TWI277657B - beta-type titanium alloy - Google Patents

Abstract

It is an object of the present invention to provide a beta titanium alloy having a good cold workability, as well as a higher strength than a Ti-20V-4Al-1Snbeta titanium alloy. There is provided a beta titanium alloy which is characterized in that it comprises, in weight %, V: 5-15%, Fe: 0.5-2.5%, Mo: 0.5-6% and Cr: 0.5-5%, in which the value of Xv+2.95XFe+1.5XMo+1.65XCr is 15-23%, in which Xv represents the weight % of the contained V, XFe represents the weight % of the contained Fe, XMo represents the weight % of the contained MO and XCr represents the weight % of the contained Cr, said beta titanium alloy further comprises, in weight %, Al: 1.5-5%, and the residue comprises Ti and impurities.

Description

1277657 (1) Description of the Invention [Technical Field of the Invention] The present invention relates to a /3 type titanium alloy and a heat treatment method therefor. [Prior Art] Titanium alloys are very light and have high strength. Among them, the alloys made of Θ phase monomers, which are called "Θ-type titanium alloys", mostly have titanium alloys mainly based on α-phases. More excellent cold workability, and many "stone-type titanium alloys" can obtain excellent strength by aging treatment. Known stone-type titanium alloys are: Ti-20V-4Al-lSn (Patent Document 1); Ti-15V-3Cr-3Al-3Sn; Ti-22V-4A1 (Patent Document 2); Ti-15V-6Cr -4Al (Patent Document 3); Ti-13V-9Cr-3Al;

