JPH05117813A - Stainless steel for metal gasket having excellent formability and fatigue characteristic and this manufacture - Google Patents

Abstract

PURPOSE:To provide a stainless steel material for metal gasket having fatigue characteristic and high strength. CONSTITUTION:This stainless steel is composed of by wt.% <=0.03% C, >1.0-3.0% Si, <=4.0% Mn, 4.0-10.0% Ni, 13.0-20.0% Cr, <=0.30% N, <=0.01% <=0.007% O and adjusted so as to become 30-100M value according to M=330-(480XC%)-(2XSi%)-(10XMn%)-(14XNi%)-(5.7XCr%)-(5XMo%)-(14XCu%)-(3 20XN%) and the balance Fe with the inevitable impurities. At the time of manufacturing the steel sheet by temper-rolling after annealing through hot-rolling process and cold-rolling process to this steel material, this sheet is made to fine grain structure composed of substantially austenitic phase having <=10mum crystal grain diameter with this annealing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stainless steel for metal gaskets having excellent formability and fatigue properties and a method for producing the same, and more specifically, it requires high strength and formability, and fatigue in the processed part. For example, metal gaskets that make up engines such as automobiles and motorcycles that require characteristics, gaskets where asbestos has been used because heat resistance is required in the past, and repetitive fluctuating stress on the processed parts such as auto fasteners. TECHNICAL FIELD The present invention relates to a stainless steel suitable for a spring component to which a load is applied and a manufacturing method thereof.

[0002]

2. Description of the Related Art Conventionally, asbestos has been used as a gasket material in parts where the temperature rises such as an engine, but metal gaskets have been used in response to the trend toward higher engine performance and non-asbestos legal regulations. It is being used. The gasket must have the properties required to maintain the airtightness of the mating surfaces. . For example, metal gaskets used in components of engines such as automobiles and motorcycles are required to have characteristics that can cope with temperature and pressure changes that are repeated under high temperature, high pressure, and high vibration peculiar to engines. There is. Also, from the viewpoint of preventing leakage, even O-rings that enclose asbestos, which can be said to have a similar purpose, are being metallized in response to the movement of non-asbestos legislation, and a strip-shaped coil is wound into a cylindrical shape. Further, it is being formed into a donut type O-ring (metal packing). The material for these metal gaskets and metal packings is SUS301, which is a work-hardening metastable austenitic stainless steel that can easily obtain high strength by cold working.
Steels are mainly used. The gasket is made of a thin plate with a thickness of 0.1 to 0.4 mm. For example, in the case of an engine head gasket, a gasket with beads formed around the combustion chamber and around water holes and oil holes is used. It is common to mold and seal gas, water and oil with the high surface pressure generated when the bead is tightened.
Further, in the metal packing, a strip-shaped coil is wound into a cylindrical shape and further formed into a donut shape, which is used as an O-ring to maintain the airtightness of the joint surface.

[0003]

For example, since a metal gasket used for a cylinder head is subjected to a high pressure especially during compression, a high surface pressure is required to improve the gas sealability. For this reason, it is necessary to increase the bead molding height and the material strength. The steel that can handle this is SUS301 series steel, which is used as described above. However, in order to obtain high strength, SUS301 series steel needs to be subjected to strong cold working, and therefore ductility, There was a problem that the workability was lowered and cracks were generated in the R portion outside the bead during the bead forming process. Therefore, it was unavoidable that the strength be low. When the material strength was lowered, a higher bead forming process was required to improve the sealing property, and a bead shape that increased the surface pressure was required. Therefore,
Even when the material strength is lowered, micro-cracks and cracks are generated on both sides of the bead shoulder R part (inner R part, outer R part), and cracks occur from the micro-crack starting point during use, resulting in poor seal resistance. Then, there arises such a problem. There is a problem that the characteristics as a gasket are not sufficiently satisfied.
Similarly, metal packing also has the problem that microcracks occur when it is processed into a cylindrical shape, and cracks start from the microcracks due to stress fluctuations caused by vibration during use. The present invention intends to solve the problem of cracking from microcracks generated by such a molding process, and aims to develop a material having excellent properties as a metal gasket.

