Classifications

• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
  • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
  • C22F1/04—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of aluminium or alloys based thereon
  • C22F1/05—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of aluminium or alloys based thereon of alloys of the Al-Si-Mg type, i.e. containing silicon and magnesium in approximately equal proportions
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21B—ROLLING OF METAL
  • B21B3/00—Rolling materials of special alloys so far as the composition of the alloy requires or permits special rolling methods or sequences ; Rolling of aluminium, copper, zinc or other non-ferrous metals
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21C—MANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES, PROFILES OR LIKE SEMI-MANUFACTURED PRODUCTS OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL
  • B21C1/00—Manufacture of metal sheets, wire, rods, tubes or like semi-manufactured products by drawing
  • B21C1/003—Drawing materials of special alloys so far as the composition of the alloy requires or permits special drawing methods or sequences
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C1/00—Making non-ferrous alloys
  • C22C1/02—Making non-ferrous alloys by melting
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C21/00—Alloys based on aluminium
  • C22C21/02—Alloys based on aluminium with silicon as the next major constituent
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C21/00—Alloys based on aluminium
  • C22C21/06—Alloys based on aluminium with magnesium as the next major constituent
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C21/00—Alloys based on aluminium
  • C22C21/06—Alloys based on aluminium with magnesium as the next major constituent
  • C22C21/08—Alloys based on aluminium with magnesium as the next major constituent with silicon
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
  • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16B—DEVICES FOR FASTENING OR SECURING CONSTRUCTIONAL ELEMENTS OR MACHINE PARTS TOGETHER, e.g. NAILS, BOLTS, CIRCLIPS, CLAMPS, CLIPS OR WEDGES; JOINTS OR JOINTING
  • F16B33/00—Features common to bolt and nut
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16B—DEVICES FOR FASTENING OR SECURING CONSTRUCTIONAL ELEMENTS OR MACHINE PARTS TOGETHER, e.g. NAILS, BOLTS, CIRCLIPS, CLAMPS, CLIPS OR WEDGES; JOINTS OR JOINTING
  • F16B35/00—Screw-bolts; Stay-bolts; Screw-threaded studs; Screws; Set screws
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21B—ROLLING OF METAL
  • B21B3/00—Rolling materials of special alloys so far as the composition of the alloy requires or permits special rolling methods or sequences ; Rolling of aluminium, copper, zinc or other non-ferrous metals
  • B21B2003/001—Aluminium or its alloys

Definitions

• the present invention relates to aluminum alloy wires for bolts and bolts, and methods for producing them.
• the present invention relates to an aluminum alloy wire for bolts that is excellent in workability at the time of bolt manufacture and from which a bolt having sufficient strength can be obtained.
• A6056 is known as a material for aluminum alloy bolts.
• an aluminum alloy wire rod described in Patent Document 1 Japanese Patent Laid-Open No. 2011-1602
• the aluminum alloy wire rod described in Patent Literature 1 has a rolled structure with a composition of 6000 series and includes fine crystals having a predetermined average crystal grain size.
• Patent Document 1 describes that this aluminum alloy wire rod is excellent in bolt formability, and also describes that a predetermined tensile strength can be obtained by performing appropriate heat treatment and processing. ing.
• A6056 is inferior in formability. Therefore, cracks occur during bolting due to defects generated during casting or rolling, and intergranular corrosion occurs due to minute cracks. Also, the bolt made of A6056 cannot obtain sufficient strength even after artificial age hardening.
• Patent Document 1 describes an aluminum alloy wire rod that can improve the formability of A6056 and can provide strength when used as a bolt.
• development of an aluminum alloy wire that can obtain higher strength after being formed into a bolt while ensuring formability is desired.
• the development of an aluminum alloy wire for a bolt that has a small decrease in strength and can maintain high strength is expected.
• the present invention has been made in view of the above circumstances, and one of its purposes is to provide an aluminum alloy wire for bolts having sufficient formability when being formed into a bolt and having high strength as a bolt and its manufacture. It is to provide a method. Another object of the present invention is to provide a bolt using the aluminum alloy wire for bolts of the present invention and a method for manufacturing the same.
