CN114480971A - 38CrMoAl steel and preparation method thereof - Google Patents
38CrMoAl steel and preparation method thereof Download PDFInfo
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- CN114480971A CN114480971A CN202210099370.XA CN202210099370A CN114480971A CN 114480971 A CN114480971 A CN 114480971A CN 202210099370 A CN202210099370 A CN 202210099370A CN 114480971 A CN114480971 A CN 114480971A
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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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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
- B21B1/46—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling metal immediately subsequent to continuous casting
- B21B1/463—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling metal immediately subsequent to continuous casting in a continuous process, i.e. the cast not being cut before rolling
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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
- C22C33/06—Making ferrous alloys by melting using master alloys
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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
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
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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
- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
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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
- C22C38/22—Ferrous alloys, e.g. steel alloys containing chromium with molybdenum or tungsten
Abstract
The invention discloses 38CrMoAl steel which comprises the following chemical components in percentage by mass: 0.37 to 0.40 percent of C, 0.22 to 0.35 percent of Si, 0.40 to 0.50 percent of Mn, 1.40 to 1.50 percent of Cr, Mo: 0.21-0.25 percent of Al, 0.7-1.00 percent of Al, and the balance of Fe and inevitable impurities, wherein P in the impurities is less than or equal to 0.030 percent, and S in the impurities is less than or equal to 0.030 percent. Its preparing process is also disclosed. The invention aims to solve the problems of wire breakage in the drawing process, low hardness of a workpiece after heat treatment, low fatigue life and the like; the universality of the product used by downstream users is increased.
Description
Technical Field
The invention relates to the technical field of metallurgy and rolling, in particular to 38CrMoAl steel and a preparation method thereof.
Background
The 38CrMoAl steel is high-grade nitrided steel and has better mechanical property. The 38CrMoAl steel belongs to alloy structural steel, and the HRC hardness requirement of a workpiece after quenching and tempering is more than or equal to 45. The steel has high nitriding speed, can obtain deep nitriding layer depth in a short time, has high obdurability, surface hardness and high wear resistance after heat treatment, and is commonly used for manufacturing various wear-resistant parts on mechanical parts bearing impact load and workpieces under the condition of reciprocating wear, such as boring bars, grinding machine spindles, automatic lathe spindles, screw rods, precision gears, rubber and plastic extruders and the like. The steel grade is successfully produced, the technical content of the product is improved, the market competitiveness of enterprises is enhanced, and good economic and social benefits are achieved.
Disclosure of Invention
The invention aims to provide 38CrMoAl steel and a preparation method thereof, which are used for solving the problems of wire breakage in the drawing process, low hardness of a workpiece after heat treatment, low fatigue life and the like; the universality of the product used by downstream users is increased.
In order to solve the technical problem, the invention adopts the following technical scheme:
the invention relates to 38CrMoAl steel which comprises the following chemical components in percentage by mass: 0.37 to 0.40 percent of C, 0.22 to 0.35 percent of Si, 0.40 to 0.50 percent of Mn, 1.40 to 1.50 percent of Cr, Mo: 0.21-0.25 percent of Al, 0.7-1.00 percent of Al, and the balance of Fe and inevitable impurities, wherein P in the impurities is less than or equal to 0.030 percent, and S in the impurities is less than or equal to 0.030 percent.
Further, the chemical components of the material comprise the following components in percentage by mass: 0.422% of C, 0.217% of Si, 0.437% of Mn, 1.48% of Cr, Mo: 0.221%, 0.851% of Al, and the balance of Fe and inevitable impurities, wherein the balance of the impurities is 0.0108% of P, and the ratio of S: 0.002%.
Further, the chemical components of the material comprise the following components in percentage by mass: 0.401% of C, 0.222% of Si, 0.451% of Mn, 1.49% of Cr, Mo: 0.232%, 0.913%, and the balance of Fe and inevitable impurities, 0.0112% of P in the impurities, S: 0.002%.
Further, the chemical components of the material comprise the following components in percentage by mass: 0.410% of C, 0.393% of Si, 0.489% of Mn, 1.61% of Cr, Mo: 0.234%, Al 0.870%, and the balance Fe and unavoidable impurities, 0.0178% of P in the impurities, S: 0.009%.
