JP2003089853A - HIGH PURITY Fe-Cr ALLOY HAVING EXCELLENT FORMING WORKABILITY - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an Fe-Cr alloy which has excellent forming workability by clearing up the relation between the contents of impurities and the form of nonmetallic inclusions in a high purity Fe-Cr alloy. SOLUTION: In the Fe-Cr alloy containing 8 to 90 mass% Cr, the total content of C, N, O, S and P is controlled to <=0.020 mass%, and the ratio of the total content of MnO and SiO2 in oxide inclusions is controlled to >=60 mass%. By increasing the total content of MnO and SiO2 in the inclusions, they become soft ones finely dispersed in the production, and cause no cracking on forming.

Description

DETAILED DESCRIPTION OF THE INVENTION [0001] FIELD OF THE INVENTION The present invention relates to Fe-- which has excellent corrosion resistance.
High purity alloy with improved formability and Cr alloy
Related. [0002] In general, Fe-Cr alloys are required to have corrosion resistance.
Demand for functional materials such as electronic parts is increasing
The Various shapes when used as electronic components
However, when processing with a particularly high drawing ratio is performed
There are many, and it is drawn into an ultra-thin plate. Drawing
Often causes cracking due to inclusions
Therefore, a material with high cleanliness is required. On the other hand, C
As the r content increases, the corrosion resistance improves.
On the contrary, the workability is lowered. The higher the Cr alloy,
C and N have an adverse effect on the ductility and toughness of the material. Addition
Of course, O, S, and P also have an adverse effect. Especially containing Cr
In high alloy steels with an amount of 30% by mass or more, the tendency is
It is remarkable. [0003] Therefore, the Cr content
Fe-Cr alloy with high corrosion resistance Electronic parts that require corrosion resistance
If you are going to use it after molding it,
There is a problem that cracks occur. Various for improving workability
An attempt has been made. One of them is the above C, N
Reduce the content of such impurities
It has been proposed. Melt using vacuum induction melting furnace
Remove moisture adhering or adsorbed to the raw material or the crucible used before
Evaporation and removal as much as possible, and the atmosphere even during dissolution
The N and O pickups are suppressed as much as possible.
C, N, desulfurization using basicity flux
Manufactures materials with reduced O, S, P content as much as possible
The Even with such high-purity alloys, sufficient formability can be obtained.
It may not be possible. As factors affecting molding processability, ingredients and groups
In addition to composition, the structure or form of non-metallic inclusions
However, the impurity content and non-metallic
It is not clear about the relationship between the forms of nature. So book
The invention was devised to solve such problems.
In the high purity Fe-Cr alloy,
Clarified the relationship between the forms of non-metallic inclusions and improved formability
An object is to provide an excellent Fe—Cr alloy. [0005] [Means for Solving the Problems] The processability of the present invention is excellent.
The high-purity Fe-Cr alloy thus achieved achieves its purpose.
Therefore, 8 to 90% by mass of Cr, C content, N content
Amount, O content, S content and P content are 0.
020% by mass or less with the balance being substantially Fe
MnO and SiO in oxide inclusions₂Total content of
The ratio of the amount is 60% by mass or more. [0006] The present inventors are able to improve the workability of Fe-Cr alloys.
Impurity components C, N, S, P, O and non-metal via
We studied earnestly about the influence of nature. As a result, first
The total C, N, S, P, O content is 0.020% by mass.
If exceeded, the ductility and toughness of the material itself will decrease, and the workability will be low.
I found out that Furthermore, C, N, S, P, O
Reduced content and high purity to improve ductility and toughness
However, workability varies greatly depending on the form of non-metallic inclusions.
I found out. In particular, the Cr content exceeds 30% by mass.
Since the ductility and toughness of the material itself will be reduced
Moreover, this tendency is remarkable. Therefore, C, N, S, P,
Non-metallic intermediary that reduces O content and is a foreign material
It is necessary to detoxify the form of the natural thing against the molding method to be applied.
I found out that there was a point. Non-metallic inclusions in high purity Fe-Cr alloys
Al₂O_ThreeAnd SiO₂, MgO, MnO and other acids
There are many chemical inclusions, which have an effect on moldability
is doing. Specifically, C, N, S, P, O content is low
When forming a high purity Fe-Cr alloy
SiO₂Oxide with a total content of less than 60% by mass
In the case of system inclusions, cracks starting from the inclusions during molding
Was found to occur. MnO and SiO₂Including the total
Less abundance, Al₂O_ThreeOxide-based inclusions with high content such as
Since the material is hard with a high melting point, it is not dispersed during hot rolling, and is a thin plate
It remains in the size of the state generated during refining even after becoming
Yes. Therefore, it becomes a starting point of cracking during molding. In contrast, Al₂O_ThreeThe content of etc. is low
Low melting point and soft MnO and SiO ₂Acid based on
Fe-Cr alloy containing compound inclusions
Since the material is also soft, the ductility and toughness of the material itself will decrease.
In addition, soft inclusions with a low melting point can be made by finishing the material.
It is finely dispersed at different stages and becomes the starting point of cracking during molding.
Never happen. In addition, SiO in oxide inclusions₂, M
nO content can be either acidic solution, iodine alcohol or non-
Dissolve the metal using an aqueous solvent solution to remove the oxide inclusions.
After extraction, the wet analysis method may be used. The present invention is organized again.Cr content: 8 to 90% by mass If the Cr content is less than 8% by mass, the corrosion resistance will be inferior,