• the present inventors Based on the composition of the 6000 series aluminum alloy, the present inventors have conducted intensive studies aimed at further improving the formability and strength, and as a result, when a part of Si and Mg is included as Mg 2 Si, and the content of mg 2 Si, thereby completing the knowledge present invention to obtain the it is effective to adjust the ratio mg 2 Si / (Mn + Cr ) a predetermined range of the total content of Mn and Cr It was.
• the aluminum alloy wire for bolts of the present invention is, by mass, Si: 0.60 to 1.5%, Fe: 0.02 to 0.40%, Cu: 0.50 to 1.2%, Mn: 0.50 to 1.1%, Mg: 0.70 to 1.3%, Cr : 0.01 to 0.30%, Zn: 0.005 to 0.50%, Ti: 0.01 to 0.20%, Zr: 0.05 to 0.20%, with the balance being Al and inevitable impurities.
• part of the Si and Mg are contained as Mg 2 Si, and the content of Mg 2 Si, the ratio Mg 2 between the total content of Mn and Cr Si / (Mn + Cr) is from 1.0 to 2.1.
• This composition is sometimes referred to as the first composition.
• the strength of the bolts obtained varies.
• Si and Mg is precipitated as Mg 2 Si by solution treatment and aging treatment, and the strength of the bolt is improved.
• an alloy wire having the above composition it is excellent in formability when forming into a bolt, and a bolt having sufficient strength can be obtained after forming.
• Mg 2 Si / (Mn + Cr) a bolt excellent in heat resistance can be obtained.
• This ratio Mg 2 Si / (Mn + Cr) is 1.0 to 2.1 at the stage of the cast material, and after that, each stage of the drawn material obtained by rolling and drawing the cast material or the bolt formed from the drawn material. Is substantially maintained.
• the aluminum alloy wire for bolts of the present invention by mass, Si: 0.80 to 1.4%, Fe: 0.05 to 0.30%, Cu: 0.50 to 1.2%, Mn: 0.50 to 1.1%, Mg: 0.80 to 1.3 %, Cr: 0.05 to 0.30%, Zn: 0.05 to 0.25%, Ti: 0.01 to 0.10%, Zr: 0.10 to 0.20%.
• This composition is sometimes referred to as a second composition.
• a bolt having further excellent mechanical properties can be obtained. Specifically, a bolt having a tensile strength of 400 MPa or more, 0.2% proof stress: 360 MPa or more, and elongation: 6% or more can be obtained.
• One form of the aluminum alloy wire for bolts of the present invention having the second composition includes Cu: 0.80 to 1.2%, Mn: 0.70 to 1.1%, and Cr: 0.05 to 0.30% by mass. This composition is sometimes referred to as a third composition.
• a bolt having further excellent mechanical properties can be obtained. Specifically, a bolt having excellent heat resistance can be obtained with tensile strength: 430 MPa or more, 0.2% proof stress: 370 MPa or more, and elongation: 6% or more.
• the aluminum alloy wire for bolts of the present invention having any composition from the first composition to the third composition, it may be mentioned that Sr: 0.005 to 0.05% is contained in mass%.
• the aluminum alloy wire for bolts of the present invention containing Sr contains by mass%, Sr: 0.005 to 0.03%, and the ratio Zr / Sr of Zr content to Sr content is 3 to 50 Can be mentioned.
• the manufacturing method of the aluminum alloy wire for bolts of this invention comprises the following process. Casting process:% by mass, Si: 0.60 to 1.5%, Fe: 0.02 to 0.40%, Cu: 0.50 to 1.2%, Mn: 0.50 to 1.1%, Mg: 0.70 to 1.3%, Cr: 0.01 to 0.30%, Zn : 0.005 ⁇ 0.50%, Ti: 0.01 ⁇ 0.20%, Zr: includes 0.05 to 0.20%, and the balance of Al and unavoidable impurities, a portion of the Si and Mg are contained as Mg 2 Si, Mg 2 Si And a cast material having a ratio Mg 2 Si / (Mn + Cr) of 1.0 to 2.1 of the total content of Mn and Cr is obtained.
