JP4339209B2 - High Al content α-type stainless steel plate for weight detection sensor substrate with excellent impact resistance, its manufacturing method and weight detection sensor - Google Patents

Description

  The present invention relates to a high Al content ferritic stainless steel sheet for a weight detection sensor substrate of an automobile airbag, a manufacturing method thereof, and a weight detection sensor.

  Automobiles are equipped with seat belts and airbags as equipment for ensuring the safety of passengers. Recently, in order to further improve the performance of seat belts and airbags, there is a trend to control the operation of these safety equipment according to the weight (weight) of the occupant. For example, the deployment gas amount and deployment speed of the airbag are adjusted according to the weight of the occupant, and the pretension of the seat belt is adjusted. For that purpose, it is necessary to know the weight of the passenger sitting on the seat by some means. As an example of such means, there is a proposal that the load sensor (load cell) is arranged at the four corners of the seat rail and the seat weight including the weight of the occupant is measured by totaling the vertical loads applied to the load cell. (Patent Document 1).

  Various mechanical quantity sensors for detecting loads, pressures, and the like have been proposed depending on the type of substrate and the type of strain-sensitive material used for the resistance element. As a typical example, (1) a film made of a resin such as polyester, epoxy, polyimide or the like is used as a substrate, and a thin film resistance element made of a Cu—Ni alloy, Ni—Cr alloy or the like is formed on this surface by vapor deposition or sputtering. The formed substrate, (2) a substrate using a glass plate instead of the above resin film (Patent Document 2), and (3) a metal substrate whose surface is coated with a crystallized glass layer is used as a substrate, A material in which a resistive element is formed by applying and baking a paste (Patent Document 3) has been proposed.

  The magnitude of the mechanical quantity is measured as follows. When an external force or load is applied to the mechanical quantity sensor, the resistance element formed on the surface of the substrate is deformed together with the substrate. The applied mechanical quantity is detected by measuring a change in electrical resistance due to a change in the length and cross-sectional area of the resistance element between a pair of electrodes formed connected to the resistance element. Unlike other methods, the mechanical quantity sensor using a metal substrate with a crystallized glass layer formed on the surface as a substrate differs between the metal substrate and the crystallized glass layer and between the crystallized glass layer and the resistive element. Since the component elements are interdiffused, the adhesion between them is strong, making it ideal as a sensor for use in harsh environmental conditions. As a resistance element of this type of mechanical quantity sensor, one formed by applying, drying and firing a resistance paste containing ruthenium oxide as a resistance material is known.

  As the metal substrate used for the mechanical quantity sensor, various alloy materials such as horo steel, stainless steel, silicon steel, nickel-chromium-iron, nickel-iron, kovar, and invar, and clad materials thereof are selected. Patent Document 4 discloses a technique of using a stainless steel plate as a metal substrate. Patent Document 5 discloses a technique of using SUS430 as a metal substrate from the viewpoint of adhesion with an insulating glass layer. Since it is necessary to match the expansion coefficient of a metal base material with a glass layer in patent document 3, the technique made into SUS430 is specifically disclosed.

  However, the metal substrate of the above prior art has not been put into practical use because of insufficient glass adhesion and high-temperature oxidation resistance during firing. It is preferable that the sensor substrate is a stainless steel plate, and each layer of the insulating glass layer, the resistance element, and the electrode is solidified by firing (a conceptual diagram is shown in FIG. 1). Therefore, there has been a strong demand for stainless steel with high heat resistance and excellent glass adhesion that can be fired together with the sensor member when firing each layer at a high temperature.

  Furthermore, when the impact is applied to the weight detection sensor, if the proof stress of the stainless steel of the substrate is low, there is a problem that a crack occurs in the crystallized glass layer with a relatively small impact load. Since the crystallized glass layer has almost no ductility, it cannot follow the plastic deformation of the stainless steel of the substrate, and cracks are generated. Accordingly, there has been a strong demand in practice as a characteristic of the substrate material to improve the yield strength of the stainless steel material of the substrate material and to maintain a low strain that does not easily deform even during an impact.