A preparation method of 38CrMoAl steel mainly comprises the following processes: the method comprises the following steps of molten iron pretreatment, converter refining, VD vacuum treatment, continuous casting, cogging and rolling, wherein: after the molten iron pretreatment process, Si in the molten iron: 0.3-0.7 percent of S, less than or equal to 0.015 percent of P, less than or equal to 0.120 percent of P, less than or equal to 0.10 percent of Ti and more than or equal to 1250 ℃ of T; the converter process adopts top-bottom combined blowing for decarburization and dephosphorization, and the steel is smelted at 1650 ℃ until the carbon content in the molten steel is not less than 0.15 percent and the phosphorus content is less than 0.01 percent, the steel end point component C is not less than 0.15 percent, P is not more than 0.020 percent, S is not more than 0.015 percent, and T: 1610 to 1630 ℃. In the VD vacuum treatment process, the VD vacuum degree is less than or equal to 0.10KPa, the target value is less than or equal to 0.06KPa, the deep vacuum time is more than or equal to 15min, a calcium-silicon wire is fed after the vacuum is broken, and the soft blowing time is controlled by soft blowing for more than 15 min; in the continuous casting process, the superheat degree is controlled to control the temperature of a first furnace 1 to be 35-55 ℃, the tundish temperature in the second furnace after the 2 nd furnace is controlled to be 20-30 ℃, the casting first furnace is controlled to be at the pulling speed of 0.4m/min, and the constant pulling speed of the other furnaces is controlled to be 0.65 m/min; in the rolling process, the heating temperature of the rolling heating furnace is controlled as follows: preheating at 850 + -50 deg.C, heating at 1030 + -50 deg.C, soaking at 1060 + -420 deg.C, controlling residual oxygen at 1% -4%, and heating for 90 + -5 min; the initial rolling temperature is 990 +/-15 ℃, the finish rolling inlet temperature is 910 +/-20 ℃, the starting roller speed is 0.76m/s, the opening degree of 1-5 fans is 100%, 6-10 fans are closed, and the heat-insulating cover is fully opened.
Compared with the prior art, the invention has the beneficial technical effects that:
the invention successfully develops the 38CrMoAl high-grade nitrided steel, simultaneously solves the problems of wire breakage in the drawing process, low hardness of a workpiece after heat treatment, low fatigue life and the like, and increases the universality of the product used by downstream users.
Drawings
The invention is further illustrated in the following description with reference to the drawings.
FIG. 1 is a photograph of the metallographic structure of a 38CrMoAl steel nitride according to the invention.
Detailed Description
The invention aims to provide a production method of 38CrMoAl nitrided steel, which aims to solve the problems of wire breakage in the drawing process, low hardness of a workpiece after heat treatment, low fatigue life and the like. The universality of the product used by downstream users is increased.
The invention firstly reasonably designs chemical components based on the following principles: c and Fe are the most main compositions in steel, the higher the content of C, the greater the contribution to the strength of the steel, but the higher the content of C, the greater the binding capacity with oxygen, the more easily chemical reaction occurs, the increased decarburization degree, and the increased content of C increases the hardness of the steel. Therefore, in the present invention, the C content is preferably controlled to 0.37% to 0.40% from the middle to lower limit. Si is a ferrite strengthening element, improves the ferrite strength through solid solution strengthening, and is used as a widely used deoxidizer, thereby being beneficial to reducing the oxygen content in steel and reducing inclusions. However, high Si causes decarburization of the material, prolongs the incubation period and the transformation time in the phase transformation process, and is not beneficial to control of the structure and the mechanical properties. Therefore, the Si content in the present invention is preferably 0.22% to 0.35%. Cr is a strong carbide forming element, has the capability of reducing the decarburization depth, can remarkably improve the strength, the hardness and the wear resistance, and can also improve the oxidation resistance, the corrosion resistance and the hardenability of steel, the content of Cr alloy is properly increased in 38CrMoAl steel, and the Cr content is preferably 1.40-1.50 percent in the invention. Mo can refine crystal grains of steel, improve hardenability and heat strength, maintain enough strength and creep resistance at high temperature, improve mechanical properties by adding Mo into structural steel, and inhibit brittleness caused by quenching steel, wherein the content of Mo in the invention is preferably 0.16-0.25%. A small amount of Al is added into the steel, so that crystal grains can be refined, the impact toughness is improved, the steel has oxidation resistance and corrosion resistance, and the high-temperature corrosion resistance of the steel can be obviously improved by combining the Al with Cr and Si. Al has a disadvantage of affecting hot workability, weldability, and machinability of steel, and therefore, the Al content is preferably 0.70% to 1.00% in the present invention. Namely, the 38CrMoAl nitride produced by the invention comprises the following chemical components in percentage by mass: 0.35-0.42% of C, 0.20-0.45% of Si, 0.30-0.60% of Mn, 1.35-1.65% of Cr, 0.7-1.1% of Al, and the balance of Fe and inevitable impurities, wherein P in the impurities is less than or equal to 0.030%, and S in the impurities is less than or equal to 0.030%.