[0004]

According to the present invention, the weight percent is
, C: 0.03% or less, Si: more than 1.0% to 3.0%,
Mn: 4.0% or less, Ni: 4.0% to 10.0%, Cr: 13.0 to 20.
0%, N: 0.30% or less, S: 0.01% or less, O: 0.007% or less, and M = 330− (480 × C%) − (2 × Si%) − (10 × Mn%) − According to the formula (14 × Ni%)-(5.7 × Cr%)-(320 × N%), C, Si, M
The amount of n, Ni, Cr, N is adjusted, the balance is Fe and impurities inevitably mixed in, and the stainless steel for metal gasket excellent in moldability and fatigue characteristics, and this steel, Mo less than 3.0% or 0.5-3.0
% Cu of 1 or 2 and / or Ti, Nb, V
In the range of 0.1 to 1.0%, one kind or two or more kinds are contained, and M = 330− (480 × C%) − (2 × Si%) − (10 × Mn%) − (14 × Ni%) − C, Si, M according to the formula of (5.7 × Cr%) − (5 × Mo%) − (14 × Cu%) − (320 × N%) so that the M value is 30 or more and 100 or less.
Provided is a stainless steel for a metal gasket, which has an adjusted amount of n, Ni, Cr, Mo, Cu, N and is excellent in formability and fatigue characteristics.

As a method for producing the steel sheet material for metal gaskets made of the stainless steel advantageously on an industrial scale, the stainless steel having the above-mentioned composition is subjected to the usual hot rolling step and cold rolling step. Prior to the tempering before temper rolling, cold rolling with a rolling reduction of 50% or more was performed before temper tempering to obtain a steel sheet after annealing. Provided is a method for producing a stainless steel for a metal gasket, which is excellent in formability and fatigue characteristics, characterized by performing the temper rolling after forming a fine grain structure composed of an austenite phase. At that time, it is advantageous to carry out temper rolling at a rolling ratio of 25 to less than 45%, and annealing before temper rolling is carried out in the temperature range of 700 ° C to 1000 ° C. The temper-rolled steel sheet exhibits even higher strength by subjecting it to a desired gasket shape and subjecting it to an aging treatment for 10 seconds or longer in the temperature range of 300 ° C to 600 ° C.

[Detailed Description of the Invention] First, the outline of the reason for limiting the content range of each component in the steel of the present invention will be described. C is an austenite forming element, and is formed at high temperature δ
It is extremely effective in suppressing ferrite and strengthening the martensite phase induced by cold working, but in order to obtain better formability after temper rolling as in the steel of the present invention, strengthening by cold working is notable. Then, it becomes inferior in moldability. Further, if the C content is too high, carbide may be precipitated depending on the pre-annealing annealing or aging treatment conditions. Therefore, C is 0.03% or less.

Si is effective as a deoxidizing agent, but from the viewpoint of deoxidizing effect, even if added in excess of 1.0%, the effect does not change and the cost rises. However, Si densifies the work-induced martensite phase that occurs during cold working,
It works very effectively to improve ductility and toughness and increase the strength increase by aging treatment after cold working. That is, even when the strength level after cold working is kept low and high ductility, high strength and high ductility can be obtained after aging treatment. To obtain this effect, Si of at least 1.0% is required. However, if it is too high, a large amount of δ-ferrite is produced and the effect on the strength increase is saturated.
Considering this point, the upper limit of Si is 3.0%.

[0008] Mn is an element which works effectively as a deoxidizing agent but governs the stability of the austenite phase, and its utilization is considered in balance with other elements. For the steel of the present invention, 4.
It can be used with Mn amount up to 0%. However, in the steel of the present invention, high strength and forming workability are important. Especially, in the case where the forming workability is severe, the Mn content is less than 0.5%, and it is preferable to avoid the formation of inclusions such as MnS as much as possible.

Cr is an essential component for corrosion resistance. At least 13 to provide the intended corrosion and heat resistance
Need more than%. However, since Cr is a ferrite-forming element, if it is made too high, a large amount of δ-ferrite will be generated at high temperatures. Therefore, in order to suppress the δ-ferrite phase, it is necessary to add austenite-forming elements (C, N, Ni, Mn, etc.) in an amount commensurate with that. However, adding a large amount of austenite-forming elements stabilizes the austenite phase at room temperature. However, high strength cannot be obtained after cold working or aging treatment. Therefore, the upper limit of Cr is 2
It was set to 0%.