• Rolling process The cast material is rolled into a rolled material.
• Wire drawing step The rolled material is drawn into a wire drawing material having a predetermined wire diameter.
• the wire material in the middle of the wire drawing step is subjected to a softening treatment at 250 to 500 ° C. for 0.5 to 40 hours.
• an aluminum alloy wire suitable for bolt production can be obtained.
• an aluminum alloy wire that is a bolt material excellent in productivity and mechanical properties can be obtained.
• the bolt of the present invention is a bolt made of an aluminum alloy, and the aluminum alloy is Si: 0.60 to 1.5%, Fe: 0.02 to 0.40%, Cu: 0.50 to 1.2%, Mn: 0.50 to 1.1% by mass. Mg: 0.70 to 1.3%, Cr: 0.01 to 0.30%, Zn: 0.005 to 0.50%, Ti: 0.01 to 0.20%, Zr: 0.05 to 0.20%, with the balance being Al and inevitable impurities. Moreover, the above alloy, the portion of the Si and Mg are contained as Mg 2 Si, Mg 2 and the content of Si, the total content and ratio Mg 2 Si / Mn of the Cr (Mn + Cr) is 1.0 - 2.1.
• the bolt has a tensile strength of 380 MPa or more, a 0.2% proof stress: 350 MPa or more, and an elongation of 6% or more.
• a bolt having excellent mechanical properties such as tensile strength, 0.2% proof stress and elongation can be obtained.
• the bolt manufacturing method of the present invention includes the following steps. Cutting step: The above-described aluminum alloy wire of the present invention is cut into a predetermined length.
• Header process Forms the head of the bolt by processing the cut aluminum alloy wire for the bolt.
• Rolling process The cut aluminum alloy wire for the bolt is rolled to form the thread portion of the bolt.
• Heat treatment step Solution treatment and aging treatment are performed on the object in the process from the production of bolts to aluminum alloy wires for bolts.
• the bolt According to this method, it is difficult for cracks to occur during the molding of the bolt, and the bolt can be manufactured with high productivity. Further, the obtained bolt is excellent in mechanical strength such as tensile strength. Furthermore, depending on the composition of the aluminum alloy wire of the present invention, a bolt having excellent heat resistance can be obtained.
• the aluminum alloy wire of the present invention and the aluminum alloy wire obtained by the method for producing the aluminum alloy wire of the present invention have the first composition, a bolt excellent in workability at the time of bolt forming and excellent in mechanical properties is used. Can be provided. Therefore, the bolt of the present invention is excellent in mechanical characteristics, and the bolt manufacturing method of the present invention can provide a bolt excellent in mechanical characteristics.
• the aluminum alloy wire for bolts according to the present invention comprises 0.60 to 1.5 mass% Si, 0.02 to 0.40 mass% Fe, 0.50 to 1.2 mass% Cu, 0.50 to 1.1 mass% Mn, and 0.70 to 1.3 mass%.
• a bolt for aluminum alloy wire according to the present invention a part of Si and Mg is contained as Mg 2 Si, Mg 2 Si content and the ratio of the total content of Mn and Cr Mg 2 Si / (Mn + Cr) is 1.0 to 2.1 (first composition).
• the aluminum alloy wire for bolts according to the present invention comprises 0.80 to 1.4 mass% Si, 0.05 to 0.30 mass% Fe, 0.50 to 1.2 mass% Cu, 0.50 to 1.1 mass% Mn, and 0.80 to 1.3 mass%. It is preferable to contain Mg by mass, 0.05 to 0.30 mass% Cr, 0.05 to 0.25 mass% Zn, 0.01 to 0.10 mass% Ti, and 0.10 to 0.20 mass% Zr (second composition) ). Thereby, it is possible to provide a bolt that is further excellent in mechanical strength and excellent in heat resistance.
• the Cu content is preferably 0.80 to 1.2% by mass
• the Mn content is 0.70 to 1.1% by mass
• the Cr content is preferably 0.05 to 0.30% by mass (third composition) ).
