JPH028321A - Production of ultrathin martensitic stainless steel sheet for wafer slicer with low in-plane anisotropy in tensile strength - Google Patents

Abstract

PURPOSE:To produce the title high-strength ultrathin stainless steel sheet for slicer material with low in-plane anisotropy in tensile strength by cold-rolling the hot-rolled and annealed sheet having a specified composition, heating under specified conditions, hardening, and then continuously annealing the sheet. CONSTITUTION:The hot-rolled and annealed stainless steel sheet contg., by weight, 0.20-0.50% C, <=1% Si, <=2% Mn, <=0.3% Ni, 10.5-15% Cr, the balance Fe, and inevitable impurities is cold-rolled, and the cold rolling including process annealing is repeated more than once to <=0.3mm sheet thickness. The cold- rolled sheet is heated, and then hardened from 1040-1100 deg.C. The sheet is then continuously annealed at 250-400 deg.C for 10sec to 10min. As a result, an ultrathin martensitic stainless steel sheet for a wafer slicer having >=170kgf/mm<2> tensile strength, >=6% elongation, and <=5kgf/mm<2> in plane anisotropy in tensile strength is obtained. An ultrathin blade can be easily produced from this material.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method for manufacturing a martensitic stainless steel plate suitable for a blade material for a ceramic or St wafer slicer.

<Prior Art> As a prior art, there is a technology related to a method of manufacturing an ultra-thin austenitic stainless steel plate for a wafer slicer, such as Japanese Patent Application Laid-Open No. 62-238333. This publication describes ultra-thin austenitic stainless steel sheets for wafer slicers that have high strength and small in-plane anisotropy of tensile strength, especially Si
A method for manufacturing a stainless steel plate suitable as a material for a wafer slicer is disclosed.

As disclosed in the above-mentioned publication, materials for ceramic or Si wafer slicers are generally made of austenitic stainless steel that is cold-rolled and work-hardened to obtain high strength. However, in this method, in-plane anisotropy of tensile strength of about 6 to 7 kgf/- remains, including the case of the above-mentioned publication.

This residual in-plane anisotropy is caused by the fact that when a ring-shaped blade is set in a cutting jig, radial tension is applied to the blade.
This impairs the flatness and makes it impossible to cut the wafer with high precision.

<Problems to be Solved by the Invention> An object of the present invention is to provide a method for manufacturing a martensitic stainless steel plate for a wafer slicer that is cheaper than conventional austenitic stainless steel sheets.

Another object of the present invention is to have a tensile strength of 170 kgf/■
It is an object of the present invention to provide a method for manufacturing a martensitic stainless steel plate for a wafer slicer, which has an elongation of 6% or more, and an in-plane anisotropy of tensile strength of 5 kgf/- or less.

<Means for solving the problems> The present invention has C: 0.20 to 0.50%, S: 0.20 to 0.50%, S
i: 1% or less, Mn: 2% or less, Ni: 0.3% or less,
A hot-rolled annealed plate containing Cr: 10.5 to 15% and the remainder Fe and unavoidable impurities is cold-rolled or cold-rolled with intermediate annealing at least once to give a plate thickness of 0.3 m.
After forming a cold-rolled sheet with a thickness of 1040 m or less, the cold-rolled sheet is heated to 1040
Quenching from a temperature of ~1100℃, then 250~40℃
A tensile strength of 170 kgf/mj or more, an elongation of 6% or more, and an in-plane anisotropy of tensile strength of 5 kgf/award, characterized by continuous annealing at 0°C for 10 seconds or more and 10 minutes or less. The following is a method for manufacturing an ultra-thin martensitic stainless steel plate for a wafer slicer.

<Function> The material for the slicer must have a tensile strength of 170 kgf/mj or more in order to withstand the circumferential stress generated by ultra-high speed rotation. In addition, because the blade is ribbed, the elongation is 6.
% or more, and as mentioned above, it is desirable that there be no in-plane anisotropy in tensile strength.

The present inventors investigated various manufacturing conditions for this purpose, and as a result, achieved this by combining the selection of steel components and the heat treatment conditions at the final plate thickness.

The reasons for limiting the constituent elements of the present invention will be explained below.

C is an element that greatly affects the strength and ductility of martenitic stainless steel, but if it is less than 0.20%, the
Tensile strength of kgf/mm2 or more cannot be obtained, or 0,
If it exceeds 50%, the elongation will be 5% or less, and the required elongation of 6% or more cannot be obtained, so it is limited to 0.20 to 0.50%.

Si is an element used to deoxidize steel, but if it exceeds 1%, the ferrite region increases at high temperatures and the tensile strength decreases, making it impossible to obtain the required strength, so it is limited to 1% or less. be done.

Mn, like Si, is an element used for deoxidizing steel, but if it exceeds 2%, residual austenite will occur after quenching, resulting in lower tensile strength and the required strength cannot be obtained, so 2% Mn is used. Limited to:

Ni is often mixed in from scraps of austenitic stainless steel, but if the content exceeds 0.3%, the γ transformation point will be lower than the recrystallization temperature of the steel, and the difference between cold rolling and recrystallization annealing will decrease. Repeated rolling makes it difficult to cold-roll the sheet to a thickness of 0.3 mm or less.

Therefore, Ni is limited to 0.3% or less.

From the viewpoint of rust resistance of stainless steel, less than 1000% Cr is insufficient, and if it exceeds 15%, a ferrite phase appears in a high temperature region, resulting in a decrease in hardness after quenching. Therefore, Cr is limited to a range of 10.5 to 15%.

Heat treatment to increase strength is performed after cold rolling.