Ni is an essential component for obtaining an austenite phase at high temperature and room temperature, but in the present invention, it is suitable for low cold working in order to obtain a better formability by forming a metastable austenite phase at room temperature. It is necessary to induce a strong martensite phase and obtain high strength. In the present invention, when Ni is lower than 4%, a large amount of δ-ferrite phase is generated at high temperature, and a martensite phase other than the austenite phase is easily generated at room temperature. If it exceeds 10%, the martensite phase is less likely to be induced by cold working. Therefore, the amount of Ni is set to 4.0 to 10.0%. It is more preferably 5.0 to 8.0%. Furthermore, from the viewpoint of durability and heat resistance 4.
It is advantageous to add 0% or more of Ni. However, even if added over 10%, the effect is saturated. N from this aspect
i is preferably 4.0 to 10.0%.

Mo increases the base hardness of the steel and also increases the hardness after aging treatment, and effectively acts to obtain high strength. However, since it is a ferrite former, if it is added in a large amount, the δ-ferrite phase is crystallized, which rather causes a decrease in strength, so the upper limit was made 3.0%.

[0012] Cu hardens the steel by interaction with Si during the aging treatment, but if it is too small, its effect is small, and if it is too large, it deteriorates hot workability and causes cracking. Therefore, it is set to 0.5 to 3.0%.

Ti, Nb and V act effectively in increasing the hardness after aging treatment. In order to express this effect
Addition of 0.1% or more is required. However, if added more than necessary, a large amount of non-metallic inclusions will be formed and the fatigue strength will decrease.
The upper limit of each is 1.0% as it leads to deterioration of surface cleaning.
And

Like C, N is an austenite-forming element and is an element effective for hardening the austenite phase and martensite phase. It is also effective in terms of durability because it is less likely to form precipitates than C. Therefore, in order to impart an appropriate cold work hardening ability, it is added in place of C. However, addition of a large amount causes blowholes, so the content was made 0.30% or less. The addition amount varies depending on the amounts of Si and Cu contributing to age hardening, but is more preferably 0.06 to 0.20%.

S produces MnS under the coexistence of Mn,
0.01 because it causes deterioration of workability such as ductility and bending
0% or less. Further, in a thin plate and in a region where the forming process is severe, it is preferable that Mn and S are further low, and the Mn amount is less than 0.5% and the S amount is preferably 0.004% or less.

O is an element which easily forms a non-metallic inclusion which becomes a starting point of fatigue fracture, and is particularly remarkable when an element having a high affinity with O such as Al and Ti is contained. Therefore, the lower the O content, the more preferable, but the target can be achieved if the O content is 0.007% or less. Therefore, O is set to 0.007% or less.

M value: 30 or more and 100 or less. C, Si,
Mn, Ni, Cr, Mo, Cu and N are contained in the above ranges, but each component is adjusted so that the M value according to the following formula (1) is 30 or more and 100 or less. M = 330- (480xC%)-(2xSi%)-(10xMn%)-(14xNi%)-(5.7xCr%)-(5xMo%)-(14xCu %) − (320 × N%) ··· (1) The constants of each component of the equation (1) were confirmed in the laboratory during the development of the material of the present invention. This M value serves as an index of austenite stability. If the value is less than 30, it is necessary to carry out 70% or more strong working at room temperature to obtain high strength after cold rolling or aging treatment, and ductility decreases. To do. Therefore, it should be 30 or more in terms of moldability. On the other hand, when it exceeds 100, it becomes difficult to maintain the formability because a martensite phase is remarkably generated in low cold working. For this reason 10
Set to 0 or less. In this way, the present invention balances the components so as to form an appropriate amount of martensite phase generated by cold working in order to enhance the formability after cold working as much as possible. In order to avoid the precipitation of Cr carbide during the low temperature or short-time recrystallization annealing (fine crystal treatment before temper rolling) described later, the C is lowered, and the strength is lowered with the decrease of C. (Decrease in work hardening) is supplemented by the addition of N, and the age hardening by N-added steel and the increase in age hardening degree by fine crystal treatment are effectively utilized, and higher strength can be expressed. There is. And by fine crystallization and addition of an appropriate amount of Si, the work-induced martensite phase (α ^- phase) can be finely and densely formed even at a low temper rolling rate.
It is possible to keep the temper rolling rate low by the fact that it is possible to disperse the alloy and the fact that the addition of N causes a large increase in strength due to aging. ..

