阅读说明：本技术 高耐腐蚀超易切削的软磁铁素体不锈钢盘条及其制备方法 (High-corrosion-resistance super-free-cutting soft magnet ferrite stainless steel wire rod and preparation method thereof ) 是由 严道聪 季灯平 李立 王贞应 马振宇 于 2021-07-16 设计创作，主要内容包括：本发明涉及金属冶炼技术领域,尤其涉及高耐腐蚀超易切削的软磁铁素体不锈钢盘条,其特征是,按质量百分比计,包括S:0.05～0.15％、Si:1.0～2.0％、Cu:0.1～0.4％、Cr：17.0～19.0％、Mo:1.0～2.0％、Nb:0.2～0.4％、Te:0.005～0.015％、C≤0.03％、N≤0.03％、P≤0.03％、Mn≤0.8％、Ni≤0.4％,余量为Fe和其他杂质。还涉及该不锈钢盘条的制备方法,包括将原料依次经电弧炉冶炼、AOD炉冶炼、LF钢包精炼、连铸、连铸坯加热、轧制、固溶以及酸洗,最终制得不锈钢盘条成品。本发明通过成分优化和碲合金化以及生产过程工艺控制,制造出一种既具有高耐蚀性,又超易切削性的软磁不锈钢盘条,该软磁不锈钢盘条同时也具有优良的机加工性能和软磁性能。本发明生产的软磁不锈钢盘条总成材率≥95％,生产成本低。(The invention relates to the technical field of metal smelting, in particular to a high-corrosion-resistance super-free-cutting soft ferrite stainless steel wire rod which is characterized by comprising, by mass, 0.05-0.15% of S, 1.0-2.0% of Si, 0.1-0.4% of Cu, and Cr: 17.0-19.0% of Mo, 1.0-2.0% of Nb, 0.2-0.4% of Te, 0.005-0.015% of Te, less than or equal to 0.03% of C, less than or equal to 0.03% of N, less than or equal to 0.03% of P, less than or equal to 0.8% of Mn, less than or equal to 0.4% of Ni, and the balance of Fe and other impurities. The method comprises the steps of sequentially carrying out electric arc furnace smelting, AOD furnace smelting, LF ladle refining, continuous casting billet heating, rolling, solid solution and acid pickling on raw materials, and finally obtaining the finished stainless steel wire rod. The invention produces the soft magnetic stainless steel wire rod with high corrosion resistance and super-machinability through component optimization, tellurium alloying and production process control, and the soft magnetic stainless steel wire rod also has excellent machining performance and soft magnetic performance. The total material yield of the soft magnetic stainless steel wire rod produced by the invention is more than or equal to 95 percent, and the production cost is low.)

1. The high-corrosion-resistance super-free-cutting soft magnetic ferrite stainless steel wire rod is characterized by comprising, by mass, 0.05-0.15% of S, 1.0-2.0% of Si, 0.1-0.4% of Cu, and Cr: 17.0-19.0% of Mo, 1.0-2.0% of Nb, 0.2-0.4% of Te, 0.005-0.015% of Te, less than or equal to 0.03% of C, less than or equal to 0.03% of N, less than or equal to 0.03% of P, less than or equal to 0.8% of Mn, less than or equal to 0.4% of Ni, and the balance of Fe and other inevitable impurities.

2. The highly corrosion-resistant ultra-free-cutting soft magnetic ferrite stainless steel wire rod according to claim 1, comprising, by mass, 0.08 to 0.15% of S, 1.0 to 1.6% of Si, 0.2 to 0.4% of Cu, 17.5 to 18.5% of Cr, 1.0 to 1.5% of Mo, 0.2 to 0.3% of Nb, 0.006 to 0.012% of Te, 0.3 to 0.8% of Mn, 0.15 to 0.4% of Ni, 0.025% or less of C, 0.025% or less of N, 0.025% or less of P, and the balance of Fe and other unavoidable impurities.

3. A highly corrosion-resistant ultra-free-cutting soft magnetic ferritic stainless steel wire rod according to claim 1 or 2 characterized in that 3. ltoreq. Mn/S, 0.05. ltoreq. Te/S0.5 by mass%.

4. The method for preparing the high corrosion-resistant ultra-free-cutting soft magnetic ferrite stainless steel wire rod according to any one of claims 1 to 3, which is characterized by comprising the steps of sequentially carrying out electric arc furnace smelting, AOD furnace smelting, LF ladle refining, continuous casting billet heating, rolling, solid solution and acid pickling on raw materials to finally prepare a finished stainless steel wire rod product; wherein the content of the first and second substances,

controlling the P content of the tapping to be less than or equal to 0.025 percent in the smelting process of the electric arc furnace;

in the smelting process of the AOD furnace, the alkalinity of furnace slag is controlled to be 3.0-4.0 during oxygen blowing decarburization, and the content of C at the decarburization end point is controlled to be less than or equal to 0.025%; after smelting, decarbonizing and reducing in an AOD furnace, adding ferrosulfur in batches, stirring, and controlling the S content to be 0.08-0.15%;

when LF ladle refining is carried out, ferrochrome, ferronickel, pure iron, pure molybdenum, ferrosilicon, pure manganese, pure niobium and ferro-sulphur alloy are added for component fine adjustment, then molten steel temperature is adjusted to 1600-1620 ℃, pure tellurium wires are fed, and Te content is adjusted to 0.006-0.012%;

the contents of the substances are calculated according to the mass percentage.

