JP2002317234A - Titanium sheet having excellent ductility and production method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a titanium sheet which combines strength and ductility of high orders, and a production method therefor. SOLUTION: (1) The titanium sheet has a composition in which the contents of H, O, N and Fe are the ones prescribed by the class 1 or class 2 in JIS H4600, and containing 50 to 800 ppm C, and the balance titanium with inevitable impurities. (2) Alternatively, the titanium sheet further contains 100 to 5,000 ppm Al. (3) In the production of the same titanium sheet, as a melting process, a cold crucible induction melting process is used. (4) In the production of the titanium sheet in the above (2), as a melting process, a VAR (Vacuum Argon Degassing) process is used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention belongs to the technical field of a titanium plate having excellent ductility and a method for producing the same.

[0002]

2. Description of the Related Art Titanium (Ti) specified in JIS H 4600 has excellent corrosion resistance and is light in weight. Therefore, chemical industrial equipment such as heat exchangers, camera bodies, watches, glasses, leisure equipment, etc. Applications are expanding to consumer goods such as supplies. Since these products are manufactured by plastic working from a plate, the titanium plate is required to have excellent mechanical properties such as strength, ductility, and formability.

[0003] Various attempts to improve the ductility of a titanium plate have been made and studied so far, for example, by suppressing the amount of Fe and O to a certain amount or less, or by increasing the crystal grain size. The ductility has been improved (see, for example, JP-A-10-30160). On the other hand, there is a strength level as a required characteristic of the titanium plate, and Fe and O are added for the purpose of increasing the strength. However, if added too much, ductility is deteriorated, and desired characteristics cannot be satisfied. That is, it was difficult at the current technical level to achieve both improvement in strength and improvement in ductility by increasing the amount of added elements.

[0004] From the viewpoint of moldability, the strength and
The in-plane anisotropy of the ductility characteristics is also an influencing factor, and in the conventional titanium plate, the anisotropy between the characteristics in the rolling direction and the characteristics in the rolling vertical direction (direction perpendicular to the rolling direction, that is, the sheet width direction) is not sufficient. strongly,
For example, since the proof stress is lower in the rolling direction, when the proof stress level in the rolling direction does not satisfy the required characteristics, the proof stress is increased by adding a pre-strain, but in this case, the ductility is deteriorated by the pre-strain However, there is a problem that the moldability is deteriorated due to this, and there is a limit in improving the moldability. Further, depending on the molded part, deep drawability is also required, and improvement of the r value, which is an index of the deep drawability, is insufficient with the conventional technology.

[0005] Under such circumstances, the demand for improvement in ductility has become more and more strict, and it has been required to achieve both high strength and ductility at a high level (high level).

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and an object of the present invention is to improve the ductility without lowering the strength of a titanium plate, and to improve the strength and ductility. And a method for manufacturing the same.

[0007]

In order to achieve the above object, a titanium plate according to the present invention and a method for producing the same are provided by a titanium plate according to claims 1 to 3 and a titanium plate according to claims 4 to 6. The manufacturing method is as follows.

That is, the titanium plate according to the first aspect is characterized in that:
O, N, Fe content is one or more of JIS H 4600
This is a titanium plate excellent in ductility, characterized in that it is an amount specified by the species and contains 50 to 800 ppm of C and the balance has a composition consisting of titanium and unavoidable impurities (first invention).

[0009] The titanium plate according to claim 2 further comprises Al: 1
The titanium plate having excellent ductility according to claim 1, wherein the titanium plate contains from 0.00 to 5000 ppm (second invention).

The titanium plate according to claim 3 is a titanium plate excellent in ductility according to claim 1 or 2, which is manufactured by using a cold crucible induction melting method as a melting method (third invention).

On the other hand, in the method of manufacturing a titanium plate according to the present invention, the amount of H, O, N and Fe is reduced by JI by melting after cold melting induction melting and then casting.
SH 4600 is an amount defined as one or two kinds, and obtains a titanium material containing C: 50 to 800 ppm and a balance of titanium and unavoidable impurities,
Next, this titanium material is subjected to hot working and / or cold working, processed into a plate shape, and then subjected to final annealing. invention).