JP-A-11-304579 Japanese Patent Publication No. 3-20682 JP-A-5-93659 JP 2000-180255 A Japanese Patent Laid-Open No. 10-38733

In order to improve the adhesion between the metal substrate and the glass layer when solidified by firing each layer of the crystallized glass layer, the strain sensitive resistance element, and the electrode, which is an insulating layer, to the stainless steel that is the substrate of the sensor, It is necessary to match the linear expansion coefficient. Since firing is performed at 900 ° C. or lower, it is necessary that the linear expansion coefficient of 20 to 900 ° C. is approximated in addition to the vicinity of room temperature. If the difference in the average linear expansion coefficient is large, the adhesion between the metal base and the crystallized glass layer is remarkably lowered, so that it does not function as a substrate for a resistance element. The average linear expansion coefficient of the crystallized glass which is generally used while a 13~16 × 10 ^-6 / ℃, the average linear expansion coefficient of the conventionally used stainless steel 13 × 10 ^-6 / The difference in linear expansion coefficient between the stainless steel substrate and the glass layer was too large, and sufficient glass adhesion could not be realized. Furthermore, in order to improve the impact resistance characteristics of the weight detection sensor, it is indispensable to increase the yield strength of the stainless steel of the substrate, but no technology has been found to significantly improve the yield strength at room temperature.

  The present invention improves the high-temperature oxidation resistance during sintering with the crystallized glass layer and provides close contact with the glass layer by providing an optimum stainless steel as a metal base material for a vehicle airbag weight detection sensor substrate. It is intended to improve the properties of the weight sensor substrate material by improving the properties and further imparting high impact resistance properties.

  For this purpose, the present invention has been completed as a result of examining the components, metal structure, manufacturing method, proof stress, linear expansion coefficient, and high-temperature oxidation resistance. It has been found that applying a steel plate containing Ti and further containing Ti and Zr meets such a purpose. The gist is as follows.

That is, the object of the present invention is achieved by the high Al-containing ferritic stainless steel sheet described in (1) to (7) below and a method for producing the same.
(1) In mass%,
C: 0.025% or less,
N: 0.025% or less,
C + N: 0.030% or less Cr: 12-30%,
Al: 2.5-8%,
Nb: more than % and not more than 0.7%, with the balance being Fe and inevitable impurities, and the metal structure being an unrecrystallized structure. High Al content ferritic stainless steel sheet for weight detection sensor substrate.
(2) Further, it contains at least one of Ti: 0.02-0.2% by mass and Zr: 0.02-0.2% by mass. High Al content ferritic stainless steel sheet for impact detection weight detection sensor substrate.
(3) Recrystallization temperature is higher than 850 ° C. and not higher than 1150 ° C. The high Al content ferritic stainless steel for weight detection sensor substrate having high proof strength and high impact resistance as described in (1) or (2) steel sheet.
(4) The average linear expansion coefficient from 20 to 900 ° C. is 13.5 to 15.5 × 10 ⁻⁶ / ° C. The high yield strength according to any one of (1) to (3) High Al content ferritic stainless steel sheet for weight detection sensor substrates with high impact resistance.
(5) The difference in average linear expansion coefficient from 20 to 900 ° C. between the stainless steel plate and the crystallized glass for weight detection sensor is less than 10%, according to any one of (1) to (3) High Al content ferritic stainless steel sheet for weight detection sensor substrate with high proof stress and high impact resistance described.
(6) The high Al-containing ferritic stainless steel sheet according to any one of (1) to (5) is punched into a desired shape, and subsequently heat-treated at 800 to 900 ° C. for 20 to 120 minutes. A method for producing a high Al content ferritic stainless steel sheet for a weight detection sensor substrate having high proof stress and high impact resistance.
(7) A weight detection sensor substrate made of a high Al-containing ferritic stainless steel plate having high yield strength and high impact resistance according to any one of (1) to (5), a crystallized glass layer coated on the substrate surface, A weight detection sensor comprising: a strain sensitive resistance element formed on a surface of the crystallized glass layer; and a pair of electrodes for detecting a change in electric resistance of the strain sensitive resistance element.

  The high Al content ferritic stainless steel sheet of the present invention is a material for an automobile airbag weight detection sensor substrate having excellent glass adhesion and high-temperature oxidation resistance, and excellent impact resistance, and a sensor substrate material that adheres an insulating layer. This is an essential technique for developing characteristics as a high sensor substrate material, and its industrial value is remarkably large.