5. The method for preparing the highly corrosion-resistant ultra-free-cutting soft ferrite stainless steel wire rod according to claim 4, wherein in LF ladle refining, the speed of feeding a pure tellurium wire is 100-200 m/min, the distance between the outlet of a wire feeding pipe and the molten steel surface is controlled to be 5-50 cm, and after wire feeding is finished, argon gas is blown for soft blowing for 8-15 min.

6. The method for preparing a highly corrosion-resistant ultra-free-cutting soft magnetic ferrite stainless steel wire rod according to claim 4, wherein argon gas is blown and stirred all the way during the AOD furnace smelting process.

7. The method for preparing a highly corrosion-resistant ultra-free-cutting soft magnetic ferrite stainless steel wire rod according to claim 4, wherein the temperature of the continuous casting tundish is controlled to 1510 to 1520 ℃ during the continuous casting process.

8. The method for preparing a highly corrosion-resistant and ultra-free-cutting soft magnetic ferrite stainless steel wire rod according to claim 4, wherein in the process of heating the continuous casting billet, when the temperature of a heating furnace is 900 ℃, the continuous casting billet is heated in the furnace, then the temperature is increased to 1020-1050 ℃, and after the temperature is maintained for 40-80 min, the continuous casting billet is taken out of the furnace for rolling.

9. The method for preparing a highly corrosion-resistant ultra-free-cutting soft ferrite stainless steel wire rod according to claim 4, wherein in the rolling process, the finish rolling temperature is controlled to be 850 to 900 ℃, the rolling speed is controlled to be 40 to 55m/s when the wire rod diameter is 5.5 to 8.5mm, the rolling speed is controlled to be 20 to 40m/s when the wire rod diameter is 9.0 to 14mm, and the wire rod is air-cooled after rolling.

10. The method for preparing a highly corrosion-resistant ultra-free-cutting soft magnetic ferrite stainless steel wire rod according to claim 4, wherein the heating temperature is controlled to 820 to 850 ℃ during the solution process, the heating time is 90 to 120min, and then the wire rod is immersed in water.

[ technical field ] A method for producing a semiconductor device

The invention relates to the technical field of metal smelting, in particular to a high-corrosion-resistance super-free-cutting soft-magnetic ferrite stainless steel wire rod and a preparation method thereof.

[ background of the invention ]

The soft magnetic material is a magnetic material, has high magnetic conductivity, high saturation magnetic induction and low coercive force, is easy to magnetize under the action of a magnetic field, and is easy to demagnetize after the magnetic field is cancelled, so the soft magnetic material is widely used for manufacturing magnetic conductors, iron cores of transformers and relays, electromagnetic valves of household appliances, electromagnetic valves of control systems for automobiles and the like.

Common soft magnetic materials include pure iron, silicon steel, iron-nickel alloy, ferritic stainless steel, and the like. Pure iron and silicon steel have poor corrosion resistance, and electroplating is needed to increase the corrosion resistance after components are manufactured, so that the cost is increased, the environment is polluted, and the cost of the iron-nickel alloy is high, so that the soft magnetic ferrite stainless steel has more advantages in the use of the electromagnetic valve.

With the rapid development of household appliances and automobile industries, the soft magnetic ferrite stainless steel has wider and wider application in the products, higher corrosion resistance is required for some circulation valves, and good turning performance is also required for ensuring that the materials are beneficial to turning. Generally, in order to improve the turning performance of stainless steel, a certain content of sulfur element is added into the steel, sulfur and manganese in the steel form manganese sulfide which can play a role in lubricating a cutter and forming a chip fracture source, but too high sulfur easily forms a pitting source and reduces the corrosion resistance of the stainless steel, and too low sulfur also does not play a role in easy cutting, so that the control of the sulfur content is very critical. At present, the soft magnetic stainless steel is mainly imported from Italy, Japan and the like in China, and imported products are high in price and are not beneficial to localization, so that the manufacture of the soft magnetic stainless steel with high corrosion resistance and super free cutting instead of the imported products is urgently needed.

The following related patents are inquired for the composition design and the manufacturing method of the soft magnetic stainless steel: (1) the invention patent with the publication number of CN106636894A and the name of 'low-carbon ferrite soft magnetic free-cutting stainless steel and the production method thereof'; (2) an invention patent with publication number CN1594637A entitled "stainless steel core iron for solenoid valve and method for manufacturing the same"; (3) the invention patent with the publication number of CN102363869A and the name of 'a manufacturing method of free-cutting ferritic stainless steel 430 FM'; (4) the invention has the publication number of CN109628855A and is named as 'a molybdenum-containing ferrite free-cutting soft magnetic stainless steel and a heat treatment production method thereof'; (5) an invention patent publication No. CN111471918A entitled "Soft magnetic stainless Steel and manufacturing method for manufacturing Soft magnetic stainless Steel wire rod"; (6) the invention discloses a patent with the publication number of CN107012401A and the name of 'a low-carbon ferrite soft magnetic stainless steel and a production method thereof'. The corresponding main chemical components in the above prior patent application documents are shown in table 3 below.

TABLE 3

In combination with the patents disclosed in table 3 and nos. 1 to 4, a large amount of sulfur (S > 0.15) is added to the soft magnetic ferrite stainless steel to improve the machinability of the material and achieve a certain effect, which indicates that the addition of sulfur is a way to improve the machinability, but the excessive sulfur and manganese generate coarse manganese sulfide and accumulate, so that the corrosion source of the component material seriously affects the corrosion resistance, and the inventions disclosed in nos. 1 to 4 do not describe how to eliminate the influence of the excessive sulfur. In both of the patents 5 and 6, a small amount of sulfur (S < 0.05) was added to the soft-magnetic ferritic stainless steel, but it was found that a very small amount of free-cutting element S did not provide a good free-cutting effect.