The method for manufacturing a titanium plate according to claim 5 is characterized in that
By melting and casting by the AR method or the cold crucible induction melting method, the amounts of H, O, N and Fe are reduced to J.
It is an amount specified for one or two types of ISH 4600, C: 50 to 800 ppm, Al: 100 to 5000
ppm, the balance being titanium and having a composition consisting of titanium and unavoidable impurities, and then subjecting the titanium material to hot working and / or cold working to form a plate, This is a method for producing a titanium sheet having excellent ductility, which is characterized by performing final annealing (fifth invention).

The method of manufacturing a titanium plate according to claim 6 is the method of manufacturing a titanium plate having excellent ductility according to claim 5, wherein Al carbide is added to the molten metal during the melting. .

Here, ppm means mass ppm (ppm in mass ratio), that is, parts per million (hereinafter the same).

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention is embodied in the following manner, for example. Dissolution by the cold crucible induction melting method, and then casting to obtain H, O, N,
The amount of Fe is an amount specified in one or two types of JIS H 4600, and a titanium material (ingot) containing 50 to 800 ppm of C and having a balance of titanium and unavoidable impurities is obtained. Next, the titanium material is subjected to hot working and / or cold working to be processed into a plate shape, and then subjected to final annealing. Then, a titanium plate excellent in ductility according to the present invention is obtained. At this time, further Al: 100
When the content of ５5000 ppm is contained, a titanium plate excellent in the r value which is an index of deep drawability can be obtained.

In such a form, the method for producing a titanium plate according to the present invention is carried out, and the titanium plate excellent in ductility according to the present invention is obtained.

The present invention has been accomplished based on new findings obtained as a result of intensive studies to achieve the above object. The details will be described below.

As a result of repeated studies to achieve the above object, the present inventors have found that C in a titanium plate corresponding to one or two of JIS H 4600 is 50 to 800 pp.
By adding m, the level of strength and ductility in the rolling direction is improved without lowering the ductility of the titanium sheet in the vertical direction of rolling, and both strength and ductility are balanced at a higher level (high level). I found that I can do it. Although the mechanism is not clear, there has been no investigation on the effect of C so far, and much less the above-mentioned knowledge has been obtained so far, which is a new knowledge.

The reason why the effect of C has not been studied so far is as follows. Conventionally, Ti (titanium) has been melted by a method called a consumable electrode arc melting method (for example, see Nikkan Kogyo Shimbun, "Metal titanium and its application", edited by Hidetake Kusamichi, p.16-). . In this consumable electrode type arc melting method, the Ti melting raw material itself is compacted to form a large electrode (consumable electrode) having a large cross section, suspended in a water-cooled copper crucible, and a DC arc is applied between the tip and the molten metal in the copper crucible. This is a method in which the electrode itself melts down to form a molten metal pool, and the molten metal pool in which the droplets are collected is cooled from below and solidifies to produce an ingot in a manner close to unidirectional solidification. In this method, titanium sponge is press-formed together with an alloy raw material to form a briquette, which is welded to form a consumable electrode. Therefore, since the amount (concentration) of the alloy component differs depending on the location of the consumable electrode, it is necessary to homogenize the alloy component. However, in this method, the entire consumable electrode is not melted at once as described above, but is partially melted. Homogenization of the alloy components becomes insufficient because re-solidification occurs only in the partially melted portion. Therefore, double melting is usually performed in which the ingot obtained in the first melting is melted again as a consumable electrode. But,
Since it is very difficult to uniformly disperse C at a level of several hundred ppm or less even by the dissolution method as described above, the idea of C addition has never been considered, and the effect of C addition has not been studied.

On the other hand, a method called a cold crucible induction melting method is being put to practical use as a new melting method (for example, Tatsuhiko Kusamichi et al., Kobe Steel Engineering Reports, Vol. 49, N.
o.3, 1999, pp.13-14). This is a melting method in which a refractory crucible in the vacuum induction melting method is replaced with a crucible composed of a large number of segments made of water-cooled copper. In this melting method, unlike the consumable electrode arc melting method, since the melting material is a method in which all of the melting raw materials are melted at once, it is hard to cause inhomogeneity as in the case of the consumable electrode type arc melting method,
Since the adjustment of the molten metal component is facilitated, the addition of trace elements can be adjusted, and the elements can be uniformly dispersed.

Therefore, a titanium material having a composition to which C was added was produced by a cold crucible induction melting method, and a titanium plate was produced using the titanium material. As a result, even if the addition amount of C is as small as several hundreds to several tens of ppm, or even as small as several ppm, it is confirmed that C can be uniformly dispersed, C: By adding 50 to 800 ppm, it is possible to improve the strength and ductility level in the rolling direction and reduce both the strength and ductility at a higher level without lowering the ductility of the titanium sheet in the vertical direction. I knew I could do it.

