Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
  • B22D11/16—Controlling or regulating processes or operations
  • B22D11/22—Controlling or regulating processes or operations for cooling cast stock or mould
  • B22D11/225—Controlling or regulating processes or operations for cooling cast stock or mould for secondary cooling
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
  • B22D11/10—Supplying or treating molten metal
  • B22D11/11—Treating the molten metal
  • B22D11/114—Treating the molten metal by using agitating or vibrating means
  • B22D11/115—Treating the molten metal by using agitating or vibrating means by using magnetic fields
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
  • B22D11/12—Accessories for subsequent treating or working cast stock in situ
  • B22D11/1206—Accessories for subsequent treating or working cast stock in situ for plastic shaping of strands
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
  • B22D11/16—Controlling or regulating processes or operations
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
  • B22D11/16—Controlling or regulating processes or operations
  • B22D11/18—Controlling or regulating processes or operations for pouring
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
  • B22D11/16—Controlling or regulating processes or operations
  • B22D11/20—Controlling or regulating processes or operations for removing cast stock
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
  • B22D11/16—Controlling or regulating processes or operations
  • B22D11/20—Controlling or regulating processes or operations for removing cast stock
  • B22D11/201—Controlling or regulating processes or operations for removing cast stock responsive to molten metal level or slag level
  • B22D11/205—Controlling or regulating processes or operations for removing cast stock responsive to molten metal level or slag level by using electric, magnetic, sonic or ultrasonic means
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D6/00—Heat treatment of ferrous alloys
  • C21D6/002—Heat treatment of ferrous alloys containing Cr
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
  • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
  • C21D8/0278—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips involving a particular surface treatment
• • 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
• • 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
  • C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
• • 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
  • C22C38/005—Ferrous alloys, e.g. steel alloys containing rare earths, i.e. Sc, Y, Lanthanides
• • 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
• • 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
• • 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
• • 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
• • 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
  • C22C38/26—Ferrous alloys, e.g. steel alloys containing chromium with niobium or tantalum
• • 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
  • C22C38/30—Ferrous alloys, e.g. steel alloys containing chromium with cobalt

Definitions

• the present invention relates to a metal material and a manufacturing method thereof, in particular to a rare earth-bearing heat-resistant alloy steel and a continuous casting production process therefor.
• heat-resistant alloys In industrial production, heat-resistant alloys have been produced for many years, and many well-known foreign metallurgical enterprises produce heat-resistant alloys.
• the heat-resistant alloys have the advantages of high aperture ratio, large specific surface area, low heat capacity, high thermal conductivity and high strength.
• the heat-resistant alloys can be used as main raw materials for metal carriers in an exhaust gas purification device, and are widely used in automobiles, diesel locomotives, motorcycles, small general machinery and other industries.
• a rare earth-bearing heat-resistant alloy is a material with Fe, Cr and Al as the matrix and adding some alloys such as Mo, Cu, Nb, V and mixed rare earths, which can improve high-temperature performance, electrical resistivity and grain refinement.
• die casting and electroslag processes are mainly used at present, and continuous casting process is used in a few cases, followed by hot rolling and cold rolling.
• One of the objectives of the present invention is to provide a rare earth-bearing heat-resistant alloy steel, which has an electrical resistivity of 1.3-1.5 ⁇ •m at room temperature, can withstand an applicable temperature of 1000-1300 °C, and has an elongation of 5-25% and an oxidative weight loss of 0.2-8.0 g/(cm 2 •h) at the applicable temperature of 1000-1300 °C, thus exhibiting good quality and excellent heat resistance.
• the present invention provides a rare earth-bearing heat-resistant alloy steel, which comprises the following chemical elements in mass percentage: 0 ⁇ C ⁇ 0.05%, 0 ⁇ Si ⁇ 1.0%, 0 ⁇ Mn ⁇ 1.0%, Cr: 13.0-28.0%, Al: 2.0-8.0%, 0 ⁇ Nb ⁇ 0.50%, 0 ⁇ Co ⁇ 0.50%, Mo: 0.5-6.0%, Y: 0.01-0.2%, and at least one of rare earth elements Nos. 57 to 71 in Periodic Table of Elements: 0.01-0.1%.