In addition to these components, Ca, REM (rare earth elements) added as a deoxidizing agent, B (0.01% or less) which is effective in improving hot workability, etc. are added to the steel of the present invention as required. Can be included as well as impurities that are inevitably mixed in. However, Al is not used when high strength and high fatigue strength is required, or it is desirable to use an amount that does not form nonmetallic inclusions in the steel.

The steel of the present invention adjusted to the above-mentioned range has substantially the austenite structure in the solution treatment state. A uniform fine crystal structure can be obtained by subjecting the steel in this structure state to cold rolling of more than 50% and pre-annealing at a temperature of 700 to 1000 ° C. And
By performing temper rolling in the state of this fine crystal structure, the characteristics as a metal gasket material can be obtained. In addition, the hardness and strength can be further enhanced by subjecting the gasket to an aging treatment in which it is kept in the temperature range of 300 ° C or more and 600 ° C or less for 10 seconds or more before or after the forming process, and the durability can be further improved with metal gaskets. be able to.

Next, the manufacturing conditions according to the present invention will be described. The steel obtained by the conventional manufacturing method generally has a grain size of around 25μ, and during the forming process after temper rolling, as shown in the examples described later, due to the grain boundary and processing strain in the processed part. Micro-cracks are generated from the generated slip band, which shortens the service life of machined parts such as metal gaskets. According to the manufacturing method of the present invention, first, a reduction in area (cold rolling rate) of more than 50% is given in the cold rolling before the pre-annealing annealing, and in the pre-annealing annealing, it is shown in the examples described later. Thus, uniform and fine crystal grains can be obtained in a short time, and sufficient strength characteristics can be obtained even at a low temper rolling rate by increasing the strength level in the pre-annealing pre-annealed state. As a result, a steel sheet with excellent formability can be obtained, and even if this sheet is formed, a machined part that does not have surface roughness or microcracks can be obtained, and the life of the machined part can be significantly extended. In addition, the strength increase by aging treatment after temper rolling is larger than that by the conventional method by adding Si and N and fine crystal treatment. If the same strength is obtained after aging treatment, the strength level after temper rolling is lowered. It is possible to provide a material having excellent molding processability.

In particular, annealing before temper rolling is performed at 700 ° C. or higher and 100
Although the temperature is set to 0 ° C or less, it takes a long time to obtain fine crystal grains below 700 ° C, which is not industrial.
This is because recrystallization and grain growth remarkably occur at a temperature higher than ° C and it is difficult to stably obtain crystal grains having a grain size of 10 µ or less. This annealing can be carried out on a continuous annealing line on an industrial scale.

The temper rolling ratio is governed by the strength level after pre-annealing annealing, the stability of the austenite phase, etc., and can be variously changed according to this, but essentially as shown in the examples. The target strength is achieved at a rolling rate lower than that of conventional steel, and it is considered that 25% or more and less than 45% is appropriate.

As for the aging treatment, a temperature range of 300 ° C. or higher and 600 ° C. or lower is preferable in order to obtain strength characteristics as a processed part such as a metal gasket. The lower limit of 300 ° C is not economical because it takes a long time to obtain the target strength level at temperatures lower than this, and the upper limit of 600 ° C is significantly higher before the strength increases. This is because the progress of various recovery occurs and the strength required as a metal gasket cannot be obtained. The reason why the aging treatment time is 10 seconds or more is that sufficient strength characteristics cannot be obtained in a shorter time. The upper limit of the aging treatment time is not particularly limited, but about 1 hour is preferable from the viewpoint of manufacturing cost.

As described above, according to the present invention, in addition to adopting the above-mentioned composition, the steel strip is subjected to cold working of more than 50% before pre-annealing, and 700 ° C to 1000 ° C. Recrystallized grain size is 10μ or less in the temperature range of 1 to 5μ
By performing pre-annealing in a continuous annealing furnace under the treatment conditions that give the following conditions, and then temper-rolling it, it is possible to obtain the same or higher strength as the conventional material, but with a formability that was not possible with the conventional material. Excellent metal gasket material can be obtained. That is, by adopting the above-described composition and fine grain treatment, it is possible to prevent the occurrence of microcracks in the processed part of the metal gasket, which requires high strength and moldability.
In addition, the service life of the metal gasket can be improved.

