JPS63206431A - Production of thin stainless steel strip for cutlery - Google Patents

Abstract

PURPOSE:To permit production of a thin stainless steel strip for cutlery which is resistant to rusting and has excellent durability by ejecting a molten carbon steel having a specific compsn. onto a moving cooling surface to cool and solidify the molten steel and rolling the resultant thin strip at a specific draft. CONSTITUTION:The molten steel which consists of 0.5-0.8wt.% C, <=2.0% Si, <=1.0% Mn, 10.0-15.0% Cr, and the balance Fe and inevitable impurities and is further added with <=1.0% Mo at need is ejected from a nozzle onto the moving cooing surface. The molten steel is cooled and solidified at >=10<3> deg.C/sec cooling rate to form the thin strip sized <=300mum. Such thin strip is used as it its as a thin stainless steel strip for cutlery such as razor edge or is subjected to rolling at <=30% draft. The strip is thereafter subjected to a subzero treatment to <=-50 deg.C at need.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for manufacturing a stainless steel ribbon for cutlery, and more particularly to a method for manufacturing a stainless steel ribbon for cutlery by rapid cooling solidification.

[Prior Art] Carbon steel is generally used as a material for razor blades. However, the disadvantages of this replacement blade are that it rusts easily and has poor durability, so improvements have long been sought.

In response to these demands, replacement blades made of stainless steel were created to increase the effectiveness of the razor.
Technologies such as sub-zero treatment immediately after quenching, Teflon resin coating, and chrome sputtering have been developed.

In this way, stainless steel replacement blades that meet ideal conditions such as rust-free, soft to the touch, sharp cutting ability, and durability have been well-received by consumers, and social awareness of stainless steel replacement blades has increased. It's increasing.

However, such stainless steel replacement blades were not always satisfactory due to the following reasons.

1) The most important characteristic required for a razor blade is the quenching hardness of the cutting edge, but in the relationship between the heating temperature and quenching hardness during quenching heat treatment, a hardness peak exists under optimal conditions. Therefore, it is important to maintain this optimum condition in order to obtain high quenched hardness, but this optimum temperature range is narrow and temperature control in actual production lines is extremely difficult, often resulting in insufficient hardness.

2) This stainless steel contains 0.6 to 0.8 wt% of C in order to obtain the hardness required for a razor blade (quenched → tempered). , carbides M, , C, , M7C3 are present. This fine MtsCa etc. quickly decomposes into a solid solution during the solution treatment process during quenching, resulting in high hardening hardness, but depending on the manufacturing conditions up to the previous process and solution treatment conditions, coarse MtsCa etc. exists in unsolidified form,
This may cause the blade to spill.

In order to eliminate undissolved carbides and obtain the necessary hardening hardness, the C content must be controlled within an extremely narrow optimum range.

3) In order to satisfy the required hardness for razor blades, such steel is inherently hard and must be cold rolled and annealed many times to process it into the thinness required for razor blades. This makes the work complicated and causes a significant increase in costs.

[Problems to be Solved by the Invention] In view of the various problems of conventional razor blades as explained above, the present inventor has conducted extensive research, and as a result, the present invention has been developed to provide a razor blade that is resistant to rust and has excellent durability. We have developed a method for manufacturing stainless steel ribbon suitable for razor blades.

[Means for solving the problems] The method for manufacturing the stainless steel ribbon for cutlery according to the present invention includes (1)
CG, 5~OJwt%, Si2.0wt% or less, Mn
1.0wt% or less, Cr L0. O~15. ht%ner A death 1 π Somen Rie collar and A C buma 9p round lecture ＼(-
Nurse molten steel is ejected from a nozzle onto the moving cooling surface of the cooling body, and the thin ribbon of 300 μm or less is cooled and solidified at a cooling rate of 103 ° C / sec or more, or it can be used as it is or at a rolling reduction rate of 3.
The first invention is a method for manufacturing a stainless steel ribbon for cutlery, which is characterized by performing rolling of 0% or less, (2) G 0.5 to G, 8 wt%, Si 2.0 wt%
Below, Mn 1.0wt% or less, Cr 10.0-15
．． Molten steel containing 0 wt% or less of Mo and 1.0 wt% or less of Fe and unavoidable impurities is spouted from a nozzle onto the moving cooling surface of the cooling body and heated to 103°C.
300μm cooled and solidified at a cooling rate of /sec or more
The second invention is a method for manufacturing a stainless steel ribbon for cutlery, characterized in that the following ribbon is rolled as it is or rolled at a reduction rate of 30% or less: (3) C0.5 to 0.8 wt%; Si 2.0wt% or less, Mn 1.0wt% or less, Cr 10.0-15.
molten steel containing 0 wt% and the remainder consisting of Fe and unavoidable impurities is ejected from a nozzle onto the moving cooling surface of the cooling body,
Cooled and solidified at a cooling rate of 103°C/sec or higher 3
00μm or less ribbon as is or rolling reduction rate 30%
A third invention provides a method for manufacturing a stainless steel ribbon for cutlery, which is characterized in that after the following rolling is performed, sub-zero treatment is performed at a temperature of -50°C or lower, (4) C0.5 to 0.8 wt% , Si 2.0wt% or less, Mn 1.0wt% or less, Cr 10.0-15.
Molten steel containing 0 wt% or less of Mo and 1.0 wt% or less of Fe and unavoidable impurities is spouted from a nozzle onto the moving cooling surface of the cooling body and heated to 103°C.
300μm cooled and solidified at a cooling rate of /sec or more
A fourth invention provides a method for manufacturing a stainless steel ribbon for cutlery, characterized in that the following ribbon is rolled as it is or after being rolled at a reduction rate of 30% or less and then subjected to sub-zero treatment at a temperature of -50°C or lower. This invention consists of four inventions.