Furthermore, conventionally, JIS H 4600-1
It was generally thought that the addition of Al in a titanium plate corresponding to one or two species deteriorates ductility and is not preferred. However, according to further studies and studies by the present inventors, It became clear that the r value of the deep drawability index was improved by adding a small amount of C and Al in combination. Although this mechanism is not clear at present, the effect of the composite addition of C and Al has not been investigated so far, and the above-mentioned findings have not been obtained so far, and are new findings. In addition, in the case of such a composite addition of Al and C, by adding this in the form of an Al carbide such as Al ₄ C _3, it is possible to reduce the inhomogeneity at the time of dissolution even if the addition amount is increased. I found out what I can do.
Therefore, it has been found that if Al and C are added in the form of Al carbide in a composite manner, the addition can be easily performed by the VAR method which is a usual mass production method.

The present invention has been completed based on such findings, and the titanium plate according to the present invention has the following features.
The amounts of H, O, N, and Fe are those specified in one or two of JIS H 4600, and C is 50 to 800 ppm.
And a balance of which is composed of titanium and inevitable impurities (first invention). Therefore, the titanium plate according to the present invention is a titanium plate having both strength and ductility at a higher level.

Further, as described above, the titanium plate according to the present invention is characterized by further containing 100 to 5000 ppm of Al (second invention). That is, this titanium plate has H, O, N, and Fe contents according to JIS H460.
0 is one or two types, and C: 50 to
It is characterized in that it contains 800 ppm, Al: 100 to 5000 ppm, and the balance has titanium and inevitable impurities. Therefore, this titanium plate combines strength and ductility at a higher level, and has an improved r value of a deep drawability index, and is an excellent titanium plate.

Here, C: 50 to 800 ppm (mass p
pm: parts per million by mass): C: 50 ppm
If it is less than 10%, the effect of improving the ductility in the rolling direction of the titanium plate is small and insufficient, and if C is more than 800 ppm, the strength of the titanium plate is excessively increased and the ductility is deteriorated and becomes insufficient. It is. In the case of a conventional titanium plate, generally, C of 30 ppm or less is inevitably contained, but ductility cannot be improved with such an amount of C.

When Al is also contained (in the case of the second invention),
Al: 100 to 5000 ppm is defined as:
When the content is less than 100 ppm, the effect of improving the r value is small and insufficient, and when the content is more than 5000 ppm, the strength of the titanium plate is excessively increased, the ductility is deteriorated, and the formability is deteriorated. In addition, in a titanium plate normally defined as one or two types of JIS H 4600, Al is not an element to be positively added, and even if it is mixed in some form, Al is usually below the detection limit. .

The amount of H, O, N, Fe is JIS H460
0 means that the amount is H: 0.01.
3% by mass or less, O: 0.15% by mass or less, N: 0.05
% By mass and Fe: 0.20% by mass or less (however, in each case, 0% by mass is included). H, O,
The amounts of N and Fe are defined by two types of JIS H 4600, which means that H: 0.013% by mass or less, O:
0.20% by mass or less, N: 0.05% by mass or less, Fe:
It is 0.25% by mass or less (however, 0% by mass is included in each case).

Of the above elements (H, O, N, Fe), both O and Fe have a function of improving the strength. However, if any of these elements is added too much, the strength is too high and the ductility is deteriorated.
From this point, the amounts of O and Fe are 1 of JIS H 4600.
O, Fe
In the range of the amount, the C addition (C: 50 to 800 pp)
The effect of m) is equivalent. H and N are elements belonging to unavoidable impurities and have a function of deteriorating properties such as mechanical properties of the titanium plate.
If the amount is one or two types of H4600, there is no problem such as deterioration of the characteristics, and thus the amounts of H and N are set as such.

In the titanium plate according to the present invention, C is an extremely important additive element, and as described above, C: 50 to 800 p
Although it is set to pm, it is desirable to set C: 120 to 600 ppm, so that strength and ductility can be combined at a higher level. Further, C: 250 to 5
The content is more preferably set to 00 ppm, and strength and ductility can be combined at a higher level.

