JP2013177651A - Heat-resistant titanium alloy cold-rolling stock excellent in cold rollability and cold handleability and production method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat-resistant titanium alloy cold-rolling stock having a higher impact resistance than a conventional one and excellent in cold rollability and cold handleability, at low cost.SOLUTION: A heat-resistant titanium alloy cold-rolling stock excellent in cold rollability and cold handleability is characterized in that a heat-resistant titanium alloy hot-rolled sheet contains, by mass, 0.2% to below 0.5% Si, 0.10% to less than 0.40% Fe, and 0.01% to less than 0.10% O, and has a maximum value of the distribution in the rolling direction of the (0002) plane orientation of the α phase tilting from the sheet normal direction to the rolling direction in the range of from 10° to less than 20°. This stock can be produced by performing unidirectional hot rolling at a heating temperature of 800°C to 870°C, at a final rolling temperature of 700°C or less, and at a reduction ratio of 95% or more. Thus, a heat-resistant titanium alloy sheet excellent in cold rollability and cold handleability can be produced more inexpensively than in a conventional case, to thereby obtain extensive utilization effects owing to its properties of lightness and high strength.

Description

  The present invention relates to a heat-resistant titanium alloy cold-rolling material, a heat-resistant titanium alloy cold-rolled annealed plate excellent in cold-rollability and cold handleability, and a method for producing them.

  In order to expand the application range of titanium materials, titanium alloys have been developed in which small amounts of inexpensive elements are added to improve strength, workability, heat resistance, and the like. In particular, heat-resistant parts such as automotive muffler materials are examples of applications where the advantages of lightweight and high-strength titanium materials can be utilized, and many new alloys have been developed because they require high levels of heat resistance and workability. Has been.

  In order to increase the high temperature strength and oxidation resistance, alloy elements such as Si, Cu, Fe, Sn, and Nb are added to the titanium material for the heat-resistant member, and Ti—Cu (Patent Document 1), Ti— Examples include Cu-Si (Patent Document 2) and Ti-Fe-Si (Patent Document 3).

  Patent Document 2 discloses a titanium alloy member containing Cu: 0.5 to 1.8%, Si: 0.1 to 0.6%, oxygen: 0.1% or less, and hot rolling as a manufacturing process thereof. , Cold rolling, final annealing or hot rolling, hot rolled sheet annealing, cold rolling, and final annealing are described.

  Ti-Fe-Si alloys include high-strength, high-ductility titanium alloys containing Fe excellent in high-temperature atmospheric oxidation resistance (Patent Document 4), high-strength titanium alloys and their products, and methods for producing the products ( Although there is Patent Document 5), cold workability is low because it contains any one of Fe, Si, O, or two or more elements, and there is no description regarding cold rolling.

  Addition of Si or Fe lowers the room temperature ductility and worsens the manufacturability in the cold. In particular, due to minute cracks generated at the edge during cold rolling, cracks tend to break in the plate width direction during cold rolling or during sheet passing, leading to breakage of the plate, and cold rolling properties are reduced.

  Since Cu and Nb hardly inhibit room temperature ductility, it is considered that problems in the cold rolling process are relatively difficult to occur in alloys for heat-resistant members using Cu alone or Cu and Nb as reinforcing elements.

  By the way, in order to achieve a significant cost reduction according to the expansion of use, it is also important to select a melting process that is a manufacturing process of a titanium alloy material. Among the beam melting method and the plasma arc melting method, it is said that the electron beam melting method has a low manufacturing cost in mass production. Since the electron beam melting method has a large contact area between the molten metal and vacuum and a long time, among the above alloys for heat-resistant members, when manufacturing an alloy to which Cu having a high vapor pressure is added, the Cu content It is thought that it is difficult to control precisely.

  Therefore, it is necessary to take measures for containing Si and Fe and ensuring manufacturability. Operationally, it is possible to avoid fracture troubles by performing intermediate annealing to recover impact resistance during cold rolling and continuing cold rolling again, but this increases costs.

  Therefore, there is a demand for a method of cold rolling to a target thickness without performing intermediate annealing by increasing the impact resistance of the cold rolled material while maintaining heat resistance without reducing Si and Fe.

  Further, when processing into a muffler part, an r value (plastic strain ratio) having a deep drawability and a phase is used as an index of formability. It is therefore important to establish a manufacturing method that increases the r value.

