KR20170056007A - Austenitic stainless steel plate - Google Patents

Abstract

And a balance of Fe and unavoidable impurities, wherein the steel contains C of 0.03% or less, Si of 1.0% or less, Mn of 1.5% or less, Cr of 15.0-20.0%, Ni of 6.0-9.0% and N of 0.03-0.15% In addition, when the Md30 value calculated by 497-462 (C + N) -9.2 (Si) -8.1 (Mn) -13.7 (Cr) -20 Wherein the average value of the amount of the processed organic martensite is not more than 5.0% by volume, the average value of the austenite particle size is not more than 5.0 mu m, and the X-ray diffraction half width Of not less than 0.50 DEG and a difference therebetween of not more than 0.10 DEG. This steel sheet is suitable, for example, for a laser metal mask.

Description

[0001] AUSTENITIC STAINLESS STEEL PLATE [0002]

The present invention relates to an austenitic stainless steel sheet.

An austenitic stainless steel sheet is used for the precision machining, particularly the photoetching, and the subsequent heat application by diffusion bonding or the like. Photoetching is a method in which a pattern is formed on the surface of a metal plate, which is a workpiece, by a photoresist method, and then the metal plate is dissolved by etching by spraying or dipping, and the metal plate is processed in substantially the same shape as the photoresist pattern. Laser processing is a method of forming a hole or a predetermined pattern by melting a surface of a metal plate with a laser based on CAD data or the like.

Since the metal plate thus processed is used for a metal mask or the like, the material of the metal plate is required to have excellent flatness and high hardness. Particularly in the case of photoetching, in order to suppress the smut, Is required to be smooth and to have a small warp even after the half-etching treatment.

In recent years, there has also been an increase in the case of manufacturing a heat exchanger and a complicated flow path component by laminating stainless steel sheets subjected to photoetching or laser processing and performing diffusion bonding at a temperature of about 700 캜 or higher. For such applications, in addition to the above-mentioned properties, it is required that the bonding property is good, and the volume change and shrinkage after heating are small.

For example, Patent Document 1 discloses a method of flattening and stress relaxation of a material for photoetching processing by a method (tension annealing method) of adjusting the hardness of a stainless steel foil by temper rolling and then performing heat treatment while applying a tensile force Method is disclosed.

Patent Literature 2 discloses a technique in which a hardness of an austenitic stainless steel strip is adjusted by temper rolling and then calibrated by a tension leveler and thereafter a tensile force equivalent to 0.7 to 1.0 times of a 0.2% To 800 占 폚, thereby producing a stainless steel sheet excellent in flatness after etching.

The stainless steel sheet produced by the method disclosed in Patent Document 2 can be obtained by extinction of the work strain imparted to the work by temper rolling or tension leveler calibrating by final annealing at 700 to 800 ° C, And the warp after the half-etching is suppressed. The stainless steel sheet is characterized in that the martensite is reversely transformed into austenite at 700 to 800 ° C, so that even when heat is applied at the subsequent diffusion bonding, the volume change and heat shrinkage are small.

Patent Document 3 discloses a stainless steel excellent in diffusion bonding property and having an average grain size of 0.001 to 5 mu m in the direction of heading, and having an Al content of fine grains of 0.5 to 8% (in this specification, "% & % &Quot; means "% " unless otherwise stated).

Japanese Patent Publication No. Hei 4-69229 Japanese Patent No. 3573047 Specification Japanese Patent No. 3300225

The method disclosed in Patent Document 1 requires a special annealing facility capable of applying a tensile force to the stainless steel foil in the furnace or requires a low annealing temperature at a low temperature of about 400 DEG C Plate), the productivity is lowered and the manufacturing cost of the photoetching processing material is increased.

Some of the stainless steel foils produced by the method disclosed in Patent Document 1 satisfy the requirements for photoetching, but there is also a problem that there is a large volume change or heat shrinkage at the time of diffusion bonding after photoetching do. This problem is also the same when heat is applied by laser machining. According to the examination results of the inventors of the present invention, this problem is that since the machined organic martensite produced by the temper rolling remains after the tension annealing, when heat is applied at the subsequent diffusion joining, martensite It is believed that this is due to the reverse transformation into austenite.

