JPS62150159A - Ultrasonic flaw detection and inspection for beta-type titanium alloy - Google Patents

Abstract

PURPOSE:To enable accurate ultrasonic flaw detection, by applying aging to a beta-type titanium alloy material before finished as solution treated product thereof to perform a ultrasonic flaw detection with alpha phase deposited. CONSTITUTION:When manufacture a product from beta-type titanium alloy material by having hot worked material undergoing a solution treatment at a temperature range exceeding beta transformation point, the dumping of ultrasonic wave is large in an ultrasonic flaw detection and inspection of a solution treated product itself. Therefore, execution of an ultrasonic flaw detection with a high sensitivity will cause upright echoes frequently due to coarser particle size which make it impossible to detect internal defects accurately. To avoid this, an aging is applied to the alloy material to deepest alpha phase before finished as solution treated products, a condition which an ultrasonic is performed and thus, accurate ultrasonic flaw detection is made possible.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an inspection method using ultrasonic flaw detection for β-type titanium alloy material, and particularly relates to an ultrasonic flaw detection method for using solution-treated β-type titanium alloy material as a product. The present invention relates to an inspection method characterized in that when carrying out a flaw detection inspection, an ultrasonic flaw detection inspection is carried out not directly on a solution-treated material product, but on a material that has been subjected to an aging treatment to precipitate an α phase. The present invention is based on β
It is possible to perform ultrasonic flaw detection with good quality even on solution-treated material products that are easily subjected to phase coarsening, for example, after hot processing.

BACKGROUND OF THE INVENTION Titanium and titanium alloys have excellent specific strength, corrosion resistance, and heat resistance, and are therefore used in a wide variety of applications such as aerospace materials, various chemical plants, and seawater desalination equipment.

Conventionally, α+β type alloys such as Ti-6AI-4V have been widely used as titanium alloys, but α+
β-type alloys have poor formability and rely on cutting for much of the processing, resulting in a very low yield rate for final products. Therefore.

The use of β-type titanium alloys has been gaining momentum in recent years because they have superior cold workability and high strength compared to α+β-type alloys.

The β-type titanium alloys in the present invention are Ti-15V-11Cr-3AI, Ti-11,
5Mo-4,5Sn-6ZrTi-15V-3Cr-3
Contains alloys such as Sn-5Al and Ti-10V-2Fe-3A1.

β-type titanium alloys are alloys in which the β phase is relatively stable, so the β phase can be easily brought to room temperature by solution treatment, and in this solution treatment state, it has excellent workability. .

Therefore, the manufacturer ships the solution-treated alloy material as a product, and the user receives the solution-treated material and processes it according to the purpose, followed by aging treatment to obtain the required strength. It is common to do this.

Therefore, manufacturers of β-type titanium alloys generally inspect products shipped in a solution-treated state using ultrasonic flaw detection.

Conventional technology and problems In solution treatment of β-type titanium alloys, in order to make the metal structure into a single β phase, the α phase is heated and held at a temperature above the β transformation point to disappear, and then the α phase is precipitated. This is a heat treatment in which cooling is performed at a cooling rate that does not occur.

However, the growth rate of β-phase crystal grains due to heating in the β region is high, and especially in materials after hot working, the crystal grains become coarser.

Since coarse crystal grains that have grown in this way have large attenuation of ultrasonic waves, ultrasonic flaw detection must be performed with high sensitivity.

However, when ultrasonic flaw detection with increased sensitivity is performed on solution-treated β-type titanium alloy materials with coarse grains, high noise occurs frequently and the S/N ratio is small, so it is difficult to detect the presence or absence of internal defects. There was a problem in that it was difficult to accurately grasp the position, etc., and it was difficult to perform accurate inspection.

At present, there are several reports on the manufacturing method of β-type titanium alloy, but there are no reports on non-destructive testing of the product.

Under these circumstances, countermeasures are needed to overcome the above-mentioned difficulties.

Summary of the Invention The present invention provides an accurate inspection method that can accurately detect the presence or absence and location of internal defects in ultrasonic testing of solution-treated β-type titanium alloy materials. For the purpose of providing.