  The reason for limitation of the present invention will be described in detail below.

  The present inventor was completed as a result of examining the components, metal structure, manufacturing method, proof stress, linear expansion coefficient and high temperature oxidation resistance of stainless steel, and Nb was added to the high Al content ferritic stainless steel plate of the metal substrate. Further, by applying a steel plate containing Ti and Zr, an automobile airbag weight detection sensor substrate material having excellent glass adhesion and excellent impact resistance is provided.

  First, the reasons for limiting each component range of the stainless steel targeted by the present invention will be described.

  C, N: When C and N are present in excess of 0.025%, the toughness of the hot-rolled steel strip, which is a cold-rolled material, is reduced and the manufacturability of the material, that is, the cold-rollability is deteriorated. 0.025% or less, and the total amount of C + N is 0.03% or less. A preferable range is 0.010% or less for each of C and N, and a total amount of C + N is 0.010% or less.

  Cr: Cr is the most basic element that ensures the heat resistance or high temperature oxidation resistance of stainless steel. In the present invention, when the content is less than 12%, these characteristics are not sufficiently ensured. On the other hand, when the content exceeds 30%, the toughness and ductility of the hot-rolled steel strip are particularly lowered and the manufacturability of the material is deteriorated. Therefore, the Cr component range is 12-30%. A preferred range is 15-16%.

Al: Al is an element that significantly improves high-temperature oxidation resistance and electrical resistivity of ferritic stainless steel, and at the same time, the linear expansion coefficient increases as the Al content increases. Therefore, in the present invention, the linear expansion coefficient can be approximated and matched even for crystallized glass layers having various linear expansion coefficients by the alloy design in which Al mass% is mainly adjusted. FIG. 2 shows a Cr—Al map of an average linear expansion coefficient from room temperature (20 ° C.) to 900 ° C. It can be seen that the average linear expansion coefficient does not depend on the Cr content, but substantially depends only on the Al content. FIG. 3 shows the relationship between the Al content and the average linear expansion coefficient. The approximate expression of the average linear expansion coefficient from room temperature (20 ° C.) to 900 ° C./(10 ⁻⁶ / ° C.) is 12.8 + 0.28 * (Al mass%) at 8 mass% Al or more, and more than 8 mass% Al. Then, it can be expressed by 2.9 + 1.4 * (Al mass%). If this element is 2.5% or less, the high-temperature oxidation resistance is insufficient. On the other hand, if the content exceeds 8%, the average linear expansion coefficient increases rapidly, and the toughness of the hot-rolled steel strip is remarkably lowered, which deteriorates the manufacturability of the material. Therefore, the Al component range is set to 2.5 to 8%. A preferred range is 4-6%.

  Nb: Nb is an element that forms carbonitride and prevents grain boundary precipitation of Cr carbide, suppresses coarsening of crystal grains, improves toughness of hot-rolled steel strip, and improves material productivity. is there. At the same time, in the present invention, Nb is an element that significantly increases the recrystallization temperature during annealing after cold rolling. As a result, even in annealing in a temperature range higher than the glass firing temperature described later, it becomes possible to suppress the progress of recrystallization and control the metal structure to an unrecrystallized structure, and the yield strength at room temperature is remarkably improved. In other words, by designing the components and processes such as the recrystallization temperature of the steel material> the annealing temperature after cold rolling> the glass firing temperature, the metal structure changes little after the glass firing treatment, and high proof stress can be maintained. is there. If this effect is less than 0.3%, it is not sufficient, and if it exceeds 0.7%, the workability in the cold state is remarkably deteriorated. Therefore, the component range is set to 0.3 to 0.7%. A preferable range is 0.4 to 0.6%. FIG. 4 shows an example of the relationship between the Nb content of the stainless steel plate and the 0.2% proof stress. The hot-rolled steel strip is descaled and then cold-rolled and subsequently annealed at 900 ° C. for 150 s. It can be seen that the 0.2% yield strength increases almost in proportion to the Nb content. FIG. 5 shows the influence of the Nb content of the stainless steel sheet on the relationship between the annealing temperature and the hardness of the cold rolled sheet. It can be seen that as the Nb content increases, the Vickers hardness increases and the recrystallization temperature (the definition in the present invention will be described later) increases. For example, in annealing at 850 ° C., 0.3% by mass of Nb is required to make the Vickers hardness 200 or more, and in annealing at 900 ° C., Nb of more than 0.3% by mass is required.