• At least one of rare earth elements Nos. 57 to 71 in Periodic Table of Elements: 0.01-0.1% means that: when the alloy steel comprises one of the rare earth elements Nos. 57 to 71, the content of the rare earth element is 0.01-0.1%; and when the alloy steel comprises more than one of the rare earth elements Nos. 57 to 71, the total content of these rare earth elements is 0.01-0.1%.
• the content of chemical elements in mass percentage is as follows: 0 ⁇ C ⁇ 0.05%, 0 ⁇ Si ⁇ 1.0%, 0 ⁇ Mn ⁇ 1.0%, Cr: 13.0-28.0%, Al: 2.0-8.0%, 0 ⁇ Nb ⁇ 0.50%, 0 ⁇ Co ⁇ 0.50%, Mo: 0.5-6.0%, Y: 0.01-0.2%, at least one of rare earth elements Nos. 57 to 71 in Periodic Table of Elements: 0.01-0.1%, and the balance being Fe and inevitable impurities.
• each chemical element In the rare earth-bearing heat-resistant alloy steel of the present invention, the design principles of each chemical element are as follows: C: In the rare earth-bearing heat-resistant alloy steel of the present invention, carbon can increase the electrical resistance of the steel and increase the strength of the steel.
• the content of C in mass percentage is controlled to be 0 ⁇ C ⁇ 0.05%.
• the content of C in mass percentage can be controlled to be 0.01 ⁇ C ⁇ 0.05%.
• the content of C in mass percentage can be controlled to be 0.01 ⁇ C ⁇ 0.03%.
• Si In the rare earth-bearing heat-resistant alloy steel of the present invention, silicon is generally brought in by the raw materials and alloy materials. A high content of silicon in the steel will increase electrical resistance and room-temperature strength; the anti-oxidation effect of silicon at a medium temperature can reduce the loss of aluminum and rare earth; and silicon can reduce nitrogen absorption at a high temperature. However, it should be noted that silicate inclusions will adversely affect the alloy matrix. Especially in a high-temperature anti-oxidation film composition, if there is silicon oxide, the integrity of an Al 2 O 3 oxide film will be affected. Therefore, the silicon content should not be too high. In the rare earth-bearing heat-resistant alloy steel of the present invention, the content of Si in mass percentage is controlled to be 0 ⁇ Si ⁇ 1.0%.
• the content of Si in mass percentage can be controlled to be 0.02 ⁇ Si ⁇ 1.0%.
• the content of Si in mass percentage can be controlled to be 0.2 ⁇ Si ⁇ 0.5%.
• Mn In the rare earth-bearing heat-resistant alloy steel of the present invention, manganese can increase the toughness of the steel, and is prone to be austenitized. However, it should be noted that manganese can form oxides with a low melting point in the rare earth-bearing heat-resistant alloy steel, thereby reducing the thermal stability of the alloy. Therefore, in the rare earth-bearing heat-resistant alloy steel of the present invention, the content of Mn in mass percentage is controlled to be 0 ⁇ Mn ⁇ 1.0%.
• the content of Mn in mass percentage can be controlled to be 0.05 ⁇ Mn ⁇ 1.0%.
• the content of Mn in mass percentage can be controlled to be 0.2 ⁇ Mn ⁇ 0.4%.
• chromium and iron have many properties that are not very different, both of which are body-centered cubic lattices, and their lattice constants are similar.
• the chromium content in ferrite stainless steel is usually not less than 13%.
• the addition of chromium to iron can greatly increase the electrical resistivity of iron, and the electrical resistivity of iron will increase rapidly with the increasing content of Cr.
• a ⁇ brittle phase will precipitate and a hardening phase will be dissolved, and the electrical resistivity will gradually decrease.
• the addition of chromium will cause the strength of the steel to improve rapidly and the brittleness of the steel to increase continuously. Therefore, in the rare earth-bearing heat-resistant alloy steel of the present invention, the content of Cr in mass percentage is controlled to be 13.0-28.0%.
• the content of Cr in mass percentage can be controlled to be 17.0-25.0%.
• the content of aluminum in the Fe-Cr alloy is not less than 2%, the anti-oxidation performance will be improved; especially at a high temperature, an oxide film composition can be transformed from Cr 2 O 3 to Al 2 O 3 , so that an oxide film is more stable and firmer, which greatly increases the applicable temperature and prolongs the service life.
• the addition of aluminum will increase the brittleness of the alloy steel.
• the content of Al in mass percentage is controlled to be 2.0-8.0%.
• the content of Al in mass percentage can be controlled to be 3.0-6.0%.
