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
  • C22F1/16—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of other metals or alloys based thereon
  • C22F1/18—High-melting or refractory metals or alloys based thereon
  • C22F1/183—High-melting or refractory metals or alloys based thereon of titanium or alloys based thereon
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C14/00—Alloys based on titanium
• • 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

Definitions

• the present invention relates to a titanium alloy bar excellent in ductility, fatigue characteristics and workability, particularly to an a + i3 type titanium alloy bar and a method for manufacturing the same.
• BACKGROUND ART Titanium alloys are used as structural materials in chemical plants, generators, aircraft, and other fields because of their high strength, lightness, and excellent corrosion resistance.
• ⁇ +] 3 type titanium alloys that have high strength and relatively good workability.
• Products using titanium alloy include various shapes such as thin plates, thick plates and bars.
• the rod is used in its original shape, but in some cases it is processed into a complex shape, such as a threaded part of Porto, or it is used as a forged material. Excellent workability is required in addition to ductility and fatigue properties.
• Figure 1 shows a typical method of manufacturing a bar.
• the temperature of the material to be rolled increases during hot rolling due to the heat generated during processing, so that stable hot rolling cannot be performed and ductility and fatigue properties
• the temperature of the material to be rolled rises to the i3 transformation point or higher, the ⁇ ⁇ Therefore, excellent ductility and fatigue properties cannot be obtained.
• the transformation point is high, the temperature of the material to be rolled hardly becomes higher than the i3 transformation point due to the heat generated during processing. Ductile, fatigue properties and workability cannot be obtained.
• Japanese Patent Application Laid-Open No. 59-82101 discloses a method of reducing the cross-sectional reduction rate per rolling pass at 0: zone temperature and + / 3 zone temperature to 40% or less. Is disclosed.
• Japanese Patent Application Laid-Open No. 58-25465 discloses a method of water-cooling a material to be rolled in order to suppress a rise in temperature due to heat generated during processing.
• Paper 1 “Hot Bar Rolling of Ti-6A1-4V in a Controllable Continuous Mill (Titanium '92 Science and Technology)”, the rolling speed is used to suppress the heat generated during processing.
• Figure 3 shows the relationship between the temperature of the material to be rolled and the rolling time in bar rolling of the Ti-6A4V alloy and the Ti-44.5Al-3V-2Fe-2Mo alloy.
• the heating temperature is 950 ° for the Ti-6A4 4V alloy (: for the Ti-4.5A3 3V-2Fe-2 ⁇ 'alloy, the j3 transformation point of which is 100 ° C lower than the Ti-6A4V alloy)
• the temperature was lowered to 850 ° C by the difference between the three transformation points.
• Rolling was performed using a reverse mill and a tandem mill, and the rolling speed, rolling reduction, and pass schedule were the same for both alloys. Rolling on a reverse rolling mill was 2.7 mI sec for both alloys, and rolling 3 ⁇ 4i in the tandem rolling mill was 2.25 m / sec for both alloys in the final rolling pass, which was the fastest.
• the rolling speed is lower than the rolling speed (6 m / sec) described in the above paper 1.
• the cross-sectional reduction rate is set to 26% at maximum for both alloys.
• the a + jS type titanium alloy bar has a process of hot rolling the titanium alloy of the above component so that the surface temperature is always below the ⁇ transformation point. It can be manufactured by a method. Brief description of the drawings- FIG. 1 is a diagram showing a typical method of manufacturing a bar.
• A1 It is an essential element for stabilizing the phase and also contributes to high strength. If it is less than 4, high strength is not sufficiently achieved, and if it exceeds 5%, ductility deteriorates.
• V An element that stabilizes the three phases and also contributes to high strength. If it is less than 2.5%, high strength is not sufficiently achieved, and) the three phases are not stable. If it exceeds 3.5%, the transformation temperature range is reduced due to the decrease of the 0 transformation point, and the cost is increased. Invite.
• the temperature rise due to the heat generated during the process causes coarsening of crystal grains and formation of a needle-like structure. Furthermore, the reason why the finished surface temperature, which is the surface temperature immediately after the rolled material has completed the final rolling pass, is in the range of -300) ° C or more and (T 3-100) ° C or less is ⁇ -300) ° c If it is less than the above, cracking sensitivity and deformation resistance will increase, and if it exceeds (Tjs-loo) ° c, crystal grains will be coarse.
