Classifications

• • 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
  • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
  • C21D1/26—Methods of annealing
• • 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
  • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
  • C21D1/18—Hardening; Quenching with or without subsequent tempering
• • 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
  • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
  • C21D1/78—Combined heat-treatments not provided for above
• • 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
  • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
  • C21D1/78—Combined heat-treatments not provided for above
  • C21D1/785—Thermocycling
• • 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
  • C21D6/001—Heat treatment of ferrous alloys containing Ni
• • 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
  • C21D6/04—Hardening by cooling below 0 degrees Celsius
• • 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
  • C22C38/004—Very low carbon steels, i.e. having a carbon content of less than 0,01%
• • 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
  • C22C38/10—Ferrous alloys, e.g. steel alloys containing cobalt
  • C22C38/105—Ferrous alloys, e.g. steel alloys containing cobalt containing Co and Ni
• • 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
  • C21D2211/00—Microstructure comprising significant phases
  • C21D2211/001—Austenite

Definitions

• the present invention relates to a low thermal expansion casting, and more particularly to a low thermal expansion casting having excellent high temperature strength.
• CFRP carbon fiber reinforced plastic
• the coefficient of thermal expansion of CFRP is smaller than that of steel, and in order to ensure high dimensional accuracy even after molding, it is necessary to construct the molding die with a material having a coefficient of thermal expansion of the same degree. Therefore, Invar alloy and Super Invar alloy are selected as the material of the molding die.
• Patent Document 1 describes, as a molding die, in cast iron having a graphite structure in austenite base iron, solid-dissolved carbon is 0.09% or more and 0.43% or less and silicon 1.0 as a component composition expressed in% by weight.
• Low thermal expansion cast iron with a coefficient of thermal expansion of 4 ⁇ 10 -6 / ° C or less in the temperature range of 0 to 200 ° C. Is disclosed to be used.
• Patent Document 2 describes C: 0.1 wt.C. as a member of an ultra-precision instrument including a CFRP mold. % Or less, Si: 0.1 to 0.4 wt. %, Mn: 0.15 to 0.4 wt. %, Ti: Over 2-4 wt. %, Al: 1 wt. % Or less, Ni: 30.7-43.0 wt. % And Co: 14 wt. % Or less, the content of Ni and Co satisfies the following formula (1), has a component composition consisting of the balance Fe and unavoidable impurities, and thermal expansion in the temperature range of -40 to 100 ° C. It discloses that an alloy steel having an excellent thermal shape stability and rigidity having a coefficient of 4 ⁇ 10 -6 / ° C. or less and a Young's modulus of 16100 kgf / mm 2 or more is used.
• Invar alloys and super Invar alloys used in conventional CFRP molding dies have low strength at high temperatures, which is the operating temperature range of the dies, and therefore there is a problem to be solved that the dies are easily damaged.
• the present invention provides a low thermal expansion casting having sufficient strength even at 300 ° C., which is the operating temperature range of the CFRP mold, and having a low coefficient of thermal expansion in the range of 25 to 300 ° C. That is the issue.
• the present inventors have diligently studied a method for increasing the yield strength at high temperatures in low thermal expansion castings.
• expensive alloying elements such as Nb, Ti, and Al are used by controlling the Ni and Co contents within an appropriate range and further performing an appropriate heat treatment after casting. It was found that it is possible to increase the yield strength at high temperatures.
• the present invention has been made based on the above findings, and the gist thereof is as follows.
• Ingredient composition is C: 0 to 0.100%, Si: 0 to 1.00%, Mn: 0 to 1.00%, Co: 8.0 to 13.0%, and Ni containing -2.5 x% Ni + 85.5 ⁇ % Co ⁇ -2.5 x% Ni + 90.5 (% Ni and% Co are Ni and Co contents (mass%), respectively), and the balance Is Fe and unavoidable impurities, the 0.2% proof stress of the tensile test at 300 ° C is 125 MPa or more, the average coefficient of thermal expansion at 25 to 300 ° C is 4.0 ppm / ° C or less, and the Curie temperature is 250 ° C or more.
• a low thermal expansion casting characterized by.
• a method for producing a low thermal expansion casting which comprises, in order, a recrystallization treatment step of heating to ⁇ 1200 ° C., holding for 0.5 to 5 hr, and then quenching.
• a method for producing a low thermal expansion casting which comprises, in order, a second cryo-treatment step of raising the temperature, and a reverse transformation treatment step of heating the casting to 550 to 750 ° C., holding it for 0.5 to 5 hours, and then quenching it.
• a method for producing a low thermal expansion casting which comprises, in order, a reverse transformation treatment step of heating to 750 ° C., holding for 0.5 to 5 hr, and then quenching.
• a low thermal expansion casting having a high yield strength in a high temperature range and a lower coefficient of thermal expansion can be obtained, it can be applied to a member of an ultraprecision device such as a CFRP mold used at a high temperature.