• Nb In the rare earth-bearing heat-resistant alloy steel of the present invention, Nb can improve the high-temperature strength, reduce high-temperature creep, and prolong the service life of the rare earth-bearing heat-resistant alloy steel. However, considering that the cost and the production difficulty will increase as the content of Nb increases, the content of Nb in mass percentage in the rare earth-bearing heat-resistant alloy steel of the present invention is controlled to be 0 ⁇ Nb ⁇ 0.50%.
• the content of Nb in mass percentage can be controlled to be 0 ⁇ Nb ⁇ 0.40%.
• the content of Nb in mass percentage can be controlled to be 0.02 ⁇ Nb ⁇ 0.40%.
• the content of Nb in mass percentage can be controlled to be 0.05 ⁇ Nb ⁇ 0.40%.
• Co In the rare earth-bearing heat-resistant alloy steel of the present invention, Co has similar effect with Nb, and Co can also increase the high-temperature strength, reduce high-temperature creep, and prolong the service life of the rare earth-bearing heat-resistant alloy. Similarly, considering that the production cost and the production difficulty will increase as the content of Co increases, the content of Co in mass percentage in the rare earth-bearing heat-resistant alloy steel of the present invention is controlled to be 0 ⁇ Co ⁇ 0.50%.
• the content of Co in mass percentage can be controlled to be 0 ⁇ Co ⁇ 0.20%.
• the content of Co in mass percentage can be controlled to be 0.01 ⁇ Co ⁇ 0.20%.
• the content of Co in mass percentage can be controlled to be 0.05 ⁇ Nb ⁇ 0.20%.
• Mo, Y In the rare earth-bearing heat-resistant alloy steel of the present invention, a small amount of molybdenum (Mo) and yttrium (Y) are added. Molybdenum can effectively reduce the high-temperature creep rate and prolong the service life of the steel. Yttrium can refine alloy grains, thereby improving the room-temperature strength and high-temperature strength of the steel, and reducing the brittleness. The affinity of yttrium to oxygen is between that of lanthanum and that of aluminum, and it can form an enamel-like oxide film, thereby improving the high-temperature oxidation resistance and the nitriding resistance of the alloy steel.
• yttrium can effectively reduce the high-temperature creep rate and prolong the service life of the steel.
• the content of molybdenum in the steel is too high, it is difficult to perform both hot and cold machining.
• pickling the oxide scales peeling or overwashing is common.
• it tends to burn during smelting when the content of yttrium in the steel is too high. Therefore, in the rare earth-bearing heat-resistant alloy steel of the present invention, the content of Mo in mass percentage is controlled to be 0.5-6.0%, and the content of Y in mass percentage is controlled to be 0.01-0.2%.
• the content of Mo in mass percentage can be controlled to be 1.5-5.0%, and the content of Y in mass percentage can be controlled to be 0.05-0.15%.
• the present inventors use lanthanide rare earth elements Nos. 57 to 71 while using Y, which mainly play the role of significantly prolonging the service life.
• a larger added content of rare earths indicates a higher service life value.
• more rare earths are added, more rare earths will be burned, and the possibility of increasing impurities and hydrogen absorption will be larger, while the increase in the residual content of rare earths in the alloy after burning is less.
• the amount of the lanthanide rare earth added in the alloy is greater than 0.1%, the service life value of the steel shows a downward trend.
• the cost of the lanthanide rare earth is high, and the content should not be too high. Therefore, in the rare earth-bearing heat-resistant alloy steel of the present invention, the added content of at least one of rare earth elements Nos. 57 to 71 in Periodic Table of Elements in mass percentage is controlled to be 0.01-0.1%.
• the content of at least one of rare earth elements Nos. 57 to 71 in Periodic Table of Elements in mass percentage can be controlled to be 0.02-0.05%.
• the content of Nb and Co in mass percentage further satisfies: Nb+Co ⁇ 0.50%, which can increase the high-temperature strength, reduce the high-temperature creep, and prolong the service life of the rare earth-bearing heat-resistant alloy.
• Nb+Co>0.5% the continuous casting production is difficult, the crack sensitivity is high, and the alloy cost is increased.
• Nb and Co in the formula represent the content of each corresponding element in mass percentage respectively.
• the content of P, S and N satisfies at least one of: P ⁇ 0.040%, S ⁇ 0.020%, and N ⁇ 0.020%.