Ti-15Mo-5Zr-3Al ; T i - 3 A1 - 8 V - 6 C r - 4 Μ ο - 4 Z r ; Ti-13V-llCr-3A1; Ti-4.5Fe-6.8Mo-l.5Al. Among them, Ti-15V-6Cr-4Al; Ti-13V-9Cr-3Al; Ti_15Mo-_ 5Zr-3Al; Ti-3 Al-8V-6Cr-4Mo-4Zr; Ti -1 3 V · 1 1 Cr-3 A1 Although the strength is high, the deformation resistance is large due to the cold and hot occasions, and the workability is poor, and it can be used only for special purposes. On the contrary, Ti-20V-4Al-lSn; Ti-15V-3Cr-3Al-3Sn; Ti-22V-4A1, although it has a slightly lower strength, has excellent cold workability, so it is widely used in general. In particular, Ti-20V_4Al-lSn is used in various applications including sporting goods such as golf clubs and bicycles because of its excellent cold-working property and high strength. -4- (2) 1277657 - In recent years, the niobium-type titanium alloy is required to have higher strength for various purposes such as expanding the use, reducing the weight, and reducing the cost. It is desirable to have both Ti-20V_4Al-lSn and the above. Also excellent in cold workability and higher strength. However, as a result of the research so far, 冷 has not found a cold-type alloy which has excellent cold-workability and higher strength than Ti-20V-4Al-lSn, so it fails to meet the above-mentioned Claim. [Patent Document 1] Patent Document 1 refers to Japanese Patent No. 26404-15. [Patent Document 2] Patent Document 2 refers to Japanese Patent Publication No. Hei 6-99765. [Patent Document 3] Patent Document 3 refers to Japanese Laid-Open Patent Publication No. 2000-144286. SUMMARY OF THE INVENTION [Problems to be Solved by the Invention] The technical problem of the present invention is to provide an excellent cold interprocessability and a Ti-20V-4A1-1 Sn / in view of the above problems. Titanium alloy with higher strength of type 3 titanium alloy. [Means for Solving the Problem] -5 - 1277657 (3) In order to solve the above problems, the inventors have found out the following findings based on the results of a comprehensive review: How to determine the Θ phase of titanium alloy The amount of stabilizing elements (ie, 乂, 66, ]\4 〇, 0) is not the minimum amount required to stabilize the /3 phase when it is separately added to titanium alone according to the usual practice. The ratio is determined by the comparison, and the new coefficient after considering the interaction of each element can be used as an index to correctly show the stabilization of the Θ phase. More specifically, the element contained in the bismuth type titanium alloy generally provides an index of the phase stabilizing effect of each element based on the inverse number of the minimum amount required to change the titanium into the yS phase monomer by each element monomer. The general opinion is because it is known that, in terms of % by weight, including V: 15%, Fe: 3.6%, Mo: 10%, Cr: 6.3%, titanium can be changed into a cold phase monomer, so if V is As a standard, the number obtained by multiplying the weight % of Fe contained by 15/3.6 (ie, 15/3.6) is equivalent to the case of v containing the number 値. Based on this insight, if you want to calculate the degree of Θ phase stabilization based on the conventional idea, when V is used as a reference, the weight % of V contained is Xv, and the weight % of Fe contained is XFe. The weight % of Mo is Xm. When the weight % of Cr contained is XCr, it is supposed to be obtained from Xv + (15/3.6) XFe + (15/10) XM 〇 + (15/6.3) XCr, but according to the present inventors After reviewing the results of the experiment, it was found that the enthalpy of using: Xv + 2.95XFe + 1.5XMo + 1.65Xcr can be used as an index for accurately indicating the degree of stabilization of the /3 phase, and the present invention has been completed. -6 - (4) 1277657 That is, the titanium alloy of the type /3 provided by the present invention is characterized by containing V: 5 to 15% by weight, Fe: 〇·5 to 2.5%, M〇· 〇·5 to 6 %, Cr: 0.5 to 5%, and the weight % of V contained is Xv, the weight % of Fe contained is xFe, the weight % of Mo contained is Xm°, and the contained Cr When the weight % is xCr, the enthalpy of xv + 2.95XFe + 1.5XM 〇 + 1.65Xcr is 15 to 23%, and contains A1: 1.5 to 5%, and the rest is composed of Tl and impurities. [Effects of the Invention] The /3 type titanium alloy according to the present invention, in addition to V, contains V in addition to V, in addition to τί-2〇ν-4Α1"δη/3 type alloy. 5 to 15%, Fe: 0.5 to 2.5%, Mo: 0.5 to 6%, Cr: 0.5 to 5%, and the weight % of V contained is Xv, and the weight % of Fe contained is XFe, which is contained The weight % of Mo is χΜ. When the weight % of Cr contained is XCr, the enthalpy of Xv + 2.95XFe + 1.5XM 〇 + l_65XCr is 15 to 23%, so that excellent cold workability can be maintained. It is possible to have more excellent strength than the Ti-20V-4A1-1SnP type niobium alloy by the action of solid solution strengthening. [Embodiment] [Best Embodiment of the Invention] It is explained that the titanium alloy of the present embodiment is included. The reason for the amount of each element is as follows. The amount of each element contained in the titanium alloy of the present embodiment is % by weight (5) 1277657 · V: 5 to 15%, Fe: 0.5 to 2.5%, Mo : 0.5 to 6%, Cr: 0.5 to 5%, Al: 1.5 to 5%, and the rest is composed of Ti and tannin. After the titanium alloy composed of these elements is melted and then rapidly cooled, it becomes have Different cold-processed niobium-type titanium alloys. Next, after processing the above-mentioned /3 type titanium alloy into a desired shape, a so-called "aging treatment" heat treatment is performed to make the strength higher than that of A ® . Crystallization of the alpha phase in the above-described niobium-type titanium alloy can increase the strength. The reason why the weight % of V is selected to be 5 to 15% is that if V is less than 5%, the cold workability of the yS type titanium alloy is lowered, and excellent cold workability cannot be obtained. Further, if V is more than 15%, the above-mentioned aging treatment will hinder the crystallization of the α phase, and the strength superior to that of the Ti-20V-4Al-1Sny3 type titanium alloy cannot be obtained.