• Ni and Co are essential elements that contribute to a decrease in the coefficient of thermal expansion when added in combination.
• a certain amount or more of Co is contained, and in order to sufficiently reduce the coefficient of thermal expansion in a wide temperature range, Ni appropriate according to the amount of Co. Incorporate an amount. If the amount of Ni and Co is too large, the Ms point becomes too low and it becomes difficult to cause martensitic transformation by cooling described later. Therefore, the range of the amount of Ni and Co is determined in consideration of this.
• the Co content is 8.0 to 13.0%, and the Ni content is the Co content of% Co.
• the range satisfies ⁇ 2.5 ⁇ % Ni + 85.5 ⁇ % Co ⁇ ⁇ 2.5 ⁇ % Ni + 90.5.
• the upper limit of the amount of Co is preferably 12.0%, more preferably 11.0%.
• the Ni content is preferably ⁇ 2.5 ⁇ % Ni + 86.5 ⁇ % Co ⁇ ⁇ 2.5 ⁇ % Ni + 89.5, more preferably ⁇ 2.5 ⁇ % Ni + 87.0 ⁇ % Co ⁇ -2. It is better to satisfy 5 ⁇ % Ni + 89.0.
• the Curie temperature is set to 250 ° C or higher in order to obtain a low coefficient of thermal expansion even at high temperatures. There is a close relationship between the Curie temperature and the coefficient of thermal expansion. In Invar alloys, the coefficient of thermal expansion is close to 0 below the Curie temperature, but the coefficient of thermal expansion increases sharply above the Curie temperature. ..
• the low thermal expansion casting of the present invention is assumed to be used in the vicinity of 300 ° C, which is the operating temperature range of the CFRP mold, and the Curie temperature is set to 250 ° C or higher in order to set the coefficient of thermal expansion in this temperature range to a low value. And.
• the Curie temperature is preferably 280 ° C. or higher, more preferably 300 ° C. or higher, and even more preferably 310 ° C. or higher.
• C is dissolved in austenite and contributes to an increase in strength, so it may be contained if necessary. Although this effect can be obtained even in a small amount, it is effective when the amount of C is 0.010% or more, which is preferable.
• the content of C is large, the coefficient of thermal expansion becomes large, the ductility is lowered, and casting cracks are likely to occur. Therefore, the content is 0.100% or less, preferably 0.050% or less, more preferably. Is 0.020% or less.
• C is not an essential element and the content may be 0.
• Si may be added as a deoxidizing material.
• the fluidity of the molten metal can be improved. Although this effect can be obtained even in a small amount, it is effective when the amount of Si is 0.05% or more, which is preferable.
• the amount of Si is set to 1.00% or less, preferably 0.50% or less, and more preferably 0.20% or less. In the low thermal expansion casting of the present invention, Si is not an essential element and the content may be 0.
• Mn may be added as a deoxidizing material. It also contributes to improving the strength by strengthening the solid solution. Although this effect can be obtained even in a small amount, it is effective when the amount of Mn is 0.10% or more, which is preferable. Even if the Mn content exceeds 1.00%, the effect is saturated and the cost is high. Therefore, the Mn amount is 1.00% or less, preferably 0.80% or less, more preferably 0.60% or less. More preferably, it is 0.50% or less. In the low thermal expansion casting of the present invention, Mn is not an essential element and the content may be 0.
• the rest of the component composition is Fe and unavoidable impurities.
• the unavoidable impurities refer to those that are unavoidably mixed from the raw materials, the manufacturing environment, etc. when the steel having the component composition specified in the present invention is industrially manufactured. Specifically, P, S, O, N and the like of 0.02% or less can be mentioned.
• a casting having a desired composition is manufactured by casting.
• the mold used for casting, the apparatus for injecting molten steel into the mold, and the injection method are not particularly limited, and known apparatus and methods may be used.
• the casting is cooled to the Ms point or less, maintained at a temperature of the Ms point or less for 0.5 to 3 hours, and then heated to room temperature.
• the cooling method is not particularly limited.
• the Ms point referred to here is an Ms point at a stage before the effect of the present invention is exhibited. Since the cooling temperature may be set to a temperature sufficiently lower than the Ms point, it is not necessary to know the exact Ms point at this stage.
• the Ms point can be estimated by the following formula using the steel component.
• Ms 521-353C-22Si-24.3Mn-7.7Cu-17.3Ni -17.7Cr-25.8Mo
• C, Si, Mn, Cu, Ni, Cr, and Mo are the contents (mass%) of each element. The element not contained is set to 0.
• the Ms point calculated by the above formula is about -100 ° C or lower from room temperature, particularly depending on the amount of Ni, so that the cooling medium is up to -80 ° C.
• Dry ice and methyl alcohol or ethyl alcohol can be used.
• a method of immersing in liquid nitrogen or a method of spraying liquid nitrogen can be used up to a low temperature of -196 ° C. As a result, a tissue containing martensite is formed. Further, the temperature rise may be performed by raising the temperature to the atmosphere at room temperature.
• the casting is reheated to 800-1200 ° C, held at 800-1200 ° C for 0.5-5 hr and rapidly cooled to room temperature.
• the crystal grain size of the structure formed by normal solidification is about 1 to 10 mm, but the austenite grain size becomes finer and the crystal orientation is reduced by going through the above cryotreatment step and the subsequent recrystallization treatment step.