In table 3, in the inventions disclosed in nos. 1 to 6, Mo is added to the material to improve the corrosion resistance, which indicates that Mo can improve the corrosion resistance of the material to some extent, and Ti, Re, and V are added to some of the materials (nos. 2, 3, and 6) to improve the corrosion resistance of the material, but this increases the production difficulty, and is expensive, which increases the production cost.

In conclusion, the soft magnetic stainless steel used in the advanced products needs not only good corrosion resistance but also good machinability, and also good machinability and soft magnetic properties, and the traditional soft magnetic stainless steel materials cannot meet the requirements, and the high-end soft magnetic materials are monopolized abroad for a long time, and the development of the high-quality soft magnetic stainless steel in China is urgently needed.

[ summary of the invention ]

In order to solve the problems proposed in the background art, the present invention provides a highly corrosion-resistant super-free-cutting soft magnetic ferritic stainless steel wire rod for manufacturing ferromagnetic parts; also provides a manufacturing method of the high-corrosion-resistance super-free-cutting soft magnetic ferrite stainless steel wire rod for manufacturing the ferromagnetic component.

In order to achieve the purpose, the invention provides the following technical scheme: a high-corrosion-resistance super-free-cutting soft ferrite stainless steel wire rod comprises, by mass, 0.05-0.15% of S, 1.0-2.0% of Si, 0.1-0.4% of Cu, and Cr: 17.0-19.0% of Mo, 1.0-2.0% of Nb, 0.2-0.4% of Te, 0.005-0.015% of Te, less than or equal to 0.03% of C, less than or equal to 0.03% of N, less than or equal to 0.03% of P, less than or equal to 0.8% of Mn, less than or equal to 0.4% of Ni, and the balance of Fe and other inevitable impurities.

Preferably, the stainless steel wire rod comprises, by mass, 0.08 to 0.15% of S, 1.0 to 1.6% of Si, 0.2 to 0.4% of Cu, 17.5 to 18.5% of Cr, 1.0 to 1.5% of Mo, 0.2 to 0.3% of Nb, 0.006 to 0.012% of Te, 0.3 to 0.8% of Mn, 0.15 to 0.4% of Ni, 0.025% or less of C, 0.025% or less of N, 0.025% or less of P, and the balance of Fe and other unavoidable impurities.

Preferably, in the stainless steel wire rod, the ratio of the Mn content to the S content satisfies, in terms of mass percent: Mn/S is more than or equal to 3, and the ratio of the Te content to the S content satisfies the following conditions: Te/S is more than or equal to 0.05 and less than or equal to 0.5.

A preparation method of a high-corrosion-resistance ultra-free-cutting soft ferrite stainless steel wire rod comprises the steps of sequentially carrying out electric arc furnace smelting, AOD furnace smelting, LF ladle refining, continuous casting billet heating, rolling, solid solution and acid pickling on raw materials to finally prepare a finished stainless steel wire rod product; wherein, the continuous casting is produced into a continuous casting billet after continuous casting, and the continuous casting billet is rolled after being reheated; in particular, the amount of the solvent to be used,

1) smelting in an electric arc furnace: melting the scrap steel raw material by an electric arc furnace, and controlling the P content of the tapped steel to be less than or equal to 0.025 percent; preferably, the electric arc furnace can adopt a high-impedance ultrahigh-power electric arc furnace to smelt steel so as to reduce or remove phosphorus and gas contents in steel;

2) smelting in an AOD furnace: in the smelting process of the AOD furnace, the alkalinity R of slag during oxygen blowing decarburization is controlled to be 3.0-4.0, and the content of C at the end point of decarburization is controlled to be within 0.025%, preferably within 0.010%; and adding ferrosilicon in the reduction period for reduction; in order to ensure that the finished product has lower nitrogen content, argon is blown and stirred in the whole smelting process;

after smelting, decarbonizing and reducing in an AOD furnace, adding pyrite in batches, controlling the S content to be 0.08-0.15%, and fully stirring for more than 8min after adding pyrite each time to uniformly distribute sulfur in molten steel;

3) LF ladle refining: firstly adding ferrochrome, ferronickel, pure iron, pure molybdenum, ferrosilicon, pure manganese, pure niobium and ferro-sulphur alloy for component fine adjustment to enable components (except Te) of molten steel to meet the requirement of design content proportion, then adjusting the temperature of the molten steel to 1600-1620 ℃, feeding a pure tellurium wire at the feeding speed of 100-200 m/min, controlling the distance between the outlet of a wire feeding pipe and the surface of the molten steel to be 5-50 cm to improve the yield of tellurium, adjusting the content of Te to be 0.006-0.012%, blowing argon for soft blowing for 8-15 min after the wire feeding is finished to ensure the sufficient homogenization of alloy elements, taking the pressure and flow of soft blowing gas as the basis of non-exposed molten steel, then measuring the temperature and sampling, adjusting the temperature of the molten steel to be 1580-1600 ℃, adding carbonized rice hulls for heat preservation, taking the amount of the carbonized rice hulls as the basis of covering the molten steel, and carrying out ladle and tapping;

