JPH0995757A - Quasi-stable austenitic stainless steel thin sheet for id brade substrate and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably produce a steel thin sheet having high tensile strength and fracture elongation and furthermore excellent in corrosion resistance by specifying the componental compsn. of a quasi-stable austenitic stainless steel, the amt. of strain induced martensite and the grain size of austenite before the formation of the above phases. SOLUTION: A quasi-stable austenitic stainless steel contg., by weight, 0.01 to 0.2% C, 0.05 to 3% Si, 0.08 to 3% Mn, 6 to 7.4% Ni, 13 to 20% Cr and 0.05 to 0.5% Cu is used. This steel is produced into a steel thin sheet by the process of cold rolling before final annealing-final annealing-final cold rolling-aging treatment. Then, the cold rolling ratio in the final cold rolling is regulated to >=40%, the temp. in the final annealing is regulated to 950 to 1,000 deg.C, and the time therefor is regulated to the range of 1 to 30sec. By this method, the objective steel thin sheet composed of the steel having the above compsn. and contg. strain induced martensitic phases by >=30vol.%, and in which the grain size of austenite before the formation of the strain induced martensitic phases is regulated to <=15μ can be obtd.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention mainly relates to Si, G
The present invention relates to a metastable austenitic stainless steel thin plate for a substrate of an ID blade used when cutting a wafer from an ingot of a semiconductor single crystal such as aAs.

[0002]

2. Description of the Related Art Strength and ductility are important properties required of a material for an ID blade substrate.

Regarding the strength, not only is it necessary to "pull up" the surface of the ID blade with a considerable surface tension when it is set in the cutting device, but it is necessary to increase the strength in order to withstand the cutting at high speed. Although desired, it has been examined by the present inventors that a tensile strength of 170 kgf / mm ² or more is required.

For ductility, the "pull up" of the blade
In order to give a strain of 0.9-1.0%, a breaking elongation of at least 1.0% was required, but there is a demand to reduce the breaking frequency of ID blades during single crystal cutting. It is becoming more and more severe, and breaking elongation of 1.5% or more is required. Further, it is desirable that the ductility be as high as possible in order to absorb the impact due to the vibration of the blade during the wafer cutting.

FIG. 1 shows a stress-strain curve obtained by a tensile test. The breaking elongation is the amount of strain (%) at the breaking position in FIG.

In addition, high rigidity, corrosion resistance, and low in-plane anisotropy of mechanical properties are also necessary properties for the material for the ID blade substrate.

Considering such required characteristics, precipitation hardening stainless steel and metastable austenitic stainless steel represented by SUS301 and SUS304 have been used as materials for ID blade substrates.

In the case of the precipitation hardening stainless steels described in JP-A-61-295356 and JP-A-4-202643, the strengthening mechanism is due to the precipitation of fine intermetallic compounds, so that they break. Even if the material has a high ductility (for example, a breaking elongation of 2% or more), the blade may suddenly break during wafer cutting. Therefore, in the precipitation hardening stainless steel, the fracture resistance of the blade cannot be evaluated by the elongation at break in the tensile test, and its quality control becomes difficult.

On the other hand, in the case of metastable austenitic stainless steel, Japanese Patent Publication No. 44891/1990 and Japanese Patent Laid-Open No.
As described in Japanese Patent Publication No. 41686-41, since strengthening is achieved by performing cold working after annealing to work-harden and producing a work-induced martensite phase, or by performing an aging treatment thereafter. However, problems such as those found in precipitation hardening stainless steel do not occur.

[0010]

However, in the metastable austenitic stainless steel, it is necessary to carry out a strong cold working to obtain high strength as described above, so that the breaking elongation is 1.0 to 1. Remarkably low at around 4%. further,
Since the value of break elongation varies due to slight differences in manufacturing conditions, the break frequency of the ID blade during wafer cutting also varies, and the reliability of the material is low. In addition, JP-A-6-41
In Japanese Patent No. 686, the strength is increased by reducing the effective grain size of the processing-induced martensite, but the grain size measurement in a high processing state has a large error, and it is difficult to control the strength. .

The present invention has been made to solve the above problems, and has a tensile strength of 170 kgf / mm ² or more and a breaking elongation of 1.5% or more, and is excellent in corrosion resistance for ID blade substrates. Another object of the present invention is to provide a metastable austenitic stainless steel sheet and a method for producing the same.

[0012]

Means for Solving the Problems The above problems can be solved by a metastable austenitic stainless steel thin plate for an ID blade substrate, which satisfies the following conditions.

(1) C: 0.01 to 0.2 by weight%
%, Si: 0.05 to 3%, Mn: 0.08 to 3%, N
i: 6 to 7.4%, Cr: 13 to 20%, Cu: 0.0
It consists of steel containing 5 to 0.5%.

