CN116065085A - Super-thick large spheroidal graphite cast iron and preparation method thereof - Google Patents

Super-thick large spheroidal graphite cast iron and preparation method thereof Download PDF

Info

Publication number
CN116065085A
CN116065085A CN202310005362.9A CN202310005362A CN116065085A CN 116065085 A CN116065085 A CN 116065085A CN 202310005362 A CN202310005362 A CN 202310005362A CN 116065085 A CN116065085 A CN 116065085A
Authority
CN
China
Prior art keywords
percent
iron
spheroidal graphite
graphite cast
cast iron
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
CN202310005362.9A
Other languages
Chinese (zh)
Inventor
刘明宇
毛成荣
刘万里
锁必胜
熊六一
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
RIYUE HEAVY INDUSTRY CO LTD
Original Assignee
RIYUE HEAVY INDUSTRY CO LTD
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by RIYUE HEAVY INDUSTRY CO LTD filed Critical RIYUE HEAVY INDUSTRY CO LTD
Priority to CN202310005362.9A priority Critical patent/CN116065085A/en
Publication of CN116065085A publication Critical patent/CN116065085A/en
Pending legal-status Critical Current

Links

Images

Classifications

    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C37/00—Cast-iron alloys
    • C22C37/04—Cast-iron alloys containing spheroidal graphite
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D1/00—Treatment of fused masses in the ladle or the supply runners before casting
    • 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
    • C21C1/00—Refining of pig-iron; Cast iron
    • C21C1/02—Dephosphorising or desulfurising
    • 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
    • C21C1/00—Refining of pig-iron; Cast iron
    • C21C1/02—Dephosphorising or desulfurising
    • C21C1/025—Agents used for dephosphorising or desulfurising
    • 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
    • C21C1/00—Refining of pig-iron; Cast iron
    • C21C1/10—Making spheroidal graphite cast-iron
    • 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
    • C21C1/00—Refining of pig-iron; Cast iron
    • C21C1/10—Making spheroidal graphite cast-iron
    • C21C1/105—Nodularising additive agents
    • 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
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C33/00—Making ferrous alloys
    • C22C33/08—Making cast-iron alloys
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C35/00—Master alloys for iron or steel
    • C22C35/005—Master alloys for iron or steel based on iron, e.g. ferro-alloys
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C37/00—Cast-iron alloys
    • C22C37/10—Cast-iron alloys containing aluminium or silicon
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/20—Recycling

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Mechanical Engineering (AREA)
  • Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)

Abstract

The invention belongs to the technical field of metal casting, and particularly relates to ultra-thick large spheroidal graphite cast iron and a preparation method thereof. The ultra-thick spheroidal graphite cast iron comprises the following components in percentage by weight: 3.35 to 3.45 percent of carbon, 2.40 to 2.80 percent of silicon, less than or equal to 0.025 percent of phosphorus, less than or equal to 0.15 percent of manganese, 0.040 to 0.055 percent of magnesium, 0.003 to 0.008 percent of rare earth element, less than or equal to 0.018 percent of sulfur, 0.003 to 0.006 percent of antimony and the balance of iron. The chemical components are designed by adjusting the content of elements such as silicon, carbon and the like, and the ultra-thick spheroidal graphite cast iron with good mechanical properties is prepared by combining a cupola-electric furnace duplex smelting mode and a reasonable inoculation mode, and has good mechanical properties, wherein the tensile strength is more than or equal to 320MPa, the yield strength is more than or equal to 255MPa, and the elongation is more than or equal to 4% at the position of the thickest wall of the spheroidal graphite cast iron casting with the thickness of 1500 mm.