• hot rolling is performed in a plurality of rolling passes, it is preferable to reduce the rolling reduction per rolling pass to 40% or less in order to prevent a temperature rise due to heat generated during processing.
• the rolling speed is preferably set to 6 m / sec or less in order to prevent a temperature rise due to heat generated during processing.
• Rolled material of 125 thigh angle was cut out from titanium alloys AO1 (within the scope of the present invention) and A02 (outside the scope of the present invention) of the chemical composition shown in Table 1 and A02 (within the scope of the present invention). Under the indicated rolling conditions B01-B18, rods having a diameter of 0 strokes or 50 bars were manufactured.
• the time between rolling passes in Table 2 is ⁇ when the time between rolling passes is 0.167 XS 1/2 sec or more in all rolling passes and X when not.
• Table 3-Table 20 show the cross-sectional area S, rolling reduction, 0.167 XS 1/2 time between rolling passes, surface temperature and rolled body of the material to be rolled in each rolling pass under each rolling condition.
• R represents a reverse rolling mill
• T represents a tandem rolling mill.
• Tensile tests were performed on the manufactured rods after annealing at 700 ° C or more and 720 ° C or less, and the yield strength (0.2 3 ⁇ 4PS), tensile strength (UTS), extension (El), and drawing (RA) were measured.
• Table 21 shows the results.
• the absence of the crystal grain size in the microstructures in the table means that the site consisted only of the ⁇ -structure mainly composed of acicular a, and no equiaxed pro-eutectoid ⁇ -phase could be observed.
• the finished surface temperature is lower than (T) 3-300) ° C, the temperature of the material to be rolled is too low, the workability is reduced, and cracks occur during rolling.
• the surface temperature is higher than (T) 3-100), as in the rolling conditions # 04, # 05 and # 07, the microstructure cannot be refined and the ductility and fatigue properties deteriorate.
• the surface temperature of the material to be rolled is lower than (T j8-300) ° C, the surface temperature of the material to be rolled is too low and cracks occur during rolling.
• the surface temperature of the material to be rolled is higher than ( ⁇ ⁇ -50) ° C, the center of the roll and the 1 / 4D yarn 13 ⁇ 4 are stitched as in the rolling conditions B02-B05, B07 and B11. It becomes a ⁇ -yarn mainly composed of a shape and has poor ductility and fatigue properties.
• ⁇ + type titanium alloys in which the volume fraction of proeutectoid ⁇ phase is 50% or more and 80% or less and the average crystal grain size of proeutectoid phase is 6 m or less
• Kt 3) fatigue strength of 200 MPa.
• the bar manufactured using rolling conditions B10 and B12 using A02 whose chemical composition is out of the range of the present invention since the rolling conditions were within the range of the present invention, the heat generation during processing was suppressed. Since the particle size exceeds 10, sufficient ductility and fatigue strength cannot be obtained.
• a cylindrical test piece of ⁇ 8 thigh ⁇ 12 thigh was collected from the radial center of the bar manufactured under the rolling conditions B0-B18 in Example 1 and heated to 800 ° C., compressed by 70%, and compressed. The hot forgeability was evaluated by examining the surface for cracks and rough surfaces.
• Bars manufactured under rolling conditions B01, B06, B08, B09, B16, ⁇ , and B18 in which the microfilament falls within the scope of the present invention did not cause cracking or roughening, and obtained good hot forgeability.
• rods manufactured under rolling conditions B10 and B12 in which the crystal grain size of the pro-eutectoid ⁇ phase exceeded 10 m did not crack, but roughened the surface.
• both the cracks and the rough surface occurred in the bars manufactured under the rolling conditions ⁇ 02, ⁇ 03, ⁇ 04, ⁇ 05, ⁇ 07, Bll, ⁇ 14, and B15 in which the center and the 1 / 4D part consisted of only / 3 phase. .
• the crystal grain size and the volume fraction of the pro-eutectoid ⁇ phase are within the range of the present invention, but the aspect ratio of the crystal grains in a cross section parallel to the rolling direction is determined. With rolling condition B13 exceeding 4, the surface roughness still occurred c
• the unit is mass%

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• 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)
• Metal Rolling (AREA)

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• 2002
  • 2002-02-26 JP JP2002570785A patent/JP4013761B2/ja not_active Expired - Fee Related
  • 2002-02-26 EP EP02703899A patent/EP1382695A4/en not_active Withdrawn
  • 2002-02-26 WO PCT/JP2002/001710 patent/WO2002070763A1/ja not_active Application Discontinuation
  • 2002-02-26 RU RU2003126234/02A patent/RU2259413C2/ru not_active IP Right Cessation
  • 2002-02-27 TW TW091103561A patent/TWI293987B/zh not_active IP Right Cessation
• 2003
  • 2003-04-17 US US10/418,252 patent/US20030223902A1/en not_active Abandoned
• 2004
  • 2004-10-18 US US10/968,521 patent/US20050051245A1/en not_active Abandoned

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