JPS5976858A - Fe-cr-al alloy - Google Patents

Abstract

PURPOSE:To improve the adhesive strength of a protective oxide film to an Fe- Cr-Al alloy having a specified composition and the processability of the alloy by adding a proper amount of Ti to the alloy in proportion to the C+N content. CONSTITUTION:This Fe-Cr-Al alloy consists of, by weight, 18'26% Cr, 3-6% Al, <=1.5% Si, <=0.5% Ti, <=0.1% C, <=0.1% N and the balance Fe with inevitable impurities and satisfies Ti/(C+N)=3-7. The ratio of Ti/(C+N) in the alloy relates closely to the adhesive strength of a protective oxide film to the alloy and the processability of the alloy. The alloy can be provided with high oxidation resistance and favorable processability by regulating the ratio as mentioned above.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an oxide film having good adhesion and superior strength.

Fe containing 0rlO~26% and At1~6% in weight%
-0r-At-based alloys are heated to high temperatures to form dense O
Generates a new protective film mainly consisting of r and At oxides.

- It has the characteristic of preventing the progress of oxidation, and is used in heating elements, resistors, and structures that require oxidation resistance.

The oxidation resistance is mainly determined by the sustainability of the supply of 0rSkl that is selectively oxidized on the surface and the properties and adhesion of the oxide film. Sustainability of supply improves as the content of 0rSAt in the base material increases, so when used at temperatures above red-hot water temperature, even if the workability is made somewhat axial, the oxidation resistance will be affected.
, the content of At is increased. Furthermore, it is known that the adhesion of the acidified coating can be improved by adding rare earth elements in addition to T1 or Zr.

Automotive cigarette lighters are used in a red-hot state, so Fe-0r-A with 18-26% 0r and 3-6% At
L series steel is used, but in the case of this steel, adhesion of the oxide film during cold opening is also required. In other words, cigarette lighters are made by bending and forming a ribbon-like strip into a spiral shape.The cigarette lighter is then oxidized to form a dense and uniform oxide film with a thickness of micrometers, which also serves as insulation, and is then rolled and tightened. This process causes cracks in the coating, and the coating is likely to peel off. and conventional Fe −0
If rare earth elements such as T1 or Zr are simply added to r-), l-based alloys, the above-mentioned cracks and peeling will occur during oxidation treatment or surface tightening, and abnormal oxidation will occur in those areas during use. There was a drawback that there were many accidents that progressed rapidly and resulted in meltdowns.

The object of the present invention is to provide an oxidation-resistant alloy for F'e-0r-AL yarn that improves and stabilizes the adhesion of the preserved oxide film and has excellent processability.

The present invention is 0r18-26%, At3-6%, S
1≦1.5%, Ti≦0.5%, 0≦0.1%, and N
Contains ≦0.1%, and %T1/(%O + %N) from 3 to
7, the oxide film consisting of the remainder Fθ and unavoidable impurities has good adhesion and good workability. It is an e -Or -At based alloy.

Next, Table 1 shows the chemical composition and %T1/(%0+%N) of the inventive steel examples and comparative steels (%T1, %C and %N are the percentages of T1.0 and N content, respectively). Hereinafter, this formula is simply written as Ti/(0-1-N) and shows the results of 11 evaluations of the adhesion and workability of the oxide film using the method described later.

The d12 value of the adhesion of the oxide film was determined by forming a film by oxidation treatment on a test piece that had been cold-worked to a thickness of 0.25 mm and width of 1.6 wn under the same conditions, and then annealed to remove stress. , washed and dried, wrapped around a 10.0 diameter mandrel, unwound, washed and dried again, 1 for each washing V
Evaluation was made based on the weight difference (reduction amount) after drying.

From Table 1, the density of the oxide film is Ti/(0-1-N
) is less than about 2.5, as seen in the comparative steels, the adhesion becomes poor, and when the ratio is about 3 (invention-(a)) or more, sufficient adhesion is exhibited.