If it exceeds 90% by mass, the effect of improving corrosion resistance will be saturated.
Ductility and toughness are reduced and workability is deteriorated. [0010][C] + [N] + [O] + [S] + [P]
≦ 0.020% by mass The total content of C, N, O, S and P is 0.020% by mass.
If exceededThe ductility and toughness of the material itselfReduced processability
Becomes worse. Especially for Cr content of 30% by mass or more
In that case, the tendency becomes stronger. Specifically, it contains the above impurities.
When the amount increases, during cold rolling, the plate breaks and edge cracks.
This is likely to occur, the productivity is significantly reduced, and the product yield
Therefore, the total impurity content is
0.020 mass% or less. [X] is the X component
Indicates the content. Further, the Fe—Cr alloy of the present invention is C
o, Mo, Nb, Ti, V, W, Re, Sr, Zn, N
i, B, Cu, Al, Si, Mn, Zr, REM, C
10% by mass or less of optional components such as a and Mg depending on the purpose
It may be contained to some extent. [0011]Combination of SiO ₂ and MnO in oxide inclusions
Ratio of weighing: 60% by mass or more SiO in oxide inclusions₂And the ratio of the total amount of MnO is
When the amount is less than 60% by mass, the inclusions become hard at the time of manufacture.
It is easy to become a starting point of cracking when drawing.
Yes. Fe- having a low impurity content as described above
Cr alloy is made of basic refractory using vacuum induction melting furnace
The raw material is charged into the crucible and 10^-3-10^-FourAbout Torr
Raw material is heated and held at a temperature at which the raw material does not melt under vacuum
Evaporates and removes water adhering to and adsorbing on crucibles
Later, to prevent O and N pickup from the atmosphere
Change the melting furnace quickly to a high purity dry Ar gas atmosphere,
Can be manufactured by dissolving and deoxidizing in this Ar gas atmosphere
The During deoxidation refining, a deoxidizer mainly composed of Si and Mn
If used, SiO₂, MnO as the main component
Can be manufactured. I want to lower [O] further
In some cases, in addition to Si and Mn, A is used to achieve a combined deoxidation effect.
Deoxidation refining may be performed by adding l. [0013] EXAMPLE 80 kg Fe using 100 kg VIM
-Cr alloy was melted and cast. In the crucible, the CaO chestnut
95% by mass purity CaO crucible prefired
It was used. 99% electrolytic Fe, electrolytic Cr is used as the melting raw material
Was used. 1 × 10^-FourIngredients with Torr vacuum
Thoroughly bake the crucible and use the raw materials, crucible water, etc.
After fully evaporating and removing, Ar gas is introduced into the dissolution tank
did. Ar pressure was 1 atm, and Ar gas was kept flowing.
To minimize O and N pickup from Ar gas
In addition, the Ar gas used is N₂Content: 0.0005 volume
% Or less, dew point: -50 ℃ high purity dry Ar gas
It was. A raw material is melted in an Ar gas atmosphere to achieve a target temperature.
As a deoxidizer, Si, Mn and Al are combined.
Add appropriate amount of CaO and SiO₂Mass ratio (Ca
O / SiO₂) With a high basicity flux of 2.0
To deoxidize and refine. Then, under Ar gas atmosphere
It was poured into a mold to obtain an ingot. As a comparative example, 10^-3To
The raw material was melted and cast under vacuum of rr (Test No.
6, 9). Other melting and refining conditions are the same as in the present invention example.
It was. Test No. In comparative examples 7 and 8, MgO crucible
Test no. 10 comparative examples using a CaO crucible
It melt | dissolved and Al deoxidation was performed. Other melting, refining, casting
The conditions were the same as those of the example of the present invention. Invention conditions and ratios
Ingot chemical composition and oxides obtained under comparative conditions
The inclusion composition is shown in Table 1. In addition, S in oxide inclusions
iO₂And MnO content is 10 quality to methyl alcohol
Amount of acetylacetone and 1% by weight of tetramethylan
Using a non-aqueous solvent solution to which monium chloride is added,
After electrolytic dissolution of tal and extraction of oxide inclusions,
It was determined using an analysis method. These ingots are subjected to hot rolling and cold rolling.
The cold rolled sheet having a thickness of 0.2 mm was carried out. Cold rolling obtained
The plate was subjected to multistage drawing and the occurrence of processing cracks was investigated.
The results are also shown in Table 1. Ingredients within the scope of the present invention and
Test No. which is an oxide-based inclusion 1-5, oxide
Cracks caused by system inclusions did not occur. on the other hand,
[C] + [N] + [O] + [S] + [P]> 0.020
Comparative example No. which became mass%. For materials 6 and 9,
Due to lack of workability and toughness, causing cracks during cold working
Could not be commercialized. [C] + [N] + [O] +
Although [S] + [P] is 0.020 mass% or less,
SiO in oxide inclusions₂And the total content of MnO is 6
Comparative Example No. less than 0% by mass In 7, 8 and 10, acid
Cracks originating from the inclusions of the chemicals were generated. [0016][0017] As described above, high purity Fe-
Containing impurities such as C, N, O, S, and P in Cr alloy
A set of oxide inclusions that reduce the amount as much as possible and intervene
The composition is SiO₂And having a high MnO content
The oxide inclusions in the product are soft and finely divided.
It has a dispersed form and no cracking occurs during molding.
The molding processability was remarkably improved.

   ──────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yasuhiko Kenji             2-1-1 Katahira, Aoba-ku, Sendai, Miyagi             University Institute for Materials Research

Claims (1)

[Claim 1] The content of Cr is 8 to 90% by mass, and the total content of C content, N content, O content, S content and P content is 0.020% by mass or less. And the balance is substantially composed of Fe, and MnO and SiO ₂ in the oxide inclusions.
A high-purity Fe—Cr alloy excellent in moldability, characterized in that the ratio of the total amount is 60% by mass or more.