• the aluminum alloy wire for bolts according to the present invention more preferably contains 0.005 to 0.05% by mass of Sr. Thereby, the bolt excellent in mechanical strength can be provided, without causing embrittlement of an aluminum alloy wire. More preferably, the aluminum alloy wire for bolts according to the present invention contains 0.005 to 0.03% by mass of Sr, and the ratio Zr / Sr of the Zr content to the Sr content is 3 to 50. is there. By setting the ratio Zr / Sr to 3 to 50, remelting due to the inclusion of Zr and embrittlement of the aluminum alloy wire due to the inclusion of Sr can be effectively suppressed.
• Si ⁇ composition ⁇ (Si: 0.60-1.5%) Si is partly dissolved in the aluminum alloy matrix together with Mg to strengthen the aluminum alloy wire.
• Si is an element necessary for improving the strength by forming aging precipitates during artificial aging of the aluminum alloy wire and obtaining predetermined mechanical characteristics required for the bolt.
• the lower limit value of the Si content By setting the lower limit value of the Si content to 0.60%, the effects of solid solution strengthening and age hardening can be appropriately expressed, and thus a bolt having a predetermined strength can be obtained.
• the upper limit to 1.5%, the workability from the cast material to the wire and the formability to the bolt are not hindered, and the formation of coarse crystals and precipitates that are the starting point of cracking is suppressed. Therefore, it can contribute to the high strength of the bolt.
• a more preferable Si content is 0.80 to 1.4%. By setting it within this range, it is easy to obtain a bolt having further excellent mechanical strength.
• Fe 0.02-0.40% Fe is necessary to promote the effect of the crystal refining agent containing Ti during casting in the presence of an alkaline earth metal element (for example, Mg or Sr).
• an alkaline earth metal element for example, Mg or Sr.
• the lower limit of the Fe content 0.02%, it contributes effectively to the refinement of crystal grains in the alloy.
• the upper limit value 0.40%, it is possible to suppress a decrease in the plastic workability of the alloy due to the formation of Fe-based crystallized grains at grain boundaries in the alloy structure.
• a more preferable Fe content is 0.05 to 0.30%, and a still more preferable content is 0.05 to 0.25%. By setting it within this range, it is easy to obtain a bolt having further excellent mechanical strength.
• Cu contributes to strength improvement together with Mg and Si.
• the lower limit of the Cu content By setting the lower limit of the Cu content to 0.50%, the effect can be easily obtained.
• the upper limit value By setting the upper limit value to 1.2%, it is easy to ensure the formability to the bolt.
• a more preferable Cu content is 0.80 to 1.2%. By setting it as this range, it is easy to obtain a bolt having further excellent mechanical strength and good heat resistance.
• Mn 0.50-1.1%) Mn is partly dissolved in an aluminum alloy matrix to strengthen the aluminum alloy wire. Further, Mn forms Al-Mn-based dispersed particles, the crystal grains of the wire structure can be refined, and the strength, formability, corrosion resistance, and the like can be improved.
• the lower limit value of the Mn content 0.50%
• the aluminum alloy wire is strengthened by solid solution, so that sufficient strength as a bolt can be easily obtained.
• the upper limit value to 1.1%, formation of coarse crystallized substances and precipitates that are the starting points of cracking can be suppressed, thereby contributing to an increase in bolt strength.
• a more preferable content of Mn is 0.70 to 1.1%. By setting it as this range, it is easy to obtain a bolt having further excellent mechanical strength and good heat resistance.
• Mg 0.70 to 1.3%)
• Mg is an element necessary for satisfying the mechanical properties required for bolts by solid solution strengthening of aluminum alloy wires and forming aging precipitates that contribute to strength improvement together with Si during artificial aging.
• the lower limit of the Mg content 0.70%
• a sufficient solid solution strengthening function and age hardening function can be exhibited.
• the upper limit 0.3%
• a more preferable Mg content is 0.80 to 1.3%.