Since the steel of the present invention exhibits a metastable austenite phase in a solid solution state, the steps prior to pre-annealing can be manufactured in the same manner as conventional materials. However, in order to obtain stable fine crystal grains, 50
As described above, it is necessary to perform cold rolling in excess of%. The effects of the present invention will be specifically described below with reference to examples.

[0026]

EXAMPLES Steels of the present invention (N1) having the components (% by weight) shown in Table 1
9), the conventional steel (A) and the comparative steels (a, b, c) are melted in a normal atmospheric melting furnace, hot-rolled, and then cold-rolled,
After annealing and pickling, the plate thickness after final temper rolling was 0.25 mm. This was taken as a sample as cold rolled. Further, the steel sheet was subjected to an aging treatment at 400 ° C for 30 minutes, and this was used as a sample after the aging treatment. The details of the cold rolling rate before pre-annealing, the pre-annealing conditions, and the temper rolling rate for each steel are shown in Table 2.

A tensile test was carried out on each of the collected samples, a forming workability test was carried out on the as-cold rolled sample before the aging treatment, and a fatigue test was further carried out on the sample after the aging treatment. The results are also shown in Table 2. Note that ΔTS in Table 2 is the tensile strength before and after aging treatment.
(TS) difference. In addition, Table 2 also shows the crystal grain size (μ) in the state annealed before tempering. In the forming workability test, the outer R part and the inner R part (R = 0.2) when the test piece was formed into the shape shown in Fig. 4 were observed, and there were no microcracks (○ marks), and there were fine microcracks. The evaluation was made by (marked with △) and with cracks (×). As for the fatigue test, as shown in FIG. 5, the test piece formed into the W bead shape shown in FIG. 4 was subjected to a compression repeated fatigue test of compressing from state A without load to state B under load for 1 million times. After repeated times, evaluation was made with no cracks (marked with ○) and with cracks (marked with ×).

[0028]

[Table 1]

[0029]

[Table 2]

From the results of Table 2, the following is clear.
It should be noted that it is desirable that the metal gasket material has high strength. Here, the target tensile strength after aging treatment is at least about 175 kg / mm ² .

In Examples Nos. 1 to 10 according to the present invention, that is, in the case of the fine crystallized material in which the composition of components and the manufacturing conditions are within the ranges specified in the present invention, any of the steels will generate microcracks or cracks during forming. Moreover, it has sufficient tensile strength after aging treatment. In the case of the present invention steel (N1) as well, in the conventional production, it is necessary to increase the temper rolling ratio before aging treatment (57.5%) to obtain high strength after aging treatment as shown in Comparative Example No. 11. Therefore, microcracks are generated in both the inner (F) and outer (R) R portions during the forming process. Also, as in Comparative Example No. 12, if the temper rolling rate is lowered to improve the forming workability (40%), the outer (R) R part can be formed without cracking, but the inner R part can be formed. Microcracks are generated in (F). Therefore, it is recognized that the characteristics as metal gaskets are inferior in each case, and ΔTS is lower than those of the examples of the present invention in any case.

Comparative Example No. 13 is an example of the steel (N3) of the present invention in which the rolling ratio of pre-annealing is lower than the range specified by the method of the present invention. Even if it is applied, it becomes mixed particles and fine microcracks are generated in the inner (F) R portion.

Comparative Steel No. 16 was produced by the method of the present invention for the steel (a) in which N was lower than the steel of the present invention and was deviated. However, in order to obtain high strength after aging treatment, C Since N is low and work hardening is small, it is necessary to increase the temper rolling ratio before aging treatment. Therefore, micro cracks do not occur in the inner (F) R portion, but cracks occur in the outer (R) R portion.

Comparative Steel No. 17 was manufactured by the method of the present invention for the steel (b) having a lower M value than the steel of the present invention and deviated. However, since the M value is low, the work hardening is small and the aging is small. Attempts to obtain high strength after treatment give results similar to comparative steel (a).

Comparative Steel No. 18 was manufactured by the method of the present invention for steel (C) having a higher M value than the steel of the present invention, but the M value is high, so that even if the rolling ratio is low, a large amount is produced. Therefore, the bending workability is poor and the object of the present invention cannot be achieved.