Regarding the manufacturing method of the stainless steel ribbon for cutlery according to the present invention,
This will be explained in detail below.

First, the components and content ratios of the steel used in the method for manufacturing the stainless steel ribbon for cutlery according to the present invention will be explained.

The higher the C content in solid solution in the γ phase, the higher the hardness of martensite.In the conventional method, the temperature is raised to a high temperature above the transformation point for quenching, and 100% of the carbide is dissolved in the γ phase. Since it must be decomposed into solid solution, the upper limit of C content is 0.6
Although it is necessary to control the C content within an extremely narrow range of 8 wt% and a lower limit of 0.6 wt%, since there is no precipitation of carbides in the method for producing stainless steel ribbon for cutlery according to the present invention, the C content is 0.
．． Content up to 8 wt% is allowed, and the lower limit is 0.5 wt% to obtain the necessary hardness, although it depends on the Cr content.

Since Si deteriorates toughness, it is preferable to reduce the amount of Si.
The inclusion of i increases the resistance to tempering and softening during the final resin coating treatment. Therefore, the Si content is 2.0w
t% or less.

Since Mn is contained for deoxidation, the content should be 0 wt % or less in accordance with JIS standards.

Cr hardens by turning into martensite even during slow cooling quenching,
Furthermore, in order to provide corrosion resistance, it is usually 12 to 14 wt.
However, in the manufacturing method of the stainless steel ribbon for cutlery according to the present invention, an austenite phase is obtained during rapid solidification, and martensitic transformation is caused by the final heat treatment or sub-zero treatment, so it is regulated.
Although it depends on the content, the above effects can be obtained within the range of 10 to 15 wt%, and the necessary corrosion resistance can be obtained within this range.

MO is included to supplement the effect of Cr, and Cr
MOC content of 1.0 wt is used when it is necessary to reduce the Cr content because the hardness does not increase even if the C content is high and to prevent the generation of giant carbides.
% or less.

If the content is more than this, the toughness will deteriorate.

Next, the rapid solidification, rolling reduction, and sub-zero treatment in the manufacturing method of the stainless steel ribbon for cutlery according to the present invention will be explained.

Rapid solidification is performed by ejecting molten steel from a container containing molten steel suitable for forming a steel ribbon with the above-mentioned components and content ratio onto the moving cooling surface of a moving cooling body using an appropriately shaped nozzle attached to the container. Any method may be used as long as a ribbon can be produced by rapidly cooling and solidifying the thin film.For example, a single roll, twin rolls, drum, etc. can be used as the moving cooling body.

In the method for manufacturing stainless steel ribbon for cutlery according to the present invention, since the C content of the sea bream used is high, it is necessary to set the cooling rate to 103°C/sec or more in order to dissolve C into solid solution. Yes, if the cooling rate is slower than this, MzsCs
,M? Carbides such as Cs are precipitated.

By such rapid solidification, not only can ribbons with a thickness of 50 to 300 μm be produced instantly without the need for multiple cold rolling and annealing steps as in the conventional method, but also the solidification cooling rate is extremely fast. A homogeneous ribbon can be produced without the formation of giant carbides such as Mn 3C-1M 70s, which are generated during the cooling process in conventional ingot making and cause deterioration of product toughness and chipping. Then, by rapid solidification, a ribbon of austenitic structure containing a large amount of solid solution of C is obtained, so the optimum temperature ±
There is no need for extremely strict temperature control during heat treatment such as 10°C, and it is possible to obtain heat treatment at a wide temperature range of 1040 to 1120°C, and even without using water quenching at such high temperatures. By simply subjecting the thin ribbon to sub-zero treatment at a temperature below -50℃, Hv78
0 to 810 and tensile strength of 150 kgf/mm” or more, it has good hardness and toughness as a razor blade, has sufficient hardness even after tempering for resin coating, and is free of carbides. Therefore, it is possible to increase the C content and increase the hardness after the final heat treatment.The reason why high hardness can be obtained only with sub-zero treatment is that a large amount of austenite phase is produced in the rapidly solidified state, which is equivalent to that obtained by high temperature heating. Because it exists.

The reduction rate can be determined by applying a light reduction to the produced rapidly solidified ribbon, and its deformation-induced transformation (austenite → martensite) can promote the transformation during sub-zero treatment and obtain high hardness. shall be 30% or less.