Description

Super-thick large spheroidal graphite cast iron and preparation method thereof
Technical Field
The invention belongs to the technical field of metal casting, and particularly relates to ultra-thick large spheroidal graphite cast iron and a preparation method thereof.
Background
In recent years, with the rapid development of large die casting machines, the requirements of spheroidal graphite cast iron on functions of spheroidal graphite cast iron are increasingly enhanced, and the requirements of low cost, energy conservation, emission reduction, and resource deliberation are also increased, so that some small die casting machines cannot meet the production requirements. From the preparation of primary and auxiliary materials, charging and molten iron melting processes to the whole processes of spheroidization, pouring and inoculation, any link is critical to the performance of cast iron.
For nodular cast iron, the solidification mode is different from the sequential solidification of cast steel, graphite is precipitated in the solidification process, the solidification mode of pasty solidification is followed, the outside is solidified first, the core part is solidified last, the thicker the wall thickness of the casting is, the slower the cooling speed is, the longer the solidification time is, the more sufficient the graphite growth time is, some alloy chemical components are gathered in the core part of the hot section of the casting, the uneven distribution of the inner and outer wall thickness is caused, so that the poor matrix structure and poor graphite form of the core part of the casting are caused, the fragment graphite or the float grass graphite is formed, and the mechanical property of the core part is seriously reduced.
In order to avoid abnormal graphite such as broken blocks, nails and the like in the graphite form of large ductile iron castings, heavy rare earth nodulizer with high rare earth content is often adopted for spheroidizing treatment, so that spheroidizing degradation of molten iron is avoided. In the technical requirements of actual production, besides the performance requirements of the casting attached casting test block, the mechanical properties of the body are required to be detected, so that the production difficulty of the large-scale ultra-thick large ductile iron casting is greatly increased. If the heavy rare earth nodulizer is still adopted for spheroidization, the residual quantity of magnesium and rare earth in the molten iron after spheroidization is higher, the graphite form is seriously deteriorated, the core of the casting is extremely easy to produce broken graphite, and the mechanical property of the nodular cast iron is reduced. Therefore, the residual quantity of rare earth is controlled to ensure the roundness of graphite, thereby improving the mechanical property of the ductile iron casting.
Disclosure of Invention
The invention aims to solve the technical problems and provides ultra-thick large spheroidal graphite cast iron which has good mechanical properties when being applied to large spheroidal graphite cast iron.
The super-thick large spheroidal graphite cast iron in the technical scheme comprises the following components in percentage by weight: 3.35 to 3.45 percent of carbon, 2.40 to 2.80 percent of silicon, less than or equal to 0.025 percent of phosphorus, less than or equal to 0.15 percent of manganese, 0.040 to 0.055 percent of magnesium, 0.003 to 0.008 percent of rare earth element, less than or equal to 0.018 percent of sulfur, 0.003 to 0.006 percent of antimony and the balance of iron.
Under the condition of ensuring that graphite floating does not occur, the carbon content is increased as much as possible so as to improve the graphite nodule count of the spheroidal graphite cast iron and reduce the shrinkage porosity defect of the core part; the silicon element can promote graphitization, improve the tensile strength, yield strength and elongation of the spheroidal graphite cast iron, and simultaneously improve the ductile-brittle transition temperature and eutectoid transition temperature of the spheroidal graphite cast iron, and the silicon element with too high content can easily form the fragment-shaped graphite on the core part of the casting, so that the bloom-shaped graphite is formed on the surface, and the performance of the cast iron is influenced; the phosphorus element can improve the fluidity of molten iron, and when the content is too high, phosphorus eutectic is formed at a crystal boundary, so that the extensibility of the material is obviously reduced; the manganese element can promote the generation of pearlite, improve the tensile strength of the spheroidal graphite cast iron, and simultaneously can obviously reduce the elongation of the spheroidal graphite cast iron core structure as well as the Mn content as far as possible as the pearlite generated at the core grain boundary as an alloy element easy to positively segregate, so that the pearlite is avoided from being generated at the grain boundary; the magnesium element can stabilize carbide, promote the formation of spheroidal graphite and ensure spheroidization effect; the rare earth elements have the functions of deoxidizing, desulfurizing and the like, and can neutralize the anti-spheroidizing elements in the molten iron, but the graphite morphology can be deteriorated when the content is too high, so that the mechanical property of the spheroidal graphite cast iron is reduced; the content of sulfur element is too high, which can bring adverse effect to spheroidization performance and crystal nucleus morphology; the antimony element can improve the roundness of graphite and eliminate the influence of rare earth element on graphite deterioration.
The invention also aims at providing a preparation method of the super-thick spheroidal graphite cast iron, which comprises the steps of charging smelting, desulfurization treatment, spheroidizing tapping and pouring inoculation.
The smelting adopts a cupola-electric furnace duplex smelting mode, oxidation-reduction reaction is carried out on molten iron of the cupola, the molten iron is further overheated, partial impurities are eliminated, the nucleation of the molten iron is facilitated, and the mechanical properties of the spheroidal graphite cast iron are improved. Sulfur content control is a key process, and nitrogen stirring is adopted to purify molten iron during desulfurization, and the high-temperature burning loss effect of a cupola furnace is matched, so that the gas and impurity content in the molten iron is further reduced.