4) continuous casting: pouring by adopting an arc continuous casting machine, wherein the temperature of a continuous casting tundish is controlled at 1510-1520 ℃;

5) heating a continuous casting blank: when the temperature of a heating furnace is 900 ℃, the continuous casting billet enters the furnace to be heated, when the temperature is increased to 1020-1050 ℃, the temperature is kept for 40-80 min, and then the continuous casting billet begins to be discharged from the furnace for rolling;

6) rolling: in the rolling process, the final rolling temperature is controlled to be 850-900 ℃, when the diameter of a wire rod is 5.5-8.5 mm, the rolling speed is controlled to be 40-55 m/s, when the diameter of the wire rod is 9.0-14 mm, the rolling speed is controlled to be 20-40 m/s, and air cooling is carried out after rolling;

7) solid solution: carrying out solid solution treatment by adopting an annular solid solution furnace, controlling the solid solution temperature at 820-850 ℃, heating for 90-120 min, then discharging from the furnace, feeding water for cooling, and controlling the time from discharging to completely feeding water for finishing within 1 min;

8) acid washing: removing oxide skin on the surface of the wire rod by adopting acid washing, and then packaging and warehousing;

wherein, the content of the substances involved in the steps is calculated according to the mass percentage.

The effects of the chemical components of the corrosion-resistant free-cutting soft magnetic ferritic stainless steel of the present invention in the material will be explained below.

Carbon (C): carbon in stainless steel is easy to form a series of complex carbides with chromium in steel, so that chromium is poor, the corrosion resistance of the steel is reduced, and the magnetism of the stainless steel is weakened or deteriorated by the carbon, so that the lower the carbon content is, the better the invention has the carbon content in a certain range, and the C is less than or equal to 0.030 percent, and preferably less than or equal to 0.025 percent.

Silicon (Si): silicon is a strong ferrite-forming element, and makes stainless steel have a magnetic structure, which is beneficial to enhancing magnetic performance. Silicon has a good effect on improving the oxidation resistance and the heat strength of the stainless steel, but the higher silicon also reduces the cold processing performance of the stainless steel and influences the plasticity and the chloride ion corrosion resistance of the stainless steel, so that the silicon content of the invention is controlled to be 1.0-2.0%, and preferably 1.0-1.6%.

Phosphorus (P): phosphorus is a harmful element in steel, the lower the phosphorus content, the better, the invention P is less than or equal to 0.030%, preferably, P is less than or equal to 0.025%.

Sulfur (S): the sulfur is a free-cutting element, the sulfur and manganese (Mn) in the steel form manganese sulfide, the manganese sulfide can become a stress notch during turning, the cutting resistance of the stainless steel is reduced, and the effect of lubricating a cutter is achieved, the machinability of the stainless steel is obviously improved along with the increase of the sulfur content, but the sulfide is deformed along the rolling direction by too high sulfur to form a strip shape and gather together, the mechanical property of the material is seriously influenced, and the corrosion resistance is influenced, so that the sulfur content is controlled to be 0.05-0.15%, and preferably, the sulfur content is controlled to be 0.08-0.15%.

Nickel (Ni): in the ferritic stainless steel, the ductility and toughness of the material can be improved by properly adding nickel, the mechanical property can be improved, and the corrosion rate of the stainless steel in an acid environment can also be reduced, but the saturation magnetization intensity of the ferritic stainless steel is reduced along with the increase of the nickel content when the nickel is higher, so that the nickel content is controlled to be less than or equal to 0.40%, and preferably, the nickel content is controlled to be 0.15-0.4%.

Chromium (Cr): chromium is a ferrite forming element, when the chromium content in the steel exceeds 10.5%, a layer of passive film is formed on the surface of the steel to prevent further oxidation reaction, so that the stainless steel has obvious corrosion resistance, the pitting point position of the ferritic stainless steel is increased along with the increase of the chromium content in the stainless steel, the corrosion resistance is improved, but the saturation magnetization intensity of the material is reduced along with the increase of the chromium content, therefore, the chromium content is controlled to be 17.00-19.00%, and preferably, the chromium content is controlled to be 17.5-18.5%.

Copper (Cu): copper has strong corrosion resistance to reducing media such as seawater, sulfuric acid, hydrochloric acid and hydrochloric acid, the cold workability of the ferritic stainless steel can be improved by copper, but the thermoplasticity of the material is reduced by excessively high copper, the hot rolling is not facilitated, and the coercive force of the material is increased along with the increase of the copper (Cu) content, so that the copper content is controlled to be 0.10-0.40%, and preferably, the copper content is controlled to be 0.20-0.40%.

Molybdenum (Mo): molybdenum is a ferrite forming element, and molybdenum is added into ferrite to catalyze chromium to gather in an oxide film, so that the stability of the oxide film is improved, and the pitting corrosion resistance and local corrosion resistance are enhanced, but the magnetic induction intensity value of the material is reduced due to too high molybdenum, therefore, the content of molybdenum in the invention is controlled to be 1.00-2.00%, and preferably, the content of molybdenum is controlled to be 1.0-1.5%.

Niobium (Nb): niobium is a strong ferrite forming element, is also a strong carbide and nitride forming element, can inhibit Cr in ferritic stainless steel from being combined with carbon and nitrogen, enhances the capability of resisting grain boundary corrosion, can also improve the content of chromium in an oxide film and improve the pitting corrosion resistance, can also inhibit crystal grains from growing up, plays a role in refining the crystal grains, and increases the strength and toughness of the material, but the finer the crystal grains, the higher the coercive force of the material is, so that the content of niobium in the invention is controlled to be 0.20-0.40%, and preferably, the content of niobium is controlled to be 0.2-0.3%.

