusted to ensure that the pitting corrosion resistance of the material is equivalent to or better than that of 304 austenitic stainless steel.
The high-nitrogen nonmagnetic austenitic stainless steel has good hot workability in the manufacturing process, the obtained solid solution product has good economical efficiency, non-magnetism and pitting corrosion resistance equal to or better than 304, and the material has good economical efficiency, good hot workability and good surface quality; the non-magnetism is better than that of 304, 305 and the prior economic non-magnetic steel, and the material can keep better non-magnetism after cold forming or deformation; the pitting corrosion resistance of the material is equal to or better than that of 304. The material has good comprehensive performance, can be used in industries such as electronics, instruments and meters and the like which have requirements on the material without magnetic characteristics, and can also be popularized and applied to industries such as panels, products and the like.
The second purpose of the invention is to provide a manufacturing method of the high-nitrogen nonmagnetic austenitic stainless steel with good comprehensive performance, which comprises the following steps:
1) smelting;
2) die casting or continuous casting;
3) forging or hot rolling: putting the die casting blank or the continuous casting plate blank into a heating furnace, heating to 1200-1280 ℃, preserving heat, and then processing to the required thickness on a forging production line or a hot rolling unit;
4) thermal annealing solid solution pickling treatment: controlling the solid solution temperature to 1060-1160 ℃, and then cooling to room temperature at an average cooling rate of more than or equal to 30 ℃/s;
wherein, the steps 1) and 2) are the conventional processes.
Further, the step 4) is followed by a step 5) of cold rolling; step 6), cold-annealing solid-solution acid pickling and leveling treatment: the solid solution temperature is controlled to be 1040-1120 ℃, and then the mixture is cooled to the room temperature at the average cooling speed of more than or equal to 30 ℃/s.
The material components obtained in the smelting step in the preparation process of the high-nitrogen nonmagnetic austenitic stainless steel have higher delta ferrite phase content, the hot working performance of the subsequent forging or hot rolling process is improved, the surface defects of 'mountain scale fold' type generated in the hot working process of the material are prevented, the hot rolling surface quality is good, the delta ferrite phase content is reduced in the forging or hot rolling process, and the nonmagnetic property of the finally obtained solid solution state high-nitrogen nonmagnetic austenitic stainless steel is ensured. Yield strength R of solid solution state material after hot rollingp0.2The corrosion resistance is more than or equal to 430 MPa, the pitting corrosion equivalent value PREN is more than or equal to 18.1, the pitting potential is more than or equal to 0.34V, and the pitting corrosion resistance is higher than the pitting corrosion potential of 304 stainless steel of 0.32V, so that the corrosion resistance is better.
Drawings
FIG. 1 is a hot-rolled solid-solution longitudinal sectional microstructure according to example 1 of the present invention;
FIG. 2 is a comparison of pitting potential curves for examples 1 and 304 stainless steel of the present invention.
Detailed Description
The invention is further illustrated by the following figures and examples.
Example 1:
a high-nitrogen non-magnetic stainless steel with good comprehensive performance comprises the following chemical components in percentage by weight: c: 0.15%, Si: 0.4%, Mn: 14.2%, P: 0.035%, S: 0007%, 18.2% of Cr, Ni: 1.8 percent, 0.32 percent of N and the balance of Fe and inevitable impurities; wherein, Creq/Nie=1.89，Creq=Cr%+1.37Mo%+1.5Si%，Nieq=Ni%+0.31Mn%+22C%+14.2N%
Taking the production flow of blast furnace low-nickel molten iron-GOR-LF smelting as an example:
the manufacturing method of the high-nitrogen nonmagnetic austenitic stainless steel with good comprehensive performance comprises the following steps:
1) smelting: melting ferrochrome in an intermediate frequency furnace, adjusting low-nickel molten iron from a blast furnace in a mixer furnace, pouring the molten steel into a GOR furnace after melting down, performing blowing for removing C, removing S, increasing N and controlling N in the GOR furnace, pouring the molten steel into a tundish when smelting components meet requirements, and casting on a vertical bending type continuous casting machine;
2) die casting or continuous casting;
3) forging or hot rolling: putting the die casting blank or the continuous casting plate blank into a heating furnace, heating to 1240 ℃, preserving heat, and then processing to the required thickness on a forging production line or a hot rolling unit;
4) thermal annealing solid solution pickling treatment: controlling the solid solution temperature to 1120 ℃, and then cooling to room temperature at the average cooling speed of 40 ℃/s to obtain a hot-rolled solid solution product;
5) cold rolling;
6) cold-annealing solid solution pickling and leveling treatment: controlling the solid solution temperature to be 1100 ℃, then cooling to room temperature at the average cooling speed of 40 ℃/s, and cold-rolling the solid solution product.
