CN115522136A - Method for controlling carbon manganese steel crystal structure through rare earth lanthanum iron microalloying - Google Patents
Method for controlling carbon manganese steel crystal structure through rare earth lanthanum iron microalloying 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
- C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/0006—Adding metallic additives
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/0075—Treating in a ladle furnace, e.g. up-/reheating of molten steel within the ladle
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/04—Removing impurities by adding a treating agent
- C21C7/06—Deoxidising, e.g. killing
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/04—Removing impurities by adding a treating agent
- C21C7/064—Dephosphorising; Desulfurising
- C21C7/0645—Agents used for dephosphorising or desulfurising
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/10—Handling in a vacuum
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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- 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
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
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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
- C22C38/14—Ferrous alloys, e.g. steel alloys containing titanium or zirconium
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- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
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Abstract
The invention discloses a method for controlling the crystal structure of carbon-manganese steel by microalloying rare earth lanthanum and iron, which is characterized in that when the oxygen and sulfur content in the steel is lower, a proper amount of rare earth alloy is added to form rare earth inclusion particles with high melting point and dispersion distribution for deoxidation and desulfurization of rare earth lanthanum, wherein the rare earth inclusion particles are used as heterogeneous nucleation cores to refine grains, and on the other hand, the resistance of crystal boundaries to dislocation can be improved, and the strength and toughness of the steel are improved.
Description
Technical Field
The invention relates to the technical field of steelmaking processes, in particular to a method for controlling a carbon manganese steel crystal structure through rare earth lanthanum iron microalloying.
Background
The rare earth alloy is added to form a rare earth deoxidation desulfurization product lanthanum La with high melting point dispersion distribution 2 O 3 、La 2 S 3 、La 2 O 2 S、LaAlO 3 The method has the advantages that the method creates conditions for effective nucleation of the acicular ferrite in the crystal by utilizing the smaller lattice mismatch degree of the acicular ferrite with the ferrite, and the formed disordered lath structure of the acicular ferrite in the crystal can effectively prevent cracks from propagating in the metal, inhibit the generation of cracks in the crystal, refine the crystal grains and improve the toughness of the steel due to the promotion effect of the method on the nucleation of the acicular ferrite.
The invention relates to a method for controlling the crystal structure of carbon-manganese steel by microalloying rare earth lanthanum iron, which strictly controls sulfur in each process, microalloying the rare earth lanthanum iron to process molten steel in the middle of refining, and adding rare earth +/-lanthanum iron alloy into the steel to form a rare earth deoxidation desulfurization product La with high melting point and dispersive distribution 2 O 3 、La( 2 S 3 、La 2 O 2 S、LaAlO 3 The steel has smaller lattice mismatching degree with ferrite, creates conditions for effective nucleation of acicular ferrite in the crystal, and can effectively prevent cracks from propagating in the metal, inhibit the generation of cracks in the crystal, refine the crystal grains and improve the toughness of the steel due to the disordered lath structure of the acicular ferrite in the crystal, which has promotion effect on the nucleation of the acicular ferriteAnd (4) sex.
Document 1: a rare earth Ce modified high-strength dissolvable aluminum alloy and a smelting process thereof are provided, wherein rare earth element Ce is added in the smelting process, the optimal smelting parameters are adopted, the dissoluble aluminum alloy as-cast crystal grains are refined while the dissolution rate is ensured to be controllable, the prepared dissoluble aluminum alloy material has good mechanical property and good dissolution property, and the dissoluble aluminum alloy as-cast structure crystal grains are effectively refined.
Document 2: the structure refinement and preparation method of the hypereutectic aluminum-iron alloy comprises the following steps: the method is characterized in that under the common casting condition, when hypereutectic Al-Fe-based alloy liquid is processed before a furnace, a trace amount of composite rare earth alterant is added for modification treatment, so that the primary iron-rich phase of the alloy is changed into fine particles from a thick needle sheet shape, and the particle size of the primary iron-rich phase can reach below 2 mu m. The mechanical property and the wear resistance of the alloy are improved, and the high temperature resistance of the alloy system is fully exerted.