JP 2005-298970 A JP 2009-68026 A US Patent 7,767,040 JP 2001-89821 A JP 10-179161 A

  In order to improve the cold manufacturability of the heat-resistant titanium alloy sheet, the present invention has higher impact resistance than conventional and excellent cold-rollability and cold handling properties by appropriately controlling the hot-rolling conditions. A heat-resistant titanium alloy plate is provided at a low cost.

  In order to achieve the above-mentioned object, the present inventors diligently investigated the influence of the microstructure of the cold rolling material on the cold rolling property.

  A Charpy impact test was simply used as a method for determining the ease of plate breakage due to minute cracks in the edges that occur during cold rolling. Test when the Charpy impact test is performed at room temperature using a 2 mm V notch impact test piece in which the longitudinal direction of the test piece is the rolling direction, has a notch penetrating the plate thickness, and the crack propagates in a direction parallel to the plate surface The energy absorbed by the strip was used. Here, the higher the shock absorption energy, that is, the higher the impact resistance, the higher the toughness and the better the cold rolling workability.

  In general, it has been considered that annealing a hot-rolled material to restore ductility is advantageous for obtaining high impact resistance.

  However, when the α phase, which is a hexagonal crystal, which is the main phase of the Ti—Si—Fe—O heat-resistant titanium alloy, has a specific texture in the hot-rolled sheet in the process of the inventors' tests. It was clarified that the impact absorption energy of the cold-rolled sheet maintained a high value. That is, when a sheet annealed after hot rolling and a sheet as hot-rolled were cold-rolled at the same rolling reduction, the material cold-rolled as hot-rolled showed higher impact resistance. This is because the c-axis direction, which is the normal direction of the (0002) crystal plane of the α phase of the material as it is hot-rolled, is dispersed with an appropriate inclination in the rolling direction, while the α phase of the annealed hot-rolled sheet It was speculated that the (0002) crystal plane c-axis orientation is related to the fact that it is not inclined in the rolling direction. Hereinafter, the α phase (0002) crystal plane normal direction is simply referred to as “c-axis direction”. The α phase, which is a highly anisotropic hexagonal crystal, has a limited orientation in which fracture surfaces are likely to be formed, and if the orientation is dispersed for each crystal grain, the fracture formed in the process of fracture progression It is estimated that a larger amount of energy is consumed by finely distributing the orientation of the surface. Therefore, it is considered that the fact that the orientation is aligned by recrystallization and the inclination of the c-axis orientation in the rolling direction is lost by annealing is disadvantageous to the action of the present estimation mechanism.

  Moreover, the hot rolling conditions for forming an orientation in which the c-axis orientation is appropriately inclined in the rolling direction have been studied, and the conditions have been obtained.

  As described above, it has been found that a heat-resistant titanium alloy plate excellent in cold rolling properties and cold handling properties can be produced by appropriately adjusting the hot rolled plate texture.

  Furthermore, the cold-rolling raw material in which the hot-rolled sheet texture was adjusted was cold-rolled to search for cold-rolled sheet annealing conditions for increasing the r value. As a result of intensive studies by the inventors, it has been found that a higher r value can be obtained by performing cold-rolled sheet annealing at a temperature higher than about 600 to 700 ° C. conventionally performed with industrial pure titanium or the like.

The gist of the present invention is as follows.
(1) In mass%, Si: 0.2% or more and less than 0.5%, Fe: 0.1% or more and less than 0.4%, O: 0.01% or more and less than 0.10%, the balance being In a titanium alloy hot-rolled sheet made of titanium and inevitable impurities, when the distribution of the (0002) plane orientation of the α phase is shown by a section from the rolling direction to the plate vertical direction, the maximum value of the distribution is rolled from the plate vertical direction. A heat-resistant titanium alloy cold-rolling material excellent in cold-rollability and cold handleability, characterized in that it is inclined in the range of 10 ° or more and less than 20 ° in the direction.
(2) In the production of the heat-resistant titanium alloy hot-rolled sheet according to (1), one-way hot rolling at a heating temperature of 800 ° C. or higher and 870 ° C. or lower, a temperature at the end of rolling of 700 ° C. or lower, and a reduction rate of 95% or higher. A method for producing a heat-resistant titanium alloy material for cold rolling excellent in cold-rollability and cold handleability.
(3) After removing the scale of the titanium alloy hot-rolled sheet, which is the material for cold rolling of the titanium alloy according to (1), cold rolling and annealing are performed, and the tensile strength at room temperature in the rolling direction is less than 500 MPa, A heat-resistant titanium alloy cold-rolled annealed plate having an elongation of 30% or more, an r value of 1.7 or more, and a tensile strength at 700 ° C. of 50 MPa or more.
(4) A method for producing a heat-resistant titanium alloy cold-rolled annealed sheet according to (3), wherein cold rolling is performed at a rolling reduction of 40% or more, and annealing is performed in a temperature range of 700 ° C to 850 ° C. A method for producing a heat-resistant titanium alloy cold-rolled annealed sheet.