The production process flow of the 38CrMoAl steel nitride which is commonly adopted at present is as follows: molten iron pretreatment, converter, refining, VD vacuum treatment and continuous casting.
Pretreating molten iron: and desulfurizing the molten iron for the converter by adopting a KR method, stirring the molten iron by adopting a stirring paddle with the rotating speed of 90r/min, and adding a desulfurizing agent after stirring for 2min, wherein the desulfurizing agent is 9: 1, stirring and reacting the mixed lime powder and fluorite for 10min, and standing for 5 min. The desulfurization effect is stabilized by removing the desulfurization slag after the molten iron is desulfurized and left standing, the desulfurization slag is prevented from entering the converter to cause the resulfurization of the converter, and the Si in the molten iron is pretreated: 0.3-0.7%, S is less than or equal to 0.015%, P is less than or equal to 0.120%, Ti is less than or equal to 0.10%, and T is more than or equal to 1250 ℃.
Converter: the top-bottom combined blowing is adopted for decarburization and dephosphorization, the steel is smelted at 1650 ℃ until the carbon content in the molten steel is not lower than 0.15 percent and the phosphorus content is lower than 0.01 percent, protective gas is adopted to stir the molten steel at the pressure of 0.5MPa in the tapping process, ferrosilicon and silicomanganese alloy are added for deoxidation when the steel is tapped to 1/4, carbon powder and slagging material are added, and slag is blocked during tapping to prevent a large amount of slag from being discharged.
Refining: the method comprises the following steps of refining outside an LF furnace, deoxidizing at 1525 ℃ until the oxygen content in molten steel is 0.002%, adding ferromanganese, ferrosilicon, ferrochrome and ferrovanadium alloy elements, performing aluminum-free deoxidation in the refining, adding quartz sand and small ash during heating, adding ferrosilicon powder according to the conditions of fixed oxygen and furnace slag, spraying the deoxidizer on the surface of the slag, dipping a sample after the next heating is stopped, observing the color of the slag, and if transparent glass slag is adopted, determining that white slag is well produced, otherwise, continuously spraying the deoxidizer.
VD vacuum treatment: the actual VD vacuum degree is controlled to be 0.06KPa, the deep vacuum time is 18min, a calcium silicon wire is fed after the vacuum is broken, the soft blowing time is controlled to be 19min by soft blowing, and the molten steel is not exposed in the soft blowing process.
Continuous casting: and drawing steel at a constant drawing speed as far as possible, wherein the drawing speed is controlled to be 0.65m/min, the section of the casting blank is 280 mm-380 mm, and the length of the casting blank is 10.0 m. The casting blank has good control on the external dimension and the surface quality, and has no defects of stripping, scabbing, connecting marks, slag inclusion, sinking and the like.