Tellurium (Te): tellurium is an easy-cutting element, a small amount of tellurium can obviously improve the cutting performance of the stainless steel, when sulfur is contained in the steel, part of tellurium can be dissolved in manganese sulfide, and the manganese sulfide is usually coated outside MnS in a MnTe form, so that the manganese sulfide is not easy to extend during rolling, the sulfide is spheroidized, dispersed and finely distributed, the cutting performance of the stainless steel can be obviously improved, long-strip-shaped coarse sulfide is eliminated, the machining performance and the corrosion resistance are improved, but the too high tellurium can influence the hot working performance of the material and is not beneficial to rolling, so that the tellurium content is controlled to be 0.005-0.015%, and preferably, the tellurium content is controlled to be 0.006-0.012%.

The invention has the beneficial effects that:

(1) in order to improve the cutting performance, the ferro-sulphur is added in batches in the smelting process, the content of sulphur is controlled to be 0.05-0.15%, and the ferro-sulphur is added each time and then needs to be fully stirred for more than 8min, so that the sulphur is more uniformly distributed in the molten steel;

(2) by feeding a tellurium wire at the later stage of LF smelting, adding Te element, Te can modify MnS in steel and fully stir to spheroidize manganese sulfide, and meanwhile, the manganese sulfide is fine, dispersed and uniformly distributed, so that turning chips are thinned, the cutting performance of the steel is obviously improved, sulfides do not influence corrosion resistance, the corrosion resistance is improved, the distribution appearance of the sulfides is shown in figure 1, and the appearance of the turning chips is shown in figure 2;

(3) in order to improve the corrosion resistance, Nb and Mo elements are added, and the contents of Cr, Cu, Mn, Ni and Si are reasonably controlled.

(4) The addition of Te modifies manganese sulfide in the stainless steel, eliminates the influence of strip manganese sulfide on the machining performance of the material, and improves the machining performance of the material;

(5) the rolling and cooling control method adopts 820-850 ℃ for complete solid solution, so that the metallographic structure is uniform (as shown in figure 3), the plasticity of the material is improved, and the machining performance is improved;

(6) in the invention, the content of C, N is controlled to be lower, the content of Si is controlled to be higher, and the metallographic structure of the wire rod is uniform, so that the soft magnetic stainless steel has higher saturation magnetic induction intensity, lower coercive force and excellent soft magnetic performance.

(7) When the LF furnace is used for feeding pure tellurium wires, the feeding speed is controlled to be 100-200 m/min, the distance between the outlet of the wire feeding pipe and the liquid level of molten steel is controlled to be 5-50 cm, the yield of tellurium can be remarkably improved (more than or equal to 50 percent), and the loss of tellurium is reduced.

In conclusion, the present invention produces a soft magnetic stainless steel wire rod having both high corrosion resistance and super-machinability, which has excellent machinability and soft magnetic properties simultaneously, through composition optimization and tellurium (Te) alloying and production process control. The total material yield of the soft magnetic stainless steel wire rod produced by the invention is more than or equal to 95 percent, and the production cost is low.

The wire rod produced by the invention has the specification of 5.5-14 mm in diameter, 6-7 grades of grain size after solid solution, 470-540 MPa of tensile strength, 25-40% of elongation and 70-85% of shrinkage, does not rust in a neutral salt spray test for 96 hours, has the saturated magnetic induction strength Bs of not less than 1.4T and the coercive force Hc of not more than 250 A.m < -1 >, and is spherical or short-strip-shaped, fine, dispersed and uniformly distributed.

[ description of the drawings ]

FIG. 1 shows the morphology of spherical or short strip-shaped sulfides dispersed, uniformly and finely distributed in the soft magnetic ferritic stainless steel wire rod of the invention;

FIG. 2 is a chip-breaking morphology of the soft-magnetic ferrite stainless steel wire rod after turning;

fig. 3 shows the metallographic structure (structure uniformity) of the soft magnetic ferritic stainless steel wire rod of the present invention.

[ detailed description ] embodiments

The present application will be described in further detail with reference to specific examples.

A high-corrosion-resistance super-free-cutting soft ferrite stainless steel wire rod comprises, by mass, 0.05-0.15% of S, 1.0-2.0% of Si, 0.1-0.4% of Cu, and Cr: 17.0-19.0% of Mo, 1.0-2.0% of Nb, 0.2-0.4% of Te, 0.005-0.015% of Te, less than or equal to 0.03% of C, less than or equal to 0.03% of N, less than or equal to 0.03% of P, less than or equal to 0.8% of Mn, less than or equal to 0.4% of Ni, and the balance of Fe and other inevitable impurities.

Further, the stainless steel wire rod comprises, by mass, 0.08-0.15% of S, 1.0-1.6% of Si, 0.2-0.4% of Cu, 17.5-18.5% of Cr, 1.0-1.5% of Mo, 0.2-0.3% of Nb, 0.006-0.012% of Te, 0.3-0.8% of Mn, 0.15-0.4% of Ni, less than or equal to 0.025% of C, less than or equal to 0.025% of N, less than or equal to 0.025% of P, and the balance Fe and other unavoidable impurities.