  The titanium alloy plate of the present invention makes it possible to manufacture a titanium alloy plate having excellent heat resistance at low cost, making it possible to widely use the product and obtaining a wide range of effects. Therefore, the industrial effects are immeasurable.

α phase (0002) crystal face Pole figure Illustration of c-axis orientation X-ray intensity distribution chart X-ray measuring device and sample arrangement schematic

  The present invention will be described in detail below.

  In the heat-resistant titanium alloy cold rolling material of the present invention, the contents of Si, Fe, and O are first defined as the composition of the titanium alloy. These additive elements improve the cold-rollability of the titanium alloy cold-rolling material of the present invention and are used or processed when the material is cold-rolled and annealed and then processed into an automotive muffler part. It is useful for improving the formability at room temperature, the strength at high temperature, and the oxidation resistance required for the production.

Si improves solid solution strengthening and oxidation resistance at room temperature and high temperature. On the other hand, it is an element that forms a silicide phase Ti _x Si _y and reduces ductility. In order to ensure high temperature strength and oxidation resistance, addition of 0.20% or more, preferably 0.25% or more is necessary. On the other hand, to ensure room temperature ductility, it is necessary to suppress it to less than 0.50%.

  Fe is an element that solid-solution strengthens the β phase and suppresses the expansion of the particle size of the α phase by forming the β phase. Addition of 0.10% or more is necessary for securing high-temperature strength. On the other hand, in order to ensure room temperature ductility, it is necessary to suppress to less than 0.40%.

  O is an element for solid solution strengthening of the α phase. When the addition amount is increased, the room temperature ductility is lowered and workability is deteriorated. Therefore, it was made into less than 0.10%. Preferably, it is less than 0.08%. On the other hand, in order to ensure strength, the lower limit of the O content is set to 0.01% or more. Preferably it is 0.02% or more, More preferably, it is 0.03% or more.

  Furthermore, the present invention defines an α-phase texture. The α phase texture is represented by a (0002) pole figure measured by X-ray diffraction. An example of a (0002) pole figure is shown in FIG. Here, as shown in FIG. 2, the rolling direction (RD), the rolling surface normal direction (ND), and the plate width direction (TD) are used. The α-phase c-axis orientation (α-phase (0002) crystal plane normal orientation) is the angle θ between the c-axis and the ND, and the angle φ between the plane including the c-axis and the ND direction and the plane including the ND and TD directions It is expressed using

  The pole figure shown in FIG. 1 is expressed from the measurement result of the (0002) X-ray reflection relative intensity that is quantified at intervals of 5 ° in the range of θ = 0 to 90 ° and φ = 0 to 360 °. The distribution relating to the RD direction as an index in the present invention corresponds to a cross section including the RD direction and the ND direction, and the above pole figure cut out, that is, φ = 90 ° and 270 °, θ = 0 to 90 °. Since φ = 90 ° and 270 ° are equivalent in the longitudinal direction of rolling, the average value of the X-ray reflection intensities at φ = 90 ° and 270 ° at each θ is used. The extracted c-axis orientation distribution is shown in FIG. 3 with the vertical axis representing the X-ray reflection intensity obtained by averaging φ = 90 and 270 ° and the horizontal axis representing θ. In FIG. 3, the pole figure of FIG. 1 extracted from the RD-ND cross section corresponds to the symbol A, and another example extracted from the RD-ND cross section corresponds to the symbol B. In general, the symbol A is called Split-RD-texture, and the symbol B is called B-texture.