If the heating and quenching temperature at this time is less than 1040°C, the tensile strength in the quenching and tempering state will not exceed 170 kgf/mm2. Further, when the temperature exceeds 1100°C, δ ferrite appears and the tensile strength after quenching decreases, and the tensile strength does not exceed 170 kgf/Ii in the quenched and tempered state.

In order to ensure elongation, low temperature annealing is required, but
Conventionally, it was believed that long-time annealing was required to form ultrafine carbides due to the diffusion of C from the martensitic phase. However, in the present invention, this problem was solved by a combination of short-time continuous annealing and regulation of the chemical composition in the steel.

If the annealing temperature during continuous annealing is less than 250°C, elongation of 6% or more cannot be achieved. On the other hand, when the annealing temperature exceeds 400℃, the elongation increases but the tensile strength is 170 kgf/*
j or more cannot be satisfied. Also, the annealing time is 1
If the elongation is less than 0 seconds, the elongation will not be large, and if it exceeds 10 minutes, the tensile strength will decrease and the economical efficiency of manufacturing the plate will become extremely poor, so the time is limited to 10 seconds to 10 minutes.

Furthermore, the steel plate for slicers needs to be as thin as 0.3 mm or less in order to reduce the cutting resistance during slicing and to increase the yield of cut objects.

However, normal martensitic stainless steel has many additive elements, and even if it is adjusted to have a ferrite and carbide structure, the base steel is hard. It is also conceivable to soften the steel by increasing the recrystallization annealing temperature after cold rolling, but if the temperature is raised, a T-transformation phase appears, making it impossible to achieve the desired softening. - In the strength wood invention, in order to ensure tensile strength, it is necessary to ensure that martensitic transformation occurs during quenching, and for this purpose it is advantageous to increase the content of Ni, which is an austenite-forming element. However, if Ni is contained in an amount of 0.3% or more, the γ transformation temperature decreases to near the recrystallization temperature as described above, making recrystallization annealing after cold rolling impossible. If this happens, even if repeated cold rolling and annealing, 0.3
It becomes difficult to economically manufacture steel plates of nwn or less.

In the present invention, since the content of stale is limited to 0.3% or less, recrystallization annealing after cold rolling can be performed sufficiently.
It has become possible to manufacture cold-rolled steel sheets with a thickness of 0.3 mm or less.

In addition, since sufficient tensile strength can be ensured by the quenching treatment, in-plane anisotropy of tensile strength, which could not be achieved with the conventional method of increasing strength by cold rolling strain, that is, work hardening, can be significantly reduced.

<Example> Cr-based stainless steel having the composition shown in Table 1 was refined in a converter, made into a slab by continuous casting, and then made into a hot-rolled steel strip with a plate thickness of 3 mm by hot rolling. Then, it is subjected to hell annealing (box annealing) similar to ordinary stainless steel strips, pickled, and then cold rolled and annealed 2 to 4 times until the plate thickness is 0.
A cold-rolled steel strip of 15n++++ was used.

After that, quenching is performed on a continuous annealing line under the conditions shown in Table 2, followed by continuous annealing at a low temperature,
It was used as a material for slicers.

Table 2 also shows the manufacturing conditions, tensile strength, in-plane anisotropy, and elongation according to the method of the present invention and the comparative method.

The tensile test was conducted in accordance with JIS Z2241 by taking test pieces from a direction parallel to the rolling direction.

The in-plane anisotropy of tensile strength is parallel to the rolling direction, 4
A tensile test piece was taken from a perpendicular direction at 5°C, and the tensile strength was measured, and the value was calculated by subtracting the minimum value from the maximum value.

The E steel in Table 1 contains 0.43% Ni, and even when annealed after hot rolling, the softening did not progress sufficiently, and cracks occurred at the edge of the steel strip 9 during subsequent cold rolling. ,0.15mm
It was impossible to commercialize the product. Therefore, the properties of the slicer materials in Table 2 do not include values such as tensile strength. Even if the sample material satisfies the chemical composition shown in Table 1, it is not possible to obtain a material with high strength and high ductility unless the heat treatment conditions according to the present invention are applied. Further, even if the heat treatment conditions are satisfied, if the chemical composition defined in the present invention is not satisfied, the material will not be suitable for a slicer. Compared to the comparative material, the method of the present invention has a tensile strength of 170 kgf/m or more, an elongation of 6% or more, and an in-plane anisotropy of 5 kgf/- or less, making it an excellent material for slicers.

<Effects of the Invention> According to the present invention, the required tensile strength of the material for the slider is 17
Ultra-thin blades can be easily manufactured using this material, which can be used to manufacture extremely tensile stainless steel sheets with a strength of 0 kgf/mm2 or more, an in-plane difference of 5 kgf/md or less, and an elongation of 6% or more. It is possible to slice wafers with high precision, significantly increasing productivity and significantly improving wafer yield.

Claims (1)

[Claims] In weight%, C: 0.20 to 0.50%, Si: 1% or less, Mn: 2% or less, Ni: 0.3% or less, Cr: 10
．． A hot-rolled annealed sheet containing 5 to 15% Fe and unavoidable impurities is subjected to cold rolling or cold rolling with intermediate annealing one or more times to a thickness of 0.3 mm or less. After that, the cold rolled sheet is heated to 1040 to 1100
Quenching from a temperature of 10°C, then 10°C at 250-400°C
Wafers with a tensile strength of 170 kgf/mm^2 or more, an elongation of 6% or more, and an in-plane anisotropy of tensile strength of 5 kgf/mm^2 or less, characterized by being subjected to continuous annealing for a period of seconds or more and 10 minutes or less. A method for manufacturing ultra-thin martensitic stainless steel sheets for slicers.