• the method of quenching is not particularly limited, but water cooling is preferable.
• the martensite structure returns to austenite by heating to 550 ° C or higher, but when the heating temperature exceeds 750 ° C, austenite recrystallizes with dislocation as a driving force, so the heating temperature should be 750 ° C or lower.
• the size of the austenite crystal grains does not change due to the cryo-treatment step and the subsequent reverse transformation treatment step.
• a high Young's modulus and a high 0.2% proof stress at 300 ° C can be obtained by the cryo-treatment step ⁇ recrystallization treatment step, and a higher 0 at 300 ° C. can be obtained by the cryo-treatment step ⁇ reverse transformation treatment step. Since a 0.2% proof stress can be obtained, the above steps [1] to [3] may be selected according to the required characteristics.
• a tempering treatment step of heating the casting to 300 to 500 ° C. and holding it for 2 to 6 hours may be provided.
• the tempering treatment step may be provided only after either the first cryo treatment step or the second cryo treatment step, or may be provided after both steps.
• the tempering may lower the temperature of subsequent recrystallization and reverse transformation, which may improve the efficiency of the treatment.
• a solution treatment step may be provided in which the casting is heated to 800 to 1200 ° C., held for 0.5 to 5 hr, and rapidly cooled to room temperature. Due to the solution formation, the precipitates precipitated during casting are solid-dissolved, and the ductility and toughness are improved.
• the method of quenching is not particularly limited, but water cooling is preferable.
• the molten metal may contain Nb, Ti, B, Mg, Ce, and La as an inoculum to facilitate the formation of solidified nuclei. Further, by applying an inoculant material such as Co (AlO 2 ), CoSiO 3 , Co-borate or the like to the surface of the mold together with the coating material usually applied to the mold, solidified nuclei may be easily generated. Further, the molten metal in the mold may be stirred and flowed by a method using an electromagnetic stirring device, a method of mechanically vibrating the mold, a method of vibrating the molten metal with ultrasonic waves, or the like. By applying these methods, the structure of the casting is more likely to be equiaxed, so that the low thermal expansion casting of the present invention can be produced more efficiently.
• an inoculant material such as Co (AlO 2 ), CoSiO 3 , Co-borate or the like
• the excellent high temperature strength of the low thermal expansion casting of the present invention can be evaluated from the result of the tensile test at 300 ° C.
• the low thermal expansion casting of the present invention has a 0.2% proof stress of 125 MPa or more, preferably 130 MPa or more, more preferably 140 MPa or more, still more preferably 150 MPa or more as measured by a tensile test at 300 ° C. Have.
• the low thermal expansion casting of the present invention further has a wide temperature range of an average coefficient of thermal expansion at 25 to 300 ° C. of 4.0 ppm / ° C or less, preferably 3.5 ppm / ° C or less, and more preferably 3.0 ppm / ° C or less.
• a low coefficient of thermal expansion can be obtained with.
• the components are adjusted so that the average coefficient of thermal expansion is 2.0 to 4.0 ppm, it matches the coefficient of thermal expansion of CFRP, and is therefore suitable as a member of a CFRP molding die.
• the low thermal expansion casting of the present invention has a high Curie temperature, the coefficient of thermal expansion does not increase significantly even at high temperatures, and it has a high high temperature yield strength. Also, the damage can be suppressed.
• the Y block was immersed in liquid nitrogen to cool it below the Ms point and then held for 1.5 hours, then taken out of the liquid nitrogen and left at room temperature to raise the temperature to room temperature.
• the Y block was heated to the temperature shown in Table 1, held for 3 hours, and then cooled with water.
• the same treatment as in the first cryo treatment step was performed.
• the Y block was heated to the temperature shown in Table 1, held for 3 hours, and then cooled with water.
• the low thermal expansion casting of the present invention had a low coefficient of thermal expansion and showed a high 0.2% proof stress in a tensile test at 300 ° C.
• the target characteristics could not be obtained at least one of 0.2% proof stress and thermal expansion coefficient at 300 ° C.

Landscapes

• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Crystallography & Structural Chemistry (AREA)
• Heat Treatment Of Articles (AREA)
• Moulds For Moulding Plastics Or The Like (AREA)
• Heat Treatment Of Steel (AREA)
• Heat Treatment Of Sheet Steel (AREA)

Priority Applications (5)

Applications Claiming Priority (2)

Publications (1)

Family

ID=79554849

Family Applications (1)

Country Status (5)

Citations (7)

Family Cites Families (7)

• 2021
  • 2021-07-12 WO PCT/JP2021/026189 patent/WO2022014544A1/ja not_active Ceased
  • 2021-07-12 EP EP21841197.3A patent/EP4183501A4/en active Pending
  • 2021-07-12 JP JP2022536355A patent/JP7315273B2/ja active Active
  • 2021-07-12 CN CN202180060596.2A patent/CN116157217B/zh active Active
  • 2021-07-12 US US17/908,550 patent/US12421584B2/en active Active
  • 2021-07-12 CN CN202511443046.5A patent/CN121250240A/zh active Pending

Patent Citations (7)

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events