• the content of P, S and N satisfies at least one of: P ⁇ 0.020%, S ⁇ 0.010%, and N ⁇ 0.010%.
• P, N and S are all inevitable impurity elements in the steel, and the content of these impurity elements in the steel should not be too high. Both P and S can generate brittle substances with a low melting point, which tend to cause hot brittleness.
• the content of N in the rare earth-bearing heat-resistant alloy steel is too high, brittle aluminum nitride will be formed, which tend to cause brittle fracture and hinder the formation of Al 2 O 3 oxide film.
• the content of chemical elements in mass percentage satisfies at least one of: 0.01 ⁇ C ⁇ 0.03%, 0.2 ⁇ Si ⁇ 0.5%, 0.2 ⁇ Mn ⁇ 0.4%, Cr: 17.0-25.0%, Al: 3.0-6.0%, 0 ⁇ Nb ⁇ 0.40%, 0 ⁇ Co ⁇ 0.20%, Mo: 1.5-5.0%, Y: 0.05-0.15%, and at least one of rare earth elements Nos. 57 to 71 in Periodic Table of Elements: 0.02-0.05%.
• the main microstructure is ferrite.
• the properties of the rare earth-bearing heat-resistant alloy steel of the present invention satisfy at least one of: being able to withstand an applicable temperature of 1000-1300 °C; having an elongation of 5-25% and an oxidative weight loss of 0.2-8.0 g/(cm 2 •h) at the applicable temperature of 1000-1300 °C; and having an electrical resistivity of 1.3-1.5 ⁇ •m at room temperature.
• another objective of the present invention is to provide a slab continuous casting production process for rare earth-bearing heat-resistant alloy steel.
• the slab continuous casting production process can effectively improve the quality of the continuous casting slab, and the produced continuous casting slab has excellent characteristics of good quality on a surface and center of the continuous casting slab. It can fully exert the advantages of continuous casting production, can effectively suppress recesses and cracks of the casting slab, significantly improve the surface and center quality of the casting slab and achieve sequence casting.
• the slab continuous casting production process of the present invention is a key technology for achieving continuous casting production and quality assurance of rare earth-bearing heat-resistant alloy slabs, and has extremely high promotion and application value for the development of rare-earth-bearing varieties and optimization of the process for enterprises that use a continuous casting process to achieve production and testing. It can not only increase production capacity, and but also effectively reduce production cost, so that the comprehensive competitiveness of an enterprise is greatly enhanced.
• the present invention provides the above-mentioned slab continuous casting production process for the rare earth-bearing heat-resistant alloy steel.
• the specific water ratio of secondary cooling is controlled to be 1.02 ⁇ 0.10 L/kg.
• the present inventors have designed that: a strong cooling process is performed on the rare earth-bearing heat-resistant alloy steel in the secondary cooling zone, wherein when the specific water ratio of secondary cooling is controlled to be 1.02 ⁇ 0.10 L/kg, the lengths of primary columnar crystal and the spacing of secondary columnar crystals are the shortest, which are the prerequisites for improving the internal quality of the casting slab; and the electromagnetic stirring and soft reduction process of the present invention is further used to further ensure the internal quality of the casting slab.
• the specific water ratio of secondary cooling can be controlled to be 1.02 ⁇ 0.06 L/kg, and the Mannesmann rating of the casting slab at low magnification is M1.7-2.0.
• a temperature for hot grinding the casting slab is controlled to be 100-600 °C.
• the surface of the continuous casting slab of the rare earth-bearing heat-resistant alloy steel will have defects such as local recesses, slag pits and deep vibration marks in different degrees. These defects will affect the surface quality of subsequent hot-rolled and cold-rolled products.
• a hot grinding process can be used for the casting slab to effectively alleviate the above defects.
• the temperature for hot grinding the casting slab is controlled to be 100-600 °C. In some preferred embodiments, in the slab continuous casting production process of the present invention, the temperature for hot grinding the casting slab can be controlled to be 300-500 °C.
• process parameters of the continuous casting process are controlled to satisfy at least one of:
• an electromagnetic stirring in the secondary cooling zone and dynamic soft reduction process can be added in the slab continuous casting production process of the present invention.