The heating temperature of the rolling heating furnace is controlled as follows: preheating at 850 + -50 deg.C, heating at 1030 + -50 deg.C, soaking at 1060 + -420 deg.C, controlling residual oxygen at 1% -4%, and heating for 90 + -5 min; the initial rolling temperature is 990 +/-15 ℃, the finish rolling inlet temperature is 910 +/-20 ℃, the starting roller speed is 0.76m/s, the opening degree of 1-5 fans is 100%, the opening degrees of 6-7 fans are closed, the opening degree of 8 fans is 50%, the opening degrees of 9-10 fans are closed, and the heat-insulating cover is fully opened. The specific chemical components of the 38CrMoAl nitrided steel are shown in Table 1, and the mechanical property test results of the wire rod for the nitrided steel are shown in Table 2. And (3) carrying out mechanical property inspection after heat treatment on a part of the rolled wire rod, wherein the heat treatment process comprises the steps of quenching at 940 ℃, tempering at 640 ℃ and water as a medium. The results of mechanical property tests after the specific heat treatment are shown in Table 3.
TABLE 1 chemical composition/% of wire rod for nitrided steel
| Examples | C | Si | Mn | P | S | Cr | Mo | Al |
| Example 1 | 0.422 | 0.217 | 0.437 | 0.0108 | 0.002 | 1.48 | 0.221 | 0.851 |
| Example 2 | 0.401 | 0.222 | 0.451 | 0.0112 | 0.002 | 1.49 | 0.232 | 0.913 |
| Example 3 | 0.410 | 0.393 | 0.489 | 0.0178 | 0.009 | 1.61 | 0.234 | 0.870 |
TABLE 2 rolled mechanical Properties test results of wire rods for nitrided steels
TABLE 3 mechanical Property test results (after heat treatment) of wire rod for nitrided steel
The above-described embodiments are merely illustrative of the preferred embodiments of the present invention, and do not limit the scope of the present invention, and various modifications and improvements of the technical solutions of the present invention can be made by those skilled in the art without departing from the spirit of the present invention, and the technical solutions of the present invention are within the scope of the present invention defined by the claims.
Claims (5)
1. The 38CrMoAl steel is characterized by comprising the following chemical components in percentage by mass: 0.37 to 0.40 percent of C, 0.22 to 0.35 percent of Si, 0.40 to 0.50 percent of Mn, 1.40 to 1.50 percent of Cr, Mo: 0.21-0.25 percent of Al, 0.7-1.00 percent of Al, and the balance of Fe and inevitable impurities, wherein P in the impurities is less than or equal to 0.030 percent, and S in the impurities is less than or equal to 0.030 percent.
2. The 38CrMoAl steel according to claim 1, characterized in that its chemical composition comprises, in mass%: 0.422% of C, 0.217% of Si, 0.437% of Mn, 1.48% of Cr, Mo: 0.221%, 0.851% of Al, and the balance of Fe and inevitable impurities, wherein the balance of the impurities is 0.0108% of P, and the ratio of S: 0.002%.
3. The 38CrMoAl steel according to claim 1, characterized in that its chemical composition comprises, in mass%: 0.401% of C, 0.222% of Si, 0.451% of Mn, 1.49% of Cr, Mo: 0.232%, 0.913%, and the balance of Fe and inevitable impurities, 0.0112% of P in the impurities, S: 0.002%.
4. The 38CrMoAl steel according to claim 1, characterized in that its chemical composition comprises, in mass%: 0.410% of C, 0.393% of Si, 0.489% of Mn, 1.61% of Cr, Mo: 0.234%, 0.870% of Al, and the balance of Fe and inevitable impurities, 0.0178% of P in the impurities, S: 0.009%.