The stainless steel sheet produced by the method disclosed in Patent Document 2 has a problem that sufficient low hardness content can not be obtained due to the disappearance of processing strain.

Further, the invention disclosed in Patent Document 3 is directed to ferritic stainless steels, and it is considered that even in the case of austenitic stainless steels, the diffusion bondability can be improved by making crystal grains finer.

The object of the present invention is to provide a semiconductor laser device which is capable of performing heat treatment by two kinds of photoetching which are not obtained by the inventions disclosed in Patent Documents 1 and 2, Austenitic stainless steel sheet suitable for a material to be provided for precision machining such as a laser metal mask and the like and capable of satisfying the required characteristics (characteristic II) when it is used for the purpose of being used for the purpose of being used.

(Characteristic I) As a property required for photoetching or laser machining, a material having a flatness, a high hardness and a low carbon content in order to suppress the smut during photoetching can be obtained, The etching surface and the laser-processed surface are smooth.

(Characteristic II) As a required property when it is used in applications where heat can be applied by diffusion bonding or laser processing, the volume change or shrinkage due to heating is small.

Figs. 1 (a) to 1 (c) are explanatory diagrams conceptually showing the distribution of processing deformation on a plate surface and a plate surface. Fig.

As shown in Fig. 1 (a), the processing strain distribution of the plate after calibration by the conventional temper rolling and tension leveler becomes larger on the plate surface and becomes smaller on the inside of the plate. In this state, when the half-etching is performed, the compressive stress in the vicinity of the plate surface is released, and the half-etched surface is warped.

On the other hand, as disclosed in Patent Document 2, by performing annealing (SR treatment: abbreviation of stress relief, which is an abbreviation of stress relief) for about 30 seconds to 10 minutes at 700 to 800 ° C, (b), the deformation of the entire plate including the plate surface and the inside of the plate can be eliminated, whereby the occurrence of the warp after the half-etching can be reliably suppressed. However, as described above, since the processing strain is eliminated, the hardness of the plate is lowered, and the properties required in recent years as the etching material may not be satisfied.

As a result of intensive investigations to solve these problems, the inventors of the present invention have found that, as shown in Fig. 1 (c), the machining deformation of the entire plate is not eliminated by the SR treatment, It is possible to satisfy the hardness required as an etching material while suppressing the occurrence of warpage after half-etching.

However, simply by lowering the conventional SR treatment simply, the processed organic martensite (? ') Produced by temper rolling and tension leveler remained, and the volume change at the time of diffusion bonding becomes large. In addition, simply by shortening the SR treatment time, the processed organic martensite (? ') Disappears but does not disappear, and the warp after half-etching becomes large.

2 (a) to 2 (c) are explanatory diagrams showing various SR processing conditions.

As a result of further investigations by the present inventors, the present inventors have found that, in order to reduce the machining organic martensite amount while having a uniform work deformation in the plate thickness direction as shown in Fig. 1 (c) As in the case of conventional SR treatment conditions, not only the reverse transformation of the machined organic martensite to austenite and the disappearance of the machining strain are simultaneously carried out at a high temperature and for a long time after the heat treatment, but after calibrating by temper rolling and tension leveler 2 (b) or 2 (c), the temperature is raised to 700 to 800 ° C. at a heating rate of 10 ° C./second or more at the temperature of the plate thickness surface, A heat treatment X for performing a heat treatment to cool the surface of the treated martensite to austenite at a cooling rate of 10 deg. C / sec or more and a heat treatment X for 10 seconds By carrying out the holding of the heat treatment and it found that it is to adopt the SR treatment conditions including a heat treatment step of carrying out adjustment of Y effective processing strain.

There is no restriction on the order of the heat treatment X step and the heat treatment Y step, and the heat treatment Y step may be performed after the heat treatment X step, or the heat treatment X step may be performed after the heat treatment Y step. In either case, it is possible to satisfy the characteristics required in the present invention. It is also possible to satisfy the characteristics required in the present invention even if the heat treatment Y step is performed continuously after the heat treatment X step, and the heat treatment X step is performed continuously after the heat treatment Y step.

