Near β-type titanium alloy
View Patent ↗A near-beta titanium alloy having higher strength than ‘Ti-17’ is provided, while suppressing cost increase. Such a near-&bgr; titanium alloy consists of, in weight percent, 0.5-7% of V, 0.5-2.5% of Fe, 0.5-5% of Mo, 0.5-5% of Cr, 3-7% of Al, and the balance of Ti and impurities. When the weight % of V content is expressed as X V , the weight % of Fe content is expressed as X Fe , the weight % of Mo content is expressed as X Mo , and the weight % of Cr content is expressed as X Cr ; the value of X V +2.95X Fe +1.5 X Mo +1.65X Cr is 9-17%.
1. A near β-type titanium alloy consisting essentially of, by mass %, V: 0.5 to 1.0%, Fe: 0.5 to 2.5%, Mo: 0.5 to 2% and Cr: 3 to 5%, wherein the value of X V +2.95X Fe +1.5X Mo +1.65X Cr is from 9 to 17%, wherein X V represents the mass % of the V, X Fe represents the mass % of the Fe, X Mo represents the mass % of the Mo and X Cr represents the mass % of the Cr, and further comprising, by mass %, Al: 3 to 7%, wherein Ti and impurities constitute the residue, wherein the near β-type titanium alloy has a microstructure formed into an equiaxial structure.
2. A near β-type titanium alloy consisting essentially of, by mass %, V: 0.5 to 1.0%, Fe: 0.5 to 2.5%, Mo: 0.5 to 2% and Cr: 3 to 5%, wherein the value of X V +2.95X Fe +1.5X Mo +1.65X Cr is from 9 to 17%, wherein X V represents the mass % of the V, X Fe represents the mass % of the Fe, X Mo represents the mass % of the Mo, and X Cr represents the mass % of the Cr, and
further comprising, by mass %, Al: 3% to less than 7% and at least one of the group consisting of Sn: not less than 3% and not more than 4% and Zr: not more than 4%, wherein the value of X Al +(X Sn /3)+(X Zr /6) is from 3 to 7, wherein X Al represents the mass % of the Al, X Sn represents the mass % of the Sn and X Zr represents the mass of the Zr, wherein Ti and impurities constitute the residue, wherein the near β-type titanium alloy has a microstructure formed into an equiaxial structure.
3. A near β-type titanium alloy comprising, by mass %, V: 0.5 to 1.0%, Fe: 0.5 to 2.5%, Mo: 0.5 to 2%, Cr: 3 to 5% and at least one selected from the group consisting of Nb: 0.5 to 2%, Ta: 0.5 to 2%, Ni: 0.25 to 1%, Mn: 0.25 to 1% and Co: 0.25 to 1%, wherein the value of X V +2.95X Fe +1.5X Mo +1.65X Cr +0.4X Nb +0.3X Ta +1.6X Ni +2.3X Mn +2.1X Co is from 9 to 17%, wherein X V represents the mass % of the V, X Fe represents the mass % of the Fe, X Mo represents the mass % of the Mo, X Cr represents the mass % of the Cr, X Nb represents the mass % of the Nb, X Ta represents the mass % of the Ta, X Ni represents the mass % of the Ni, X Mn represents the mass % of the Mn and X Co represents the mass % of the Co, and further comprising, by mass %, Al: 3 to 7%, wherein Ti and impurities constitute the residue, wherein the near β-type titanium alloy has a microstructure formed into an equiaxial structure.
4. A near β-type titanium alloy comprising, by mass %, V: 0.5 to 1.0%, Fe: 0.5 to 2.5%, Mo: 0.5 to 2%, Cr: 3 to 5% and at least one selected from the group consisting of Nb: 0.5 to 2%, Ta: 0.5 to 2%, Ni: 0.25 to 1%, Mn: 0.25 to 1% and Co: 0.25 to 1%, wherein the value of X V +2.95X Fe +1.5X Mo +1.65X Cr +0.4X Nb +0.3X Ta +1.6X Ni +2.3X Mn +2.1X Co is from 9 to 17%, wherein X V represents the mass % of the V, X Fe represents the mass % of the Fe, X Mo represents the mass % of the Mo, X Cr represents the mass % of the Cr, X Nb represents the mass % of the Nb, X Ta represents the mass % of the Ta, X Ni represents the mass % of the Ni, X Mn represents the mass % of the Mn and X Co represents the mass % of the Co, and
further comprising, by mass %, Al: 3% to less than 7% and at least one selected from the group consisting of Sn: not less than 3% and not more than 4% and Zr: not more than 4%, wherein the value of X Al +(X Sn /3)+(X Zr /6) is from 3 to 7, wherein X Al represents the mass % of the Al, X Sn represents the mass % of the Sn and X Zr represents the mass % of the Zr, and wherein Ti and impurities constitute the residue, wherein the near β-type titanium alloy has a microstructure formed into an equiaxial structure.
5. A method for hot working of the near β-type titanium alloy of claim 1 , comprising hot working a near β-type titanium alloy at a temperature lower than the β transformation point and equal to or higher than a temperature 100° C. lower than the β transformation point.
6. A method for hot working of the near β-type titanium alloy of claim 2 , comprising hot working a near β-type titanium alloy at a temperature lower than the β transformation point and equal to or higher than a temperature 100° C. lower than the β transformation point.
7. A method for hot working of the near β-type titanium alloy of claim 3 , comprising hot working a near β-type titanium alloy at a temperature lower than the β transformation point and equal to or higher than a temperature 100° C. lower than the β transformation point.
8. A method for hot working of the near β-type titanium alloy of claim 4 , comprising hot working a near β-type titanium alloy at a temperature lower than the β transformation point and equal to or higher than a temperature 100° C. lower than the β transformation point.