The titanium plate according to the present invention can be produced by a conventional production process (melting, remelting, casting, hot forging, hot rolling, hot rolling, or the like by a consumable electrode type arc melting method) without considering the yield and other problems. Cold rolling, final annealing). That is, in a conventional ordinary production process, if an appropriate amount of C is contained at the time of dissolution, the C
Is not uniformly dispersed, but when the site of the obtained titanium plate is analyzed in detail, the titanium plate is like a set of titanium pieces having various C contents. May also exist. If the use in the region having the C content range is possible, the titanium plate can be cut out from this region and used, regardless of the yield. Therefore, in consideration of such a case, it is not necessary to particularly define conditions and methods for producing the titanium plate according to the present invention.

However, in order to efficiently achieve uniform dispersion of C and to improve the yield, it is recommended to employ a cold crucible induction melting method as a melting method in the production of a titanium plate. This is because according to the cold crucible induction dissolution method, C can be uniformly dispersed even if the amount of C added is very small as described above.

From such a point, it is preferable that the titanium plate according to the present invention is manufactured by using a cold crucible induction melting method as a melting method (third invention). In this titanium plate, C is uniformly dispersed, and the mechanical properties are excellent in uniformity.

On the other hand, as a method for manufacturing a titanium plate according to the present invention, it is desirable to employ a method in which melting is performed by a cold crucible induction melting method. More specifically, the following manufacturing method can be given as such a manufacturing method. That is, the production method is such that the H, O, N, and Fe contents are JIS H 46 by melting after being melted by the cold crucible induction melting method and then casting.
00: one or two of the following: C: 50
To 800 ppm, the balance being a titanium material having a composition consisting of titanium and unavoidable impurities, and then subjecting the titanium material to hot working and / or cold working to form a plate shape. And final annealing (fourth invention). According to this manufacturing method, C is uniformly dispersed, and the titanium plate according to the present invention can be obtained with a high yield.

As a method for producing a titanium plate also containing Al (titanium plate according to the second invention), a method performed by a VAR method can be adopted. More specifically, the following manufacturing method can be given as such a manufacturing method. That is, the production method is such that the amounts of H, O, N and Fe are JIS H 46 by melting and casting by the VAR method or the cold crucible induction melting method.
00: one or two of the following: C: 50
To 800 ppm, Al: 100 to 5000 ppm, the balance being a titanium material having a composition consisting of titanium and unavoidable impurities, and then subjecting the titanium material to hot working and / or cold working to obtain a plate shape And after this,
It is characterized by final annealing (fifth invention).

In producing a titanium plate also containing Al (titanium plate according to the second invention), a combination of Al and C is added. At the time of this composite addition, if Al and C are added in the form of Al carbide, the addition becomes easy even in the VAR method which is a usual mass production method.

[0036] Such addition of Al carbide can be performed by a method of adding Al carbide to the molten metal at the time of melting (sixth invention). When dissolving by the VAR method, the raw material is mixed in advance in the electrode, and
It can also be carried out by dissolving AR.

[0037]

EXAMPLES Examples and comparative examples of the present invention will be described below.
Note that the present invention is not limited to this embodiment.

[Examples and Comparative Examples Related to C-Containing Titanium Material] The raw materials were melted by a cold crucible induction melting method, and after maintaining the molten metal temperature at about 1700 ° C., C powder (carbon powder) was added, followed by 30 minutes. After holding, casting was performed to obtain a titanium material (titanium ingot). Next, this titanium material was heated to 950 ° C. and hot forged until the thickness became 40.0 mm, and then the thickness was 4.0 mm at a temperature of 850 ° C.
Hot-rolled so that Next, the scale after hot rolling was removed, and then cold rolling was performed at a rolling reduction of 86%, followed by final annealing to produce a titanium plate having a thickness of 0.5 mm.

In this titanium plate, the amounts of Fe, O and C are as shown in Table 1, the amount of H is 0.013% by mass or less, the amount of N is 0.05% by mass or less, and the balance is titanium and unavoidable. It has a composition consisting of a target impurity. The average grain size after the final annealing was 80 μm.

The titanium plate thus obtained was subjected to a tensile test using a JIS No. 13 B-type test piece.
The proof stress and total elongation in the rolling direction and the vertical direction of the rolling were measured. A part (test No. 9) was subjected to a tensile test after a pre-strain was applied.