In the chemical composition to which the present invention is applied, the processed organic martensite produced by cold rolling or further tension leveling is a shearing type (non-diffusion) and reversely transforms into austenite. Therefore, do.

In the austenitic stainless steel sheet provided by the present invention, since the processed organic martensite (? ') Is reduced in this way, the reverse transformation of the treated organic martensite to the austenite during heating of the diffusion bonding And the like. Also, when heat is applied by laser machining or the like, the shape change due to the reverse transformation of the processed organic martensite to the austenite on the machined surface is suppressed.

On the other hand, when the SR treatment at a temperature of 700 ° C or higher is performed in a short time, most of all of the processed deformation remains, and therefore, a certain deformation can not be uniformly left in the thickness direction as shown in Fig. 1 (c) . However, by performing the SR treatment at a lower temperature for a suitable period of time, the diffusion in the vicinity of the surface with a lot of processing deformation is preferentially proceeded, and a certain machining strain remains uniformly in the thickness direction as shown in Fig. 1 (c) Lt; / RTI >

Further, in order to quantitatively evaluate the processing strain, the half-value width of the peak obtained by the X-ray diffraction measurement can be utilized. When the amount of deformation is large, the inter-crystal lattice distance is elongated or contracted from the original length, and the behavior appears in the half-width of the peak obtained by X-ray diffraction measurement. That is, the greater the deformation amount, the longer the crystal lattice distance is from the original length, or the shorter the crystal lattice distance is, the larger the half value width of the peak becomes.

The present invention is as described below.

In terms of% by mass,

C: 0.03% or less,

Si: 1.0% or less,

Mn: 1.5% or less,

Cr: 15.0 to 20.0%

Ni: 6.0 to 9.0%

N: 0.03 to 0.15%

Nb: 0 to 0.50%,

V: 0 to 0.50%,

Ti: 0 to 0.20%,

Cu: 0 to 1.5%,

Mo: 0 to 2.0%,

The remainder being Fe and unavoidable impurities,

Has a chemical composition having an Md30 value of 30.0 to 50.0 DEG C calculated by the following formula (1)

The average value of the amount of the processed organic martensite is 5.0% or less by volume,

The mean value of the austenite grain size is 5.0 占 퐉 or less,

An austenitic stainless steel sheet having a metal structure in which the X-ray diffraction half-width on? (220) in each of the plate surface and the plate center is 0.50 or more and the difference therebetween is 0.10 or less.

Md30 value (° C) = 497-462 (C + N) -9.2 (Si) -8.1 (Mn) -13.7 (Cr) -20 (Ni + Cu) -18.7 ... (One)

However, the symbol of the element in the formula (1) represents the content of each element.

The austenitic stainless steel sheet according to the present invention can be obtained by, for example, subjecting an austenitic stainless steel cold rolled steel strip to temper rolling at a reduction ratio of 30% or more and adjusting the hardness, Followed by heat treatment including the heat treatment X and the heat treatment Y described below.

Heat treatment X: Heat treatment at a temperature elevation rate of 10 占 폚 / sec or more at 700 占 폚 to 800 占 폚 for 10 seconds or less at the above-mentioned temperature range, followed by cooling at a cooling rate of 10 占 폚 /

Heat treatment Y: Heat treatment maintained for more than 10 seconds in a temperature range of 600 ° C to 700 ° C.

According to the present invention, it is possible to provide a substrate having a desired property (such as flatness of material, high hardness, low carbon content in order to suppress smut during photoetching, small warpage even after half- (Having a small volume change or shrinkage due to heating) when used in applications where heat can be applied by diffusion bonding, laser processing, or the like, Based stainless steel sheet can be obtained. The austenitic stainless steel sheet of the present invention is suitable for a material provided for precision machining, for example, for a laser metal mask.