In the preparation method of the ultra-thick spheroidal graphite cast iron, the following raw materials in percentage by mass are used in charging and smelting: 58.0 to 60.0 percent of pig iron, 35.0 to 38.0 percent of first scrap steel, 2.0 to 2.2 percent of ferrosilicon, 1.8 to 2.0 percent of carburant and 0.002 to 0.004 percent of metallic antimony.
Further, pig iron is prepared by mixing rare Wang Shengtie and shou pig iron in a mass ratio of 1:1-2, wherein the components of rare Wang Shengtie comprise 4.2-4.5% of carbon, 0.5-0.7% of silicon, 0.05-0.10% of manganese, 0.02-0.03% of phosphorus, 0.02-0.03% of sulfur, 0.005-0.006% of chromium, 0.02-0.03% of titanium, 0.001-0.002% of copper, 0.003-0.005% of vanadium and the balance of iron; the compositions of the longevity pig iron comprise 3.2-4.2% of carbon, 0.3-0.5% of silicon, 0.005-0.10% of manganese, 0.003-0.004% of phosphorus, 0.01-0.02% of sulfur, 0.001-0.004% of chromium, 0.002-0.003% of titanium and the balance of iron. The compound use of the two pig irons can better coordinate the element content of the added raw materials, eliminate the influence of difficult regulation and control of the element content caused by the use of single pig iron, obtain more excellent element proportion and finally obtain the spheroidal graphite cast iron with good mechanical properties.
Further, the first scrap steel comprises 0.02 to 0.03 percent of carbon, 0.03 to 0.04 percent of silicon, 0.05 to 0.20 percent of manganese, 0.01 to 0.02 percent of phosphorus, 0.008 to 0.009 percent of sulfur, 0.01 to 0.02 percent of chromium and the balance of iron; the ferrosilicon comprises 0.04-0.05% of carbon, 70.0-75.0% of silicon, 0.10-0.20% of manganese, 0.02-0.03% of phosphorus, 0.005-0.006% of sulfur, 0.01-0.02% of chromium, 0.70-0.80% of aluminum and the balance of iron; the carburant has a carbon content of 99.0% or more.
Further, the carburant is one or more of artificial graphite, petroleum coke, natural graphite, coke and anthracite.
Further, the smelting temperature in charging smelting is 1440-1490 ℃.
In the preparation method of the super-thick spheroidal graphite cast iron, a desulfurizing agent accounting for 0.8 to 1.2 percent of the mass of molten iron is added into a ladle during desulfurization treatment, and nitrogen is introduced into the ladle for desulfurization; the desulfurizing agent comprises 50.0-52.0% of calcium oxide, 6.0-8.0% of calcium fluoride and 40.0-44.0% of calcium carbide. Proper sulfur content can be obtained in the ball-milling cast iron by proper content of the desulfurizing agent so as to ensure the spheroidizing effect and obtain the spheroidal graphite cast iron with good graphite morphology and mechanical property.
In the preparation method of the super-thick spheroidal graphite cast iron, 0.25 to 0.50 percent of silicon-calcium-barium inoculant, 0.5 to 0.7 percent of second scrap steel and 0.3 to 0.4 percent of pretreatment agent of molten iron are sequentially covered on the surface of the nodulizer during nodulizing tapping. The second scrap steel is covered on the surface of the silicon-calcium-barium inoculant, so that molten iron can be prevented from directly rushing on a nodulizer during tapping, spheroidization recession is caused, the mechanical properties of spheroidal graphite cast iron are affected, the oxygen content/sulfur content in the molten iron is controlled to be low and stable by pretreatment, stable nucleation points are formed, graphite cores can be increased, the number of graphite spheres is increased, intercrystalline segregation is reduced, good conditions are provided for spheroidization reaction, and a foundation is laid for obtaining qualified metallographic structures and mechanical properties.
Further, the silicon-calcium-barium inoculant comprises 70.0-71.0% of silicon, 1.0-1.5% of aluminum, 0.7-0.8% of calcium, 2.0-2.2% of barium and the balance of iron; the second scrap steel comprises 0.05-0.06% of carbon, 0.04-0.05% of silicon, 0.10-0.20% of manganese, 0.01-0.02% of phosphorus, 0.006-0.007% of sulfur, 0.02-0.03% of copper, 0.02-0.03% of chromium, 0.002-0.003% of molybdenum, 0.001-0.002% of titanium and the balance of iron; the pretreatment agent comprises 60-65% of silicon, 1.0-1.2% of calcium, 3.0-4.0% of zirconium, 3.0-4.0% of aluminum and the balance of iron.
Further, the adding amount of the nodulizer is 1.0-1.25% of the mass of the molten iron, the molten iron comprises a first nodulizer and a second nodulizer, and the mass ratio of the first nodulizer to the second nodulizer is 2.0-3.0:1.0; the first nodulizer comprises the components of 71.0 to 72.0 percent of silicon, 5.78 to 5.80 percent of magnesium, 0.3 to 0.4 percent of rare earth element, 0.6 to 0.7 percent of aluminum, 0.35 to 0.37 percent of magnesium oxide, 0.93 to 1.0 percent of calcium and the balance of iron, and the second nodulizer comprises the components of 71.0 to 72.0 percent of silicon, 5.78 to 5.80 percent of magnesium, 0.9 to 1.0 percent of rare earth element, 0.6 to 0.7 percent of aluminum, 0.35 to 0.37 percent of magnesium oxide, 0.93 to 1.0 percent of calcium and the balance of iron. The nodulizer with proper content and proportion is beneficial to the nodulization of graphite in the spheroidal graphite cast iron forming process, and avoids the abnormal graphite such as broken blocks, nails and the like in the graphite form of large spheroidal graphite cast iron, thereby ensuring good mechanical property and mechanical property of spheroidal graphite cast iron.
Further, the tapping temperature during spheroidizing tapping is 1450-1500 ℃. When the tapping temperature of the molten iron is too high, the cooling rate of the molten iron in a ladle is too slow, so that spheroidization degradation of the molten iron is easily caused, and the mechanical properties are influenced; when the tapping temperature is too low, the temperature of molten iron is reduced too fast, the mold filling is risky, cold separation defects are easy to occur in castings, and quality accidents are generated.
In the preparation method of the super-thick spheroidal graphite cast iron, the sulfur-oxygen inoculant with the mass of 0.1-0.2% of the molten iron is added along with the molten iron flow during pouring inoculation for secondary inoculation.