5. The method for preparing 38CrMoAl steel according to claim 1, which is characterized by mainly comprising the following processes: the method comprises the following steps of molten iron pretreatment, converter refining, VD vacuum treatment, continuous casting, cogging and rolling, wherein: after the molten iron pretreatment process, Si in the molten iron: 0.3-0.7%, S is less than or equal to 0.015%, P is less than or equal to 0.120%, Ti is less than or equal to 0.10%, and T is more than or equal to 1250 ℃; the converter process adopts top-bottom combined blowing for decarburization and dephosphorization, and the steel is smelted at 1650 ℃ until the carbon content in the molten steel is not less than 0.15 percent and the phosphorus content is less than 0.01 percent, the steel end point component C is not less than 0.15 percent, P is not more than 0.020 percent, S is not more than 0.015 percent, and T: 1610 to 1630 ℃; in the VD vacuum treatment process, the VD vacuum degree is less than or equal to 0.10KPa, the target value is less than or equal to 0.06KPa, the deep vacuum time is more than or equal to 15min, a calcium-silicon wire is fed after the vacuum is broken, and the soft blowing time is controlled by soft blowing for more than 15 min; in the continuous casting process, the superheat degree is controlled to control the temperature of a first furnace 1 to be 35-55 ℃, the tundish temperature in the second furnace after the 2 nd furnace is controlled to be 20-30 ℃, the casting first furnace is controlled to be at the pulling speed of 0.4m/min, and the constant pulling speed of the other furnaces is controlled to be 0.65 m/min; in the rolling process, the heating temperature of the rolling heating furnace is controlled as follows: preheating at 850 + -50 deg.C, heating at 1030 + -50 deg.C, soaking at 1060 + -420 deg.C, controlling residual oxygen at 1% -4%, and heating for 90 + -5 min; the initial rolling temperature is 990 +/-15 ℃, the finish rolling inlet temperature is 910 +/-20 ℃, the starting roller speed is 0.76m/s, the opening degree of 1-5 fans is 100%, 6-10 fans are closed, and the heat-insulating cover is fully opened.
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Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
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| US20140283954A1 (en) * | 2013-03-22 | 2014-09-25 | Caterpiller Inc. | Bainitic microalloy steel with enhanced nitriding characteristics |
| JP2015229780A (en) * | 2014-06-03 | 2015-12-21 | 山陽特殊製鋼株式会社 | Steel for nitriding excellent in nitriding property |
| CN105463299A (en) * | 2015-12-07 | 2016-04-06 | 中天钢铁集团有限公司 | Smelting method of high-aluminum nitriding steel |
| CN110117747A (en) * | 2019-05-22 | 2019-08-13 | 湖南华菱湘潭钢铁有限公司 | A kind of production method of high Al nitrided steel |
| CN110616361A (en) * | 2019-11-06 | 2019-12-27 | 湖南华菱湘潭钢铁有限公司 | Production method of steel for annealing-free nitriding |
| CN111020387A (en) * | 2019-12-25 | 2020-04-17 | 南阳汉冶特钢有限公司 | Seawater corrosion resistant nitrided steel plate 38CrMoAl and production method thereof |
| CN111979475A (en) * | 2020-06-05 | 2020-11-24 | 包头钢铁（集团）有限责任公司 | Wire rod for ultrahigh-strength steel strand and preparation method thereof |
-
2022
- 2022-01-26 CN CN202210099370.XA patent/CN114480971A/en active Pending
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20140283954A1 (en) * | 2013-03-22 | 2014-09-25 | Caterpiller Inc. | Bainitic microalloy steel with enhanced nitriding characteristics |
| JP2015229780A (en) * | 2014-06-03 | 2015-12-21 | 山陽特殊製鋼株式会社 | Steel for nitriding excellent in nitriding property |
| CN105463299A (en) * | 2015-12-07 | 2016-04-06 | 中天钢铁集团有限公司 | Smelting method of high-aluminum nitriding steel |
| CN110117747A (en) * | 2019-05-22 | 2019-08-13 | 湖南华菱湘潭钢铁有限公司 | A kind of production method of high Al nitrided steel |
| CN110616361A (en) * | 2019-11-06 | 2019-12-27 | 湖南华菱湘潭钢铁有限公司 | Production method of steel for annealing-free nitriding |
| CN111020387A (en) * | 2019-12-25 | 2020-04-17 | 南阳汉冶特钢有限公司 | Seawater corrosion resistant nitrided steel plate 38CrMoAl and production method thereof |
| CN111979475A (en) * | 2020-06-05 | 2020-11-24 | 包头钢铁（集团）有限责任公司 | Wire rod for ultrahigh-strength steel strand and preparation method thereof |
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