Figs. 1 (a) to 1 (c) are explanatory diagrams conceptually showing the distribution of processing deformation on a plate surface and a plate surface. Fig.
2 (a) to 2 (c) are explanatory diagrams showing various SR processing conditions.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described.

1. Austenitic stainless steel sheet according to the present invention

The present invention is intended for metastable austenitic stainless steels. From the viewpoint of the smoothness of the etched surface, it is preferable that the average crystal grain size is small and that no smut is produced at the time of etching. As well.

(1-1) Chemical Composition

[C: 0.03% or less]

If the C content is more than 0.03%, Cr precipitates on the grain boundaries as crude Cr carbide during the production, which may cause smudging during etching, so that the C content is preferably small. However, since C is an element capable of increasing the strength of the steel sheet at low cost, C may be contained in a range of 0.03% or less without adverse effect of smut. Therefore, the C content is set to 0.03% or less. In applications where the smoothness after etching is strictly required, the C content is preferably 0.02% or less. The C content is preferably 0.012% or less.

[Si: 1.0% or less]

Si is used as a deagglomeration material for the application and contributes to strengthening of the steel. However, when the Si content exceeds 1.0%, the etching rate is lowered. Therefore, the Si content is set to 1.0% or less. , Preferably not more than 0.8%, and more preferably not more than 0.6%. The Si content is more preferably 0.3% or less.

[Mn: 1.5% or less]

Mn contributes to prevention of brittle fracture in hot working and strengthening of steel. However, since Mn is a strong austenite generating element, when the Mn content exceeds 1.5%, the amount of the processed organic martensite produced at the time of cold rolling becomes small, and the fine grain can not be obtained by subsequent annealing. Therefore, the Mn content is set to 1.5% or less. And preferably 1.2% or less.

[Cr: 15.0 to 20.0%]

Cr is a basic element of stainless steel, and when Cr is contained in an amount of 15.0% or more, a metal oxide layer is formed on the surface of the steel and the corrosion resistance is enhanced. However, since Cr is a strong ferrite stabilizing element, when the Cr content exceeds 20.0%,? Ferrite is produced, and this ferrite degrades the hot workability of the material. Therefore, the Cr content is set to 15.0% or more and 20.0% or less.

[Ni: 6.0 to 9.0%]

Ni is an austenite generating element and is an element for stably obtaining an austenite phase at room temperature. Therefore, the lower limit of the Ni content is set to 6.0%. The preferred lower limit is 6.1%. However, when the Ni content exceeds 9.0%, the austenite phase is too stabilized and the processed organic martensite transformation during cold rolling is suppressed. Further, Ni is an expensive element, and an increase in the Ni content causes a significant increase in cost. Therefore, the upper limit of the Ni content is set to 9.0%. The preferred upper limit is 8.9%.

[N: 0.03 to 0.15%]

N, like C, is a solid solution strengthening element and contributes to the improvement of the strength of the steel. Further, N is bonded to Nb to precipitate as a fine Nb compound at the time of annealing, and has the effect of suppressing grain growth. Therefore, the N content should be 0.03% or more. However, when the N content exceeds 0.15%, a large number of coarse nitrides are produced in the process of producing the steel sheet, and these coarse nitrides become destructive starting points, thereby remarkably deteriorating the hot workability and making production difficult. Therefore, the N content should be 0.15% or less. The preferred upper limit is 0.13%.

[Md30 value determined by the above formula (1): 30.0 DEG C or more and 50.0 DEG C or less]

The metastable austenitic stainless steels to which the present invention is applied are austenite ⇒ machined organic martensitic (martensitic) transformation in cold rolling and processed organic martensite ⇒ osteite in the subsequent heat treatment By utilizing the inverse transformation of the nitride, fine grain grains are obtained. The Md30 value is less than 30.0 DEG C, the austenite stability is high, and sufficient processed organic martensite is hardly produced at the time of cold rolling. On the other hand, when the Md30 value exceeds 50.0 DEG C, the austenite stability is low and the load of cold rolling increases. Therefore, the Md30 value is set to 30.0 DEG C or more and 50.0 DEG C or less. The preferred lower limit is 36.0 占 폚, and the preferred upper limit is 48.0 占 폚.