The inventors of the present invention have conducted extensive research on methods that can improve the accuracy of ultrasonic flaw detection of β-type titanium alloys when solution-treated materials are used as products. The small S/N ratio in sonic flaw detection is due to the grain growth of the β single phase, which has a large attenuation of ultrasonic waves. We have obtained new knowledge that the S/N ratio can be greatly improved by subjecting the alloy material in this state to ultrasonic flaw detection.

In other words, when a β-type titanium alloy material, especially a hot-worked material, is solution-treated at a temperature above the β-transformation point to produce a product, it is necessary to perform ultrasonic flaw detection on the solution-treated material product itself. Since the attenuation of ultrasonic waves is large, inspection must be performed with increased sensitivity. However, when ultrasonic flaw detection is performed with high sensitivity, forest-like echoes occur frequently as noise due to the coarse grain size, making it difficult to accurately detect internal defects, if any.

However, if the β-type titanium alloy material targeted for ultrasonic flaw detection is subjected to aging treatment to finely precipitate the α phase, and then ultrasonic flaw detection is performed using a comparison test piece that has been subjected to the same treatment, the sensitivity is low. Since the echo of the standard defect of the comparison test piece can be adjusted to a predetermined level, the S/N ratio can be greatly improved. Therefore, it has been found that if an internal defect exists in the target β-type titanium alloy material, it is possible to accurately detect its presence and location. They originate from the processing process, and their presence, location, size and shape do not change through solution treatment and aging treatment.

Based on these findings, the present invention provides a method for inspecting solution-treated β-type titanium alloy products by ultrasonic flaw detection, in which the alloy material is subjected to aging treatment before being made into the solution-treated product to obtain α phase. Provided is an ultrasonic testing method for β-type titanium alloy, which is characterized by performing ultrasonic flaw detection in a precipitated state. Generally, before solution treatment, the alloy material is aged and subjected to ultrasonic flaw detection, and then solution treatment is performed to produce a solution treatment product. The alloy material may be subjected to aging treatment, subjected to ultrasonic flaw detection, and then subjected to solution treatment again to produce a solution treatment material product.

In this way, the present invention abandons the fixed idea that inspection must be performed on the final product itself, and enables highly accurate inspection while ensuring 1:1 correspondence between the final product and internal defect status. The β-type titanium alloy that is the subject of the present invention is based on the unique idea of utilizing the α phase fine precipitation state for inspection purposes.
11Cr-3Al, Ti-1t5Mo-4,5Sn
-6Zr.

Ti-15V-3Cr-3Sn-5A1. Tt-10
It is a titanium-based alloy such as V-2Fe-3A1.

Titanium alloy processed products are generally manufactured from cast ingots through processes such as rolling, forging, and extrusion, depending on the quality and shape of the product, and are then subjected to solution treatment, solution aging, etc., depending on the required quality of the product. Heat treatment such as processing is performed, and the final? The products are tested for mechanical properties, metallographic structure, non-destructive testing, etc.

The present invention is characterized by a method of ultrasonic flaw detection as a non-destructive inspection when solution-treated materials are used as products.

β-type titanium alloys are generally delivered to users in a solution-treated state, which is heated to a temperature above the β transformation point and cooled at a cooling rate that does not precipitate the α phase, and the user processes this according to the purpose. After fC, aging treatment is performed to obtain a member with high strength.

For example, taking the Ti-15V-3Cr-3Sn-3A1 alloy as an example, solution treatment is performed at the β transformation temperature (730-770℃
) is maintained at a temperature in the range of 780 to 830° C. for 3 to 60 minutes, and then cooled to room temperature 1 at a cooling rate higher than air cooling. Aging treatment is generally performed at a temperature of 400 to 600°C.

The object of the present invention is an ultrasonic flaw detection method carried out by manufacturers of titanium alloy materials to ensure the quality of solution-treated products delivered to users.

