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Titanium alloy excellent in intergranular corrosion resistance

A titanium alloy, high-quality technology, applied in the field of titanium alloys, can solve problems such as grain boundary corrosion, and achieve the effect of superior grain boundary corrosion resistance

Inactive Publication Date: 2012-01-11
KOBE STEEL LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, in some special environments, such as the premise that the Ti-Ni-Pd-Ru-Cr alloy is replaced every few years, the Ti-Ni-Pd-Ru-Cr alloy does not maintain a blunt body (not Severe use environment such as solid body), or the surrounding parts attached to the electrode of the electrolysis cell, in the environment where the anode current flows in the Ti-Ni-Pd-Ru-Cr alloy, there are corrosion forms showing grain boundaries Corrosion situation
[0008] Corrosion-resistant titanium alloys have good grain boundary corrosion resistance, and even in pure titanium, there is almost no grain boundary corrosion, but in the above special use environment, there are cases where grain boundary corrosion occurs

Method used

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  • Titanium alloy excellent in intergranular corrosion resistance
  • Titanium alloy excellent in intergranular corrosion resistance
  • Titanium alloy excellent in intergranular corrosion resistance

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0055] Use the commercially available Ti-Ni-Pd-Ru-Cr alloy, that is, JIS 14 kinds of cold-rolled annealed sheet (Ti-0.4Ni-0.015Pd-0.025Ru-0.14Cr alloy), and reduce it: 40% The cold-rolled cold-rolled steel sheet was made to have a thickness of 1.1mm, and the sheet was subdivided into the necessary amount, and the following atmospheric annealing (final annealing)→salt immersion→pickling treatment simulating the continuous annealing-pickling process was performed to produce a corroded steel sheet. test piece.

[0056] (atmospheric annealing)

[0057] Temperature: 670°C, 700°C, 725°C, 750°C, 775°C, 800°C, 830°C

[0058] Annealing time: 165 seconds

[0059] Salt immersion: Immerse for 1 minute in commercially available titanium derusting salt (チタントスケケルソルト) (trade name: manufactured by Japan Parkerizing Co., Ltd.: "Kelin DGS") heated to about 500°C

[0060] Pickling: using nitric acid (nitrate acid), pickling at a plate thickness of about 0.1mm

[0061] The obtained corrosion t...

Embodiment 2

[0070] For the corrosion test piece (the test piece whose final annealing temperature is 700° C.) made in the same way as in Example 1, Figure 5 (A drawing instead of a photograph) shows a secondary electron image (SEM image) and a result of mapping. The positions of the white precipitates seen on the SEM image roughly coincide with the parts with high concentrations of Ni, Cr, and Fe, and especially for Ni, the concentration difference between the base material part (α phase) and the precipitated part is clear, so it can be said that the precipitated part It is Ni-rich phase. On the other hand, it was found that Pd and Ru are substantially uniformly distributed.

[0071] therefore, Figure 6 (A photograph instead of a drawing) shows an example of observing the 14 μm angular field of view of the above-mentioned test piece again with a transmission electron microscope (TEM). The precipitates of 0.2 μm or more in the TEM image are surrounded by circles (◯), but the Ni conten...

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Abstract

A titanium alloy contains Ni in a content of 0.35% to 0.55%; Pd in a content of 0.01% to 0.02%; Ru in a content of 0.02% to 0.04%; and Cr in a content of 0.1% to 0.2%, with the remainder including titanium and inevitable impurities, in which the titanium alloy includes nickel-rich phases, each nickel-rich phase being a phase (other than titanium alpha phase) locally containing Ni in a content of 10 times or more the average Ni content of the titanium alloy, the nickel-rich phases are aligned along a rolling direction to form a row, and a multiplicity of the rows are aligned substantially in parallel in a cross direction. The titanium alloy minimizes the proceeding of intergranular corrosion even in specific environments where the intergranular corrosion may easily proceed.

Description

technical field [0001] The invention relates to a titanium alloy, which has good corrosion resistance in special environments, especially good grain boundary corrosion resistance. Background technique [0002] It is known that titanium exhibits good corrosion resistance in various chloride solutions including seawater, or in oxidizing acids such as nitric acid. However, in the case of being exposed to high-temperature and high-concentration conditions in a non-oxidizing environment such as hydrochloric acid or sulfuric acid, the excellent corrosion resistance cannot be exhibited. [0003] From the viewpoint of improving the corrosion resistance in the above environment, Ti—Pd alloys (JIS H 4650 11 to 13 types, ASTM Gr.7, Gr.11) containing about 0.12 to 0.25% of Pd have been used conventionally. [0004] In addition, recently, in order to make up for the above-mentioned shortcomings of the high price of Ti-Pd alloys, corrosion-resistant titanium alloys with reduced content o...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C14/00C22F1/18
CPCF28F21/086C22C14/00C22F1/183
Inventor 屋敷贵司
Owner KOBE STEEL LTD