[Nb: 0 to 0.50%]

[V: 0 to 0.50%]

[Ti: 0 to 0.20%]

Nb, V, and Ti are elements effective in producing finer carbides or nitrides and suppressing crystal grain growth due to the flux pinning effect and finer crystal grains of the material. Fine refinement of the crystal grains contributes to improvement of the smoothness of the etched surface. Therefore, these elements may be contained. However, if the content of Nb, V, and Ti is excessively large, recrystallization is suppressed, and there is an adverse effect that a large amount of the non-recrystallized portion remains after annealing. The addition of a large amount of these elements is directly linked to an increase in the cost of the material. Therefore, when these elements are contained, the upper limit values are Nb, V is 0.50%, and Ti is 0.20%. The preferable lower limit of the content of these elements is 0.001% for Nb, 0.001% for V, and 0.001% for Ti.

[Mo: 0 to 2.0%]

Mo may be appropriately added in order to improve the corrosion resistance of the material. However, when the Mo content exceeds 2.0%, the etching is inhibited, leading to an increase in cost. Therefore, when Mo is contained, the content thereof is set to 2.0% or less. , Preferably 1.8% or less, more preferably 1.0% or less. The lower limit of the Mo content is preferably 0.001%.

[Cu: 0 to 1.5%]

Cu is an austenite generating element and is an element capable of adjusting the stability of the austenite phase, so that Cu may be appropriately added. However, when the Cu content exceeds 1.5%, the grain boundaries are segregated in the grain boundary during the production process, and the grain boundary segregation significantly deteriorates the hot workability, making fabrication difficult. Therefore, when Cu is contained, the upper limit of its content is set to 1.5%. And preferably 1.4% or less. The lower limit of the Cu content is preferably 0.001%.

(1-2) Metal structure

[Average value of processed organic martensite: not more than 5.0% by volume]

When the amount of the processed organic martensite is large, when heat is applied by diffusion bonding or laser processing, it transforms into an austenite phase, which causes a change in volume. Therefore, the average value of the amount of the processed organic martensite is set to 5.0% or less by volume. The average value of the amount of the processed organic martensite is calculated from the integral intensity of the peak obtained by the X-ray diffraction measurement (BD Cullity, Element Of X-Ray Diffraction, Addison-Wesley, 1978). Specifically, the average value of the amount of the processed organic martensite is determined by the following formulas (2) and (3). Here, C _γ, C _α, respectively austenite phase, the volume ratio on the maten ZUID, I _γ, I _α is the austenite phase, the integrated intensity of the diffraction peak X-ray from the maten Xi-form, R _γ, R _α is Is a coefficient obtained by the following formula (4). Where v is the volume of the unit cell, F is the structural factor, p is the multiplicity factor ^,? Is the incident angle, and e? ^-2M is the temperature factor.

C _? + C _? = 1 ... ... (2)

I _? / I _? = R _? C _? / R _? C _? ... (3)

R = (1 / v ² ) [F ² p (1 + cos ² 2?) / (Sin ^2? Cos?)] (E ^-2M ) ... (4)

[Average value of austenite particle diameter: 5.0 占 퐉 or less]

When the average value of the austenite grain size is made to be 5.0 占 퐉 or less, the etching surface becomes smooth and the diffusion bonding property is further improved. Therefore, in the present invention, the upper limit of the average value of the austenite grain size is 5.0 탆.

The average value of the austenite grain sizes is calculated as follows. First, the vertical section of the work in the rolling direction is measured by EBSD, and the area enclosed by the boundary of 15 degrees or more is regarded as one crystal grain, and the average area S per crystal grain is calculated from the number of crystal grains contained in the predetermined area , The austenite grain size D determined by the following formula (5) is calculated from the average area S.