  Ti: Ti can be selectively added in the present invention. Ti is an element effective in improving the high temperature oxidation resistance of ferritic stainless steel and improving the adhesion of the oxide film. This effect can be exhibited with a Ti content of 0.02% or more. However, excessive Ti addition reduces the toughness of the hot rolled steel strip and degrades the manufacturability of the material. In particular, when it exceeds 0.2%, the toughness is significantly deteriorated. Therefore, the component range is set to 0.02 to 0.2% or less. A preferable range is 0.04 to 0.10%.

  Zr: Zr can be selectively added in the present invention. Zr has the same effect as Ti, is effective in improving the high-temperature oxidation resistance of ferritic stainless steel, and is an element that improves the adhesion of the oxide film. This effect can be exhibited by addition of 0.02% or more of Zr. However, excessive addition of Zr deteriorates the oxidation resistance and at the same time reduces the toughness of the hot-rolled steel strip and deteriorates the manufacturability of the material. In particular, when it exceeds 0.2%, the toughness is significantly deteriorated. Therefore, the component range is set to 0.2% or less. A preferable range is 0.05 to 0.15%.

  Next, the stainless steel targeted by the present invention will be described. The high Al content ferritic stainless steel sheet of the present invention is a cold-rolled annealed sheet obtained by cold rolling a hot-rolled steel strip followed by annealing and descaling.

  In the present invention, the metal structure of the high Al content ferritic stainless steel sheet is an unrecrystallized structure. By controlling the cold-rolled annealed plate to an unrecrystallized structure, it is possible to significantly improve the yield strength at normal temperature. FIG. 6 shows an example of the metal structure. After applying 40% cold working strain, annealing was performed at 900 ° C. The metal structure of 0.1% by mass Nb in a) is a recrystallized structure. On the other hand, in the case of 0.5% by mass Nb of b), although recrystallized grains are partially observed, most of them are non-recrystallized structures and a recovered structure in which a processed structure remains. The non-recrystallized structure in the present invention refers to a metal structure having recrystallized grains of less than 50% and a Vickers hardness Hv of 200 or more when measured with a 1 kg load.

  In the present invention, the recrystallization temperature is more than 850 ° C. and not more than 1150 ° C. It is essential that the recrystallization temperature is higher than the glass baking heat treatment temperature. If the recrystallization temperature is lower than the glass firing temperature, even if an unrecrystallized structure is formed by annealing after cold rolling, recrystallization proceeds and softens during the glass firing heat treatment, and high yield strength cannot be maintained. That is, when the recrystallization temperature is less than 850 ° C., the temperature is equal to or lower than the glass baking heat treatment temperature (800 to 900 ° C.), so that the unrecrystallized structure cannot be maintained and the proof stress is lowered. On the other hand, when the recrystallization temperature exceeds 1150 ° C., the Nb content becomes large, the toughness of the hot-rolled sheet deteriorates, and the manufacturability of the cold-rolled sheet significantly decreases. From the above, the recrystallization temperature was set to be higher than 850 ° C. and lower than 1150 ° C.

The difference in average linear expansion coefficient from 20 to 900 ° C. between the high Al content ferritic stainless steel plate of the present invention and the crystallized glass for weight detection sensor substrate is less than 10%. In order to improve the adhesion between the metal substrate and the glass layer when the crystallized glass layer, the strain sensitive resistance element and the electrode layer, which are insulating layers, are solidified by firing on the stainless steel which is the sensor substrate, both It is necessary to match the linear expansion coefficient. Since the firing is performed at 900 ° C. or less, it is desirable that the linear expansion coefficient of 20 to 900 ° C. is approximated in addition to the vicinity of room temperature. When the difference in average linear expansion coefficient is more than 10%, the adhesion between the metal substrate and the crystallized glass layer is remarkably lowered, so that it does not function as a resistor element substrate. Generally used crystallized glass has an average linear expansion coefficient of 13 to 16 × 10 ⁻⁶ / ° C.