180kg after aging treatment like conventional steel No.14
Attempts to obtain a tensile strength of about / mm ^{2 result in} microcracks and cracks in both the inner (F) and outer (R) R portions after forming before aging treatment. Even if the temper rolling rate is lowered so that the tensile strength after aging treatment is around 165 kg / mm ² like the conventional steel No. 15, the crystal grain size is large, so micro cracks are generated in the inside (F) R part. Occur.

FIG. 1 is a photograph showing the surface condition of the inner (F) R portion after the above-mentioned molding process for Comparative Example No. 11, and many microcracks are observed. FIG. 2 shows R of the inner side (F) after the molding process for the invention sample No. 1.
It is a similar photograph of the part, but no microcracks are observed.

In order to investigate the influence of the surface condition at the time of forming on the fatigue characteristics, a test piece having a W-shaped bead shape as shown in FIG. 4 was sandwiched between load variation flanges, as shown in FIG. The presence or absence of cracking after 1 million cycles of A → B compression repetition was examined, and the test results are also shown in Table 2. The results of Table 2 show that the steel and the method according to the present invention were manufactured. No cracks occur, and in the fatigue test under the same conditions, microcracks or cracks in the inner (F) R part and the outer (R) R part both occur in the fatigue test, which greatly affects the fatigue life. Is recognized.

FIG. 3 shows the effect of annealing time on the fine recrystallization characteristics. The processing temperature is 700 ° C. The test materials are all N1 of the steel of the present invention. The recrystallization characteristics differ between those subjected to the cold rolling reduction of 35% (●) and those subjected to 55% (○) before annealing (pre-annealing in the present invention). It was confirmed that when the cold rolling rate before annealing was 55%, which is within the range of the present invention, the hardness rapidly softened from around 10 minutes and sufficiently recrystallized after 20 minutes. However,
It took about 300 minutes for the 35% cold rolled material to soften, and recrystallization partially occurred, and it was difficult to obtain a uniform and fine recrystallized structure as a mixed structure including unrecrystallized parts. ..

[0040]

According to the present invention, it is possible to obtain stainless steel for metal gaskets which is excellent in formability and fatigue characteristics. The material of the present invention is SU, which is a conventional metal gasket material.
Compared with S301, the increase in strength due to aging is large, so the strength before aging treatment can be reduced, and therefore the workability is excellent. In particular, by adopting a manufacturing method that obtains fine crystal grains, the formability can be significantly improved, and this improvement in formability greatly contributes to the service life when used as a metal gasket. Further, the steel of the present invention having such characteristics can be manufactured by using the conventional equipment, and the pre-annealing annealing can be effectively performed by the continuous annealing line. it can.

[Brief description of drawings]

FIG. 1 is a photograph of the metal surface of the inner (F) R portion after the forming process of Comparative Example No. 11.

FIG. 2 R of the inner side (F) after the forming process of the invention example No. 1
It is a photograph of the metal surface of the part.

FIG. 3 is a schematic cross-sectional view showing a W bead shape evaluated for moldability.

FIG. 4 is a cross-sectional view for explaining a compression repeated variable fatigue test method for a W beading imparting material.

FIG. 5 is a diagram showing the relationship between the annealing time at 700 ° C. and the hardness and the grain size of the material of the present invention steel N1 subjected to the rolling ratios of 35% and 65% before annealing (pre-annealing). is there.

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[Procedure amendment]

[Submission date] October 14, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Brief description of the drawing

[Correction method] Change

[Correction content]

[Brief description of drawings]

FIG. 1 is a photograph showing the metal structure of the inner (F) R portion after the forming process of Comparative Example No. 11.

FIG. 2 is a photograph showing the metallographic structure of the R portion of the inner side (F) after the forming process of Inventive Example No. 1.

FIG. 3 is a schematic cross-sectional view showing a W bead shape evaluated for moldability.

FIG. 4 is a cross-sectional view for explaining a compression repeated variable fatigue test method for a W beading imparting material.

FIG. 5 is a diagram showing the relationship between the annealing time at 700 ° C., the hardness, and the grain size of the material of the present invention steel N1 before annealing (pre-annealing) at a rolling ratio of 35% and 65%. ..