Table 2 shows the results of a life test on cigarette lighters manufactured from the same cold-worked materials as in Table 1, (←), (E), and (S).

Comparison from the second table - (force (T1/(0+N)-2,46) shows that the life cycle is significantly lower than the other (e) and (IJ), and the adhesion evaluation as described above. It can be seen that the trends are almost the same, and that there is no significant difference in the number of lifetimes between (e) and (s).

Next, the workability was evaluated by the elongation at 1' in a tensile test and the number of times of bending to break 115T in a repeated bending test of 1. Since the test results for repeated songs showed almost the same tendency as the elongation in the tensile test, only the elongation measurement results in the tensile test will be explained here.

Figure 1 shows the average elongation value, variation, and range of the tensile test specimens cut from each molten steel in Table 1, plotted against the Ti/(0-)-N) ratio of each molten steel. It is something. From the figure, it can be seen that the elongation decreases rapidly when the Ti/(0+N) ratio is about 7 or more, and the range of fluctuation also expands. In particular, it can be seen that when this ratio is about 8, there is almost no elongation. 0), naka)... in the figure correspond to (a), (b)... in Table 1.

As mentioned above, in the Fθ-0r-At alloy, T
The ratio of t/(o+N) is closely related to the adhesion of the preserved oxide film and the workability of the matrix, and this ratio is adjusted to within the range of 3 to 7.
It can be seen that, by adjusting the I, the adhesion of the accompanying oxide film can be improved and stabilized, and the processability can be prevented from decreasing and the range of variation can be reduced.

Next, the reason why the phase 111 containing each element in the steel of the present invention is determined will be described.

Or, together with A4, is a major element that forms a stable and strong accompanying film. Effective hψ when the content of Or is small
The production of the film becomes insufficient, and the normal accompanying film peels off.
Sustainability of supply due to diffusion from the parent phase for III;
It becomes difficult to withstand long-term use at high temperatures that exceed the heat generation temperature. On the other hand, if Or is contained excessively, embrittlement is likely to occur due to precipitation of the σ phase.

Therefore, in the present invention, the Qr content is set to 18 to 26%.

As already mentioned, it is an element that forms a protective nΦ film together with At and Or. The case where the content of At is small is also the same as the case of Or. On the other hand, excessive Alt content impairs processability. Therefore, in the present invention, the At content 1f) is set to 3 to 6%.

Sl forms a part of the oxide film (1.) and contributes to improving oxidation resistance, but excessive content makes the square timber brittle, so it is set at 1.5% or less in the present invention.

C and N are originally harmful elements to the button 1 of the present invention, and if they are contained in excess, they will make the material brittle, impair workability, and reduce the effect of adding T1, which improves the adhesion of the oxide film, so it is best to minimize it. desirable. However, in manufacturing, it is difficult to extremely reduce the content of these elements, which increases the cost.

Therefore, in the present invention, both amounts are set to 0.1% or less.

T1 is an important element that improves the adhesion of the oxide film, but if it exceeds about 0.5%, it embrittles the material and impairs workability. Therefore, in the present invention, the content is determined so that Ti/(a+m) is 3 to 7 depending on the O+N content iii within a range of 0.5% or less.

As mentioned above, the Fe=Or A4 thread alloy of the present invention has T1 mixed with suitable stones according to the content of 0-1-H, which improves the adhesion of the oxide film without impairing processability. As a result, it has excellent properties, including high anti-oxidation properties and good workability.

[Brief explanation of drawings]

FIG. 1 shows the elongation (%) of the invention steel and comparative iTi in a tensile test with respect to the ratio of T1/(0+a). Agent: Patent Attorney Soji Honma l Figure G5 Male Ratio

Claims (1)

[Claims] II: □r18-26%, At3-6%, S1≦1.5
%, T1≦0゜5%, 0≦0.1%, and N≦0.1%
and %T1/(%0+%N) of 3 to 7, with the remainder being Fe and unavoidable impurities, the acidic acid coating has good adhesion and good caroe resistance. At thread alloy 0