If the sub-zero treatment temperature is 150℃ or higher, the austenite phase is stable and does not transform into martensite, so the necessary hardness cannot be obtained.
The temperature shall be 0°C. This effect can be obtained if the sub-zero treatment temperature is 150° C. or lower, but the lower limit may be any temperature, but the effect is saturated at the cooling medium efficiency and -150° C.

In addition, the sub-zero treated material has sufficient hardness even after tempering for resin coating treatment, and since there are no carbides, the C content can be increased, and the hardness after the sub-zero treatment also increases. .

Note that it is also possible to perform a forming process such as punching, which punches out the thin strip into a prototype of a cutter such as a replacement blade, on the thin strip that has been rapidly solidified or rapidly solidified before the sub-zero treatment, or after rolling.

[Example] An example of the method for manufacturing a stainless steel ribbon for cutlery according to the present invention will be described.

Example 1 Molten steel having the components and content ratios shown in Table 1 was
A nozzle with a rectangular slit of 4 mm thick and 25 mm wide sprays it near the roll engagement part on the outer circumferential surface of a 300 mm twin roll rotating at 1100 Crp to form a 120 mm thick sheet.
A μm thin strip was produced.

The average roughness Re of the surface of this ribbon was approximately 20 μm, which was very smooth, and the degree of oxidation on the surface was slight, and it had a considerable metallic luster.

After applying a light reduction of 0 to 20% to the ribbon thus produced, it was subjected to solution treatment and water quenching under the conditions shown in Table 1.

・Tempering temperature: 380℃ to simulate Teflon coating firing
The temperature was set to .

・Blade spillage index: Good, 2: Slightly good, 3: Fair, 4: Slightly bad.
5. Evil. (Nos. 4 and 5 are too brittle to be used.) Example 2 Molten steel having the components and content ratios shown in Table 2 was mixed with 0,
A nozzle with a rectangular slit of 4 mm thickness x 25 + nm width sprays it near the roll engagement part on the outer circumferential surface of a 300 mm twin roll rotating at 1100 Crp, resulting in a thickness of 12 mm.
A thin ribbon of 0 μm was produced.

The average roughness Re of the surface of this ribbon was approximately 20 ttIIl, which was very smooth, and the degree of oxidation on the surface was slight, and it had a considerable metallic luster.

After applying a light reduction of 0 to 20% to the ribbon thus produced, subzero treatment was performed under the conditions shown in Table 2. For comparison, some of the samples were subjected to water quenching after solution treatment at 1080°C.

・Tempering temperature: 380℃ to simulate Teflon coating firing
The temperature was set to .

・Blade spillage index 1: Good, 2: Fairly good, 3: Fair, 4: Fairly bad.
S...evil. (Nos. 4 and 5 are used because they are too brittle. [Effects of the Invention] As explained above, since the method for manufacturing the stainless steel ribbon for cutlery according to the present invention has the above structure, it is resistant to rust as a razor blade, and has good durability. It has the effect of being excellent in terms of performance.

Claims (4)

[Claims] (1) C0.5-0.8wt%, Si2.0wt% or less, Mn1.0wt% or less, Cr10.0-15.0wt
%, with the balance consisting of Fe and unavoidable impurities, is spouted from a nozzle onto the moving cooling surface of the cooling body.
300 cooled and solidified at a cooling rate of 3°C/sec or more
A method for producing a stainless steel ribbon for cutlery, which comprises rolling the ribbon as it is or at a rolling reduction of 30% or less. (2) C0.5-0.8wt%, Si2.0wt% or less, Mn1.0wt% or less, Cr10.0-15.0wt
%, Mo 1.0wt% or less, and the balance consists of Fe and unavoidable impurities, is spouted from a nozzle onto the moving cooling surface of the cooling body, and 10^3
300μ cooled and solidified at a cooling rate of ℃/sec or higher
A method for manufacturing a stainless steel ribbon for cutlery, which comprises rolling the ribbon as it is or at a reduction rate of 30% or less. (3) C0.5-0.8wt%, Si2.0wt% or less, Mn1.0wt% or less, Cr10.0-15.0wt
%, with the balance consisting of Fe and unavoidable impurities, is spouted from a nozzle onto the moving cooling surface of the cooling body.
300 cooled and solidified at a cooling rate of 3°C/sec or more
A method for manufacturing a stainless steel ribbon for cutlery, characterized in that the ribbon with a diameter of μm or less is subjected to sub-zero treatment at a temperature of -50° C. or lower after being rolled as it is or after being rolled at a reduction rate of 30% or lower. (4) C0.5-0.8wt%, Si2.0wt% or less, Mn1.0wt% or less, Cr10.0-15.0wt
%, Mo 1.0wt% or less, and the balance consists of Fe and unavoidable impurities, is spouted from a nozzle onto the moving cooling surface of the cooling body, and 10^3
300μ cooled and solidified at a cooling rate of ℃/sec or higher
A method for manufacturing a stainless steel ribbon for cutlery, characterized in that the ribbon is subjected to sub-zero treatment at a temperature of -50°C or lower, either as it is or after being rolled at a reduction rate of 30% or lower.