(2) 30 vol. % Or more of the work-induced martensite phase.

(3) The grain size of austenite before forming the work-induced martensite phase is 15 μm or less.

The reason for the limitation will be described below. C: An element that suppresses the formation of the δ ferrite phase and promotes the formation of the austenite phase. In addition to controlling the amount and hardness of the martensite phase produced by processing, it also contributes to strengthening the solution by strengthening its solid solution and age hardening. Further, it suppresses the formation of martensite phase and stabilizes the austenite phase, which also contributes to high ductility. 0.
If it is less than 01%, a tensile strength of 170 kgf / mm ² or more and a breaking elongation of 1.5% or more cannot be obtained at the same time. If it exceeds 0.2%, a large amount of Cr carbide is precipitated, resulting in deterioration of corrosion resistance and ductility.

Si: 0.05% or more is necessary for solid solution strengthening the austenite phase and the work-induced martensite phase, but if it exceeds 3%, a δ ferrite phase is formed and hot workability is deteriorated.

Mn: an element that promotes the formation of an austenite phase, and is required to be 0.08% or more for the single phase formation and deoxidation of the austenite phase during solution treatment. Is excessively stabilized, and the formation of processing-induced mattensite phase is extremely suppressed, resulting in 170 kgf /
A tensile strength of mm ² or more cannot be obtained.

Ni: An element that promotes the formation of a strong austenite phase and suppresses the formation of the δ ferrite phase.
6% or more is necessary for making the austenite phase into a single phase during solution treatment, but if it exceeds 7.4%, the austenite phase is excessively stabilized and the formation of the work-induced mattensite phase is extremely suppressed, and 170 kgf / Mm ² or more tensile strength cannot be obtained.

Cr: An essential element of stainless steel, 13% or more is necessary to obtain sufficient corrosion resistance, but 20%
If it exceeds, δ ferrite phase is generated and hot workability is deteriorated.

Cu: To strengthen the passivation film and to provide the necessary corrosion resistance when used as an ID blade,
It is necessary to be 05% or more, but if it exceeds 0.5%, the effect is saturated, and undissolved C in the austenite phase is present.
u increases and hot workability deteriorates.

In order to obtain a tensile strength of 170 kgf / mm ² or more, not only these components are adjusted to the appropriate range, but also 30 vol. % Or more of the work-induced martensite phase must be formed. Further, in order to secure a breaking elongation of 1.5% or more, the austenite grain size before forming the work-induced martensite phase is set to 15 μm.
m or less.

Such a metastable austenitic stainless steel thin plate for an ID blade substrate can be manufactured by a manufacturing method satisfying the following conditions.

(1) A steel having the above components is used.

(2) Manufactured by the steps of cold rolling before final annealing-final annealing-final cold rolling-aging treatment.

(3) The cold rolling ratio of the cold rolling before final annealing of (2) is set to 40% or more.

(4) The temperature of the final annealing of (2) is set to 950 to
The temperature is 1000 ° C. and the time is in the range of 1 to 30 seconds.

The reason for the limitation will be described below. The reason for limiting the components is as described above.

In the manufacturing method of the present invention, cold rolling before final annealing is performed.
Final annealing-final cold rolling-final cold rolling in the process of aging treatment
By changing the cold rolling rate of 30 vol. % Or more
Work-induced martensite phase can be formed and subsequent aging treatment
170 kgf / mm ²To obtain the above tensile strength
Can be.

If the cold rolling rate of the cold rolling before the final annealing is 40% or more, the temperature of the final annealing is 950 to 1000 ° C., and the time is in the range of 1 to 30 seconds, the work-induced martensite phase is not formed. The austenite grain size can be 15 μm or less, and a breaking elongation of 1.5% or more can be secured.

If the cold rolling ratio in the cold rolling before the final annealing is less than 40%, the frequency of recrystallization nucleation in the final annealing is reduced and the austenite grains are coarsened. If the temperature of the final annealing is less than 950 ° C, the unrecrystallized structure remains, and if it exceeds 1000 ° C, the grain growth is fast and the austenite grains become coarse. If the final annealing time is less than 1 second, it is impossible to control the annealing time with an actual machine, and if it exceeds 30 seconds, the austenite grains become coarse.

For fine graining, within the scope of the present invention, it is desirable that the cold rolling ratio of the cold rolling before final annealing is as high as possible, the temperature of final annealing is as low as possible, and the time of final annealing is as short as possible.