D = (2S /?) ^0.5 ... ... (5)

[The X-ray diffraction half-width of the austenite? (220) phase measured at each of the plate surface and the plate center: all 0.50 or more, the difference therebetween: 0.10 or less)

As described above, one of the basic ideas of the present invention is to control the distribution of deformation amount in the plate thickness direction. In the present invention, in order to maintain the hardness of the material, the amount of deformation in each of the surface of the plate and the center of the plate needs to be equal to or larger than a predetermined value.

In order to suppress warpage and deformation of the plate in the half-etching process, it is necessary that the difference in deformation amount between the plate surface and the center of the plate is small. ° or less.

In the X-ray diffraction measurement, the half value width of? (220) is used by using the Co-K? Line in the characteristic X-ray. The measurement of the center of the plate thickness is carried out on a polished surface which is chemically polished until one side is masked and the plate thickness is halved.

2. Manufacturing Method

(2-1) Quality rolling and tension leveler calibration

The austenitic stainless steel sheet according to the present invention is subjected to temper rolling at a reduction ratio of 30% or more in the austenitic stainless steel cold rolled steel sheet having the chemical composition described above to adjust the hardness. That is, after the finish annealing, temper rolling is performed to adjust the hardness. More specifically, temper rolling is performed at a reduction ratio of 30% or more to secure a hardness of about the HV370-specified 304-H specification or higher.

Since the austenitic stainless steel sheet after temper rolling has a wavy shape, it is preferable to perform a tension leveling treatment with a tension leveler to correct the shape in order to secure the flatness of the plate.

The temper rolling and the tension leveler calibration may be performed by means known to those skilled in the art, and are not limited to specific means.

(2-2) SR processing

In the conventional SR process, as shown in Fig. 2 (a), the process is performed at a temperature of about 700 to 800 ° C for a certain period of time, thereby extinguishing the deformation of the entire plate as shown in Fig. 1 (b).

On the other hand, the method of the present invention performs heat treatment including the following heat treatment X and heat treatment Y to adjust the processing strain.

Heat treatment X: Heat treatment at a temperature elevation rate of 10 占 폚 / sec or more at 700 占 폚 to 800 占 폚 for 10 seconds or less at the above-mentioned temperature range, followed by cooling at a cooling rate of 10 占 폚 /

Heat treatment Y: Heat treatment maintained for more than 10 seconds in a temperature range of 600 ° C to 700 ° C.

The heat treatment in the method of the present invention is a heat-treated surface including the heat treatment X and the heat treatment Y. For example, as shown in Fig. 2 (b) or Fig. 2 (c) Or may be a heat treatment in which the heat treatment X is performed after the heat treatment Y is performed. As a result, as shown in Fig. 1 (c), it is possible to uniformly maintain a certain machining deformation in the thickness direction, and to satisfy the hardness required as an etching material while suppressing the occurrence of warping after half etching.

In the heat treatment X, when the heating rate is less than 10 ° C / second, the heat treatment temperature is more than 800 ° C, the heat treatment time is more than 10 seconds, or the cooling rate is less than 10 ° C / Not only the reverse transformation is excessive but also the processing strain is relaxed excessively and it becomes difficult to obtain the necessary strength. On the other hand, when the heat treatment temperature is as low as less than 700 占 폚, the reverse transformation into austenite becomes insufficient. Therefore, the temperature is raised from 700 ° C to 800 ° C at a temperature raising rate of 10 ° C / sec or more on the surface of the plate, and the temperature is maintained for 10 seconds or less before cooling at a cooling rate of 10 ° C / second or more. The temperature raising rate depends on the performance of the equipment to be used but is preferably 50 DEG C / sec or less from the viewpoint of uniform heating and suppressing the shape defect due to thermal deformation. The cooling rate is preferably 20 占 폚 / second or less. The heat treatment Y is maintained for at least 10 seconds in a temperature range of 600 DEG C or more and less than 700 DEG C from the viewpoint of extinguishing only the processing strain in the vicinity of the surface of the steel sheet. The heat treatment time is preferably 180 seconds or less.

As shown in Fig. 2 (b), at the time of cooling in the heat treatment X, the heat treatment may proceed to the heat treatment Y. As shown in Fig. 2 (c) It may be cooled to a temperature lower than the temperature of Y (for example, room temperature), and then reheated to perform the heat treatment Y.