Table 2 shows the results of the tensile test. The titanium plate (material of the present invention) according to the example of the present invention (first invention, third invention or fourth invention) has a higher elongation than the titanium plate (comparative material) of the comparative example having the same level of yield strength. It turns out that it is excellent. That is, when the inventive material and the comparative material are compared with each other having the same level of proof stress, it can be seen that the inventive material has a larger elongation than the comparative material and is excellent in ductility. Therefore, it can be seen that the material of the present invention is a titanium plate having a higher elongation / proof strength than the comparative material, and having both strength and ductility at a higher level.

[Examples and Comparative Examples Related to C and Al-Containing Titanium Materials] Al and C in the form of Al ₄ C ₃ Al carbide were used.
Was mixed by VAR method and cast to obtain a titanium material (titanium ingot). Next, this titanium material is
After heating to 0 ° C. to perform hot forging to a thickness of 40.0 mm, hot rolling was performed at a temperature of 850 ° C. to a thickness of 4.0 mm. Next, the scale after hot rolling was removed, and then cold rolling was performed at a rolling reduction of 86%, followed by final annealing to produce a titanium plate having a thickness of 0.5 mm.

This titanium plate has Fe, O, C contents, and
The amount of Al is the amount shown in Table 3, and the amount of H is 0.013% by mass.
Hereinafter, the N content is 0.05% by mass or less, and the balance has a composition comprising titanium and inevitable impurities.
The average crystal grain size after final annealing is 70 μm.
m.

The titanium plate thus obtained was subjected to a tensile test using a JIS No. 13 B-type test piece.
The proof stress and total elongation in the rolling direction and the vertical direction of the rolling were measured. The measurement of the r value in the rolling direction was also performed. The r value was measured at a strain of 10%.

Table 4 shows the results of the tensile test and the measurement results of the r value. The present invention (second invention or fifth invention,
The titanium plate (material of the present invention) according to the example of the sixth invention) is a titanium plate (comparative material) of the comparative example having the same level of proof stress.
It can be seen that the r value is superior to that of. That is, when the inventive material and the comparative material are compared with each other having the same level of yield strength, it is understood that the inventive material has a larger r value than the comparative material. Incidentally, among the comparative materials, those of test No. 18 belong to the first invention example.

[0046]

[Table 1]

[0047]

[Table 2]

[0048]

[Table 3]

[0049]

[Table 4]

[0050]

The titanium plate according to the present invention has a large value of elongation / proof stress, and has both high strength and ductility at a high level. Therefore, both strength and ductility are compatible at a high level. It is possible to improve the moldability, and further, to improve the quality and characteristics of the equipment and parts used in this, and to contribute to the development of new applications for titanium plates. It has a remarkable effect.

The method of manufacturing a titanium plate according to the present invention has a remarkable effect that a titanium plate having the above-mentioned remarkable functions and effects can be obtained with a uniform dispersion of C and a high yield. It works.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Yasuaki Sugizaki 1-5-5 Takatsukadai, Nishi-ku, Kobe-shi, Hyogo Kobe Steel, Ltd. Kobe Research Institute

Claims (6)

[Claims] 1. The amount of H, O, N, Fe is JIS H46.
00: one or two of the following: C: 50
A titanium plate having excellent ductility, characterized in that the titanium plate has a composition of about 800 ppm and a balance of titanium and unavoidable impurities. 2. The ductile titanium plate according to claim 1, further comprising 100 to 5000 ppm of Al. 3. The titanium sheet having excellent ductility according to claim 1 or 2, which is produced by using a cold crucible induction melting method as a melting method. 4. After melting by a cold crucible induction melting method, H, O, N, F
The amount of e is an amount specified in one or two types of JIS H 4600, and obtains a titanium material containing C: 50 to 800 ppm and a balance of titanium and unavoidable impurities. A method for producing a titanium plate having excellent ductility, comprising subjecting a titanium material to hot working and / or cold working to form a plate shape, followed by final annealing. 5. A method of melting and casting by VAR method or cold crucible induction melting method.
O, N, Fe content is one or more of JIS H 4600
It is the amount specified for the species, C: 50 to 800 ppm, A
l: a titanium material containing 100 to 5000 ppm, the balance being titanium and having a composition consisting of titanium and inevitable impurities,
Next, the titanium material is subjected to hot working and / or cold working to be processed into a plate shape, and then subjected to final annealing, thereby producing a titanium sheet having excellent ductility. 6. The method for producing a titanium plate having excellent ductility according to claim 5, wherein an Al carbide is added to the molten metal during the melting.