Classifications

• • 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
  • 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 of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment
  • C21D8/02—Modifying the physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C19/00—Alloys based on nickel or cobalt
  • C22C19/03—Alloys based on nickel or cobalt based on nickel
• • 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
  • C22C38/08—Ferrous alloys, e.g. steel alloys containing nickel
• • 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
  • C21D6/00—Heat treatment of ferrous alloys
  • C21D6/001—Heat treatment of ferrous alloys containing Ni

Definitions

• the present invention relates to the manufacture of alloy parts of the Fe-Ni or Fe-Ni-Co or Fe-Ni-Co-Cu type obtained by fine mechanical cutting of blanks which may have been previously stamped. These parts are generally used in miniature electronic or electrical components.
• Many small parts such as the electron gun parts of the color display cathode ray tubes or the integrated circuit support grids or even micro motor parts, are produced by fine mechanical cutting of blanks, possibly stamped from alloy of Fe-Ni or Fe-Ni-Co type containing about 30% to 70% nickel.
• the quality of the cut is very important for this type of part, in particular to avoid the presence of burrs.
• the blanks from which the pieces are cut are taken from strips obtained by cold rolling and annealing, generally isotropic or weakly textured. In the case of flat or almost flat parts, that is to say obtained without significant plastic deformation of the blank, the strips are often used in the work-hardened state so as to have a higher hardness and a lower ductility than the strips obtained directly after annealing.
• the object of the present invention is to remedy this drawback by proposing a means for improving the cuttability of alloys of the Fe-Ni or Fe-Ni-Co or Fe-Ni-Co-Cu type used in the form of thin strips for manufacturing by fine mechanical cutting of parts used in particular in electronic or electrical equipment.
• the subject of the invention is a strip of Fe-Ni alloy or of Fe-Ni-Co or Fe-Ni-Co-Cu austenitic alloy in which the chemical composition of the alloy comprises, in% by weight:
• the alloy has a cubic texture with a cubic texture coefficient of> 7.
• the boron content is between 0.0007% and 0.004%
• the index De is greater than 10
• the carbon content is less than or equal to 0.05%
• the sulfur content is less than or equal to 0.01%
• the oxygen content is less than 0.005%.
• the invention also relates to a method for manufacturing a strip of Fe-Ni or Fe-Ni-Co or Fe-Ni-Co-Cu alloy according to which:
• an alloy strip the chemical composition of which is defined above, is produced by cold rolling, with a work hardening rate greater than 80%,
• a fine grain recrystallization annealing is carried out on the strip, - and, optionally, an additional cold rolling is carried out with a work hardening rate of less than 40%.
• the invention relates to a method for manufacturing a part by mechanical cutting or by mechanical cutting and stamping, according to which a blank is taken from a strip according to the invention and is carried out on the blank at least one mechanical cutting operation and possibly at least one stamping operation, the at least one stamping operation can be performed before or after at least one mechanical cutting operation.
• the part is, for example, an electron gun part with an electron passage hole.
• the part can also be an integrated circuit support with connection tabs.
• the part can also be a magnetic core of micro motor or transformer. This list of applications is not exhaustive.
• FIG 1- diagrammatically shows a section in a band in which a hole was drilled by mechanical cutting having a cutting facies corresponding to poor cuttability.
• the figure 1-b schematically represents in section a strip in which a hole was drilled by mechanical cutting having a cutting facies corresponding to an acceptable cuttability.
• Figure 1-c schematically shows in section a strip in which a hole was drilled by mechanical cutting having a cutting facies corresponding to good cutability.
• the strips according to the invention are thin strips (thickness generally less than 1.5 mm) cold-rolled in an alloy of the Fe-Ni or Fe-Ni-Co or Fe-Ni- Co-Cu type known per se in their most general form.
• nickel, or cobalt which is a substitute for nickel, makes it possible to adjust properties such as the coefficient of thermal expansion or the magnetic permeability.
• the nickel content is between 30% and 70%; copper and cobalt which are optional elements have contents such that the sum Cu + 2 x Co is less than or equal to 20%.
• the remainder is essentially iron, impurities such as carbon, sulfur, phosphorus, oxygen and nitrogen, and, optionally, complementary alloying elements such as manganese, chromium, tungsten, molybdenum , titanium, vanadium, niobium and aluminum.
• the iron, nickel, copper and cobalt contents must be such that: Fe + Ni + Cu + Co> 95%.
• the contents of alloying elements must be such that: Mn + Cr ⁇ 5%, W + 2 x Mo ⁇ 2% and Ti + V + Nb + Al ⁇ 1%.
• Certain impurities such as carbon, sulfur and oxygen which is in the form of inclusions, may be desirable in small quantities because they have a favorable effect on the cuttability. Nevertheless, the carbon content should preferably remain below 0.05%, the sulfur content should preferably remain below 0.01%, and better still less than 0.007%, and the oxygen content should preferably stay below 0.005%.
• the alloy contains from 0.0005% to 0.007% of boron, and preferably from 0.0007% to 0.004%, and it has a cubic texture (001) ⁇ 100>, characterized by a cubic texture index From greater than 7, and preferably greater than 10.
• the inventors have found, surprisingly, that an addition of boron combined with a strongly pronounced cubic texture very significantly improves the ability to mechanically cut the alloys of Fe-Ni or Fe-Ni-Co or Fe-Ni-Co-Cu type.
• the cubic texture index De is the cubic / lisotropic ratio I of the maximum intensities of reflected X-radiation, measured on a pole figure (111) at a point located at 54 ° 44 'from the center of the figure and on the line at 45 ° with respect to the rolling direction for a sample of the strip to be characterized on the one hand, and for an isotropic sample on the other hand.