Further, in the stainless steel wire rod, the ratio of the content of Mn to the content of S satisfies the following conditions in percentage by mass: Mn/S is more than or equal to 3, and the ratio of the Te content to the S content satisfies the following conditions: Te/S is more than or equal to 0.05 and less than or equal to 0.5.

A preparation method of a high-corrosion-resistance ultra-free-cutting soft ferrite stainless steel wire rod comprises the steps of sequentially carrying out electric arc furnace smelting, AOD furnace smelting, LF ladle refining, continuous casting billet heating, rolling, solid solution and acid pickling on raw materials to finally prepare a finished stainless steel wire rod product; wherein the content of the first and second substances,

controlling the P content of the tapping to be less than or equal to 0.025 percent in the smelting process of the electric arc furnace;

in the smelting process of the AOD furnace, the alkalinity of furnace slag is controlled to be 3.0-4.0 during oxygen blowing decarburization, and the content of C at the decarburization end point is controlled to be less than or equal to 0.010%; after smelting, decarbonizing and reducing in an AOD furnace, adding ferrosulfur in batches, stirring, and controlling the S content to be 0.05-0.15%;

when LF ladle refining is carried out, ferrochrome, ferronickel, pure iron, pure molybdenum, electrolytic copper, ferrosilicon, pure manganese, pure niobium and ferro-sulphur alloy are added for component fine adjustment to enable the components (except Te) of molten steel to meet the design content proportion requirement, namely 0.08-0.15% of S, 1.0-1.6% of Si, 0.2-0.4% of Cu, 17.5-18.5% of Cr, 1.0-1.5% of Mo, 0.2-0.3% of Nb, 0.3-0.8% of Mn and 0.15-0.4% of Ni are added into the molten steel, then molten steel temperature is adjusted to 1600-1620 ℃, pure tellurium wires are fed, and the content of Te is adjusted to 0.006-0.012%; the contents of the substances are calculated according to the mass percentage.

Further, in the LF ladle refining, the speed of feeding a pure tellurium wire is 100-200 m/min, the distance between the outlet of the wire feeding pipe and the molten steel surface is controlled to be 5-50 cm, argon is blown for soft blowing for 8-15 min after wire feeding is finished, and the pressure and the flow of soft blowing gas are based on bare molten steel.

Further, argon is blown and stirred in the whole smelting process of the AOD furnace.

Further, in the continuous casting process, the temperature of the continuous casting tundish is controlled to be 1510-1520 ℃.

Further, in the heating process of the continuous casting billet, when the temperature of a heating furnace is 900 ℃, the continuous casting billet enters the furnace to be heated, then the temperature is increased to 1020-1050 ℃, and the temperature is kept for 40-80 min, and then the continuous casting billet begins to be discharged for rolling.

Furthermore, in the rolling process, the final rolling temperature is controlled to be 850-900 ℃, the rolling speed is controlled to be 40-55 m/s when the diameter of the wire rod is 5.5-8.5 mm, the rolling speed is controlled to be 20-40 m/s when the diameter of the wire rod is 9.0-14 mm, and air cooling is carried out after rolling.

Further, in the solid solution process, the heating temperature is controlled to be 820-850 ℃, the heating time is 90-120 min, and then the wire rod is immersed in water.

Example 1

The high corrosion resistant super free-cutting soft ferrite stainless steel wire rod in this example mainly consists of the corresponding components in table 1, and the balance of Fe and unavoidable impurities by mass%.

The stainless steel wire rod is prepared by the following method: it should be noted that the following percentages are all mass percentages,

(1) smelting in an electric arc furnace: smelting by adopting a 30t electric furnace, adding the waste high-chromium steel as a raw material into an electric arc furnace for melting, and controlling the P content to be 0.020% and the crude steel yield to be 32t during steel tapping. (2) Smelting in an AOD furnace: adding 1000Kg of lime, then adding 300Kg of ferrochrome, and then adding the crude molten steel into an AOD furnace; controlling the basicity R of the slag to be 3.0 in the decarburization period, and controlling the content of C at the end point of decarburization to be 0.002%; adding 950Kg of ferrosilicon for reduction, adding 130Kg of ferrosilicon in two batches after reduction, adding 65Kg of ferrosilicon in each batch, and stirring for 8 minutes after each addition, wherein the sulfur content of the molten steel is 0.08 percent; in order to prevent nitrogen increase in the smelting process, argon is blown and stirred in the whole process. (3) LF ladle refining: the components of the molten steel (except Te) meet the requirement of the designed content ratio by adding ferrochrome, ferronickel, pure iron, pure molybdenum, ferrosilicon, pure manganese, pure niobium and ferro-sulphur alloy for component fine adjustment. And next, adjusting the temperature of the molten steel to 1607 ℃, feeding a pure tellurium wire at the feeding speed of 150m/min, controlling the distance between the outlet of the wire feeding pipe and the liquid level of the molten steel to be 20cm, and adjusting the Te to be 0.007%. And after the wire feeding is finished, argon is blown for soft blowing for 12min, and the pressure and the flow of the soft blowing gas are based on the condition that the molten steel is not exposed. And next, adjusting the temperature of the molten steel to 1595 ℃, adding carbonized rice hulls to preserve heat, taking the amount of the carbonized rice hulls to cover the molten steel as a standard, and carrying out ladle tapping. (4) Continuous casting: 3-machine 3-flow arc continuous casting machine is adopted for casting, the blank shape of the crystallizer is 180 multiplied by 180mm, the temperature of a continuous casting tundish is controlled to be 1513-1518 ℃, the average casting speed is 1.0m/min, and the water quantity of the crystallizer is 84m³And/min. The components of the finished product are detected by sampling in the casting process, and the specific components are shown in table 1. (5) Heating and rolling the blank: rolling a 7.5 mm-sized wire rod, feeding a continuous casting billet into a heating furnace for heating when the temperature of the heating furnace is 900 ℃, and preserving heat for 53min when the temperature is increased to 1020-1050 DEG CAnd (5) discharging and rolling. Controlled rolling and controlled cooling are adopted for rolling, the final rolling temperature is controlled at 882 ℃, and the rolling speed is controlled at 45 m/s; the rolling process may use a reduced diameter (TMB) to precisely control wire rod dimensions. (6) Solid furnace heat treatment: carrying out solution treatment by adopting an annular solution furnace, heating for 100min at 830 ℃, then directly discharging from the furnace, feeding water for cooling, and controlling the time from discharging of the wire rod to complete feeding of water to be 48 seconds. (7) Removing oxide skin on the surface of the wire rod by adopting acid washing to prepare a finished stainless steel wire rod product, and then packaging and warehousing.