• Cr 0.01-0.30% Since Cr forms dispersed particles in the same manner as Mn and Zr, it has the effect of preventing the crystal grains from becoming coarse during the heat treatment of the aluminum alloy wire and miniaturizing the crystal grains. By making the crystal grains finer, it contributes to improving the strength of the bolt and the formability to the bolt. Cr also has the effect of improving corrosion resistance. These effects can be appropriately obtained by setting the lower limit of the Cr content to 0.01%. Further, by setting the upper limit to 0.30%, the coarsening of the crystal grains is suppressed and the effect of refining the crystal grains is appropriately expressed. A preferable content range is 0.05 to 0.30%. By containing 0.05% or more of Cr, a bolt excellent in not only strength but also heat resistance can be obtained.
• Zn 0.005-0.50%
• Zn has a function of improving the strength of the alloy by dissolving in the aluminum matrix.
• the lower limit of the Zn content By setting the lower limit of the Zn content to 0.005%, the effect of improving the strength can be appropriately exhibited.
• appropriate corrosion resistance can be secured by setting the upper limit value to 0.50%.
• a more preferable Zn content is 0.05 to 0.25%. By setting it within this range, it is easy to secure the toughness necessary for forming the bolt, and it is easy to obtain a bolt having further excellent mechanical strength, excellent workability, heat resistance, and corrosion resistance.
• Ti 0.01-0.20%
• Ti has the effect of making the crystal structure of the cast material fine, suppressing the ratio of columnar crystals in the cast material, and increasing the ratio of equiaxed crystals. Therefore, by containing Ti, it is possible to improve the rolling workability and wire drawing workability of the cast material, and further the formability to the bolt. In addition, since the crystal structure is made finer, it is difficult for wrinkles to occur during plastic processing, so that a plastic working material with less wrinkles and an excellent surface state can be obtained. By making the lower limit of the Ti content 0.01%, the effect of crystal grain refinement can be easily obtained.
• the upper limit of Ti content is 0.20%.
• a more preferable Ti content is 0.01 to 0.10%. By setting it within this range, it is easy to obtain a bolt having further excellent mechanical strength.
• Ti may be mixed in the molten metal as TiB 2 , and B also has the effect of improving the strength by making the crystal structure finer like Ti. Therefore, the content of B is allowed to be about 50 ppm (mass ratio) or less.
• Zr 0.05-0.20%
• Zr forms dispersed particles containing the respective elements, and has the effect of preventing the crystal grains from becoming coarse during the heat treatment of the aluminum alloy wire and making the crystal grains finer. Along with this, it contributes to the improvement of bolt strength and formability to bolts.
• Zr is an element necessary for improving the heat resistance of the aluminum alloy wire.
• the lower limit of the Zr content is 0.05%, it is possible to appropriately obtain the effect of improving the strength and the formability to the bolt.
• the preferred Zr content is 0.10 to 0.20%. By setting it as this range, it is easy to obtain a bolt having further excellent mechanical strength and good heat resistance.
• Mg 2 Si / (Mn + Cr): 1.0 to 2.1 A part of Si and Mg is dissolved in the matrix of the aluminum alloy and contributes to strength improvement, and the remainder is contained as Mg 2 Si.
• both Cr and Mn have the function of forming dispersed particles and suppressing the coarsening of the structure to contribute to the improvement of strength.
• This ratio is 1.0 to 2.1. A more preferable ratio is about 1.4 to 2.0, and a particularly preferable ratio is about 1.5 to 1.8.
• Mn and Cr suppress the movement of dislocations, and may suppress the strength reduction of the portion where the strength is improved by work hardening. Conceivable.
• the content of Mg 2 Si a value calculated from the added amounts of Mg and Si is used. Specifically, the content of Mg 2 Si is obtained by the following formula 1. The calculated value indicates the content of Mg 2 Si of solution treated and aged to precipitate Mg 2 Si material.
• the total amount of Cr and Mn is preferably about 0.55 to 1.5%, more preferably about 0.70 to 1.4%, and particularly preferably about 0.75 to 1.3%.
• Sr may be included as an additional additive element.
• Sr also has the function of refining the crystal structure of the cast material and contributes to improving the strength of the obtained bolt.
• the strength can be improved without the aluminum alloy wire becoming brittle.
• the lower limit of the Sr content to 0.005%, it is easy to obtain an effect of improving the bolt strength.
• the upper limit to 0.05%, embrittlement of the aluminum alloy wire can be effectively suppressed and sufficient strength can be obtained.