The austenitic stainless steel sheet according to the present invention can be produced by the above-described production method.

[Example]

Table 1 shows the chemical compositions of the steel types A to K used in this example. The steel types A to H satisfy the chemical composition specified in the present invention, and the steel types I, J and K do not satisfy the chemical composition specified in the present invention.

A small ingot having the chemical composition of the steel types A to K was subjected to the cutting, the hot rolling, the annealing and the descaling in sequence, followed by cold rolling and annealing three times to obtain a stainless steel having a thickness of 0.2 mm It was made into steel plate. The average grain size of each stainless steel sheet at this point is about 2 占 퐉 except for the steel types I and J. In the steel types I and J which do not satisfy the chemical composition specified in the present invention, fine grain structure could not be obtained in the above process.

Thereafter, temper rolling was carried out at the temper rolling ratio shown in Table 2, and then the tension leveler correction was carried out and the SR treatment was carried out under the conditions shown in Table 2. [ Thereafter, the amount of the processed organic martensite (α '), the average value of the austenite particle size, the X-ray diffraction measurement and the section hardness of the stainless steel sheet after the SR treatment were measured by the above-described measuring method.

The average roughness, warpage, and strain after the heating test of the etched surface after half-etching were measured.

Specifically, the roughness of the half-etched surface was obtained by masking one side of a rectangular test piece of 10 mm x 100 mm, chemically dissolving it from one side until the plate thickness became half with a ferric chloride solution, Lt; / RTI > The measurement direction was the vertical direction in the rolling direction and the measurement length was 4 mm, and the average of the arithmetic average roughness measured five times was taken. The curvature in the longitudinal direction after the half-etching was measured. The strain after the heating test was calculated from the ratio of the hole sizes before and after heating by drilling holes having a diameter of 10 mm beforehand by photoetching and then heating them at 1000 占 폚 for 5 minutes.

The lamination bonding property was evaluated as follows: a stainless steel plate was stacked with a disk-shaped test piece having a diameter of 8 mm and held at 750 占 폚 for 30 seconds while applying a load of 60 MPa; X ".

In Table 2, the holding temperature of the heat treatment Y means the reached temperature, and the holding time means the time when the steel sheet was subjected to the heat treatment in a temperature range of 600 ° C or more and less than 700 ° C.

The test results are summarized in Table 2.

The steel sheets 1 to 11 in Table 2 are all examples of the present invention which satisfy the present invention. On the other hand, the steel plates 12 to 25 are comparative steels which do not satisfy the present invention.

The steel sheets 1 to 11 had a section hardness of 392 to 415 Hv, an average roughness after half-etching of 0.13 to 0.18 탆, a curvature of 0.0005 to 0.0020 mm ^-1 , and a strain after heating test of 0.015 to 0.020. It is understood that the steel sheets 1 to 11 are the austenitic stainless steel sheets for precision machining which have the above-mentioned features I and II and are suitable for laser metal masks, for example.

On the other hand, in the steel sheet 12, since the C content was out of the range of the present invention, the average value of the austenite grain size was 7 mu m, and as a result, the smoothness of the half-etched surface was inferior and the laminate bonding property was poor.

Since the value of Md30 in the steel sheet 13 was smaller than the range of the present invention, the average value of the austenite grain size was 8 mu m, and as a result, the smoothness of the half-etched surface was inferior and the lamination bonding property was poor.

Since the value of Md30 in the steel sheet 14 was larger than that of the present invention, a large amount of the processed organic martensite (? ') Remained and the deformation after the heating test was large.

Since the temper rolling rate of the steel sheet 15 is lower than the lower limit of the range of the present invention, the width of the X-ray half-width on each of the plate surface and the plate center is small and the section hardness is small.

Since the steel plate 16 was subjected to the SR treatment under the conventional general conditions, the X-ray half-width was small and the section hardness was small because the work deformation hardly remained.