Further, the composition of the sulfur-oxygen inoculant comprises less than or equal to 72.0 percent of silicon, less than or equal to 1.81 percent of rare earth elements, less than or equal to 1.2 percent of aluminum, less than or equal to 0.98 percent of calcium and the balance of iron. The sulfur-oxygen inoculant is adopted for pouring stream inoculation, so that the instantaneous inoculation intensity can be improved, elements such as sulfur, oxygen and the like in the molten iron are properly increased, a small amount of nucleation centers are added into the molten iron, the number of graphite spheres is increased, the diameter of the graphite spheres is reduced, and the mechanical property of the spheroidal graphite cast iron is improved. The excessive inoculant content can increase the viscosity of the molten iron and the tendency of slag inclusion, shrinkage cavity and shrinkage porosity.
Further, the pouring temperature during pouring inoculation is 1300-1350 ℃.
Further, the granularity of the silicon-calcium-barium inoculant is 3-8mm, the granularity of the sulfur-oxygen inoculant is 0.2-0.7 mm, and the sulfur-oxygen inoculant can be quickly melted after contacting molten iron, so that the uniformity of inoculation is improved.
Compared with the prior art, the technical scheme of the invention has the following beneficial effects:
(1) The chemical components are designed by adjusting the content of elements such as silicon, carbon and the like, and the ultra-thick large spheroidal graphite cast iron with good mechanical properties is prepared by combining a cupola-electric furnace duplex smelting mode and a reasonable inoculation mode;
(2) The tensile strength of the obtained spheroidal graphite cast iron casting is more than or equal to 320MPa, the yield strength is more than or equal to 255MPa, and the elongation is more than or equal to 4 percent at the position with the thickest wall of 1500 mm;
(3) The excellent chemical element proportion is obtained by controlling the contents of various raw materials and additives, and the spheroidal graphite cast iron with higher tensile strength, yield strength, elongation and other mechanical properties is obtained;
(4) The cupola furnace-electric furnace duplex smelting mode is adopted, so that partial impurities can be eliminated, molten iron nucleation is facilitated, the quantity and the form of the graphite are better, and the mechanical property of the spheroidal graphite cast iron is improved;
(5) Through desulfurization treatment and the high-temperature burning loss effect of a cupola furnace, the gas and impurity content in molten iron is reduced, so that the obtained ball-milled cast iron has proper sulfur content, a good spheroidizing effect is ensured, and spheroidal graphite cast iron with good graphite morphology and mechanical properties is obtained;
(6) Adding a pretreatment agent to control the oxygen content/sulfur content in the molten iron at a lower and stable level to form stable nucleation points, providing good conditions for spheroidization reaction and also laying a foundation for obtaining qualified metallographic structure and mechanical properties;
(7) The first nodulizer and the second nodulizer are compounded for use, so that the nodulizing of graphite in the spheroidal graphite cast iron forming process is facilitated, graphite morphology special-shaped graphite of large spheroidal graphite cast iron is avoided, and good mechanical properties and mechanical properties of the spheroidal graphite cast iron are ensured.
Drawings
FIG. 1 is a diagram of the phase of the ultra-thick spheroidal graphite cast iron obtained in example 1 before corrosion;
FIG. 2 is a diagram of the phase of the ultra-thick spheroidal graphite cast iron obtained in example 1 after corrosion.
Detailed Description
The technical solution of the present invention will be further described by means of specific examples and drawings, it being understood that the specific examples described herein are only for aiding in understanding the present invention and are not intended to be limiting. And the drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure. The raw materials used in the examples of the present invention are all common raw materials in the art, and the methods used in the examples are all conventional methods in the art, unless otherwise specified.
The components of the rare Wang Shengtie used in the following examples and comparative examples comprise 4.38% of carbon, 0.58% of silicon, 0.05% of manganese, 0.028% of phosphorus, 0.023% of sulfur, 0.006% of chromium, 0.023% of titanium, 0.001% of copper, 0.004% of vanadium and the balance of iron; the compositions of the longevity pig iron comprise 4.0 percent of carbon, 0.4 percent of silicon, 0.01 percent of manganese, 0.003 percent of phosphorus, 0.006 percent of sulfur, 0.003 percent of chromium, 0.002 percent of titanium and the balance of iron; the first scrap steel comprises 0.02% of carbon, 0.03% of silicon, 0.23% of manganese, 0.01% of phosphorus, 0.009% of sulfur, 0.014% of chromium and the balance of iron; the ferrosilicon comprises 0.04% of carbon, 73.5% of silicon, 0.18% of manganese, 0.029% of phosphorus, 0.005% of sulfur, 0.012% of chromium, 0.78% of aluminum and the balance of iron; the carburant is artificial graphite with carbon content of 99.5%; the desulfurizing agent comprises 50.0% of calcium oxide, 7.0% of calcium fluoride and 43.0% of calcium carbide; the silicon-calcium-barium inoculant comprises 71.0% of silicon, 1.0% of aluminum, 0.7% of calcium, 2.0% of barium and the balance of iron; the second scrap steel comprises the components of 0.05% of carbon, 0.04% of silicon, 0.17% of manganese, 0.013% of phosphorus, 0.007% of sulfur, 0.02% of copper, 0.02% of chromium, 0.002% of molybdenum, 0.001% of titanium and the balance of iron; the pretreatment agent comprises 65% of silicon, 1.2% of calcium, 4.0% of zirconium, 4.0% of aluminum and the balance of iron; the first nodulizer comprises 71.0% of silicon, 5.78% of magnesium, 0.34% of rare earth elements, 0.6% of aluminum, 0.37% of magnesium oxide, 0.93% of calcium and the balance of iron; the second nodulizer comprises 72.0% of silicon, 5.80% of magnesium, 0.99% of rare earth elements, 0.7% of aluminum, 0.35% of magnesium oxide, 1.0% of calcium and the balance of iron; the sulfur-oxygen inoculant comprises 72.0% of silicon, 1.81% of rare earth elements, 1.2% of aluminum, 0.98% of calcium and the balance of iron;