The cold-rolled solid solution product obtained by the manufacturing process can be subjected to quenching and tempering cold rolling and delivery in a hard rolling state according to specific requirements of users, and the non-magnetism is ensured. In the embodiment of the invention, the quenching and tempering cold rolling reduction is 20%, and the finished product has the thickness specification of 0.8 mm.
Examples 2-12 are the same as example 1 except for the chemical composition weight percentages and manufacturing process parameters, wherein the chemical composition weight percentages for each example are shown in table 1, and table 1 also shows the standard composition of a standard 304 austenitic stainless steel as a comparative example.
Table 1 chemical composition (wt.%) of examples and comparative examples
Table 2 shows the parameters of the manufacturing process of the steel grades according to the examples of the invention, Creq/NieqEquivalence ratio, Md30/50Temperature, pitting corrosion resistance equivalent weight PREN and mechanical propertyTable 2 gives the relevant parameters and properties of a standard 304 austenitic stainless steel as a comparative example. Cr (chromium) componenteq、NieqThe calculation formulas of (A) and (B) are respectively as follows: cr (chromium) componenteq=Cr%+1.37Mo%+1.5Si%，Nieq= Ni% +0.31Mn% +22C% + 14.2N%. The stainless steel of the embodiment of the invention belongs to Cr-Mn-N series nickel-containing austenitic stainless steel, and the pitting resistance equivalent weight is calculated according to the formula PREN = Cr% +3.3Mo% +20C% +20N% -0.5Mn% -0.25 Ni%. 304 belongs to Cr-Ni series austenitic stainless steel, and the pitting corrosion resistance equivalent is calculated according to the formula PREN = Cr% +3.3Mo% + 16N%. The mechanical property of the material is tested according to GB/T228.1 part 1 of the tensile test of metal materials: the corrosion performance test is carried out according to GB/T17899-;
TABLE 2
As can be seen from the performance test results in Table 1, the pitting potential of the examples of the present invention is comparable to or better than that of 304 stainless steel. When 1.60 is less than or equal to Creq/NieqLess than or equal to 1.96, less or no scale-fold defects on the surface of the strip steel, and the hot working performance of the surface is higher than that of Creq/NieqThe steel less than or equal to 1.55 is obviously improved.
FIG. 1 is a hot-rolled solid-solution longitudinal microstructure of example 1, which is a completely austenitic stainless steel structure obtained by subjecting a sample to electrolytic corrosion with a saturated oxalic acid solution, and has a typical grain boundary morphology with no precipitation of carbon and nitride.
FIG. 2 is a comparison of the pitting potential curves of inventive example 1 and 304 stainless steel, with example 1 having a pitting potential of 0.41V, significantly better than 0.32V for 304 stainless steel.
Table 3 shows the measurement results of the magnetic contents in the cold-rolled solid solution state and 20% cold-worked state of the examples of the present invention and the comparative example 304. The magnetic content of the material was tested by ferrite measurement.
TABLE 3 production Processes and magnetic measurement results of examples and comparative examples
As can be seen from the process parameters and test results of the examples, the invention successfully obtains the high-nitrogen nonmagnetic austenitic stainless steel with good comprehensive performance and the manufacturing method thereof, and Cr is controlled to be more than or equal to 1.60eq/NieqLess than or equal to 1.96, ensures that the material has better hot workability, and ensures the non-magnetism of the original state of the material by combining with the corresponding manufacturing process; by controlling Md30/50The temperature is not more than 497-42 (C% + N%) -9.2Si% -8.1Mn% -20Ni% -13.7Cr% -18.5Mo% ≦ 110 ℃, after cold forming or deformation of the hot-rolled solid-solution product, a magnetic martensite phase is not generated, and the material still keeps good nonmagnetic property; by controlling PREN to be more than or equal to 18.1 and designing a reasonable solid solution process, the pitting corrosion resistance of the material is equal to or better than 304. The material of the invention has good comprehensive performance, can be used in industries such as electronics, instruments and meters which have the requirements on the material without magnetic characteristics, and can also be popularized and applied in industries such as panels, products and the like.