Example 2

The high corrosion resistant super free-cutting soft ferrite stainless steel wire rod in this example mainly consists of the corresponding components in table 1, and the balance of Fe and unavoidable impurities by mass%.

The stainless steel wire rod is prepared by the following method: it should be noted that the following percentages are all mass percentages,

(1) smelting in an electric arc furnace: smelting in an electric furnace of 30t, melting the waste high-chromium steel in an electric arc furnace, and controlling the tapping P to be 0.019% and the water yield of the rough steel to be 31 t. (2) Smelting in an AOD furnace: adding 1000Kg of lime, then adding 280Kg of ferrochrome, and then adding the crude molten steel into an AOD furnace; the basicity R of the slag is controlled to be 3.3 in the decarburization period, and the content of C at the end point of decarburization is 0.001%; adding 950Kg of ferrosilicon for reduction, adding 140Kg of ferrosilicon in two batches after reduction, adding 70Kg of ferrosilicon in each batch, and stirring for 8 minutes after each addition, wherein the sulfur content of the molten steel is 0.13%; in the smelting process, argon is blown in the whole process for stirring in order to prevent nitrogen increase. (3) Smelting in a ladle refining furnace: the components of the molten steel (except Te) meet the requirement of the designed content ratio by adding ferrochrome, ferronickel, pure iron, pure molybdenum, ferrosilicon, pure manganese, pure niobium and ferro-sulphur alloy for component fine adjustment. And next, adjusting the temperature of the molten steel to be 1606 ℃, feeding a pure tellurium wire at the feeding speed of 150m/min, controlling the distance between the outlet of the wire feeding pipe and the liquid level of the molten steel to be 20cm, and adjusting the Te to be 0.008%. And after the wire feeding is finished, argon is blown for soft blowing for 12min, and the pressure and the flow of the soft blowing gas are based on the condition that the molten steel is not exposed. And next, adjusting the temperature of the molten steel to 1598 ℃, adding carbonized rice hulls to preserve heat, taking the amount of the carbonized rice hulls to cover the molten steel as a standard, and carrying out ladle tapping. (4) Continuous casting: casting by using a 3-machine 3-flow arc continuous casting machine, wherein the blank shape of the crystallizer is 180x180mm, controlling the temperature of a continuous casting tundish at 1511-1518 ℃, controlling the average casting speed to be 1.0m/min and controlling the water quantity of a crystallizer to be 85m³And/min. The components of the finished product are detected by sampling in the casting process, and the specific components are shown in table 1. (5) Heating and rolling the blank: rolling 7.5mm wire rods, feeding the continuous casting billets into a heating furnace for heating when the temperature of the heating furnace is 900 ℃, keeping the temperature for 61min and then taking out of the furnace for rolling when the temperature is increased to 1020-1050 ℃. Controlled rolling and controlled cooling are adopted for rolling, the final rolling temperature is controlled to be 852 ℃, and the rolling speed is controlled to be 45 m/s; the rolling process uses a reduced diameter (TMB) to precisely control the wire size. (6) Solid furnace heat treatment: and (3) carrying out solution treatment by adopting an annular solution furnace, heating at 830 ℃ for 110min, directly discharging from the furnace, feeding water for cooling, and controlling the time from discharging of the wire rod to complete feeding of water to 51 seconds. (7) Removing oxide skin on the surface of the wire rod by adopting acid washing to prepare a finished stainless steel wire rod product, and then packaging and warehousing.

Example 3

The high corrosion resistant super free-cutting soft ferrite stainless steel wire rod in this example mainly consists of the corresponding components in table 1, and the balance of Fe and unavoidable impurities by mass%.