• the more or less texture character of a strip can also be evaluated in a simple but approximate manner by a drawing test, by measuring the drawing horns. This method can only be used to characterize a sufficiently ductile metal.
• the alloy is produced, it is cast and it is hot rolled in a manner known per se so as to obtain a hot strip of sufficient thickness to allow '' obtaining a cold strip having the desired thickness, by cold rolling with a reduction rate greater than 80%, and better still greater than 90%.
• the thickness of the hot-rolled strip can be, for example, 5 mm.
• Cold rolling must be carried out without intermediate annealing, but may be preceded by annealing. This is the case, in particular, when, taking into account the thickness of the hot strip and the thickness targeted for the cold strip, it is necessary to carry out several successive cold rolls.
• the final cold rolling (with a reduction rate higher than 80%) is followed by recrystallization annealing generally carried out in a passage oven under a protective atmosphere consisting, for example, of a mixture of hydrogen and nitrogen with a dew point below -40 ° C.
• the oven temperature around 1000 ° C, should be sufficient to achieve fine grain recrystallization, but not too high to avoid unwanted giant grain secondary recrystallization.
• the duration of the annealing is generally of the order of a minute. Those skilled in the art know how to adapt the precise annealing conditions on a case-by-case basis in order to obtain fine-grain recrystallization while avoiding secondary recrystallization.
• the recrystallization annealing can be followed by additional cold rolling with a reduction rate of less than 50%, or better still, less than 30%, so as not to degrade too much. the initial cubic texture.
• a reduction rate of the additional cold rolling is less than 10%, a softened or slightly cold worked cold strip is obtained having a marked cubic texture.
• the reduction rate of the additional cold rolling is greater than 10%, a cold worked strip is obtained having a marked cubic texture.
• the cold rolled strips thus obtained have a thickness generally less than 0.5 mm.
• a blank is cut by mechanical cutting in a manner known per se .
• the blank can be either the finished part which is then flat, or a blank.
• the blank can be shaped by stamping and then cut again by mechanical cutting. This cut can be for example a hole. This cutting operation can be preceded by local hardening.
• the strip can be used after additional cold rolling with a reduction rate between 10% and 30% or even 50%.
• This is the case, for example, of flat parts for electron guns of color display cathode ray tubes, or of integrated circuit support grids (or “lead frames") comprising connection lugs, or of rotors or stators. micro electric motors.
• the strip When the part is strongly deformed, by stamping or by bending or by local thickness reduction, i.e. with deformation rates greater than 20%, the strip is used in the softened or slightly cold worked state, that is to say without additional cold rolling or with an additional cold rolling having a reduction rate of less than 10%. This is the case, for example, with certain parts of electron guns for color display cathode ray tubes.
• the quality of the cut is assessed by the cut facies which has a sheared area and a torn area.
• the line of demarcation between these two zones must be regular and located approximately mid-thickness. There should be no burrs.
• Three cutting facies are shown in Figures 1a, 1b and 1c. These facies are those observed on a hole 1a, 1b and 1c, drilled by punching in a strip 2a, 2b and 2c. Only half of each hole is shown after having cut the strips along a plane passing through the axis of the holes.
• the walls 3a, 3b and 3c of the holes each have a sheared area 4a, 4b and 4c, and a torn off area 5a, 5b and 5c.
• Figure 1a corresponds to an alloy strip having poor cuttability.
• the sheared zone 3a corresponds to the greater part of the thickness and ends downwards, by large burrs 6a.
• FIG. 1 b corresponds to an alloy strip having just acceptable cuttability.
• the sheared area 3b roughly corresponds to almost half the thickness and ends at the bottom with a few burrs 6b.
• Figure 1c corresponds to an alloy strip having excellent cuttability.
• the sheared zone 3c corresponds to approximately half of the thickness and does not include any burrs.
• the quality of the cutting can also be assessed by the geometric quality of the parts obtained.
• the assessment of the quality of the cut takes into account the more or less circular character of the hole.
• PV588 and PW075 alloys have analyzes in accordance with the invention, the PV408 alloy is given for comparison.
• cold strips were produced according to 6 different manufacturing ranges, marked A, B, C, D, E and F, comprising: a first cold rolling with an ECR1 hardening rate, an annealing recrystallization in a passage furnace and a second cold rolling with an ECR2 hardening rate.
• the ECR1 work hardening was in some cases preceded by a preliminary work hardening of the hot rolled strip followed by recrystallization annealing to adjust the thickness to the desired value.
• the hardening rates for each range as well as the hardnesses HV and the elongations at break A% obtained are given in Table 2.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Crystallography & Structural Chemistry (AREA)
• Heat Treatment Of Sheet Steel (AREA)
• Heat Treatment Of Steel (AREA)
• Lead Frames For Integrated Circuits (AREA)

Applications Claiming Priority (3)

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• 2000
  • 2000-07-13 FR FR0009249A patent/FR2811684B1/fr not_active Expired - Fee Related
• 2001
  • 2001-07-10 KR KR10-2003-7000089A patent/KR20030026966A/ko not_active Withdrawn
  • 2001-07-10 EP EP01955396A patent/EP1299568A1/de not_active Withdrawn
  • 2001-07-10 AU AU2001277569A patent/AU2001277569A1/en not_active Abandoned
  • 2001-07-10 JP JP2002512435A patent/JP2004517205A/ja not_active Withdrawn
  • 2001-07-10 WO PCT/FR2001/002223 patent/WO2002006548A1/fr not_active Ceased
  • 2001-07-10 US US10/332,507 patent/US20030164211A1/en not_active Abandoned

Non-Patent Citations (1)

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