JPH0995756A - Quasi-stable austenitic stainless steel thin sheet for id brade substrate - 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 and the amt. of strain induced martensite. SOLUTION: This steel thin sheet is composed of a quasi-stable austenitic stainless steel contg., by weight, 0.12 to 0.2% C, 0.05 to 3% Si, 0.08 to 3% Mn, <=0.045% P, <=0.02% S, <=0.003% Al, 0.01 to 0.04% N, <=0.02% O, 6 to 7.4% Ni, 13 to 20% Cr and 0.05 to 0.5% Cu. Then, strain induced martensite phases are contained by the amt. satisfying the inequality: 67.5-187.5 [C]<=M<=37.5+187.5 [C] in the case the volume rate thereof is defined as M%. The steel thin sheet can stably be produced, has about >=170kgf/mm<2> tensile strength and about >=1.5% fracture elongation and is moreover excellent in corrosion resistance as that for an ID brade substrate.

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 precipitation hardening stainless steel, since the strengthening mechanism is due to the precipitation of fine intermetallic compounds, they tend to be the starting points of fracture, and even if the material has high ductility (for example, elongation at break is 2 %), 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 of the tensile test,
Its quality control becomes difficult.

On the other hand, in the case of metastable austenitic stainless steel, Japanese Patent Publication No. 2-44891 and Japanese Patent Laid-Open No.
As described in Japanese Patent Laid-Open No. 2026443, high strength is achieved by performing cold working after annealing to work-harden the work and generating a work-induced martensite phase, and then performing an aging treatment. 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, the value of elongation at break varies greatly due to a slight difference in manufacturing conditions and may be less than 1.0%, so that there is a problem in that a product with high ductility cannot be manufactured stably.

The present invention has been made to solve the above problems, and 170 kgf / m that enables stable production.
having a tensile strength of m ² or more and a breaking elongation of 1.5% or more,
An object of the present invention is to provide a metastable austenitic stainless steel thin plate having excellent corrosion resistance for an ID blade substrate.

[0012]

[Means for Solving the Problems]
It is solved by a metastable austenitic stainless steel thin plate for an ID blade substrate, which satisfies the following conditions for controlling the amount and the amount of processing-induced martensite.

(1) C: 0.12 to 0.2 by weight%
%, Si: 0.05 to 3%, Mn: 0.08 to 3%,
P: 0.045% or less, S: 0.02% or less, Al:
0.003% or less, N: 0.01 to 0.04%, O:
0.02% or less, Ni: 6 to 7.4%, Cr: 13 to 2
It is made of steel containing 0% and Cu: 0.05 to 0.5%.

(2) The work-induced martensite phase is contained in an amount satisfying the expression (a) when its volume ratio is M%. 67.5-187.5 [C] ≤ M ≤ 37.5 + 187.5 [C] ··· (a) However, [C] represents the C amount (% by weight).

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. It is the most important element for the present invention because it suppresses the formation of martensite phase, stabilizes the austenite phase, and contributes to high ductility. If it is less than 0.12%, 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. 0.12%
The more the above, the more desirable, but if it exceeds 0.2%, Cr
Carbide precipitates, leading to deterioration in corrosion resistance and ductility. By limiting the amount of C to such a narrow range, variations in manufacturing can be reduced and stable manufacturing becomes possible.

Si: 0.05% or more is required to strengthen 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 purpose of single-phase conversion and deoxidation of the austenite phase during solution treatment. Is stabilized and the generation of the martensite phase is suppressed, and a tensile strength of 170 kgf / mm ² or more cannot be obtained.

P: an element effective for solid solution strengthening, but 0.
If it exceeds 045%, toughness is deteriorated.

If S: 0.02% is exceeded, non-metallic inclusions such as MnS are formed, increasing the frequency of breakage of the ID blade.

Al: an element necessary for deoxidation, but 0.0
If it exceeds 03%, non-metallic inclusions such as Al ₂ O ₃ are formed and the breakage frequency of the ID blade is increased.

N: An element that promotes the formation of an austenite phase and an element that strengthens the work-induced martensite phase, but if it is less than 0.01%, its effect is not sufficiently obtained, and if it exceeds 0.04%. And causes blowholes during casting.

O: Al ₂ O ₃ and M when 0.02% is exceeded.
A large number of non-metallic inclusions such as nO, SiO ₂ and Cr ₂ O ₃ are generated, which deteriorates hot workability and increases the frequency of breakage of the ID blade.