• a more preferable content of Sr is 0.005 to 0.03%. By setting it as this range, it is easy to obtain a bolt having further excellent mechanical strength and good heat resistance.
• Zr is an element necessary for improving the heat resistance, but if it is contained, the melting point of the alloy increases, the casting temperature becomes high, and solidification becomes difficult.
• a phenomenon in which the outer surface of the cast material is deformed easily occurs when an outer shrinkage occurs during solidification of the molten metal. This deformed part is slow to cool because the cast material does not come into contact with the mold, re-raises to a temperature higher than the melting point due to the heat inside the cast material, a remelt phenomenon occurs, the crystal grains become coarse, the cast material The surface properties of the resin are deteriorated.
• the coarsened portion of the crystal grains and the deteriorated portion of the surface properties are the starting points, and are easily wrinkled by rolling or wire drawing after casting.
• Sr has a function of improving the strength of the aluminum alloy, but easily causes embrittlement.
• the upper limit of the ratio By setting the upper limit of the ratio to 50, it can be said that an appropriate amount of Sr is contained with respect to Zn, and it is easy to eliminate the problems associated with remelting.
• a more preferable range of the ratio is about 5 to 20. By setting it as this range, it is easy to obtain a bolt having further excellent mechanical strength and good heat resistance. This limitation of the ratio is not essential in the present invention.
• the wire diameter of the aluminum alloy wire of the present invention is not particularly limited, but for example, about 12 mm to 3 mm can be selected.
• a bolt having a size suitable for fastening automobile parts can be manufactured.
• An aluminum alloy wire is typically manufactured through casting, rolling, wire drawing, and intermediate softening. Details of each step are as follows.
• a cast material having the composition described above is cast. Casting is preferably continuous casting.
• the method for producing an aluminum alloy wire of the present invention by making the aluminum alloy into a predetermined composition, it is possible to obtain a cast material having excellent surface properties and less wrinkles even by continuous casting. By using such a cast material, it is possible to reduce the occurrence of cracks and wrinkles during rolling or wire drawing, and it is possible to obtain a rolled material or wire drawing material having excellent surface properties.
• the method for producing an aluminum alloy wire of the present invention it is possible to obtain a surface state without increasing the number of peeling during drawing, increasing the amount of peeling, or increasing the sensitivity of the flaw detector as in the prior art. An excellent wire drawing material can be obtained. Therefore, the method for producing an aluminum alloy wire of the present invention can produce an aluminum alloy wire having a good yield and an excellent surface state with high productivity.
• a belt and wheel method is preferable.
• the cooling during casting is preferably performed at 5 ° C / sec or more, more preferably 8 ° C / sec or more, and further preferably 20 ° C / sec or more.
• the cooling rate is 5 ° C./sec or more at any position of the molten metal in the cooling process, that is, the whole is cooled uniformly. For example, when a continuous casting machine having a water-cooled copper mold or a forced water cooling mechanism is used, rapid solidification at the cooling rate as described above can be realized.
• the cast material is rolled into a rolled material.
• This rolling is preferably performed hot or warm.
• heat rolling can be easily performed using heat accumulated in the casting material, and energy efficiency is good. Excellent productivity.
• a casting machine combining a belt and a wheel and a rolling mill connected to the casting machine are used.
• An example of such an apparatus is a Properti type continuous casting and rolling mill.
• the rolled material is drawn and processed into a drawn material having a predetermined wire diameter.
• This wire drawing is preferably performed cold.
• stripping may be performed.
• Intermediate softening A softening process is performed on the wire in the middle of the wire drawing. This intermediate softening treatment is performed under conditions such that the elongation of the wire after the treatment is 10% or more. This intermediate softening treatment is performed in order to increase the toughness of the wire by softening without extremely reducing the strength of the wire that has been increased by refinement of the crystal structure and work hardening.
• the atmosphere during the softening treatment is preferably a non-oxidizing atmosphere in order to suppress the formation of an oxide film on the surface of the wire due to the heat during the treatment.