  In the present invention, in the distribution of the c-axis orientation (α phase (0002) plane orientation) in the rolling direction, the angle (θmax) formed by the orientation indicating the maximum value and the ND direction is inclined at 10 ° or more and less than 20 °. It is going to be. The symbol A in FIG. 3 indicates the maximum value at θ = 15 °, and the symbol B indicates the maximum value at θ = 0 °. Hereinafter, θ (θmax) that gives such a maximum value of X-ray reflection is called an integration angle. If the angle θmax between the orientation indicating the maximum value of the (0002) plane orientation distribution of the α phase and the ND direction, that is, the integrated angle is smaller than 10 °, it is difficult to reduce the plate thickness, and the impact absorption energy due to plastic deformation decreases. To do. In addition, crack propagation along the column surface is likely to occur, and the crack propagation orientation is less likely to be dispersed by the bottom surface, so that the impact absorption energy is reduced.

  On the other hand, when the angle θmax formed by the orientation indicating the maximum value of the (0002) plane orientation distribution of the α phase and the ND direction, that is, when the integration angle is 20 ° or more, anisotropy due to the in-plane orientation increases. Although resistance to crack growth in a specific direction increases, resistance to crack propagation in different directions decreases, and the impact absorption energy of the plate decreases. It is presumed that the impact absorption energy can be reduced by forming irregularly distributed orientations in the plate surface for each crystal grain. However, since a specific orientation tends to develop during the manufacturing process of wrought material, It is difficult to manufacture automatically.

  The impact resistance is improved if the angle θmax formed by the orientation indicating the maximum value of the (0002) plane orientation distribution of the α phase and the ND direction, that is, the integration angle is in the range of 10 ° or more and less than 20 °. It is presumed that crack propagation occurs irregularly along the column surface or bottom surface, so that the crack propagation direction is dispersed.

  The manufacturing method of the heat-resistant titanium alloy cold rolling raw material of this invention is demonstrated.

  In mass%, Si: 0.2% or more and less than 0.5%, Fe: 0.10% or more and less than 0.40%, O: 0.01% or more and less than 0.10%, the balance being titanium and inevitable By using a hot-rolled material made of impurities, a heating temperature of 800 ° C. or higher and 870 ° C. or lower, a temperature at the end of rolling of 700 ° C. or lower, and hot rolling in one direction at a reduction rate of 95% or higher, When the distribution of the (0002) plane orientation of the α phase is shown in a cross section from the rolling direction to the plate vertical direction, the maximum value of the distribution is inclined from the plate vertical direction to the rolling direction in a range of 10 ° or more and less than 20 °. be able to.

  When the hot-rolled sheet of the present invention thus produced is annealed and recrystallized, the crystal grain size increases and c-axis roll surface normal direction, that is, accumulation in the ND direction shown in FIG. No annealing is performed. This is because when the c-axis is accumulated in the ND direction, the impact absorption energy is lowered and the cold workability is deteriorated. However, hot-rolled sheet annealing under conditions in which the hot-rolled structure does not change, for example, annealing at 600 ° C. or lower and 3 minutes or lower is not denied. This is because annealing at a higher temperature or longer time causes recrystallization, resulting in coarsening of crystal grains and an increase in specific crystal orientation, resulting in a reduction in impact absorption energy. The reduction ratio of 95% or more defines the reduction ratio necessary for forming the hot rolled texture.

  Further, when hot rolling is performed under the above conditions, the crystal grain size of the plate cross section is 10 μm or less. Since the growth direction of a crack changes in units of crystal grains, it is considered that the smaller the crystal grain size, the greater the effect of dispersion in the crack growth direction.

  In addition, although it is a material for cold rolling, even if the hot rolled texture is a plate as hot rolled, it is hot rolled through a descaling process performed by immersion in nitric acid after shot blasting. Although it was a pickled plate, it does not change. Cold rolling is performed after the descaling process.

  In the heat-resistant titanium alloy cold-rolled annealed sheet of the present invention, after removing the scale of the hot-rolled sheet that is the cold-rolling material of the present invention, the rolling direction at room temperature of the titanium alloy sheet obtained by cold rolling and annealing Tensile strength, elongation, r value, and tensile strength in the rolling direction at 700 ° C. The scale removal is usually performed on a titanium hot-rolled sheet, and is performed by a method such as dipping in hydrofluoric acid after shot blasting. In the case of molding to an automobile muffler material or the like, if the room temperature strength is 500 MPa or more or the elongation is less than 30%, the molding becomes difficult because cracking occurs during molding, so that it is specified to be less than 500 MPa and 30% or more. Preferably it is less than 470 MPa. The r value (plastic strain ratio) is the value when the plastic strain is 5%. The r value is an index having a correlation with the deep drawability, and in the present invention, 1.7 or more is used as an index. In addition, when the tensile strength at 700 ° C. is less than 50 MPa, cracks are likely to occur during use as an automobile muffler, and therefore, 50 MPa or more. Preferably it is 55 MPa or more.