• the current of electromagnetic stirring is less than 1000 A, and the soft reduction amount is less than 3 mm, it will not be effective in improving the quality of the center of a ferrite slab. If the current of electromagnetic stirring is higher than 2000 A, a liquid level of the crystallizer fluctuates greatly, and the slab is prone to negative segregation. If the soft reduction amount is greater than 10 mm, the narrow side of the casting slab is prone to bulge, and intermediate cracks are prone to be generated in the casting slab.
• the columnar crystals are developed; and through a lot of experiments, the results have shown that dynamic soft reduction is suitable for the whole solidification process of the two-phase region. Therefore, in the slab continuous casting production process of the present invention, the current of electromagnetic stirring is controlled to be 1000-2000 A, the soft reduction amount is controlled to be 3-10 mm, and the solid fraction f s of the casting slab center corresponding to a reduction zone is controlled to be 0.10-0.90. If f s corresponding to the reduction zone is less than 0.10, which is equivalent to complete liquid phase reduction, the columnar crystals have not been completely formed, and the effect of improving segregation is not obvious.
• the solid fraction f s in the center of the casting slab corresponding to the reduction zone being 0.10-0.90 is an important condition to control the Mannesmann rating of the casting slab at low magnification to be M1.7-2.0.
• the electromagnetic stirring current can be controlled to be 1400-2000 A
• the soft reduction amount can be controlled to be 6-9 mm
• the solid fraction f s of the casting slab center corresponding to the reduction zone can be controlled to be 0.20-0.90.
• the grinding amount on one casting slab side can be controlled to be 3-10 mm. In some preferred embodiments, the grinding amount on one casting slab side can be controlled to be 5-8 mm.
• the superheat degree of molten steel in the tundish is controlled to be 10-50 °C. In some preferred embodiments, the superheat degree of molten steel in the tundish can be controlled to be 15-30 °C.
• the average casting speed of continuous casting is controlled to be 0.40-1.50 m/min. In some preferred embodiments, the average casting speed of continuous casting can be controlled to be 0.80-1.2 m/min.
• the submerged depth of the continuous casting crystallizer nozzle is controlled to be 90-130 mm. In some preferred embodiments, the submerged depth of the continuous casting crystallizer nozzle can be controlled to be 100-125 mm.
• the process parameters of the continuous casting process are controlled to satisfy at least one of:
• the rare earth-bearing heat-resistant alloy steel of the present invention has an electrical resistivity of 1.3-1.5 ⁇ •m at room temperature, can withstand an applicable temperature of 1000-1300 °C, and has an elongation of 5-25% and an oxidative weight loss of 0.2-8.0 g/(cm 2 •h) at the applicable temperature of 1000-1300 °C, exhibiting good quality and excellent properties.
• the slab continuous casting production process for the rare earth-bearing heat-resistant alloy steel of the present invention can effectively improve the quality of a continuous casting slab.
• the produced continuous casting slab has excellent characteristics such as good quality on the surface and center of the continuous casting slab. It can fully exert the advantages of continuous casting production, can effectively suppress the occurrence of recesses and cracks of the casting slab, significantly improve the surface and center quality of the casting slab and achieve sequence casting.
• the slab continuous casting production process of the present invention is a key technology for realizing continuous casting production and quality assurance of rare earth-bearing heat-resistant alloy slabs, and has extremely high promotion and application value for the development of rare-earth-bearing varieties and optimization of the process for enterprises that use a continuous casting process to achieve production and testing. It not only increases production capacity, and but also effectively reduces production cost, so that the comprehensive competitiveness of an enterprise can be greatly enhanced.
• the rare earth-bearing heat-resistant alloy steel and the slab continuous casting production process therefor according to the present invention will be further explained and illustrated below in combination with specific embodiments. However, the technical solution of the present disclosure is not limited to the explanation and illustration.
• Table 1 shows the content of chemical elements in mass percentage in rare earth-bearing heat-resistant alloy steels in Inventive Examples 1-6 and Comparative Examples 1-4. Table 1 (wt%, the balance being Fe and inevitable impurities other than P, S and N) No.
• Re in Inventive Examples 1-6 and Comparative Examples 1-4 in Table 1 represents the content of any one element or the total content of several elements among elements Nos. 57 to 71 in Periodic Table of Elements in mass percentage.
• the rare earth-bearing heat-resistant alloy steels of Inventive Examples 1-6 of the present invention and Comparative Examples 1-4 were prepared by the following continuous casting production process:
• the superheat degree of molten steel in the continuous casting tundish was controlled to be 10-50 °C and the submerged depth of the continuous casting crystallizer nozzle was controlled to be 90-130 mm.