• a vacuum atmosphere reduced pressure atmosphere
• an inert gas atmosphere such as nitrogen (N 2 ) or argon (Ar)
• a hydrogen-containing gas for example, hydrogen (H 2 ) only, an inert gas such as N 2 , Ar, helium (He), etc.
• a reducing gas atmosphere such as a mixed gas of active gas and hydrogen (H 2 ) and a carbon dioxide-containing gas (for example, a mixed gas of carbon monoxide (CO) and carbon dioxide (CO 2 )).
• Softening treatment can increase the elongation of the wire to 10% or more by setting the heating temperature to 250 ° C. or higher.
• preferable conditions are heating temperature: 250 ° C. or higher and 500 ° C. or lower, holding time: 0.5 hour or longer, more preferably 1 hour or longer.
• the heating temperature is less than 250 ° C. and the holding time is less than 0.5 hour, the effect of the softening treatment is poor, and when the heating temperature exceeds 500 ° C., the crystal grains and crystal precipitates are coarsened and the workability is liable to be lowered.
• the heating temperature is preferably 300 ° C. or higher and 450 ° C. or lower, and the holding time is preferably 2 hours or longer and 40 hours or shorter.
• the heating temperature is more preferably 380 to 420 ° C., and the holding time is 24 hours or less, particularly 15 hours or less.
• a softening process may be performed after the final wire drawing.
• This final softening treatment is also preferably performed at 300 ° C. or higher for 1 hour or longer.
• the final softening treatment can improve the formability during bolt processing.
• the tensile strength: 380 MPa or more, 0.2% proof stress: 350 MPa or more, and elongation: 6% or more can be obtained as the characteristics after bolt forming.
• the tensile strength: 400 MPa or more, 0.2% proof stress: 360 MPa or more, and elongation: 6% or more can be obtained as the characteristics after bolt forming.
• the tensile strength: 430 MPa or more, 0.2% proof stress: 370 MPa or more, and elongation: 6% or more can be obtained after the bolt forming.
• the aluminum alloy wire contains 0.005 to 0.05% by mass of Sr, a bolt having excellent mechanical strength can be obtained without causing embrittlement of the aluminum alloy wire. Further, if the aluminum alloy wire contains 0.005 to 0.03% by mass of Sr and the ratio Zr / Sr of Zr content to Sr content is 3 to 50, remelting due to the inclusion of Zr or Sr A bolt having further excellent mechanical strength can be obtained without causing embrittlement of the aluminum alloy wire due to the inclusion of.
• These characteristics are characteristics after performing bolt processing on the aluminum alloy wire after the final wire drawing, and performing solution treatment and aging treatment at the time of the processing. All of the characteristics can be measured by a tensile test using a bolt as a product according to JIS B1051.
• the bolt is typically manufactured through cutting of the aluminum alloy wire, header processing, rolling, solution treatment, and aging treatment. Therefore, a bolt having the characteristics described in [Mechanical characteristics] can be obtained. Details of each step are as follows.
• the cutting is performed by cutting the aluminum alloy wire into a length suitable for processing the bolt. What is necessary is just to select the length of the cut piece obtained suitably according to the size of the volt
• header processing In the header processing, the end of the cut piece obtained in the cutting process is forged to form the head of the bolt. Known conditions can be applied to the processing conditions.
• Rolling In the rolling process, a thread portion is formed on the cut piece obtained in the cutting step.
• Known conditions can be applied to the processing conditions. Usually, rolling is performed after header processing.
• the solution treatment and the aging treatment are performed on the workpiece to be bolted, thereby generating precipitates in the alloy and improving the strength of the workpiece.
• the procedure for solution and aging has the following pattern. (1) Cutting ⁇ Header processing ⁇ Solution + Aging ⁇ Rolling (2) Cutting ⁇ Intermediate forging ⁇ Solution + Aging ⁇ Header processing ⁇ Rolling, or Cutting ⁇ Solution + Aging ⁇ Header processing ⁇ Rolling. That is, the intermediate forging may be performed or may not be performed.
• the dimensional accuracy of the threaded portion is high by performing rolling in the final process.
• the material can be work-hardened and the strength of the bolt can be slightly increased.
• the material can be work-hardened and the strength can be further increased.