The average coefficient of linear expansion of 20 to 900 ° C. of the high Al content ferritic stainless steel sheet of the present invention is preferably 13.5 to 15.5 × 10 ⁻⁶ / ° C. The defining formula of the linear expansion coefficient α is L _T = L ₂₀ (1 + αT). Here, L _20: length at 20 ℃, L _T: is the length of the temperature T. In the high Al content ferritic stainless steel sheet of the present invention, when the 20 to 900 ° C. is less than 13.5 × 10 ⁻⁶ / ° C. and more than 15.5 × 10 ⁻⁶ / ° C., the adhesion to the crystallized glass layer is low. Not secured.

  After the cold-rolled annealed sheet of the high Al content ferritic stainless steel sheet of the present invention is punched into a desired shape, it is fired with a glass layer. Firing conditions are 800 to 900 ° C. and 20 to 120 minutes. If it is less than 800 ° C., the adhesiveness is insufficient due to insufficient mutual diffusion between the stainless steel plate and the glass layer. On the other hand, if it exceeds 900 ° C., the heat resistance of the glass layer is insufficient. The firing time is the total time of a plurality of heat treatments. If it is less than 20 minutes, the adhesion is insufficient due to insufficient mutual diffusion. On the other hand, if it exceeds 120 minutes, mutual diffusion is sufficiently performed. However, since an oxide film having a submicron thickness is formed by the progress of oxidation, an interference color is formed and the temper color resistance is deteriorated. There is no direct effect on the sensor characteristics, but the metallic luster on the stainless steel surface disappears.

  The automobile airbag weight detection sensor of the present invention includes a substrate (1) made of a metal base material of a high Al content ferritic stainless steel plate, a crystallized glass layer (2) coated on the substrate surface, and the crystallized glass layer. A weight detection sensor comprising a strain sensitive resistor element (4) formed on the surface of the substrate and a pair of electrodes (3) for detecting a change in electrical resistance of the strain sensitive resistor element (FIG. 1) It is. Since the high Al content ferritic stainless steel substrate has good adhesion to the crystallized glass layer (2), the metal substrate (1), the crystallized glass layer (2), the electrode (3), and the strain sensitive resistance element ( The baking process of 4) can be performed simultaneously or the number of baking processes can be reduced.

  Hereinafter, the present invention will be specifically described with reference to Examples.

(Example 1)
High Al content ferritic stainless steels having the components shown in Table 1 were melted by the converter AOD method or the vacuum melting method. After cleaning the surface of these steels, hot rolling at a hot rolling end temperature of 880 ° C. to 900 ° C., winding at a hot rolling winding temperature of 400 ° C. to 750 ° C., cooling by water cooling, and having a thickness of 5 mm A hot-rolled steel strip was used. Subsequently, after descaling by shot and pickling, it was cold-rolled to a plate thickness of 3 mm. Then, it annealed at 900 degreeC, and also descaled by salt treatment and pickling, and manufactured the cold-rolled steel plate. Thereafter, a heat treatment was performed at 850 ° C. for 40 minutes, which was punched into a desired shape and simulated for a close-contact firing heat treatment of crystallized glass. Crystallized glass having an average linear expansion coefficient of 14.5 × 10 ⁻⁶ / ° C. was used.

  Table 1 shows examples of the invention. The evaluation test was carried out by the following method.

  The components were analyzed by sampling a test piece from the steel plate. For C, S, N, gas analysis method (N is inert gas melting-heat conduction measurement method, C, S is oxygen gas combustion-infrared absorption method), and other elements are fluorescent X-ray analyzers ( SHIMADZU, MXF-2100).

Evaluation of manufacturability (cold workability) was conducted by taking an impact test by taking a V-notch Charpy test piece of sub-size (thickness 5 mm) conforming to JIS standard in parallel with the rolling direction, and an impact value of 2 kgf / cm ² . At a temperature (vT2: ° C.). When vT2 exceeds 90 ° C., even if preheating is performed in advance using a heating apparatus such as a box annealing furnace, the risk of sheet breakage due to impact or the like becomes extremely high when cold rolling is performed, which is substantially Since it cannot be cold-rolled, it was set as x. Each of the inventive examples showed good manufacturability. Comparative Example No. No. 10, C and C + N are outside the upper limit. No. 11 has Cr exceeding the upper limit. In No. 13, Al deviated from the upper limit. No. 15, N and C + N are outside the upper limit. In No. 17, Nb exceeded the upper limit and No. No. 18 has Ti exceeding the upper limit. In No. 19, Zr deviated from the upper limit, and in all cases, the productivity was poor.