  A plate obtained by cold-rolling and annealing a heat-resistant titanium alloy cold-rolling material according to the present invention exhibits high heat resistance, and is suitable as a heat-resistant component such as an automobile muffler material. Here, the automobile muffler includes an exhaust manifold, an exhaust pipe, a catalyst muffler, a main muffler, and the like after the engine.

  In the manufacturing method of the heat-resistant titanium alloy cold-rolled annealed plate of the present invention, the cold rolling material of the present invention is used, cold rolling is performed at a rolling reduction of 40% or more, and annealing is performed in a temperature range of 700 ° C to 850 ° C. A heat-resistant titanium alloy cold-rolled annealed plate having a tensile strength at room temperature in the rolling direction of less than 500 MPa, an elongation of 30% or more, an r value of 1.7 or more, and a tensile strength at 700 ° C. of 50 MPa or more. It can be.

  Usually, when a titanium alloy plate is produced from a hot-rolled annealed plate, the rolling reduction required to make the recrystallized structure after annealing uniform is 60% or more. In the method of the present invention, since cold rolling is performed while leaving the processed structure at the time of hot rolling, it is not necessary to provide a lower limit of the rolling reduction. However, in order to manufacture efficiently in an integrated process, for example, it is conceivable to produce a product plate having a thickness of 1.8 mm after performing hot rolling to a thickness of 3 mm. That is all. Annealing is less than 700 ° C., and the ductility recovery and texture change are insufficient, so that it is impossible to obtain both elongation of 30% or more and r value of 1.7 or more. To do. If it exceeds 850 ° C., the effect of improving elongation and r value is saturated.

  Although the details of the mechanism of improving the r value by performing cold-rolled sheet annealing at 700 ° C. or higher are unclear, it is considered that the characteristic behavior of Si and Fe has an influence on the alloy composition of the present invention. One factor is that the addition of Si promotes the accumulation of the cold-rolled annealed plate texture in an orientation in which the c-axis is parallel to the ND direction, thereby facilitating deformation within the plate surface, and thus the r value is improved. Presumed. From another point of view, Si forms a silicide phase and Fe forms a β phase, both of which suppress the growth of the α phase, but by annealing at a higher temperature, the grain growth proceeds, and the above texture It is estimated that the formation is promoted.

  A typical manufacturing process of the titanium alloy hot-rolled sheet of the present invention is as follows. A titanium ingot is obtained by using a sponge titanium and a component adjusting additive as a raw material by a consumable electrode type vacuum arc melting method, electron beam melting method or plasma arc melting method. A 80 to 250 mm thick titanium slab manufactured from this ingot is heated and hot-rolled to obtain a 3 to 6 mm thick hot rolled sheet.

  Hereinafter, the present invention will be described more specifically with reference to examples. The conditions in the examples are one condition example adopted to confirm the feasibility and effects of the present invention, and the present invention is not limited to this one condition example.

  Titanium ingots having components A to J shown in Table 1 were produced by a vacuum arc melting method and forged into slabs each having a thickness of 100 mm. The following tests were conducted using these materials. In Table 1, numerical values that deviate from the scope of the present invention are underlined. The same applies to Tables 2 and 3 below.

Example 1
Using the material F in Table 1, hot rolling was performed under the hot rolling conditions described in Table 2, and the relationship between the hot rolling conditions and the texture was investigated. The hot rolling reduction ratio was changed by changing the thickness of the hot rolled sheet. The hot-rolled sheet was not annealed or partially annealed, then shot blasted and pickled to remove the scale formed on the surface. Thereafter, a sample for X-ray measurement was taken from one part of each hot-rolled sheet. Thereafter, the hot-rolled sheet was cold-rolled at a rolling reduction of 40%.