The reason why the weight % of Fe is selected to be 0.5 to 2.5% is that if Fe is not over 0 · 5 %, the effect of solid solution strengthening cannot be obtained, and Ti-2V-4Al-lSn/3 type titanium cannot be obtained. The alloy has superior strength. Further, if Fe exceeds 2.5%, Fe crystals will be generated in the /3 type titanium alloy, resulting in unstable properties.

The reason why the weight % of Mo is selected to be 0.5 to 6% is that if Mo is less than 0.5%, the effect of solid solution strengthening cannot be obtained, and it is impossible to obtain an alloy which is superior to Ti-20V-4Al-lSnyS type titanium alloy. Strength of. In addition, if Mo exceeds 6%, excellent cold workability cannot be obtained. Moreover, Mo's raw materials are very expensive, and if the amount of addition is increased, there will be -8 - 1277657. (6) The problem of high cost.

The reason why the weight % of Cr is selected to be 0.5 to 5% is that if Cr is less than 0.5%, the effect of solid solution strengthening cannot be obtained, and it is impossible to obtain a cold titanium alloy which is more than Ti-20V-4Al-lSn. Excellent strength. Further, if Cr exceeds 5%, Cr crystals will be generated in the 0-type titanium alloy, resulting in unstable characteristics. V, Fe, Mo, and Cr are elements for stabilizing the /3 phase, whereas ® A1 has a function of stabilizing the α phase. The reason why the weight % of A1 is selected at 1.5 to 5% is that if Α1 is less than 1.5%, when the above aging treatment is carried out, the α phase crystallization cannot be promoted, and it is impossible to obtain more than 1^- 20V-4Al-lSn/3 titanium alloy has superior strength. Further, Α1 has an effect of suppressing crystallization of the ω phase, and if A1 is less than 1.5%, the ω phase will be crystallized and embrittled. In addition, if Α1 exceeds 5%, the cold workability is lowered, and excellent cold workability cannot be obtained. Further, regarding the contents of V, Fe, Mo, and Cr, it is assumed that the wt% of V contained is Xv, the wt% of Fe contained is XFe, and the weight % of Mo contained is XM. When the weight % of Cr contained is XCr, the enthalpy of Xv-f2.95XFe+1.5XM〇+ 1.65Xcr is selected to be 1 5 ～2 3 %, so that it can be made with TidOV^Al-lSnf type titanium alloy. The same cold interdability, if the number is less than 15%, even if the cooling rate from the temperature above the metamorphic point is increased, it is difficult to obtain the metallurgical structure of the single phase, and it will be because of the metal Crystallization of equal phase and α causes the processability to deteriorate. On the contrary, if the number 値 exceeds 23%, the above-mentioned aging treatment will hinder the crystallization of the α phase, and it is impossible to obtain -9 - (7) 1277657

TidOVIAl-lSnA type titanium alloy has superior strength. In addition, if there is a metal phase other than the Θ phase, for example, the crystal phase is precipitated, there is a problem that the cold workability is lowered. Therefore, based on the consideration of suppressing other metallographic crystallization, the value is above the /3 metamorphic point. When the temperature starts to cool, at least in the stage before the temperature is lowered to 500 °C, the average cooling rate is preferably 1 to 100 °C / sec, because other metallographic crystals are used in this range of cooling rate. There are fewer possibilities for analysis. In particular, XV + 2.95XFe + 1.5XM 〇 + 1.65XCr has a enthalpy of 17% or less, and it is easy to crystallize other metal phases due to a low cooling rate, so the cooling rate in the above range is employed. It is advisable to carry out cooling. The reason why the cooling rate is selected in the range of 1 to 100 ° C / sec is that if it is 1 ° C / sec or less, it is easy to crystallize other metal phases other than the Θ phase; however, even if the cooling rate is increased to 100 ° It is not easy to increase the effect of preventing the metallographic crystallization other than the phase.