Document 3: a method for refining a 800H corrosion resistant alloy ingot casting solidification structure comprises the following steps: the method aims to solve the problem that the solidification structure of the alloy cast ingot is thick, comprises the steps of melting, deoxidizing alloying, refining, casting and the like of the alloy, and is characterized in that the alloy is melted according to the ingredients of the alloy under the protective atmosphere, the temperature is kept for 3min, and the ingredients and the temperature are uniform; adding appropriate amount of aluminum wire for deoxidation, refining for 5min to control oxygen content in the melt at 60-l00ppm, and controlling temperature at 1500 deg.C and 20 deg.C; then adding 100-300ppm of refiner of rare earth Ce, la, Y and the like, refining for 1-2min, cooling the melt, and casting the melt into a metal casting mold when the temperature is reduced to 1430-1440 ℃ to obtain a cast ingot structure with fine solidification structure.
Disclosure of Invention
The invention aims to provide a method for controlling the crystal structure of carbon manganese steel by microalloying rare earth lanthanum and iron, which is characterized in that when the oxygen and sulfur content in the steel is lower, a proper amount of rare earth alloy is added to form rare earth inclusion particles with high melting point and dispersed distribution for deoxidation and desulfurization, wherein the particles of the rare earth inclusions are used as heterogeneous nucleation cores to refine grains, and on the other hand, the resistance of the grain boundaries to dislocation can be improved, and the strength and toughness of the steel can be improved.
In order to solve the technical problems, the invention adopts the following technical scheme:
the invention discloses a method for controlling a carbon manganese steel crystal structure by microalloying rare earth lanthanum iron, which comprises the following steps:
the first step is as follows: the microalloyed structural steel comprises the following main components: less than or equal to 0.25 percent of C, less than or equal to 0.15 percent of Si, less than or equal to 1.60 percent of Mn, less than or equal to 0.15 percent of Nb, V and Ti, and the contents of phosphorus and sulfur and harmful elements all meet the national standard requirements of steel grades;
the second step is that: the technological process for producing the low-carbon manganese steel by the 260-ton refining furnace comprises the following steps: KR molten iron pretreatment, BOF top and bottom combined blown converter, LF external refining, RH vacuum refining, CCM slab continuous casting process route, wherein the molten iron w [ S ] entering the converter is less than or equal to 0.005%, the tapping temperature of the converter is 1640 +/-20 ℃, the w [ S ] in the molten iron at the end point is less than 0.025%, and slag and lime are added for tapping;
the third step: 5kg/t lime and 0.5-5kg/t slagging agent are used for rapid slagging operation, aluminum particles or aluminum ingots are deoxidized, the adding amount is 0.5-1.5kg/t, and the LF dislocation w [ S ] is ensured to be less than or equal to 0.005 percent;
the fourth step: calcium treatment is carried out after LF refining treatment is finished, the alkalinity is controlled to be 4.5-9.0, and FeO + MnO is less than 1.0%;
the fifth step: the rare earth lanthanum alloy comprises the following components: the content of rare earth lanthanum is more than or equal to 5 percent, the rare earth lanthanum is iron except the rare earth simple substance, and the total content of impurity elements is less than or equal to 1 percent;
and a sixth step: adding rare earth lanthanum alloy at the final stage of RH vacuum treatment, wherein 0.5-5kg/t of rare earth alloy is added into molten steel, the cycle time is more than or equal to 4min, after breaking the air and restoring the pressure, a weak stirring and small flow argon blowing mode is adopted, the soft blowing time is more than or equal to 8min, and the sufficient denaturation and floating time of inclusions is ensured;
the seventh step: the whole process of continuous casting protects the casting and prevents the flocculation caused by secondary oxidation.
Compared with the prior art, the invention has the beneficial technical effects that:
the invention utilizes the high melting point dispersion distributed tiny rare earth deoxidation and desulfurization product La 2 O 3 、La 2 S 3 、La 2 O 2 S、 LaAlO 3 And precipitated phase particles thereof, inducing ferrite to nucleate on the surface thereof in the transformation process from austenite to ferrite, so that the ferrite is precipitated in the austenite grains to form a disordered and interlocked needle-sheet-shaped structure, and simultaneously; the method creates conditions for effective nucleation of the acicular ferrite in the crystal by utilizing the smaller lattice mismatch degree of the acicular ferrite with the ferrite, and can effectively prevent cracks from propagating in the metal, inhibit the generation of cracks in the crystal, refine the crystal grains and improve the toughness of the steel due to the disordered lath structure of the acicular ferrite in the crystal.