The above description is only an embodiment of the present invention, and not intended to limit the scope of the present invention, and all equivalent flow transformations made by the present specification, or directly or indirectly applied to other related technical fields, are included in the scope of the present invention.
Claims (5)
1. A high nitrogen non-magnetic stainless steel with good comprehensive performance is characterized in that: the weight percentage of the chemical components is as follows: c: 0.10 to 0.20%, Si: 0.20 to 0.75%, Mn: 13.0-16.0%, P is less than or equal to 0.06%, S is less than or equal to 0.015%, Cr: 17.0 to 19.0%, Ni: 1.5-2.5%, N: 0.25-0.40%; the balance of Fe and inevitable impurities; and the above elements simultaneously need to satisfy the following relations: 1.60 or more Creq/NieqLess than or equal to 1.96, wherein, Creq=Cr%+1.37Mo%+1.5Si%，Nieq=Ni%+0.31Mn%+22C%+14.2N%。
2. The high nitrogen non-magnetic stainless steel with good comprehensive performance as claimed in claim 1, which is characterized in that: the strain-induced martensite phase transition temperature point of the high-nitrogen non-magnetic stainless steel
Md30/50=497-462(C%+N%)-9.2Si%-8.1Mn%-20Ni%-13.7Cr%-18.5Mo%≤−110℃。
3. The high nitrogen non-magnetic stainless steel with good comprehensive performance as claimed in claim 1, which is characterized in that: the pitting corrosion resistance equivalent weight PREN = Cr% +3.3Mo% +20C% +20N% -0.5Mn% -0.25Ni% ≧ 18.1 of the high-nitrogen non-magnetic stainless steel.
4. A method for manufacturing a high nitrogen nonmagnetic austenitic stainless steel with good comprehensive properties as claimed in any of claims 1 to 3, characterized in that: which comprises the following steps:
1) smelting;
2) die casting or continuous casting;
3) forging or hot rolling: putting the die casting blank or the continuous casting plate blank into a heating furnace, heating to 1200-1280 ℃, preserving heat, and then processing to the required thickness on a forging production line or a hot rolling unit;
4) thermal annealing solid solution pickling treatment: controlling the solid solution temperature to 1060-1160 ℃, and then cooling to room temperature at an average cooling rate of more than or equal to 30 ℃/s;
wherein, the steps 1) and 2) are the conventional processes.
5. The method of manufacturing a high nitrogen nonmagnetic austenitic stainless steel as claimed in claim 4, characterized in that: the step 4) is followed by a step 5) of cold rolling; step 6), cold-annealing solid-solution acid pickling and leveling treatment: the solid solution temperature is controlled to be 1040-1120 ℃, and then the mixture is cooled to the room temperature at the average cooling speed of more than or equal to 30 ℃/s.
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| CN111534756A (en) * | 2020-06-30 | 2020-08-14 | 宝钢德盛不锈钢有限公司 | Medium-nickel stainless steel applied to cold box liner and manufacturing method of medium-nickel stainless steel plate |
| CN111961989A (en) * | 2020-08-05 | 2020-11-20 | 广西柳钢中金不锈钢有限公司 | Method for manufacturing high-nitrogen low-nickel copper-free austenitic stainless steel |
| CN112063936A (en) * | 2020-08-05 | 2020-12-11 | 广西柳钢中金不锈钢有限公司 | High-nitrogen low-nickel copper-free austenitic stainless steel |
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| CN111534756A (en) * | 2020-06-30 | 2020-08-14 | 宝钢德盛不锈钢有限公司 | Medium-nickel stainless steel applied to cold box liner and manufacturing method of medium-nickel stainless steel plate |
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| CN115537638A (en) * | 2022-09-15 | 2022-12-30 | 山西太钢不锈钢股份有限公司 | Method for solving edge scale defects of 304 series BA plate for precision strip steel |
| CN115537638B (en) * | 2022-09-15 | 2023-06-23 | 山西太钢不锈钢股份有限公司 | Method for solving scale defect of 304 series BA plate for precise strip steel |
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