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 required for making the austenite phase into a single phase at the time of solution treatment, but if it exceeds 7.4%, the austenite phase is stabilized and the formation of the martensite phase is suppressed, resulting in 170 k
A tensile strength of gf / mm ² or more 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, it is necessary not only to adjust these components in an appropriate range but also to form a certain amount of a work-induced martensite phase in the austenite phase of the matrix phase. . The higher the amount of this martensite phase, the higher the strength, but 1.5%
There is an upper limit for ensuring the above elongation at break. The appropriate amount range of this martensite phase is closely related to the C amount, and if the volume ratio M (%) is adjusted so as to satisfy the above formula (a), the tensile strength of 170 kgf / mm ² or more and 1. It is possible to obtain a metastable austenitic stainless steel sheet having a breaking elongation of 5% or more at the same time.

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION The method for producing a metastable austenitic stainless steel sheet according to the present invention is not particularly specified, but the most convenient method is the ordinary step. That is, hot rolling a slab of stainless steel having the components of the present invention, after annealing / pickling, cold rolling / annealing is repeated several times as necessary, and the required amount of work-induced martensite phase is obtained by final cold rolling. It is formed and subjected to an aging treatment to be manufactured. At this time, thin slab technology can also be applied to the slab production.

The annealing is preferably performed in a non-oxidizing atmosphere from the viewpoint of surface properties and corrosion resistance. Particularly, for annealing before the final cold rolling and for aging treatment after the final annealing, H ₂ gas 70% vol. The above non-oxidizing atmosphere is preferable.

The final cold rolling rate is preferably 40 to 70% in order to adjust the surface roughness of the final product and ensure higher ductility.

[0030]

EXAMPLES Steel No. 1 having the chemical composition shown in Table 1.
1-6 were melted and the hot-rolled steel strip with a plate thickness of 2.5 mm was manufactured. Here, No. Nos. 3 to 5 are steels of the present invention and No. 1, 2,
6 is a comparative steel.

This hot-rolled steel strip was annealed and pickled, and then cold-rolled for the first time at a cold rolling rate of 60% and then subjected to intermediate annealing at 1050 ° C. for 30 seconds. After that, the second cold rolling is performed at a cold rolling rate of 50 to 70%, a final annealing is performed at 1050 ° C. for 30 seconds, and the cold rolling rate is changed in a range of 50 to 70% to change the amount of martensite phase. After changing the temperature, aging treatment was performed at 450 ° C. for 30 seconds to prepare 23 kinds of samples having a final plate thickness of 0.15 mm.

Then, according to JIS-Z-2241, a tensile test (JIS 13B test piece, pulling 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.

The results are shown in Table 2. A sample having an amount of martensite within the range of the present invention is 170 kgf / mm ²
It can be seen that it has the above tensile strength and a breaking elongation of 1.5% or more, and is 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.

None of the comparative samples satisfy the tensile strength of 170 kgf / mm ² or more and the elongation at break of 1.5% or more at the same time, because the components or the amount of martensite are outside the scope of the present invention. Therefore, there is a problem in "pulling up" and the frequency of breakage during cutting. In addition, the comparative material No. In the sample of No. 21, since the amount of C is too large, the formation of Cr carbide is recognized and the corrosion resistance is deteriorated.

[0035]

[Table 1]

[0036]

[Table 2]

[0037]

EFFECTS OF THE INVENTION Since the present invention is constructed as described above, it has a tensile strength of 170 kgf / mm ² or more and a breaking elongation of 1.5% or more, which enables stable production, and is suitable for use in ID blade substrates. As a result, a metastable austenitic stainless steel thin plate having excellent corrosion resistance can be provided.

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 (1)

[Claims] 1. A metastable austenitic stainless steel thin plate for an ID blade substrate, which satisfies the following conditions. (1) C: 0.12 to 0.2% and Si: 0.
05-3%, Mn: 0.08-3%, P: 0.045%
Below, S: 0.02% or less, Al: 0.003% or less,
N: 0.01 to 0.04%, O: 0.02% or less, N
i: 6 to 7.4%, Cr: 13 to 20%, Cu: 0.0
It consists of steel containing 5 to 0.5%. (2) The work-induced martensite phase has a volume ratio of M%.
Then, an amount satisfying the expression (a) is included. 67.5-187.5 [C] ≤ M ≤ 37.5 + 187.5 [C] ··· (a) However, [C] represents the C amount (% by weight).