The structure of the finished product is shown in figures 1 and 2, the structure of the finished product without adding the rare earth lanthanum iron alloy in figure 1 is disordered, small crystal grains are gathered around large crystal grains, and in figure 2, the structure of the finished product after adding the rare earth lanthanum iron alloy forms a disordered and interlocked needle-shaped structure, so that cracks are effectively prevented from propagating in the metal, the generation of cracks in the crystal is inhibited, the crystal grains are refined, the structure is more uniform, and the toughness of the steel is improved.
Drawings
The invention is further illustrated in the following description with reference to the drawings.
FIG. 1 shows the structure of the finished product without rare earth alloy;
FIG. 2 shows the structure of the product with rare earth alloy added.
Detailed Description
A method for controlling the crystal structure of carbon manganese steel by microalloying rare earth lanthanum iron comprises the following steps:
the first step is as follows: the microalloyed structural steel comprises the following main components: less than or equal to 0.25 percent of C, less than or equal to 0.15 percent of Si, less than or equal to 1.60 percent of Mn, less than or equal to 0.15 percent of Nb, V and Ti, and the contents of phosphorus and sulfur and harmful elements all meet the national standard requirements of steel grades.
The first step is as follows: the technological process for producing the low-carbon manganese steel by the 260-ton refining furnace comprises the following steps: the technological line of KR molten iron pretreatment, BOF top and bottom combined blowing converter, LF external refining, RH vacuum refining, CCM slab continuous casting includes molten iron in converter with W S not more than 0.005%, converter tapping temperature of 1640 +/-20 deg.c, molten iron at the end point with W S not more than 0.025%, slag blocking and white ash adding and tapping.
The second step is that: 5kg/t lime and 0.5-5kg/t slagging agent are used for rapid slagging operation, aluminum particles or aluminum ingots are deoxidized, the adding amount is 0.5-1.5kg/t, and the LF dislocation w [ S ] is ensured to be less than or equal to 0.005 percent.
The third step: after LF refining treatment, calcium treatment is carried out, the alkalinity is controlled to be 4.5-9.0, and FeO + MnO is less than 1.0%.
The fourth step: the rare earth lanthanum alloy comprises the following components: the content of rare earth lanthanum is more than or equal to 5 percent, the rare earth elements except the rare earth simple substance are all iron, and the total content of impurity elements is less than or equal to 1 percent.
The fourth step: adding rare earth lanthanum alloy at the final stage of RH vacuum treatment, adding 0.5-5kg/t rare earth alloy into molten steel, circulating for more than or equal to 4min, breaking air and repressing, adopting a weak stirring small flow argon blowing mode, and soft blowing for more than or equal to 8min, thereby ensuring that the inclusions have sufficient denaturation and floating time.
The fifth step: the whole process of continuous casting protects the casting and prevents the flocculation caused by secondary oxidation.
The structure of the finished product is shown in figures 1 and 2, the structure of the finished product without adding the rare earth lanthanum iron alloy in figure 1 is disordered, small crystal grains are gathered around large crystal grains, and in figure 2, the structure of the finished product after adding the rare earth lanthanum iron alloy forms a disordered and interlocked needle-shaped structure, so that cracks are effectively prevented from propagating in the metal, the generation of cracks in the crystal is inhibited, the crystal grains are refined, the structure is more uniform, and the toughness of the steel is improved.
