Titanium alloy having high ductility, fatigue strength and rigidity and method of manufacturing same

a technology of titanium alloy and ductility, which is applied in the field of titanium alloys having high ductility, fatigue strength and rigidity and manufacturing methods, can solve the problems of not developing high hot workability and ductility, no improvement has been succeeded in achieving high ductility and ductility, and the effect of reducing fatigue strength and ductility

Inactive Publication Date: 2003-05-08
SUMITOMO METAL IND LTD +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

0048] In order to securely transform the needle structure of the matrix to the equiaxial structure, it is effective to provide a sufficient working stress and it is referable that the hot working is carried out at a working rate not less than 50%. The crystallization and/or precipitation of coarse TiB particles causes the ductility and the fatigue strength to be reduced. To avoid such reduction, it is necessary to destroy the coarse particles by the hot working. In this case, the working rate should be preferably not less than 70%.
0049] In the titanium alloy, a decreased temperature for working provides a reduction in the hot workability as well as the generation of working fractures. To obtain a proper working temperature, either a heat insulation material is coated onto the ingot, or the temperature in the circumference is appropriately increased within a temperature range for the warm working or the hot working, or the ingot is re-heated at a temperature smaller than the .beta. transu

Problems solved by technology

As described above, there is a problem that titanium alloy has a relatively higher mechanical strength, but a smaller Young's modulus, compared with the iron or steel materials.
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Method used

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  • Titanium alloy having high ductility, fatigue strength and rigidity and method of manufacturing same
  • Titanium alloy having high ductility, fatigue strength and rigidity and method of manufacturing same
  • Titanium alloy having high ductility, fatigue strength and rigidity and method of manufacturing same

Examples

Experimental program
Comparison scheme
Effect test

example 1

[0053] A titanium alloy having the composition shown in Table 1 was arc-melted in a vacuum melting furnace to form an ingot having a 140 mm diameter. The .beta. transus temperature of the titanium alloy used in the test was 1070.degree. C.

1TABLE 1 Composition of elements (mass %) Al V Mo B O H Ti 7.72 0.41 0.50 0.90 0.094 0.014 Bal.

[0054] By applying twice the hot forging and the solution treatment to the alloy ingot obtained under the following conditions, test pieces were produced:

[0055] 1. Rough-Forging

[0056] Size after forging: outside diameter 80 mm (working rate 68%, forging rate 3)

[0057] Heating temperature: 1170.degree. C. (the .beta. transus temperature+100.degree. C.)

[0058] 2. Finish Forging

[0059] Size after forging: outside diameter 25 mm (working rate 90%, forging rate 10)

[0060] Heating temperature: 1040.degree. C. to 1170.degree. C. (the respective heating temperatures being indicated in FIG. 1)

[0061] 3. Solution Treatment

[0062] Heating temperature: 700.degree. C. to 11...

example 2

[0067] Utilizing the alloy ingot obtained in Example 1, the effect of the aging treatment after the solution treatment was studied by varying the conditions of hot forging. The titanium alloys used to test were treated according to the following processes A to D.

[0068] 1. Process A (Comparative Example)

[0069] 1-1. Finishing Forging

[0070] Size after forging: outside diameter 25 mm (working rate 97%, forging rate 30)

[0071] Heating temperature: 1170.degree. C. (the .beta. transus temperature+100.degree. C.)

[0072] 1-2. Solution Treatment

[0073] Condition of treatment: 900.degree. C..times.2 hours

[0074] 2. Process B (Comparative Example)

[0075] 2-1. Finishing Forging

[0076] Size after forging: outside diameter 25 mm (working rate 97%, forging rate 30)

[0077] Heating temperature: 1170.degree. C. (the .beta. transus temperature+100.degree. C.)

[0078] 2-2. Solution Treatment

[0079] Treatment condition: 900.degree. C..times.2 hours

[0080] 2-3. Aging Treatment

[0081] Treatment condition: 580.degree. ...

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Abstract

A titanium alloy is provided wherein metal boride is uniformly crystallized and/or precipitated in the matrix. The heating temperature in the finishing hot working is set smaller than the beta transus temperature by not less than 10° C., thereby causing the matrix to include an equiaxial alpha structure in a rate of not less than 40 vol %. This titanium alloy has excellent properties, i.e., high rigidity, ductility and fatigue strength, which are all required for structural components, and therefore can be widely applied to a mechanical component such as an engine of an automobile, a structural component in an aircraft as well as a component for a high speed rail vehicle.

Description

[0001] The present invention relates to a titanium alloy having a high ductility, fatigue strength and rigidity, which alloy is used in a mechanical component requiring excellent mechanical properties and a light weight as well, for instance, a connecting rod, valve, camshaft, crankshaft and push rod in an engine of an automobile or a structural component in an aircraft, a high-speed rail vehicle or the like. The present invention also relates to a method of manufacturing such a titanium alloy.[0002] A titanium alloy has excellent properties for the corrosion resistance and the heat resistance, along with a high mechanical strength and a lightweight property, so that an application of the alloy to various mechanical components in an automobile, an aircraft and a high-speed rail vehicle is now widely extending. However, titanium alloy has a relatively small Young's modulus, i.e., about half of that in iron or steel materials. Accordingly, buckling and bending must be taken into accou...

Claims

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Application Information

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IPC IPC(8): C22C14/00C22F1/18
CPCC22F1/183C22C14/00
Inventor ARIYASU, NOZOMUMATSUMOTO, SATOSHI
Owner SUMITOMO METAL IND LTD
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