  A sample was prepared by polishing and etching from the center of the thickness of the hot-rolled sheet, and the texture was examined by X-ray diffraction. The degree of integration of the c-axis (α phase (0002) plane) is (0002) X-rays digitized at 5 ° intervals in the range of θ (0 ° to 90 °) and φ (0 ° to 360 °). It is expressed in reflected relative intensity. The integrated value of the X-ray intensity in the RD direction, that is, φ = 90 ° and 270 ° shows substantially the same value, but the relative X-ray reflection intensity (relative X-ray reflection intensity with respect to the average value of these values). When θ = 0 ° to 90 ° is plotted, θ (θmax) (also referred to as “integration angle”) at which the relative X-ray reflection intensity shows the maximum value is expressed as a peak of “α (0002)”. The orientation is shown in Table 2. Further, the X-ray intensity of θ = 0 ° to 90 ° in the RD direction, that is, φ = 90 °, 270 °, indicates that the X-ray source 1 and the sample 3 are arranged as shown in FIG. The X-ray counter 5 is obtained by fixing the X-ray counter 5 at a position where the diffracted X-ray 4 from the α-phase (0002) crystal plane is incident, and then rotating the sample 3 around the TD axis. It is equivalent to plotting the change in intensity.

  In addition, a Charpy test was performed in order to evaluate the cold-rollability and cold handling of the hot-rolled sheet. From the hot-rolled sheet (hot-rolled annealed sheet at the level of hot-rolled annealing), cold-rolled sheet, Charpy impact test piece, test piece long axis direction in RD direction, plate thickness as test piece thickness, depth A 2 mm V-shaped notch was sampled so that the notch depth was in the plate width direction, and the impact value was evaluated. The test method was performed at 23 ° C. according to JIS.

The results are shown in Table 2. No. shown in Table 2 1-4 are examples of the present invention, No.1. 5 to 9 are comparative examples. No. No. 5 has a hot rolling heating temperature as low as 750 ° C., and its texture is accumulated in the ND direction. In No. 6, the heating temperature is as high as 920 ° C., so that the texture is accumulated in an inclined manner in the RD direction. No. In No. 7, since the hot rolling end temperature was as high as 730 ° C., the integration of the c-axis in the ND direction also progressed, and the integration angle was 0 °. The effect of hot-rolled sheet annealing on the texture is No. It is clear in 4 and 8. No. which performed hot-rolled sheet annealing at 600 ° C. for 3 minutes. 4, the accumulation in the ND direction of the c-axis does not proceed so much, and the accumulation angle is 15 °. On the other hand, No. 1 was subjected to hot rolled sheet annealing at 670 ° C. for 3 minutes. In No. 8, accumulation in the ND direction of the c-axis progresses, and the accumulation angle becomes 5 °, which is outside the scope of the present invention. No. No. 9 had a hot rolling reduction ratio of 90%, which was outside the range of the present invention, and the c-axis accumulation angle was 0 °. The result of the evaluation of impact resistance by Charpy test, made to the present invention is 180 J / cm ² or more in the hot rolled sheet, a dominant 40% reduction was cold-rolled sheet 100 J / cm ² or more, as a departure from the present invention Is inferior. That is, it turned out that the cold rolling property and cold workability of the present invention are excellent.

(Example 2)
The slabs of the materials A to J were heated to 850 ° C. and hot rolled to a thickness of 4 mm with a reduction rate of 96%, and the hot rolling was finished at 600 to 700 ° C. to prepare hot rolled sheets. The hot-rolled sheet was shot blasted and pickled without annealing to remove the scale formed on the surface. A sample for X-ray measurement and a Charpy test piece from one part of each hot-rolled sheet, and a Charpy test piece from a cold-rolled sheet obtained by cold rolling the hot-rolled sheet at a rolling reduction of 40% are described in Example 1. It was collected as follows.

  Each hot-rolled sheet was subjected to vacuum annealing at 750 ° C. for 5 hours, and then subjected to a room temperature tensile test and a high-temperature tensile test at 700 ° C. Table 3 shows the tensile strength, elongation, r value, and strength at 700 ° C. (high temperature strength) in the rolling direction at room temperature. The r value was evaluated at a plastic strain of 5%.