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 (1)
1. A method for controlling the crystal structure of carbon manganese steel by microalloying rare earth lanthanum iron is characterized by comprising the following steps: the method comprises the following steps:
the first step is as follows: the microalloyed structural steel comprises the following main components: less than or equal to 0.25 percent of C, less than or equal to 0.15 percent of Si, less than or equal to 1.60 percent of Mn, less than or equal to 0.15 percent of Nb, V and Ti, and the contents of phosphorus and sulfur and harmful elements all meet the national standard requirements of steel grades;
the second step is that: the technological process for producing the low-carbon manganese steel by the 260-ton refining furnace comprises the following steps: KR molten iron pretreatment, BOF top and bottom combined blown converter, LF external refining, RH vacuum refining, CCM slab continuous casting process route, wherein the molten iron w [ S ] entering the converter is less than or equal to 0.005%, the tapping temperature of the converter is 1640 +/-20 ℃, the w [ S ] in the molten iron at the end point is less than 0.025%, and slag and lime are added for tapping;
the third step: 5kg/t lime and 0.5-5kg/t slagging agent are used for rapid slagging operation, aluminum particles or aluminum ingots are deoxidized, the adding amount is 0.5-1.5kg/t, and the LF dislocation w [ S ] is ensured to be less than or equal to 0.005 percent;
the fourth step: after LF refining treatment, calcium treatment is carried out, the alkalinity is controlled to be 4.5-9.0, and FeO + MnO is covered by 1.0%;
the fifth step: the rare earth lanthanum alloy comprises the following components: the content of rare earth lanthanum is more than or equal to 5 percent, the rare earth lanthanum is iron except the rare earth simple substance, and the total content of impurity elements is less than or equal to 1 percent;
and a sixth step: rare earth lanthanum alloy is added at the final stage of RH vacuum treatment, 0.5-5kg/t rare earth alloy is added into molten steel, the cycle time is more than or equal to 4min, after air breaking and pressure restoring, a weak stirring and small flow argon blowing mode is adopted, the soft blowing time is more than or equal to 8min, and the sufficient denaturation and floating time of inclusions is ensured;
the seventh step: the whole process of continuous casting protects the casting and prevents the flocculation caused by secondary oxidation.
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Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102732685A (en) * | 2012-06-20 | 2012-10-17 | 内蒙古包钢钢联股份有限公司 | Method for adding rare earth into RH refining furnace |
| CN106521293A (en) * | 2016-08-04 | 2017-03-22 | 中国科学院金属研究所 | Method for adding rare earth metal into steel to improve performance |
| CN110129508A (en) * | 2019-05-23 | 2019-08-16 | 包头钢铁（集团）有限责任公司 | A kind of technique improving rare earth high-strength steel impact flexibility |
| WO2019169548A1 (en) * | 2018-03-06 | 2019-09-12 | 高海艇 | Low-strength cast steel micro-alloyed with rare earth |
| CN114716256A (en) * | 2022-03-11 | 2022-07-08 | 钢铁研究总院有限公司 | Refractory material for smelting rare earth steel and method for improving rare earth yield |
| CN114774628A (en) * | 2022-04-20 | 2022-07-22 | 包头钢铁（集团）有限责任公司 | Key production method for processing steel for C-Mn low-temperature container by rare earth Ce or La microalloy |
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- 2022-09-20 CN CN202211145603.1A patent/CN115522136B/en active Active
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102732685A (en) * | 2012-06-20 | 2012-10-17 | 内蒙古包钢钢联股份有限公司 | Method for adding rare earth into RH refining furnace |
| CN106521293A (en) * | 2016-08-04 | 2017-03-22 | 中国科学院金属研究所 | Method for adding rare earth metal into steel to improve performance |
| WO2019169548A1 (en) * | 2018-03-06 | 2019-09-12 | 高海艇 | Low-strength cast steel micro-alloyed with rare earth |
| CN110129508A (en) * | 2019-05-23 | 2019-08-16 | 包头钢铁（集团）有限责任公司 | A kind of technique improving rare earth high-strength steel impact flexibility |
| CN114716256A (en) * | 2022-03-11 | 2022-07-08 | 钢铁研究总院有限公司 | Refractory material for smelting rare earth steel and method for improving rare earth yield |
| CN114774628A (en) * | 2022-04-20 | 2022-07-22 | 包头钢铁（集团）有限责任公司 | Key production method for processing steel for C-Mn low-temperature container by rare earth Ce or La microalloy |
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