The stainless steel wire rod is prepared by the following method: it should be noted that the following percentages are all mass percentages,

(1) smelting in an electric arc furnace: smelting by adopting a 30t electric furnace, melting scrap steel in an electric arc furnace, specifically high-chromium steel, controlling the P content of tapping to be 0.022%, and controlling the water amount of coarse steel to be 34 t. (2) Smelting in an AOD furnace: adding 1000Kg of lime, then adding 260Kg of ferrochrome, and then adding the crude molten steel into an AOD furnace; the slag alkalinity R in the decarburization period is controlled to be 3.0, and the content of C at the end point of decarburization is 0.005 percent; adding 960Kg of ferrosilicon for reduction, adding 138Kg of ferrosilicon in two batches after reduction, adding 69Kg of ferrosilicon in each batch, and stirring for 8 minutes after each addition, wherein the sulfur content of the molten steel is 0.11 percent; in the smelting process, argon is blown and stirred in the whole process for preventing nitrogen increase. (3) Smelting in a ladle refining furnace: the components of the molten steel (except Te) meet the requirement of the designed content ratio by adding ferrochrome, ferronickel, pure iron, pure molybdenum, ferrosilicon, pure manganese, pure niobium and ferro-sulphur alloy for component fine adjustment. Next, adjusting the temperature of the molten steel to 1603 ℃, feeding a pure tellurium wire at a feeding speed of 150m/min, and connecting the outlet of a wire feeding pipe and the steelThe liquid level distance is controlled at 20cm, and Te is adjusted to 0.011 percent. And after the wire feeding is finished, argon is blown for soft blowing for 12min, and the pressure and the flow of the soft blowing gas are based on the condition that the molten steel is not exposed. And next, adjusting the temperature of the molten steel to 1594 ℃, adding carbonized rice hulls to preserve heat, taking the amount of the carbonized rice hulls to cover the molten steel as a standard, and carrying out ladle tapping. (4) Continuous casting: adopting a 3-machine 3-flow arc continuous casting machine for casting, controlling the temperature of a continuous casting tundish at 1516-1520 ℃, the average casting speed at 1.0m/min and the water quantity of a crystallizer at 84m by using a crystallizer blank model of 180x180mm³And/min. The components of the finished product are detected by sampling in the casting process, and the specific components are shown in table 1. (5) Heating and rolling the blank: and (3) rolling a wire rod with the specification of 10.0mm, feeding the continuous casting billet into a furnace for heating when the temperature of the heating furnace is 900 ℃, keeping the temperature for 72min when the temperature is increased to 1020-1050 ℃, and taking out of the furnace for rolling. Controlled rolling and controlled cooling are adopted for rolling, the finishing temperature is controlled to be 878 ℃, the rolling speed is controlled to be 30m/s, and the size of the wire rod is accurately controlled by reducing and sizing (TMB) in the rolling process. (6) Solid furnace heat treatment: carrying out solution treatment by adopting an annular solution furnace, heating for 105min at 830 ℃, then directly discharging from the furnace, feeding water for cooling, and controlling the time from discharging of the wire rod to complete feeding of water to be 53 seconds. (7) Removing oxide skin on the surface of the wire rod by adopting acid washing to prepare a finished stainless steel wire rod product, and then packaging and warehousing.

Table 1 three examples chemistry (%):

examples	C	Si	Mn	P	S	Cr	Ni	Cu	Mo	N	Nb	Te
													1	0.010	1.55	0.31	0.022	0.086	17.89	0.26	0.24	1.46	0.013	0.28	0.007
2	0.012	1.53	0.28	0.026	0.15	18.15	0.20	0.24	1.48	0.011	0.29	0.008
													3	0.015	1.54	0.27	0.028	0.10	18.25	0.28	0.30	1.51	0.010	0.30	0.011

Table 2 specific performance parameters for three examples of stainless steel wire rods of the present invention:

as can be seen from Table 2, the neutral salt spray test of the soft magnetic ferritic stainless steel manufactured according to the invention can keep 96 hours without rusting, which shows that the soft magnetic stainless steel of the invention has super corrosion resistance;

the shape and distribution of the sulfide are important indexes for reflecting the cutting performance, and the sulfide is uniformly and dispersedly distributed, is fine and is spherical or short-strip-shaped, and shows that the material has better cutting performance. Sulfide distribution and morphology of soft magnetic stainless steel according to an embodiment of the present invention are shown in fig. 1, illustrating good machinability. FIG. 2 shows that the reaction turning chips have good breaking effect, and no cutter is wound during turning, so that turning is easy;

the elongation of the ferritic stainless steel is more than 20%, and the shrinkage is more than 50%, which shows that the soft magnetic ferritic stainless steel manufactured according to the invention has good machinability, and as can be seen from table 2, the elongation is 35%, 36%, 35%, and the shrinkage is 79%, 82%, 79%, which shows that the soft magnetic ferritic stainless steel manufactured according to the invention has more excellent machinability, and is beneficial to drawing processing of customers;

the saturation magnetic induction and the coercive force are important indexes of magnetic performance, the higher the saturation magnetic induction is, the lower the coercive force is, the better the soft magnetism of the material is, the saturation magnetic induction Bs of the soft magnetic stainless steel material according to the embodiment of the invention are 1.511T, 1.503T and 1.498T, and the coercive force Hc is 215 A.m^-1、213A·m^-1、226A·m^-1The soft magnetic ferrite stainless steel manufactured by the present invention has good soft magnetic performance.

In conclusion, the soft magnetic stainless steel manufactured according to the implementation of the invention has high corrosion resistance and super-machinability, has good machining performance and soft magnetic performance, can completely replace imported products, is used for various inductors, transformers, chokes, filters and the like on automobiles, and can be used in various severe environments.

The above description is only an embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive of changes or substitutions within the technical scope of the present invention, and all such changes or substitutions are included in the scope of the present invention. Moreover, the technical solutions in the embodiments of the present invention may be combined with each other, but it is necessary to be able to be realized by a person skilled in the art, and when the technical solutions are contradictory or cannot be realized, the combination of the technical solutions should be considered to be absent, and is not within the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the appended claims.