Since the steel sheet 17 is obtained by shortening the conventional general SR treatment conditions in a short time, the amount of the processed organic martensite (? ') Is reduced, but the deformation of the steel sheet 17 is hardly eliminated, The car was hardly changed, and the warp after half-etching was large.

Since the steel sheet 18 was obtained by lowering the conventional SR treatment conditions to a low temperature, a large amount of the processed organic martensite (? ') Remained and the deformation after the heating test was large.

The steel plate 19 is subjected to the two-stage SR treatment, but since the temperature raising rate of the first-stage SR treatment is lower than the range specified in the present invention, much work deformation is extinguished and sufficient hardness is not obtained.

The steel sheet 20 is subjected to two-stage SR treatment, but since the holding temperature of the first-stage SR treatment is lower than the range specified in the present invention, a large amount of the processed organic martensitic (? ') Remains.

The steel sheet 21 is subjected to the two-stage SR treatment, but since the cooling rate of the first-stage SR treatment is lower than the range specified in the present invention, much work deformation is extinguished and sufficient hardness is not obtained.

The steel sheet 22 is subjected to the two-stage SR treatment, but since the SR treatment temperature in the second stage exceeds the range specified by the present invention, much deformation of the steel sheet 22 is lost and sufficient hardness is not obtained.

The steel sheet 23 was subjected to two-stage SR treatment and was performed in the order of a first-stage heat treatment for adjusting and eliminating the deformation of the work and a second-stage heat treatment for performing reverse transformation of the processed organic martensite to austenite . Since the SR treatment holding time of the second-stage heat treatment exceeds the range defined by the present invention, much deformation of the workpiece is lost and sufficient hardness is not obtained.

The steel sheet 24 is to be subjected to two-stage SR treatment. The steel sheet 24 is subjected to a first-stage heat treatment for adjusting and eliminating the deformation of the work and a second-stage heat treatment for performing reverse transformation of the treated organic martensite to austenite did. Since the SR treatment temperature of the second-stage heat treatment is lower than the range specified in the present invention, a large amount of the processed organic martensite remains, and the curvature after the half-etching and the deformation after the heating test are large.

In addition, since the steel plate 25 is not subjected to the SR treatment itself, a large amount of the processed organic martensite (? ') Remains, the X-ray half width in each of the plate surface and the plate center increases, The warp after the half-etching and the strain after the heating test were all poor.

In the present embodiment, five types of steel types A to H have been described as examples. However, the present invention is applicable to a metastable austenitic stainless steel having a chemical composition that does not deviate from the scope of the present invention. There is no need.

Claims (3)

In terms of% by mass,
C: 0.03% or less,
Si: 1.0% or less,
Mn: 1.5% or less,
Cr: 15.0 to 20.0%
Ni: 6.0 to 9.0%
N: 0.03 to 0.15%
Nb: 0 to 0.50%,
V: 0 to 0.50%,
Ti: 0 to 0.20%,
Cu: 0 to 1.5%,
Mo: 0 to 2.0%,
The remainder being Fe and unavoidable impurities,
Has a chemical composition having an Md30 value of 30.0 to 50.0 DEG C calculated by the following formula (1)
The average value of the amount of processed organic martensite is not more than 5.0% by volume,
The mean value of the austenite grain size is 5.0 占 퐉 or less,
An austenitic stainless steel sheet having a metal structure in which the X-ray diffraction half-width on? (220) in each of the plate surface and the plate center is 0.50 or more and the difference therebetween is 0.10 or less.
Md30 value (° C) = 497-462 (C + N) -9.2 (Si) -8.1 (Mn) -13.7 (Cr) -20 (Ni + Cu) -18.7 ... (One)
However, the symbol of the element in the formula (1) represents the content of each element. The method according to claim 1,
Wherein said chemical composition comprises at least one selected from the group consisting of 0.001 to 0.50% of Nb, 0.001 to 0.50% of V, and 0.001 to 0.20% of Ti, in mass%. The method according to claim 1 or 2,
Wherein said chemical composition contains 0.001 to 1.5% of Cu and / or 0.001 to 2.0% of Mo in terms of% by mass.

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