• continuous casting pouring was started, wherein the average casting speed was controlled to be 0.40-1.50 m/min and the specific water ratio of secondary cooling was controlled to be 1.02 ⁇ 0.10 L/kg.
• electromagnetic stirring was started.
• the electromagnetic stirring current was 1000-2000 A, the soft reduction amount was controlled to be 3-10 mm, and the solid fraction fs of the casting slab center corresponding to the reduction zone was controlled to be 0.10-0.90. Finally, after the casting slab was released from the caster, the temperature for hot grinding the casting slab was controlled to be 100-600 °C, and the grinding amount on one casting slab side was controlled to be 3-10 mm.
• Table 2 shows specific process parameters of manufacturing methods of the rare earth-bearing heat-resistant alloy steels of Inventive Examples 1-6 and Comparative Examples 1-4.
• Table 2 No. Sectional dimension of slab (mm) Specific water ratio of secondary cooling (L/kg) Temperature for hot grinding (°C) Electromagnetic stirring current (A) Soft reduction amount (mm) Solid fraction f s of casting slab center corresponding to reduction zone Grinding amount on one casting slab side (mm) Average superheat degree of molten steel in tundish (°C) Average casting speed of continuous casting (m/min) Submerged depth of continuous casting crystallizer nozzle (mm) Inventive Example 1 250 ⁇ 1200 0.96 450 1600 8.0 0.1-0.9 8 26 0.76 120 Inventive Example 2 200 ⁇ 1140 0.98 330 1400 6.5 0.1-0.9 7 32 0.92 105 Inventive Example 3 150 ⁇ 1300 1.08 200 1200 4.5 0.1-0.9 3 12 1.2 120 Inventive Example 4 200 ⁇ 1250 1.02 350 2000 7.0 0.1-0.9 5 39 1.0
• Table 3 shows the performance test results of the rare earth-bearing heat-resistant alloy steels of Inventive Examples 1-6 and Comparative Examples 1-4.
• Table 3 No. Elongation at applicable temperature of 1000-1300 °C (%) Oxidative weight loss at applicable temperature of 1000-1300 °C g/(cm 2 ⁇ h) Electrical resistivity at room temperature ( ⁇ m) Quality of casting slab Inventive Example 1 17.3 0.46 1.303 No cracks, casting slab rating at low magnification of M1.8 Inventive Example 2 24.7 7.98 1.446 No cracks, casting slab rating at low magnification of M2.0 Inventive Example 3 13.5 0.37 1.444 No cracks, casting slab rating at low magnification of M1.7 Inventive Example 4 5.1 0.22 1.499 No cracks, casting slab rating at low magnification of M2.0 Inventive Example 5 20.1 2.33 1.496 No cracks, casting slab rating at low magnification of M2.0 Inventive Example 6 22.7 6.55 1.461 No cracks, casting slab rating at low magn
• the rare earth-bearing heat-resistant alloy steel of each Inventive Example of the present invention had an electrical resistivity of 1.3-1.5 ⁇ •m at room temperature, was able to withstand an applicable temperature of 1000-1300 °C, and had an elongation of 5-25% at the applicable temperature of 1000-1300 °C.
• Test results on oxidization resistance of alloys showed that the oxidative weight loss in each Inventive Example at the applicable temperature of 1000-1300 °C was 0.2-8.0 g/(cm 2 •h).
• the rare earth-bearing heat-resistant alloy steels in Inventive Examples exhibited excellent heat resistance.
• the casting slab in each Inventive Example of the present invention exhibited good quality, had no cracks, and had a Mannesmann rating at low magnification of M1.7-2.0.
• Comparative Examples 1 and 2 the contents of Al, Cr, Mo and Re were lower than the claimed ranges of the present invention, and the "Oxidative weight loss at applicable temperature of 1000-1300 °C" and the "Electrical resistivity at room temperature” in the heat resistance properties did not satisfy the requirements.
• Comparative Examples 3 and 4 the contents of Al, Co, Nb and Re were higher than the claimed ranges of the present invention, the "Elongation at applicable temperature of 1000-1300 °C" was less than 5%, and the rating of casting slab at low magnification exceeded M2.0.

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• 2020
  • 2020-05-08 CN CN202010383159.1A patent/CN113621897A/zh active Pending
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