In addition, the elements used to stabilize the Θ phase, in addition to V, Fe, Mo, Cr, can also be used alone or in combination with ^, ^, ..., "^ (^ and other elements. The content of these elements, Nb: 〇 · 5 〜2%, Ta: 0.5 to 2%, Nl·0.25 to 1%, Μη: 0.25 to 1%, Co·0.25 to 1%' and the weight % of V of S is Xv, and the weight % of Fe contained The weight % of Mo contained in xFe is XM. The weight % of Cr contained is Xcr, the weight % of Nb contained is XNb, and the weight % of Ta contained is XTa and the weight of Ni contained. % is XNi, the weight % of Μη contained is, and the weight % of Co contained is Xc. When xv + 2.95XFe+ 1.5XMc) + 1.65Xcr + -10- 1277657 *

[Is / 3 phase stabilization index ※1 19.8 20.6 19.6 20.5 20.5 20.5 22.0 20.1 20.9 cn rH (Ν ! 21.2 16.5 26.8 10.5 20.0 27.9 24.9 23.5 Ingredients (%) Remaining 1 remaining I remaining the rest remaining rest remaining i remaining rest remaining i rest the rest of the rest of the remaining 1 remaining 1 Μ ο ο 〇 ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο Cn ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο Mm cn mmm cn mmm (Τ) m cn inch m Μο Ο (Ν ο ο ο (Ν d ο dd ο ο ο ο ο Ο Vh U inch inch in d inch inch inch inch inch inch CN ο Ον ν〇 inch<υ ν/ τ τ-Η rH 1—H rH in t—Η Η ^T) rH τ—Η τ-Η m ο ο Ο ο rH > 00 00 00 00 00 00 00 00 00 00 00 00 ο (Ν m τ-Η ^Η τ··Η Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Example 9 Example ίο Example 11 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 M}s. UXIc^i+ixε·(N+gx9·ΐ3⁄4: εd+fx inch Όΐxς9Ί+ix "l弋3⁄4ς6·(N+>x: l※ϊi^ •12- (10) 1277657 _ After the melt treatment, it is cooled to 50 〇t at an average cooling rate of 4 °C / sec, and then naturally cooled to room temperature. After the scale was removed, cold milk was applied to prepare a sheet sample of a type 5 titanium alloy having a thickness of 1 mm. (Evaluation method) The following items were evaluated for each of the examples and the comparative examples. <Heat deformation resistance> A test piece having a diameter of 8 mm x a length of 12 mm was cut out from the ingot, and the test piece was tested by a heating type automatic recording apparatus to obtain a heat distortion resistance. Specifically, the test piece was rapidly heated to 900 ° C by infrared rays, and the stress at the time of compression processing at a compression ratio of 50% at a speed of 50 mm/sec was determined, and this stress was regarded as "heat room". Deformation impedance". <Critical Cold Rolling Emulsion Rate> After hot rolling the ingot to a thickness of 4 mm, a melt treatment was carried out, and after cooling, the upper and lower surfaces were scraped off by 0.5 mm to remove the scale, so that the thickness of the sheet became 3 mm. . Next, the end faces were honed with sandpaper of #1 〇0, and then cold rolled. After each 1% of cold rolling was performed, the end faces were observed once to confirm whether cracks were generated. If there is more than one crack per 10 mm (the depth of the crack is -13 - (11) 1277657 · the degree is 1 mm or more from the end face), the rolling rate at that time is regarded as "critical cold". Rolling rate". Further, regarding the critical cold rolling ratio, the enthalpy of 70% (〇.9 mm thickness) was taken as the maximum. <Endurance and tensile strength> A sample having a thickness of 1 mm was prepared into two samples, one of which was first subjected to heat treatment in a vacuum and then subjected to a melt treatment (800 ° C X for 15 minutes); the other was After the above melt treatment, aging treatment (500 ° C x 8 hours) was carried out. These heat-treated sheet samples were prepared such that the width of the parallel portion was 6.25 mm; the distance between the punctuation points was a half-size tensile test piece of 25 mm, and according to the tensile test method of JIS Z 2241, 0.1 mm. A tensile test was performed at a speed of /min to determine tensile strength and 0.2% endurance. The evaluation results of the above items are shown in Table 2. -14- (12) 1277657 - (12)