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Reference number within the agency FI Technical display location F16J 15/08 M 7233-3J (72) Inventor Toshihiko Takemoto 4976 Nomura Minamimachi, Shinnanyo City, Yamaguchi Prefecture Nisshin Steel Co., Ltd. Steel Research Laboratory (72) Inventor Shigeto Hayashi 4976 Nomura Minami-cho, Shinnanyo-shi, Yamaguchi Prefecture Nisshin Steel Co., Ltd. Steel Research Laboratory (72) Inventor Tomoyuki Sugino 1 Toyota-cho, Aichi Prefecture Inside Toyota Motor Co., Ltd. (72) Inventor Shinji Shibata 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Co., Ltd.

Claims (7)

[Claims] 1. In weight%, C: 0.03% or less, S
i: 1.0% to 3.0%, Mn: 4.0% or less, Ni: 4.0%
~ 10.0%, Cr: 13.0 ~ 20.0%, N: 0.30% or less, S:
0.01% or less, O: 0.007% or less, and M = 330− (480 × C%) − (2 × Si%) − (10 × Mn%) − (14 × Ni%) − (5.7 × Cr %)-(320 × N%) so that the M value is 30 or more and 100 or less, C, Si, M
Stainless steel for metal gaskets, which has an adjusted amount of n, Ni, Cr, and N, and whose balance is Fe and impurities that are inevitably mixed in and has excellent formability and fatigue characteristics. 2. In weight%, C: 0.03% or less, S
i: 1.0% to 3.0%, Mn: 4.0% or less, Ni: 4.0%
~ 10.0%, Cr: 13.0 ~ 20.0%, N: 0.30% or less, S:
0.01% or less, O: 0.007% or less, and further, 3.0% or less of Mo or 0.5 to 3.0% Cu of 1 type or 2 types and / or
Alternatively, Ti, Nb, and V each contain one or more kinds in the range of 0.1 to 1.0%, and M = 330− (480 × C%) − (2 × Si%) − (10 × Mn%) -(14 × Ni%)-(5.7 × Cr%)-(5 × Mo%)-(14 × Cu%)-(320 × N%) , Si, M
The amount of n, Ni, Cr, Mo, Cu, N is adjusted, and the balance is Fe.
And stainless steel for metal gaskets, which is excellent in forming processability and fatigue characteristics, which consists of impurities that are inevitably mixed. 3. Mn: 0.5% or less, S: 0.004% or less,
N: 0.06 to 0.20%, The stainless steel according to claim 1 or 2. 4. In weight%, C: 0.03% or less, S
i: 1.0% to 3.0%, Mn: 4.0% or less, Ni: 4.0%
~ 10.0%, Cr: 13.0 ~ 20.0%, N: 0.30% or less, S:
0.01% or less, O: 0.007% or less, and depending on the case, one or two kinds of Mo less than 3.0% or 0.5 to 3.0% Cu and / or Ti, Nb, V in the range of 0.1 to 1.0% And each contains one or more, and M = 330− (480 × C%) − (2 × Si%) − (10 × Mn%) − (14 × Ni%) − (5.7 × Cr% ) − (5 × Mo%) − (14 × Cu%) − (320 × N%) so that the M value is 30 or more and 100 or less.
The amount of n, Ni, Cr, Mo, Cu, N is adjusted, and the balance is Fe.
In addition, stainless steel consisting of impurities that are inevitably mixed is subjected to normal hot rolling and cold rolling steps and then temper-rolled after annealing to obtain a steel sheet, which is rolled prior to the annealing before temper-rolling. Forming process characterized by subjecting to cold rolling at a rate of 50% or more and performing a temper rolling after the fine grain structure consisting essentially of an austenite phase with a grain size of 10 μ or less is obtained by annealing before temper rolling Of stainless steel for metal gaskets, which has excellent fatigue and fatigue properties. 5. The manufacturing method according to claim 4, wherein the temper rolling is performed at a rolling rate of 25 to less than 45%. 6. The manufacturing method according to claim 4, wherein the annealing before temper rolling is performed in a temperature range of 700 ° C. or higher and 1000 ° C. or lower. 7. The temper-rolled steel sheet is formed into a desired gasket shape after being processed in a temperature range of 300 ° C. to 600 ° C.
The aging treatment is applied for 10 seconds or more.
The manufacturing method described in.