• the solution treatment conditions are preferably 520 to 560 ° C. for 1 to 5 hours, and the aging treatment conditions are preferably 160 to 180 ° C. for about 4 to 30 hours.
• the mechanical properties of the bolt can also be adjusted by controlling the precipitation state of Mg 2 Si by this solution treatment and aging treatment.
• the heat treatment condition is preferably 50 to 160 ° C. for about 4 to 50 hours.
• Ti and B for microstructure refinement are added by preparing Al-3% Ti-1% B (mass%) wire and casting so that the molten metal and wire are simultaneously supplied into the mold. did. Subsequently, the wire rod is cold-drawn to ⁇ 8.3 mm, followed by batch softening at 400 ° C. for 5 hours, and the softened material is drawn to ⁇ 7.05 mm. And the final softening process of 350 degreeC x 5 hours is performed by batch processing to the obtained alloy wire, and it is set as an aluminum alloy wire. In each sample, since Si was added in excess of the stoichiometric composition, the content of Mg 2 Si in Table 1 was calculated by the following formula 1.
• Evaluation of the number of flaw detection is performed by first observing the number of wrinkles on the surface of the above stripping material using an on-line eddy current flaw detector provided in a wire drawing machine and marking the flaw detection count section. And it evaluated by comparing the number of flaw detections with the sample which contains Sr, and the sample which does not contain Sr.
• a bolt is produced from the obtained aluminum alloy wire.
• an M8 bolt T6 treated material and a T9 treated material obtained by adding cold working (intermediate forging) to the T6 treated material were produced.
• the manufacturing process of each bolt is as follows. In either case, the solution treatment was 550 ° C. ⁇ 2 hours, and the aging treatment was 175 ° C. ⁇ 8 hours.
• Comparative Examples 4 and 5 since cracks occurred during the processing of the T9 treated material, a heat resistance test and mechanical characteristics evaluation described later were not performed.
• Evaluation is based on the occurrence rate of cracks in 500 bolts obtained. The presence or absence of this crack is judged by visually observing a crack generated during header processing or rolling. This evaluation was performed by comparing the occurrence rate of cracks between a sample containing Sr and a sample not containing Sr.
• the T6 treated materials of Examples 1 to 10 having Mg 2 Si / (Mn + Cr) of 1.0 to 2.1 have a tensile strength of 380 MPa or more (especially 420 MPa or more) and 0.2% Yield strength is 350MPa or more (especially 370MPa or more), elongation is 6% or more, and heat resistance is also good.
• the T9 treated materials of Examples 1 to 10 have higher mechanical strength such as a tensile strength of 460 MPa or more (especially 490 MPa or more) and a 0.2% proof stress of 440 MPa or more (especially 480 MPa or more).
• Example 10 having the second composition has improved tensile strength and 0.2% proof stress of the T9 treated material compared to Examples 1 and 8 having the first composition.
• the T6 treated materials of Examples 2 to 7 and 9 having the third composition have a tensile strength of 430 MPa or more, a 0.2% proof stress of 370 MPa or more, an elongation of 6% or more, and excellent heat resistance. Is also provided.
• the T9 treated materials of Examples 2 to 7 and 9 have a tensile strength of 510 MPa or more, a 0.2% proof stress of 500 MPa or more, and also have high heat resistance.
• the T8 treated material of Example 7 has a tensile strength of 502 MPa, a 0.2% proof stress of 482 MPa, and also has high heat resistance.
• Examples 7 to 9 containing 0.005% or more of Sr, remelting, the number of flaw detections, and cracks were all reduced compared to Examples 1 to 6 and 10 containing no Sr.
• Comparative Examples 1 to 5 where Mg 2 Si / (Mn + Cr) is out of the range of 1.0 to 2.1 or does not satisfy the first composition are insufficient in terms of heat resistance and workability (cracking). It was. In particular, no comparative examples have improved heat resistance by 20% or more.
• the aluminum alloy wire of the present invention and the manufacturing method thereof can be used for bolt strands or the manufacturing thereof, and the bolt of the present invention and the manufacturing method thereof can be suitably used for bolts for automobile parts or the manufacturing thereof.

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