[(Ns aging treatment tensile strength (MPa) 1446 1394 1334 1042 1412 1203 1405 1395 1342 1350 1305 950 1 1198 1009 1146 1190 endurance (MPa) 1360 1316 1252 1337 1345 1_ 1120 1342 1331 1295 1296 1210 870 雠1088 940 1034 1050 aging treatment tensile strength (MPa) 882 857 699 ! 844 852 845 840 845 842 850 725 839 1 672 885 856 860 endurance (MPa) 831 814 654 812 815 820 807 815 810 812 450 782 1 642 866 834 822 critical Cold rolling rate (%) 〇 〇 〇 〇 〇 〇 〇 〇 〇 〇 〇 〇 〇 〇〇 〇〇 〇〇 〇〇 〇〇 〇〇 〇 〇 〇 〇 〇 〇 〇 〇 〇 〇 〇 〇 〇 〇 205 205 205 205 205 205 205 205 205 205 205 205 205 205 205 205 205 205 215 205 210 214 213 193 233 丨 175 185 295 270 225 Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Example 9 Example 10 Example 1 Comparison Example 1 Comparison Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 -15- (13) 1277657. Further, Table 3 shows the conditions of Reference Examples 1 to 7 and the state in which it was observed whether or not other metal phases were formed. 1~7, over-melting The average cooling rate after cooling to 5 〇〇c after the treatment was a condition as shown in Table 3. The other conditions were the same as those of the sample of Example 1 except that the average cooling rate was different. The observation method is to use an X-ray diffraction device to determine from the chart whether or not a metal phase other than the Θ phase is formed. Table 3]

Average cooling rate (°C / sec) after cooling to 500 ° C after melt treatment Other forms of metallographic reference Example 1 0 0 No reference example 2 10 No reference example 3 2 No reference example 4 80 No reference example 5 0.5 Reference Example 6 was observed 0.1 Reference Example 7 was observed 0.01 iJL was observed From the results of Table 2, it was found that Examples 1 to 1 1 and Ti-20V-4A1-1 Sn 0 of Comparative Example 3 As a result of the titanium alloy, the critical cold rolling rate does not decrease, but the cold inter-processability is also excellent with the _ ^ Ti-20V-4Al-lSn/3 type titanium alloy. Further, the results of Examples 1 to 11 and Ti-20V-4AMSn3 -16-(14) and 1277657-type titanium alloys of Comparative Example 3 showed t 前后 before and after the aging treatment. Therefore, it is understood that a titanium alloy having superior strength to Ti-2〇V-4A1. alloy can be obtained according to the present invention. Further, from the results of Reference Examples 1 to 7, it is understood that the average cooling rate until the temperature is cooled to 500 ° C after the combination (in the range of ° C / sec, the metallographic phase other than the Θ phase can be lowered) 虞i higher number lSn/5 type titanium F melter) selected in the pre-3 precipitation -17-

Claims (1)