[0033]

BEST MODE FOR CARRYING OUT THE INVENTION Among the methods for producing a metastable austenitic stainless steel sheet according to the present invention, the production method prior to cold rolling before final annealing is not particularly specified, but it is easy to produce in a usual process. Is. That is, a stainless steel slab having the components of the present invention is hot-rolled, annealed and pickled, and then cold-rolled and annealed several times if necessary. At this time, thin slab technology can also be applied to the slab production.

It is preferable that the annealing is performed in a non-oxidizing atmosphere from the viewpoint of surface properties and corrosion resistance. Especially for the final annealing and aging treatment, H ₂ gas 70% vol. The above non-oxidizing atmosphere is preferable.

The final cold rolling rate is preferably 70% or less in order to adjust the surface roughness of the final product.

[0036]

Example Steels having the chemical composition shown in Table 1 were melted to produce a hot rolled steel strip having a plate thickness of 1.8 mm.

This hot-rolled steel strip is annealed and pickled to obtain 44 to 76
% Cold rolling, and 1050 ° C. × 30 seconds intermediate annealing was performed. Thereafter, under various conditions shown in Table 2, cold rolling before final annealing-final annealing-final cold rolling were sequentially performed, and an aging treatment was performed at 450 ° C for 30 seconds.

Then, according to JIS-Z-2241, a tensile test (JIS No. 13B test piece, tensile speed 2 mm / mi)
n. ) Was carried out to determine the tensile strength and the elongation at break. In addition, the corrosion resistance of some samples was investigated by a salt spray test. Further, after being processed into an ID blade, it was attached to a wafer cutting device, and the “pull-up” property and the breakage frequency during cutting were also investigated.

Table 2 shows the results. In Table 2, the material No. 1
Nos. 14 to 14 are examples of the present invention, and the material No. 15-28
Is a comparative example. Material N satisfying the conditions of the present invention
o. It can be seen that the samples 1 to 14 have a tensile strength of 170 kgf / mm ² or more and a breaking elongation of 1.5% or more, and are also excellent in corrosion resistance. Further, even when it is actually used as an ID blade, the "pull-up" property is good, and the break frequency during cutting is very low.

Material No. of Comparative Example Samples 15-27
Although the austenite grain sizes before the formation of the work-induced martensite phase are all outside the range of the present invention, 170 kgf
No one simultaneously satisfies a tensile strength of at least 1 mm2 / mm ² and an elongation at break of at least 1.5%. Therefore, there is a problem in "pull-up" property and breakage frequency during cutting. In addition, the material No. of the comparative example. 18 samples had a low final annealing temperature of 900 ° C,
Although it is a sample in which an unrecrystallized structure remains, such a sample is remarkably inferior in corrosion resistance.

Material No. of the comparative example. Sample No. 28 has the austenite grain size before the formation of the work-induced martensite phase is within the range of the present invention, but the amount of martensite is less than the range of the present invention. Is not obtained.

[0042]

[Table 1]

[0043]

[Table 2]

[0044]

Since the present invention is constructed as described above, the tensile strength of 170 kgf / mm ² or more and 1.
It is possible to provide a metastable austenitic stainless steel thin plate having a breaking elongation of 5% or more and excellent in corrosion resistance for an ID blade substrate, and a method for producing the same.

Using the stainless steel sheet of the present invention, I
Since the frequency of breakage at the time of “pulling up” when setting the D-blade in the cutting device and the breakage at the time of cutting the wafer can be significantly reduced, it can greatly contribute to the improvement of the stability of wafer manufacturing and the yield.

[Brief description of drawings]

FIG. 1 is a diagram showing how to determine elongation at break.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kaoru Sato 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Japan Steel Pipe Co., Ltd. (72) Masanori Omura 1-2-1 Marunouchi, Chiyoda-ku, Tokyo Date Main Steel Pipe Co., Ltd.

Claims (2)

[Claims] 1. A metastable austenitic stainless steel thin plate for an ID blade substrate, which satisfies the following conditions. (1) In weight%, C: 0.01 to 0.2%, Si: 0.
05-3%, Mn: 0.08-3%, Ni: 6-7.4
%, Cr: 13 to 20%, Cu: 0.05 to 0.5%. (2) 30 vol. % Or more of the work-induced martensite phase. (3) The austenite grain size before the formation of the work-induced martensite phase is 15 μm or less. 2. The method for producing a metastable austenitic stainless steel thin plate for an ID blade substrate according to claim 1, wherein the following conditions are satisfied. (1) A steel having the composition according to claim 1 is used. (2) Manufactured by the steps of cold rolling before final annealing-final annealing-final cold rolling-aging treatment. (3) The cold rolling rate of the final cold rolling is 40% or more. (4) The temperature of the final annealing is 950 to 1000 ° C., and the time is 1 to 30 seconds.