example 1
The preparation method of the super-thick large spheroidal graphite cast iron comprises the following steps:
(1) And (3) charging and smelting: 29 parts of rare Wang Shengtie, 29 parts of shou pig iron, 38 parts of first scrap steel, 2.2 parts of ferrosilicon, 1.8 parts of carburant and 0.002 part of metallic antimony are added and smelted at 1450 ℃ by using a cupola-electric furnace duplex;
(2) Desulfurization treatment: adding 1.0 part of desulfurizing agent into a ladle, connecting a nitrogen cylinder to the ladle, and adjusting a cylinder pressure valve to enable nitrogen to enter molten iron for rolling desulfurization;
(3) Spheroidizing tapping: adding 0.80 part of a first nodulizer and 0.35 part of a second nodulizer into a desulfurized ladle, tamping, and sequentially covering 0.40 part of a silicon-calcium-barium inoculant (with the grain diameter of 5 mm), 0.70 part of second scrap steel and 0.35 part of a pretreatment agent on the surface of the nodulizer, and pouring into the ladle for nodulizing when tapping at the temperature of 1480 ℃;
(4) Pouring inoculation: when in pouring at 1330 ℃, 0.15 part of sulfur-oxygen inoculant (with the grain diameter of 0.5 mm) is added along with molten iron flow for secondary inoculation, and the spheroidal graphite cast iron is obtained after cooling, wherein the components of the spheroidal graphite cast iron comprise 3.40 percent of carbon, 2.60 percent of silicon, 0.02 percent of phosphorus, 0.15 percent of manganese, 0.045 percent of magnesium, 0.006 percent of rare earth element, 0.016 percent of sulfur, 0.005 percent of antimony and the balance of iron.
Example 2
The preparation method of the super-thick large spheroidal graphite cast iron comprises the following steps:
(1) And (3) charging and smelting: adding 30 parts of rare Wang Shengtie, 30 parts of shou pig iron, 36 parts of first scrap steel, 2.1 parts of ferrosilicon, 2.0 parts of carburant and 0.002 parts of metallic antimony, and smelting at 1460 ℃ by using a cupola-electric furnace duplex;
(2) Desulfurization treatment: adding 1.2 parts of desulfurizing agent into a ladle, connecting a nitrogen cylinder to the ladle, and adjusting a cylinder pressure valve to enable nitrogen to enter molten iron for rolling desulfurization;
(3) Spheroidizing tapping: adding 0.80 part of a first nodulizer and 0.35 part of a second nodulizer into a desulfurized ladle, tamping, and sequentially covering 0.40 part of a silicon-calcium-barium inoculant (with the grain diameter of 6 mm), 0.70 part of second scrap steel and 0.35 part of a pretreatment agent on the surface of the nodulizer, and pouring the mixture into the ladle for nodulizing when tapping at the temperature of 1490 ℃;
(4) Pouring inoculation: when in pouring at 1350 ℃, 0.15 part of sulfur-oxygen inoculant (with the grain diameter of 0.5 mm) is added along with molten iron flow for secondary inoculation, and the spheroidal graphite cast iron is obtained after cooling, wherein the components of the spheroidal graphite cast iron comprise 3.45 percent of carbon, 2.65 percent of silicon, 0.02 percent of phosphorus, 0.15 percent of manganese, 0.045 percent of magnesium, 0.006 percent of rare earth element, 0.015 percent of sulfur, 0.005 percent of antimony and the balance of iron.
Example 3
The preparation method of the super-thick large spheroidal graphite cast iron comprises the following steps:
(1) And (3) charging and smelting: 29 parts of rare Wang Shengtie, 29 parts of shou pig iron, 38 parts of first scrap steel, 2.2 parts of ferrosilicon, 1.8 parts of carburant and 0.002 part of metallic antimony are added and smelted at 1480 ℃ by using a cupola-electric furnace duplex;
(2) Desulfurization treatment: adding 1.0 part of desulfurizing agent into a ladle, connecting a nitrogen cylinder to the ladle, and adjusting a cylinder pressure valve to enable nitrogen to enter molten iron for rolling desulfurization;
(3) Spheroidizing tapping: adding 0.85 part of a first nodulizer and 0.35 part of a second nodulizer into a desulfurized ladle, tamping, and sequentially covering 0.30 part of a silicon-calcium-barium inoculant (with the grain diameter of 5 mm), 0.60 part of second scrap steel and 0.40 part of a pretreatment agent on the surface of the nodulizer, and pouring into the ladle for nodulizing when tapping at the temperature of 1480 ℃;
(4) Pouring inoculation: when in pouring at 1330 ℃, 0.20 part of sulfur-oxygen inoculant (with the grain diameter of 0.6 mm) is added along with molten iron flow for secondary inoculation, and the spheroidal graphite cast iron is obtained after cooling, wherein the components of the spheroidal graphite cast iron comprise 3.38 percent of carbon, 2.45 percent of silicon, 0.02 percent of phosphorus, 0.15 percent of manganese, 0.045 percent of magnesium, 0.008 percent of rare earth element, 0.016 percent of sulfur, 0.005 percent of antimony and the balance of iron.
Example 4
This example differs from example 1 only in that step (1) feed smelting was performed by adding 58 parts of rare Wang Shengtie, 38 parts of first scrap, 2.2 parts of ferrosilicon, 1.8 parts of carburant and 0.002 parts of metallic antimony, and using cupola-electric furnace duplex smelting.
Example 5
This example differs from example 1 only in that step (1) of charging smelting was conducted by charging 58 parts of shou cast iron, 38 parts of first scrap, 2.2 parts of ferrosilicon, 1.8 parts of carburant and 0.002 parts of metallic antimony, and using cupola-electric furnace duplex smelting.
Example 6
This example differs from example 1 only in that step (1) feed smelting was performed by adding 29 parts of rare Wang Shengtie, 29 parts of shou pig iron, 38 parts of first scrap steel, 2.2 parts of ferrosilicon, 3.6 parts of carburant and 0.002 parts of metallic antimony, and smelting at 1450 ℃ using a cupola-electric furnace duplex.
Example 7
This example differs from example 1 only in that the amount of the desulfurizing agent added in step (2) is 0.5 part.
Example 8
This example differs from example 1 only in that the amount of desulfurizing agent added in step (2) is 2.0 parts.
Example 9
The preparation method of the super-thick large spheroidal graphite cast iron comprises the following steps:
(1) And (3) charging and smelting: 29 parts of rare Wang Shengtie, 29 parts of shou pig iron, 38 parts of first scrap steel, 2.2 parts of ferrosilicon, 1.8 parts of carburant and 0.002 part of metallic antimony are added and smelted at 1450 ℃ by using a cupola-electric furnace duplex;
(2) Spheroidizing tapping: adding 0.80 part of a first nodulizer and 0.35 part of a second nodulizer into a ladle, tamping, and sequentially covering 0.40 part of a silicon-calcium-barium inoculant (with the grain diameter of 5 mm), 0.70 part of second scrap steel and 0.35 part of a pretreatment agent on the surface of the nodulizer, and pouring into the ladle for nodulizing when tapping at the temperature of 1480 ℃;
(3) Pouring inoculation: when in pouring at 1330 ℃, 0.15 part of sulfur-oxygen inoculant (with the grain diameter of 0.5 mm) is added along with molten iron flow for secondary inoculation, and the spheroidal graphite cast iron is obtained after cooling, wherein the components of the spheroidal graphite cast iron comprise 3.40 percent of carbon, 2.60 percent of silicon, 0.02 percent of phosphorus, 0.15 percent of manganese, 0.045 percent of magnesium, 0.006 percent of rare earth element, 0.016 percent of sulfur, 0.005 percent of antimony and the balance of iron.
Example 10
This example differs from example 1 only in that 0.35 parts of the first nodulizer and 0.80 parts of the second nodulizer are added in step (3).
Example 11
This example differs from example 1 only in that 0.55 parts of the first nodulizer and 0.60 parts of the second nodulizer are added in step (3).
Example 12
The difference between this example and example 1 is that in step (3), 1.15 parts of the first nodulizer is added to the desulphurized ladle for tamping, and the surface of the nodulizer is covered with 0.40 parts of the Si-Ca-Ba inoculant (particle size of 5 mm), 0.70 parts of the second scrap steel and 0.35 parts of the pretreatment agent in sequence, and the mixture is poured into the ladle for nodulizing when tapping at 1480 ℃.
Example 13
The preparation method of the super-thick large spheroidal graphite cast iron comprises the following steps:
(1) And (3) charging and smelting: 29 parts of rare Wang Shengtie, 29 parts of shou pig iron, 38 parts of first scrap steel, 2.2 parts of ferrosilicon, 1.8 parts of carburant and 0.002 part of metallic antimony are added and smelted at 1450 ℃ by using a cupola-electric furnace duplex;
(2) Desulfurization treatment: adding 1.0 part of desulfurizing agent into a ladle, connecting a nitrogen cylinder to the ladle, and adjusting a cylinder pressure valve to enable nitrogen to enter molten iron for rolling desulfurization;
(3) Spheroidizing tapping: adding 0.80 part of a first nodulizer and 0.35 part of a second nodulizer into a desulfurized ladle, tamping, and sequentially covering 0.40 part of a silicon-calcium-barium inoculant (with the grain size of 5 mm) and 0.70 part of second scrap steel on the surface of the nodulizer, and pouring into the ladle for nodulizing when tapping at the temperature of 1480 ℃;
(4) Pouring inoculation: when in pouring at 1330 ℃, 0.15 part of sulfur-oxygen inoculant (with the grain diameter of 0.5 mm) is added along with molten iron flow for secondary inoculation, and the spheroidal graphite cast iron is obtained after cooling, wherein the components of the spheroidal graphite cast iron comprise 3.40 percent of carbon, 2.60 percent of silicon, 0.02 percent of phosphorus, 0.15 percent of manganese, 0.045 percent of magnesium, 0.006 percent of rare earth element, 0.016 percent of sulfur, 0.005 percent of antimony and the balance of iron.
The method adopts a CTL calculation carbon control method, combines a carbon and sulfur analysis technology and a spectrum analysis technology to achieve quick and accurate control of molten iron, and performs mechanical property test on an additional casting test block obtained by casting the obtained spheroidal graphite cast iron, and the result is shown in table 1.
TABLE 1 Performance data for ductile cast iron attached cast test blocks obtained in the above examples
Tensile strength of Yield strength of Elongation percentage Hardness of Graphite grade
Example 1 410MPa 274MPa 23.3％ 154 5-6
Example 2 405MPa 263MPa 21.0％ 150 5-6
Example 3 403MPa 261MPa 22.0％ 153 5-6
Example 4 401MPa 243MPa 19.5％ 145 5-6
Example 5 378MPa 241MPa 20.2％ 142 5-6
Example 6 398MPa 260MPa 21.9％ 150 5-6
Example 7 365MPa 243MPa 15.5％ 143 4-5
Example 8 374MPa 240MPa 20.3％ 142 5-6
Example 9 350MPa 220MPa 12.5％ 130 4-5
Example 10 365MPa 235MPa 19.8％ 141 5-6
Example 11 363MPa 230MPa 19.6％ 140 5-6
Example 12 358MPa 227MPa 19.2％ 140 5-6
Example 13 367MPa 243MPa 19.8％ 142 5-6
The bulk sleeve prepared from the spheroidal graphite cast iron obtained in example 1 has a tensile strength of 350MPa, a yield strength of 230MPa, an elongation of 10%, a spheroidization rate of 90% and a graphite size of 5 grade. The spheroidizing agents used in examples 10-12 are all more than 1.05-1.25% of the molten iron in the invention, the mass ratio of the first spheroidizing agent to the second spheroidizing agent is 2.0-3.0:1.0, and the difference of the spheroidizing agent content causes the difference of the content of other elements such as rare earth elements in the obtained spheroidal graphite cast iron, so that the product is extremely easy to generate spheroidization recession in the solidification process to form abnormal graphite, the mechanical property of the spheroidal graphite cast iron is reduced, the pretreatment agent is not added in example 13, the graphite balls are fewer, the segregation among crystals is reduced greatly, and the mechanical property is reduced. FIGS. 1-2 illustrate that the ultra-thick spheroidal graphite cast iron obtained in example 1 has a core spheroidization rate of 90% or more and a graphite size of 5-6 grade.
Finally, it should be noted that the specific embodiments described herein are merely illustrative of the spirit of the invention and are not limiting of the invention's embodiments. Those skilled in the art to which the invention pertains may make various modifications or additions to the described embodiments or may be substituted in a similar manner, without and without all of the embodiments herein being fully understood. While these obvious variations and modifications, which come within the spirit of the invention, are within the scope of the invention, they are to be construed as being without departing from the spirit of the invention.