Evaluation of high-temperature oxidation resistance was performed by using a sample whose surface was polished with a # 400 count and an oxidation increase after 900 ° C. for 120 minutes in the atmosphere. A case where the increase in oxidation was 0.2 mg / cm ² or less was indicated by ◯, and a case where the increase in oxidation was more than 0.2 mg / cm ² was indicated by x. Comparative Example No. No. 12 (sample symbol 12) shows that Cr is outside the lower limit of the claims, and No. of the comparative example. No. 14 (sample symbol 14) is inferior in oxidation resistance because Al is outside the lower limit of the claims.

The linear expansion coefficient was measured by an ISO standard test method, and an average linear expansion coefficient in a temperature range of room temperature (20 ° C.) to 900 ° C. was evaluated. The average coefficient of linear expansion ○ those range of ^{13.5~15.5 × 10 -6 / ℃, 13.5} × 10 -6 / ℃ or less than 15.5 × 10 ^-6 / ° C. greater × ones It showed in. In the present invention example, the difference in average linear expansion coefficient from 20 to 900 ° C. between the high Al content ferritic stainless steel sheet and the crystallized glass for weight detection sensor substrate is within 10%. Comparative Example No. No. 14, the amount of Al is outside the lower limit of the present invention, and the average linear expansion coefficient from room temperature to 900 ° C. is outside the lower limit of the present invention.

  The glass adhesion was evaluated by a tape peeling test JIS H 8504 (plating adhesion test method). The case where the crystallized glass layer was peeled off was indicated by ×, and the case where the crystallized glass layer was not peeled was indicated by ○. The metal substrate of the component of the present invention has greatly improved glass adhesion. Comparative Example No. No. 14 (sample symbol 14) had an Al content below the lower limit of the range of the present invention and poor glass adhesion.

  The recrystallization temperature was evaluated by heat treatment from 750 ° C. to 1100 ° C. at intervals of 50 ° C., and then the Vickers hardness (Hv) of the L cross section at a load of 1 kg at the plate thickness center, 1/4 thickness and 1 / Measurement was made at 8 thickness parts for evaluation. The temperature at which Hv was 200 or less was defined as the recrystallization temperature. In the table, ◯ indicates a recrystallization temperature of 900 ° C. or higher, and X indicates 850 ° C. or lower. In addition, after the L section was mirror-polished, electrolytic etching with nitric acid was performed to observe the metal structure, and a recrystallized structure and an unrecrystallized structure were determined. In the table, ○ indicates an unrecrystallized structure, and × indicates a recrystallized structure. The metal structure of the steel sheet having a high yield strength (450 MPa or more) of the present invention is an unrecrystallized structure. Comparative Example No. No. 16 (sample symbol 16) has an Nb content that is outside the lower limit of the claim, a recrystallization temperature that is outside the lower limit of the claim, and the metal structure is also outside the claimed range.

  The 0.2% proof stress was prepared by preparing a No. 13B test piece of JISZ 2201 from an annealed sheet after cold rolling, and using an Instron type tensile tester according to the test method of JIS Z 2241. Data in the L direction (parallel to the rolling direction) was measured at n = 2. O in the table indicates that 0.2% proof stress is 450 MPa or more, ◯, particularly 500 MPa or more is indicated by ◎, and less than 450 MPa is indicated by ×. Comparative Example No. In No. 16 (sample symbol 16), Nb is outside the lower limit of the claims, and the 0.2% yield strength is inferior.

  Impact resistance characteristics are determined by visual observation of the presence or absence of cracks in the crystallized glass layer and the deformation of the stainless steel plate on the substrate after applying a 1200G impact to the center of the sensor by fixing both ends of the weight sensor produced. did. The case where there was no deformation of the steel material of the substrate and a crack occurred in the crystallized glass layer which was in close contact was indicated by x, and the case where no crack was generated was indicated by ○. Comparative Example No. No. 16 (sample symbol 16) has a 0.2% proof stress that is outside the lower limit of the claims, and is inferior in impact resistance.