(1) 1277657 X. Patent Application Range 1. A yS type titanium alloy characterized by: V: 5 to 15% by weight, Fe: 0.5 to 2.5%, Μο: 0.5 to 6%, Cr: 0.5 to 5%, and the weight % of V contained is Xv, the weight % of Fe contained is XFe, and the weight % of Mo contained is Xm. When the weight % of Cr contained is XCr, the enthalpy of Xv + 2.95XFe + 1·5ΧΜο + 1.65XCr is 15 to 23%, and contains Al: 1.5 to 5%, and the remaining ® is composed of Ti and impurities. . 2. A type 8 titanium alloy characterized by: V: 5 to 15% by weight, Fe: 0.5 to 2.5%, Mo: 0.5 to 6%, Cr: 0.5 to 5%, and The weight % of V contained is Xv, the weight % of Fe contained is XFe, and the weight % of Mo contained is Xm. When the weight % of Cr contained is XCr, the enthalpy of Xv+ 2.95XFe + 1.5XM 〇 + 1.65XCr is 15 to 23%; and Al: 1.5 or more and less than 5%; and Sn: 5% or less and Zr: At least one of 5% or less; the weight % of A1 contained is XA1, the weight % of Sn contained is XSn, and the weight % of Zr contained is XZr, XA1+ ( XSn / 3 ) + (Xzr/ The enthalpy of 6) is 1.5 to 5, and the rest is composed of Ti and impurities. 3. A type/3 type titanium alloy characterized by: V: 5 to 15% by weight, Fe: 0.5 to 2.5%, Mo: 0.5 to 6%, Cr: 0.5 to 5%, and containing At least one selected from the group consisting of Nb: 0.5 to 2%, Ta: 0.5 to 2%, Ni: 0.25 to 1%, Μη: 0.25 to 1%, and Co: 0.25 to 1%; and Weight -18- (2) 1277657 % is Xv, and the weight % of Fe contained is XFe and % is Xm. The weight % of Cr contained is XCr, % is XNb, and the weight % of Ta contained is XTa % is XNi, and the weight % of Mn contained is XMn, and % is Xc. When, Xv + 2.95XFe + 1·5ΧΜο + 0.3XTa + 1.6XNi + 2.3XMn + 2.1Xc. The crucible is Al: 1.5 to 5%; the rest is Ti and hetero-f 4. A type/3 type titanium alloy characterized by: V: 5 to 15% by weight, Mo: 0.5 to 6 %, Cr: 0.5 to 5%, and at least one selected from Ta: 0.5 to 2%, Ni: 0.25 to 1%, Μη: 0.25 to 1%; i% is Xv, and Fe contained The weight % is XFe and the % is Xm. The weight % of Cr contained is XCr, % is XNb, and the weight % of Ta contained is XTa % is XNi, and the weight % of Μη contained is XMn and % is Xc. When Xv + 2.95XFe + 0.4XNb + 〇.3XTa+ 1.6X]SIi+2.3XMn + 2· lXc〇 and contains Al: 1.5 or more and less than 5%; and at least one of Zr: 5% or less; XA1 When the weight % of Sn contained is XSn or Xzr sold, XA1+ ( Xsn / 3 ) + ( XZr / 6 ) is composed of Ti and impurities. 5 . The heat treatment method of the type / 3 type titanium alloy, the weight of the niobium contained in the weight of the niobium contained, the weight of the Ni contained, and the weight of the C 含 contained 1.65XCr + 0.4XNb + 15~23 % ; and consists of ί. Fe: 0.5 to 2.5%, Nb: 0.5 to 2%, 0.25 to 1%, the weight of V contained in the weight of V contained in Co: L, the weight of Nb, and the weight of Ni contained. The weight of C 〇 containing 1.5 X 〇 . . . . 値 値 値 値 値 値 値 値 値 値 値 値 値 値 値 ; ; ; ; ; 有 有 有 有 有 有 有 有 有 有 有 有 有 有 有 有 有 有 有 有 有 有 有 有 有 有 有</ RTI> </ RTI> </ RTI> </ RTI> </ RTI> </ RTI> </ RTI> </ RTI> </ RTI> </ RTI> </ RTI> </ RTI> </ RTI> <RTIgt; Then, at an average cooling rate of 1 to 100 ° C / sec, cool to a temperature of at least 500 ° C. -20-