  No. shown in Table 3 Nos. 10 to 15 are examples of the present invention. 16-19 are comparative examples. The accumulated angle of the c-axis is No. 1 according to the present invention. In Nos. 10 to 15, room temperature strength, room temperature ductility, r value, and strength at 700 ° C. were the target ranges of the present invention, and it was confirmed that they would be suitable as heat-resistant parts such as automobile muffler materials. However, each of Si, Fe, and O exceeds the upper limit of the scope of the present invention. Nos. 16 to 18 are inferior in cold workability because the c-axis integration angle is within the range of the present invention and the strength is too high. No. Fe is lower than the lower limit. No. 19, the c-axis integration angle is out of the range of the present invention, impact resistance evaluated by Charpy test is deteriorated, cold-rollability and cold handleability are deteriorated, and cold yield is remarkably lowered. . Further, No. whose composition deviates from the scope of the present invention. In Nos. 16 to 19, the room temperature strength, room temperature ductility, r value, and strength at 700 ° C. It is inferior to 10-15.

(Example 3)
Using the material F, room temperature strength, elongation, r value, and strength at 700 ° C. were investigated by changing the cold rolling and annealing conditions. No. in Table 4 20 to 27 are No. in Table 2. The hot-rolled sheet used in 2 was used. As shown in Table 4, the cold rolling reduction was 30 to 80%, and cold rolling sheet annealing was performed at 670 to 870 ° C. for 5 to 300 minutes. In these examples, in the hot-rolled sheet, the accumulation angle in the texture is within the scope of the present invention, and the cold-rollability has no problem.

  In Table 4, No. 2 described as the present invention 2 was used. 20-No. No. 23 has a cold rolling reduction of 40% or more, a cold rolled sheet annealing temperature of 700 ° C. or higher, and satisfies the conditions of the method for producing a heat-resistant titanium alloy cold rolled annealed sheet of the present invention, and in particular, the r value is 1.8 or higher. And showed excellent characteristics. When manufactured under the above conditions, drawing workability, which is important in processing of muffler materials for automobiles, is particularly superior. No. in Table 2 When the hot-rolled sheet used in No. 2 was subjected to hot-rolled sheet annealing at 750 ° C. for 1 minute, the c-axis accumulated angle became 0 °, and the No. No. 27 is inferior in r value although the cold rolling reduction ratio and cold rolled sheet annealing conditions satisfy the range of claim 4.

  All the hot-rolled titanium plates according to the present invention showed high cold-rolling yield without any occurrence of cracks or cracks in subsequent sheeting and cold rolling. Further, it was confirmed that a titanium plate obtained by cold rolling and annealing the hot-rolled titanium plate exhibits high heat resistance and is suitable as a heat-resistant component such as an automobile muffler material.

1 X-ray source 2 Incident X-ray 3 Sample 4 Diffracted X-ray from α phase (0002) crystal plane 5 X-ray counter

Claims (4)

  In mass%, Si: 0.2% or more and less than 0.5%, Fe: 0.10% or more and less than 0.40%, O: 0.01% or more and less than 0.10%, the balance being titanium and inevitable In a titanium alloy hot-rolled sheet made of impurities, when the distribution of the (0002) plane orientation of the α phase is shown in a section from the rolling direction to the plate vertical direction, the maximum value of the distribution is 10 in the rolling direction from the plate vertical direction. A heat-resistant titanium alloy cold-rolling material excellent in cold-rollability and cold handling characteristics, characterized in that it is inclined in a range of at least 20 ° and less than 20 °.   In the production of the heat-resistant titanium alloy hot-rolled sheet according to claim 1, unidirectional hot rolling is performed at a heating temperature of 800 ° C. or higher and 870 ° C. or lower, a temperature at the end of rolling of 700 ° C. or lower, and a reduction rate of 95% or higher. A method for producing a heat-resistant titanium alloy cold rolling material excellent in cold rolling properties and cold handling properties.   The titanium alloy hot-rolled sheet, which is a material for cold rolling of the titanium alloy according to claim 1, is cold-rolled and annealed. The tensile strength at room temperature in the rolling direction is less than 500 MPa, the elongation is 30% or more, and the r value is A heat-resistant titanium alloy cold-rolled annealed plate having a tensile strength at 700 ° C. of not less than 1.7 and not less than 50 MPa.   It is a manufacturing method of the heat-resistant titanium alloy cold-rolled annealing board of Claim 3, Comprising: Cold rolling is performed by 40% or more of rolling reduction, and annealing is performed in a 700 to 850 degreeC temperature range. Manufacturing method of titanium alloy cold-rolled annealed sheet.

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