Claims (10)

1. The ultra-thick spheroidal graphite cast iron is characterized by comprising the following components in percentage by weight: 3.35 to 3.45 percent of carbon, 2.40 to 2.80 percent of silicon, less than or equal to 0.025 percent of phosphorus, less than or equal to 0.15 percent of manganese, 0.040 to 0.055 percent of magnesium, 0.003 to 0.008 percent of rare earth element, less than or equal to 0.018 percent of sulfur, 0.003 to 0.006 percent of antimony and the balance of iron.
2. A method of producing the ultra-thick spheroidal graphite cast iron according to claim 1, comprising charging smelting, desulphurisation, spheroidizing tapping and pouring inoculation.
3. The preparation method of the ultra-thick and large spheroidal graphite cast iron according to claim 2, wherein the following raw materials in percentage by mass are used in charging and smelting: 58.0 to 60.0 percent of pig iron, 35.0 to 38.0 percent of first scrap steel, 2.0 to 2.2 percent of ferrosilicon, 1.8 to 2.0 percent of carburant and 0.002 to 0.004 percent of metallic antimony.
4. The method for producing ultra-thick spheroidal graphite cast iron according to claim 3, wherein the pig iron is a mixture of rare Wang Shengtie and shou pig iron in a mass ratio of 1:1-2, the constituent components of rare Wang Shengtie include carbon 4.2-4.5%, silicon 0.5-0.7%, manganese 0.05-0.06%, phosphorus 0.02-0.03%, sulfur 0.02-0.03%, chromium 0.005-0.006%, titanium 0.02-0.03%, copper 0.001-0.002%, vanadium 0.003-0.005%, and the balance iron;
the compositions of the longevity pig iron comprise 4.0-5.0% of carbon, 0.4-0.5% of silicon, 0.01-0.02% of manganese, 0.003-0.004% of phosphorus, 0.005-0.006% of sulfur, 0.003-0.004% of chromium, 0.002-0.003% of titanium and the balance of iron.
5. The method for producing ultra-thick spheroidal graphite cast iron according to claim 3, wherein the first scrap steel comprises carbon 0.02-0.03%, silicon 0.03-0.04%, manganese 0.2-0.3%, phosphorus 0.01-0.02%, sulfur 0.008-0.009%, chromium 0.01-0.02%, and the balance iron;
and/or the ferrosilicon comprises 0.04-0.05% of carbon, 73.0-74.0% of silicon, 0.10-0.20% of manganese, 0.02-0.03% of phosphorus, 0.005-0.006% of sulfur, 0.01-0.02% of chromium, 0.70-0.80% of aluminum and the balance of iron;
and/or, the carbon content of the carburant is greater than or equal to 99.0%.
6. The method for preparing ultra-thick and large spheroidal graphite cast iron according to claim 2, wherein the desulfurizing treatment comprises adding 0.8-1.2% desulfurizing agent by mass of molten iron into ladle, and introducing nitrogen gas for desulfurizing;
the desulfurizing agent comprises 50.0-52.0% of calcium oxide, 6.0-8.0% of calcium fluoride and 40.0-44.0% of calcium carbide.
7. The method for preparing ultra-thick and large spheroidal graphite cast iron according to claim 2, wherein the surface of the nodulizer is covered with 0.25-0.50% of Si-Ca-Ba inoculant, 0.5-0.7% of second scrap steel and 0.3-0.4% of pretreatment agent.
8. The method for preparing super-thick spheroidal graphite cast iron according to claim 7, wherein the components of the silicon-calcium-barium inoculant comprise silicon 70.0-71.0%, aluminum 1.0-1.5%, calcium 0.7-0.8%, barium 2.0-2.2%, and the balance being iron;
and/or the second scrap steel comprises 0.05-0.06% of carbon, 0.04-0.05% of silicon, 0.10-0.20% of manganese, 0.01-0.02% of phosphorus, 0.006-0.007% of sulfur, 0.02-0.03% of copper, 0.02-0.03% of chromium, 0.002-0.003% of molybdenum, 0.001-0.002% of titanium and the balance of iron;
and/or the pretreatment agent comprises 60-65% of silicon, 1.0-1.2% of calcium, 3.0-4.0% of zirconium, 3.0-4.0% of aluminum and the balance of iron.
9. The method for preparing ultra-thick spheroidal graphite cast iron according to claim 7, wherein the adding amount of the nodulizer is 1.0-1.25% of the mass of the molten iron, the method comprises a first nodulizer and a second nodulizer, and the mass ratio of the first nodulizer to the second nodulizer is 2.0-3.0:1.0;
the first nodulizer comprises the components of 71.0 to 72.0 percent of silicon, 5.78 to 5.80 percent of magnesium, 0.3 to 0.4 percent of rare earth element, 0.6 to 0.7 percent of aluminum, 0.35 to 0.37 percent of magnesium oxide, 0.93 to 1.0 percent of calcium and the balance of iron, and the second nodulizer comprises the components of 71.0 to 72.0 percent of silicon, 5.78 to 5.80 percent of magnesium, 0.9 to 1.0 percent of rare earth element, 0.6 to 0.7 percent of aluminum, 0.35 to 0.37 percent of magnesium oxide, 0.93 to 1.0 percent of calcium and the balance of iron.
10. The method for preparing ultra-thick and large spheroidal graphite cast iron according to claim 2, wherein the sulfur-oxygen inoculant accounting for 0.1-0.2% of the molten iron mass is added along with the molten iron stream for secondary inoculation during pouring inoculation.
CN202310005362.9A 2023-01-04 2023-01-04 Super-thick large spheroidal graphite cast iron and preparation method thereof Pending CN116065085A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202310005362.9A CN116065085A (en) 2023-01-04 2023-01-04 Super-thick large spheroidal graphite cast iron and preparation method thereof