(Example 2)
The samples of sample symbol 3 (No. 1) and sample symbol 7 (No. 7) in Table 1 were subjected to firing heat treatment under the conditions shown in Table 2. The average linear expansion coefficient of the crystallized glass was 14.5 × 10 ⁻⁶ / ° C. as in Example 1.

  Temper color resistance was determined by visual observation of the presence or absence of a visible light color.

  Invention Example No. Nos. 20 to 23 adopt the firing conditions of the present invention and are excellent in glass adhesion, 0.2% proof stress, and impact resistance. Comparative Example No. In No. 24, the firing temperature deviated from the upper limit, and the glass adhesion, temper color resistance, metal structure, 0.2% proof stress, and impact resistance were all poor. Comparative Example No. No. 25 had a baking time outside the upper limit, and the temper color resistance was poor. Comparative Example No. No. 26 had a lower firing time than the lower limit, and had poor glass adhesion. Comparative Example No. In No. 27, the firing temperature was outside the lower limit, and the glass adhesion was poor.

  The present invention is a technology applicable to a material for an automobile airbag weight detection sensor substrate.

It is a conceptual diagram of the mechanical quantity sensor of this invention. Cr-Al map of average linear expansion coefficient from room temperature (20 ° C) to 900 ° C Relationship between Al content and average linear expansion coefficient at room temperature (20 ° C) to 900 ° C The figure which shows the relationship between Nb content of stainless steel plate and 0.2% yield strength Effect of Nb content of stainless steel sheet on the relationship between annealing temperature and hardness of cold rolled sheet Photograph of metal structure after annealing a cold-rolled sheet at 900 ° C., a) 0.1% by mass Nb, b) 0.5% by mass Nb

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Metal base material which consists of high Al content ferritic stainless steel plate 2 Crystallized glass layer 3 Electrode 4 Strain-resisting resistance element 5 Bolt hole

Claims (7)

% By mass
C: 0.025% or less,
N: 0.025% or less,
C + N: 0.030% or less Cr: 12-30%,
Al: 2.5-8%,
Nb: 0.3% greater than 0.7% or less containing <br/>, with the balance of Fe and unavoidable impurities, the high strength and high resistance, wherein the metal structure is non-recrystallized structure High Al content ferritic stainless steel sheet for impact detection weight detection sensor substrate.   Furthermore, Ti: 0.02-0.2 mass%, 1 type or more of Zr: 0.02-0.2 mass% is contained, The high proof stress and the high impact resistance characteristic of Claim 1 characterized by the above-mentioned. High Al content ferritic stainless steel sheet for weight detection sensor substrates.   3. The high Al content ferritic stainless steel sheet for weight detection sensor substrate having high proof strength and high impact resistance according to claim 1 or 2, wherein a recrystallization temperature is higher than 850 ° C. and not higher than 1150 ° C. The average linear expansion coefficient from 20 to 900 ° C is 13.5 to 15.5 × 10 ^-6 / ° C, and the high proof stress and high impact resistance characteristics according to any one of claims 1 to 3 High Al content ferritic stainless steel sheet for weight detection sensor substrate.   4. The difference in average linear expansion coefficient from 20 to 900 ° C. between the stainless steel plate and the crystallized glass for weight detection sensor is less than 10%. High Al content ferritic stainless steel sheet for weight detection sensor substrates with high impact resistance.   The high Al content ferritic stainless steel sheet according to any one of claims 1 to 5 is punched into a desired shape, and subsequently heat treated at 800 to 900 ° C for 20 to 120 minutes. A method for producing a high Al content ferritic stainless steel sheet for a weight detection sensor substrate having high impact resistance.   A weight detection sensor substrate made of a high Al-containing ferritic stainless steel plate having high yield strength and high impact resistance according to any one of claims 1 to 5, a crystallized glass layer coated on the substrate surface, and the crystallized glass A weight detection sensor comprising a strain sensitive resistance element formed on a surface of a layer and a pair of electrodes for detecting a change in electric resistance of the strain sensitive resistance element.