Therefore, the manufacturing method of this titanium alloy is not particularly stipulated, but it is particularly suitable for hot-worked finished materials and high-temperature solution treated materials of β-type titanium alloys, which tend to coarsen grains due to solution treatment. On the other hand, the inspection method according to the present invention is effective.

In addition, processing methods such as forging, hot rolling, and extrusion are also specified as manufacturing methods.When manufacturing a solution-treated material of 0β type titanium alloy into a product, according to conventional methods,
When performing ultrasonic flaw detection on a β single-phase product itself with coarse grains, it is difficult to accurately inspect the presence or absence and location of internal defects due to frequent forest-like echoes. Therefore, the present invention provides Before performing the final vulgarization treatment, α phase is finely precipitated in the β phase by aging treatment, and then ultra-high wave flaw detection is performed using a comparison test piece that has been subjected to the same treatment. In a situation where a product that has already undergone solution treatment is sent to the inspection stage, it may be subjected to aging treatment, ultrasonic flaw detection, and then re-solution treatment.

With this method, the noise caused by forest echoes is greatly reduced9 and the S/N ratio is improved, making it possible to accurately detect the presence or absence and location of internal defects.

Here, the aging treatment conditions performed before the final solution treatment differ depending on the type of β-type titanium alloy, but it is sufficient to select a temperature and time range in which the α phase is finely precipitated. For example, Ti
-400~ for 15V-3Cr-3Sn-3A1
Aging treatment is performed at 600°C for 1 to 20 hours.

Effects of the Invention We have succeeded in establishing an inspection method that enables highly accurate ultrasonic flaw detection when solution-treated β-type titanium alloy materials, which have been increasingly used in recent years, are used as products.

Examples and Comparative Examples β-type titanium alloy (Ti-15V-5
The chemical components of Cr-3Sn-3AI) are shown in Table 1.

The ingot used had a diameter of 550mm, which was
After heating to 050°C, a round billet with a diameter of 200++1 ml was produced, which was further heated to 900°C and then ring-rolled to produce a ring material with an outer diameter of 420, an inner diameter of 350, and a thickness of 100 m+. After removing the surface scale layer of this ring material by machining, it was heated in a vacuum heating furnace for 5 minutes.
Those subjected to aging treatment at 50°C for 14 hours, those subjected to solution treatment by heating and holding at 800°C for 30 minutes and then cooled with Ar gas (B), and (B)
Ultrasonic flaw detection was performed on two pieces of each piece (C) which had been aged at 550°C for 14 hours. The results of this ultrasonic flaw detection are shown in Table 2.

The ultrasonic flaw detection conditions are as follows.

(1) Flaw detection method Contact type % type % (4) Comparative test piece Materials with the same chemical composition manufactured in the same process and subjected to the same heat treatment (5) Standard defect 5/64 inch diameter flat bottom hole (depth 60°1) Adjusting the echo of the sieve to 50 cm of the full scale of the cathode ray tube screen λ According to the ultrasonic flaw detection results table 2, the noise of the solution-treated material is very high, and the echo due to the standard defect and 3/64 inch flat bottom hole is high. Accurate ultrasonic flaw detection is difficult because the flaw is close to 50%. However, the maximum noise height of the test object subjected to the aging treatment before solution treatment and the one subjected to aging treatment after solution treatment according to the method of the present invention is the same as the full scale of the CRT screen. On the other hand, it is less than 4%, which is very low compared to the echo of standard defects, and it can be seen that the inspection accuracy is greatly improved. Therefore, the present invention brings about a great effect on highly accurate ultrasonic flaw detection when a solution-treated β-type titanium alloy material is used as a product.

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Claims (1)

[Claims] 1) In a method of inspecting a solution-treated β-type titanium alloy product by ultrasonic flaw detection, the titanium alloy material before being made into the solution-treated product is subjected to an aging treatment to remove the α phase. An ultrasonic flaw detection method for β-type titanium alloy, characterized by performing ultrasonic flaw detection in a precipitated state. 2) The method according to claim 1, wherein the solution-treated alloy material is subjected to aging treatment, subjected to ultrasonic flaw detection, and then subjected to solution treatment again to produce a solution-treated material product.