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202310005362.9A CN116065085A (en) 2023-01-04 2023-01-04 Super-thick large spheroidal graphite cast iron and preparation method thereof

Publications (1)

Publication Number Publication Date
CN116065085A true CN116065085A (en) 2023-05-05

Family

ID=86181512

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202310005362.9A Pending CN116065085A (en) 2023-01-04 2023-01-04 Super-thick large spheroidal graphite cast iron and preparation method thereof

Country Status (1)

Country Link
CN (1) CN116065085A (en)

Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2000045011A (en) * 1998-07-27 2000-02-15 Izumi Kogyo Kk Spheroidal graphite cast iron and production of spheroidal graphite cast iron
CN102965567A (en) * 2012-11-22 2013-03-13 日月重工股份有限公司 Casting thick large-section pearlite nodular cast iron and casting method thereof
CN103422009A (en) * 2013-08-14 2013-12-04 辉县市汽车配件有限责任公司 Nodular cast iron for rear axle housing of lorry and production method of nodular cast iron
US20140271330A1 (en) * 2011-10-07 2014-09-18 Akebono Brake Industry Co., Ltd. Method for producing spheroidal graphite cast iron and vehicle component using said spheroidal graphite cast iron
CN108611551A (en) * 2018-06-28 2018-10-02 宁波日星铸业有限公司 High silicon solution strengthening Ferrite nodular iron casting and its manufacturing method
CN113106326A (en) * 2021-04-15 2021-07-13 宁波明凌科技有限公司 Nodular cast iron for nail-free graphite of wind power equipment and preparation method thereof
CN113145797A (en) * 2021-03-17 2021-07-23 宁波拓铁机械有限公司 Casting method of large-scale two-plate injection molding machine template casting
CN114769507A (en) * 2022-03-20 2022-07-22 宁波拓铁机械有限公司 Casting method of hydraulic casting
CN115074608A (en) * 2022-05-30 2022-09-20 宁波日星铸业有限公司 Nodular cast iron with good fatigue resistance and preparation method thereof
WO2022202914A1 (en) * 2021-03-24 2022-09-29 日立金属株式会社 Spheroidal graphite cast iron, spheroidal graphite cast iron manufacturing method, and spheroidizing treatment agent

Patent Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2000045011A (en) * 1998-07-27 2000-02-15 Izumi Kogyo Kk Spheroidal graphite cast iron and production of spheroidal graphite cast iron
US20140271330A1 (en) * 2011-10-07 2014-09-18 Akebono Brake Industry Co., Ltd. Method for producing spheroidal graphite cast iron and vehicle component using said spheroidal graphite cast iron
CN102965567A (en) * 2012-11-22 2013-03-13 日月重工股份有限公司 Casting thick large-section pearlite nodular cast iron and casting method thereof
CN103422009A (en) * 2013-08-14 2013-12-04 辉县市汽车配件有限责任公司 Nodular cast iron for rear axle housing of lorry and production method of nodular cast iron
CN108611551A (en) * 2018-06-28 2018-10-02 宁波日星铸业有限公司 High silicon solution strengthening Ferrite nodular iron casting and its manufacturing method
CN113145797A (en) * 2021-03-17 2021-07-23 宁波拓铁机械有限公司 Casting method of large-scale two-plate injection molding machine template casting
WO2022202914A1 (en) * 2021-03-24 2022-09-29 日立金属株式会社 Spheroidal graphite cast iron, spheroidal graphite cast iron manufacturing method, and spheroidizing treatment agent
CN113106326A (en) * 2021-04-15 2021-07-13 宁波明凌科技有限公司 Nodular cast iron for nail-free graphite of wind power equipment and preparation method thereof
CN114769507A (en) * 2022-03-20 2022-07-22 宁波拓铁机械有限公司 Casting method of hydraulic casting
CN115074608A (en) * 2022-05-30 2022-09-20 宁波日星铸业有限公司 Nodular cast iron with good fatigue resistance and preparation method thereof

Similar Documents

Publication Publication Date Title
KR101402581B1 (en) Improved method of producing ductile iron
CN108707813B (en) As-cast high-strength ductile iron and its manufacturing process
CN107177773A (en) A kind of high-strength thin-walled gray iron casting
CN110819883B (en) Cylinder cover material and preparation process method thereof
CN107716901A (en) Wearable ductile iron composite roll and its casting method
CN102400032B (en) Large-cross-section nodular cast iron
CN110964974A (en) As-cast high-strength high-elongation synthetic nodular cast iron and preparation method thereof
CN107723581A (en) Corrosion resistant ductile iron and its casting method
CN109930058B (en) Low-temperature high-strength high-toughness nodular cast iron at minus 40 ℃, preparation method thereof and railway locomotive part
CN112553521A (en) Ductile iron bearing seat and preparation method thereof
CN114381649A (en) High-strength high-toughness nodular cast iron material and casting method thereof
CN112210708B (en) Nodular cast iron and method for preparing nodular cast iron by using lost foam
CN111850385B (en) Silicon-molybdenum turbocharger shell and preparation method thereof
CN110066959B (en) High-strength low-sulfur high-manganese inoculated gray cast iron material and smelting and pouring process thereof
CN106811677A (en) A kind of piston ring carrier cast iron materials and its manufacture method
CN111455263A (en) Environment-friendly low-temperature nodular cast iron produced by using low-rare earth alloy and production process thereof
US2855336A (en) Nodular iron process of manufacture
US2867555A (en) Nodular cast iron and process of manufacture thereof
CN116065085A (en) Super-thick large spheroidal graphite cast iron and preparation method thereof
CN113999948B (en) Method for eliminating white structure of high-purity pig iron for hydrogen-based smelting reduction casting and pig iron
CN115074608A (en) Nodular cast iron with good fatigue resistance and preparation method thereof
US3975191A (en) Method of producing cast iron
CN114369756A (en) As-cast QT700-8 material and casting method and application thereof
CN112575241A (en) High-strength high-elongation as-cast nodular cast iron
CN112921233A (en) Synthetic cast iron cylinder sleeve and preparation method thereof

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination