JPS63242489A - Beta-type titanium alloy welding rod - Google Patents

Abstract

PURPOSE:To provide the beta-type Ti alloy electrode capable of preventing the reduction in ductility of weld zone at the time when using for welding beta-type Ti alloy especially, made by the Ti alloy contg. Y and/or B in specific amt. in the beta-type Ti alloy. CONSTITUTION:The beta-type Ti alloy electrode of this invention is composed of the Ti alloy contg. 0.02-0.10 wt.% Y and/or 0.002-0.10 wt.% B in the beta-type Ti alloy. As said beta-type Ti alloy Ti-15V-3Cr-3-Sn-3Al is given, for instance. In this invention, the Y and B impede the movement of grain boundary by being entering into solid solution as an intermetal compound and simple substance, working to refine crystal grains. Consequently, the ductility reduction of a weld zone can be prevented by using the welding rod of this invention.

Description

Detailed Description of the Invention [Field of Industrial Application] This invention relates to a titanium-based alloy welding rod, and in particular to a titanium-based alloy welding rod that prevents a decrease in ductility that occurs in a welded part when used for welding β-type titanium alloy. This is related to welding rods.

[Prior art] β-type titanium alloy is T i −15V −3Cr −
3Sn-3A I, Ti-13V-11Cr
-3A I, T i -11,5MO-62r -4,
53n, T i -3A I -8V -6Cr -
4Mo-4Zr and the like are known, and this is attracting attention as a titanium alloy with excellent formability and high strength, and is expected to be used in various fields. One such important field is the use as groove structures, and in this case, adaptability to welding is an essential element.

For welding β-type titanium alloys, EB welding, laser beam welding, TIG welding, or MIG:8 welding is used.

[Problems to be solved by the invention] Among the above welding methods, EB welding and laser beam welding have a small amount of heat input and there is no problem, but TIG welding and MIG welding cause a significant decrease in ductility of the welded part. The problem arises that it causes

Therefore, when such a welding method is used, it is necessary to take measures such as forced cooling of the material.

[Means for Solving the Problems] The inventor has made extensive studies to solve this problem of reduced ductility in welded parts. The reason for this decrease in ductility is that it takes a long time for the welded part of the β-type titanium alloy to melt, assimilate, and cool, and during that time, the α phase does not appear, and it is composed only of the β phase. As a result of the coarsening of the crystal grain size, stress concentration tends to occur at the grain boundaries,
It is assumed that this is because grain boundary cracking is more likely to occur.

Then, we focused on the fact that yttrium and boron are dissolved as intermetallic compounds or simple substances in titanium or titanium alloys, and have the effect of hindering the movement of grain boundaries and refining crystal grains.
We thought that the above-mentioned decrease in ductility could be improved by utilizing the effects of yttrium and boron, and as a result of repeated research, we finally developed a titanium-based alloy welding rod with the specific composition shown below. By doing so, we were able to solve the above problems.

In other words, this invention has a β-type titanium alloy containing 0 yttrium.
．． 002-0.10% by weight and/or boron 0.0
This is a welding rod made of a titanium alloy containing 0.02 to 0.10% by weight.

The reason for using 0.002 to 0.10% by weight of yttrium and boron is that if it is less than 0.0021ffi%, the crystal grains will not become fine enough, so the effect of preventing ductility reduction will be insufficient; This is because if it exceeds 10fffffi%, there will be too many inclusions and the material will become brittle regardless of the crystal grain size, which is undesirable.

[Example code] Next, the present invention will be explained in more detail with reference to examples.

The sample material was Ti-1, a typical β-type titanium alloy.
5V-3Cr-3Sn-3A I was used as the base material.

Table 1 shows the chemical composition of sample materials A-L.

From sample material A, a cold rolled plate of 1 mmt was manufactured. The sample material B-I had a composition within the scope of the present invention, and bars of 2.0 mmφ×mm were manufactured from these. After the bar material was diced, it was subjected to centerless processing, pickling, and vacuum annealing.

Sample material J-L had a composition outside the scope of the present invention, and a bar material was produced in the same manner as A-I as a comparative example.

That is, J has a boron and yttrium content of 0,00% by weight or less, which is less than the lower limit of this invention, and K has a boron content of 0.20% by weight, and L has a boron content of 0.20% by weight. The content of yttrium is 0.22% by weight, which exceeds the upper limit of this invention.

Next, sample material A was TIG-welded using a welding rod B-1. In this case, the electrode is a thoriated tungsten 3.2
Using mmφx 150mm1, the welding current is ioo ~
The welding voltage was 110 A and 11.0 to 13 OV. 1OL'mi to torch gas using argon gas as shield
n, the aftergas was flowed at 251/min.

Material A was welded in a butt-to-butt state, and after welding, the top and bottom surfaces were milled by 0.2 mm each, and the gauge distance was JIS 1 of 50 mm.
A No. 3 B test piece was cut out as shown in Figure 1, and 510'CX
After aging for 8 hours, it was subjected to a tensile test. The results of this tensile test are shown in Table 2. This is the average value of N=3.

As is clear from Table 2, in B to ■, which have compositions within the range of the present invention, the effect of making the grain size finer appears and the elongation at break is significantly improved to 3% or more. On the other hand, in J, which is a comparative example, the grain size becomes coarse, causing embrittlement, and in L, the addition amount of boron or yttrium is too large, and cracks occur from inclusions caused by these, resulting in poor fracture propagation. ing.

Table 1 55 parts of fi is substantially 7i.

Table 2 [Effects of the Invention] When the welding rod of the present invention is used for welding β-type titanium alloy, it exhibits the remarkable effect of being able to prevent a decrease in the ductility of the welded part.

[Brief Description of the Drawings] Figure 1 is a diagram showing a method for collecting tensile test pieces of welded parts. 1... Welded part, 2... Tensile test piece. Figure O1 Procedural Amendment (Master) July 1, 1988 Director General of the Patent Office Kunio Ogawa 1, Indication of Case Patent Application No. 1988-73999 2
, Title of invention β-type titanium alloy welding rod 3, Relationship with the case of the person making the amendment Name of patent applicant Nippon Mining Co., Ltd. 4, Agent S, Date of amendment order (voluntary) 6. Subject of amendment (1) Details In the book, page 3, line 1, “assimilation” is replaced by “coagulation” day.
and correct it. (2) In the second line of the same page, amend "not appearing" to "not appearing." (3) In lines 4 and 5 of the same page, "probably occurs," is corrected to "produce,". [

Claims (1)

[Claims] (1) β-type titanium alloy with 0.002 to 0.00 yttrium.
10% by weight and/or boron 0.002-0.10
Welding rod made of titanium alloy containing % by weight.