JPS61117252A - Stainless steel for edge tool - Google Patents

Abstract

PURPOSE:To obtain stainless steel for edge tools which is suitable for fine edge tools such as razor blades and which provides hardness and superior corrosion resistance at low hardening temp., by increasing the Mn and N content as compared with conventional methods. CONSTITUTION:The stainless steel for edge tools consists of, by weight, 0.4-0.8% C, <1% Si, 1-4% Mn, 11-17% Cr, 0.06-0.2% N, and the balance Fe. In this way, by increasing the Mn and N content, a high hardness satisfying the requirements of a razor blade can be obtained at hardening temps. as low as 950-1,100 deg.C.

Description

[Detailed Description of the Invention] <Object of the Invention> Industrial Application Field The present invention relates to stainless steel for cutlery, and more specifically, compared to conventional stainless steel, it has improved hardness at a lower quenching temperature by increasing Mn and N. This invention relates to stainless steel for cutlery, which is suitable for thin cutlery such as razor blades and has corrosion resistance.

Conventional technology Traditionally, the material used for razor blades is high carbon, which is hardened by quenching and has excellent sharpness! l[c:1.2
Weight% (hereinafter simply referred to as %) Cr: 0.4%] has been mainly used, but due to corrosion resistance problems such as easy rusting, razor blades made of stainless steel have become widely used instead. . The stainless steel used for this purpose is a martensitic stainless steel containing 0.6-1.2% carbon and 12-16% chromium, and in the normal process of manufacturing razor blades After that, sub-zero treatment (-70℃) is performed, and further,
When shaving, a resin coating (350°C) is applied to improve rIl friction resistance and shaving taste, but even after such heat history, the final hardness (Vickers hardness)
is required to be 600 or more to ensure excellent sharpness and durability.

In addition, since razors are thin at 0.1 mm, they tend to become distorted when hardened at high temperatures of about 1100°C, which causes problems such as asymmetrical polishing of the cutting edge when sharpening is done in the later process. . . With conventional materials, sufficient hardness cannot be obtained by quenching at temperatures below 1050°C, but it would be preferable from the above point of view and also from the perspective of energy saving if treatment could be performed at a lower temperature.

Problems to be Solved by the Invention The present invention aims to solve these problems. Specifically, the present invention aims to solve these problems. Specifically, the present invention aims at solving these problems. The purpose is to provide stainless steel materials for cutlery having the following properties.

<Structure of the Invention> Means for solving the problems and their effects, namely, 1. The stainless steel according to the present invention has C:0, . 4
0-0.80%, Sl: 1% or less, Mn: 1-4%, G
r: 11.0-17.0% Now CF Ni: 0.06
It is characterized in that it contains ~0.20% e and the remainder consists essentially of Fe.

Therefore, these configurations and their effects will be specifically explained.

As mentioned above, the present invention improves the quenching temperature range (approximately 950 to 11
It was discovered that a high hardness that satisfies the requirements for a razor blade can be obtained at a temperature of 00°C.

This will be explained below with reference to the drawings.

Figure 1 shows C: 0.65%, Cr: 13.0%, M
n: 0 of conventional steel including 0.80%, Neo, 04%
．． Quenched sub-zero ring of 10an thick cold rolled plate and 350℃
It is a graph illustrating the hardness (Vickers hardness) after 20 minutes of tempering against the quenching temperature. Note that curve 1 shows the hardness after sub-zero quenching, and curve 2 shows the hardness after tempering versus the quenching temperature.

As is clear from the figure, in order to obtain a final tempering hardness of 600 or higher, it is necessary to quench at a temperature of 1050° C. or higher.

On the other hand, C: 0.65%, Cr: 13.5%, Mn
: 1.53%, N: 0.15% compared to conventional materials,
An example of a steel according to the invention with increased Mn%N is shown in FIG.

Comparison of both figures shows that the optimum quenching temperature of the steel of the present invention is shifted to a lower temperature side compared to the conventional steel, and in particular, the final hardness of the tempered bond by quenching at 950 to 1050° C. is significantly improved. This is closely related to the fact that the solid solution of carbides is promoted by the addition of Mn, the lower limit temperature at which austenite becomes a single phase is expanded in combination with the addition of Nl, and the strengthening effect of the martensitic phase by persimmon and H. it is conceivable that.

Note that when the quenching temperature is 1125° C. or higher, the amount of austenite remaining during quenching is large and stable, resulting in a decrease in hardness.

Based on the above results by 4%, the reasons for limiting the components of the present invention will be explained.

0: 0.40-0.80% C is an essential element for increasing the hardness of martensite, which is important for cutlery such as razor blades, and providing excellent sharpness. However, if the content is small, such as less than 0.40%, even if N or Mn is added as described later, it will not be possible to obtain a desirable hardness for a razor blade. On the other hand, although the addition of Mn promotes the solid solution of carbides and suppresses the generation of giant carbides, C
If the value increases beyond 0.80%, chipping of the blade due to giant carbides becomes a problem. From the above, in the present invention, C is 0.4
Limited to the range of 0-0.80%.

Si2 1% or less Sl is added as an acid agent during the melting process of steel together with Mn (described later), and among them, Si also has the effect of increasing tempering resistance, so it is included to some extent in stainless steel for cutlery. preferable.

However, if more than 1% of Si is added, hot and cold workability deteriorates, so the upper limit was set at 1%.

The addition of Mn + 1.0 to 4.0% has the effect of lowering the quenching temperature range required to obtain sufficient hardness for razor blades, which is a feature of the present invention, but when Mn is less than 1% is not sufficient in terms of expanding the lower limit temperature at which austenite becomes a single phase and strengthening martensite, and if the upper limit exceeds 4%, the amount of retained austenite increases, and martensite transformation does not occur even with sub-zero treatment, which is necessary. Since a certain hardness cannot be obtained, the addition range is limited to 1 to 4%.

Cr: 11.0 to 17.0% Or is required to be at least 11% in order to provide corrosion resistance as a stainless steel. However, Crf
If F is added in a larger amount than necessary, it will cause a decrease in hardness through the formation of a ferrite phase, and since C is relatively expensive, too much C is not desirable from an economical point of view, so the upper limit of C is set at 17.0 %.

N: 0.06 to 0.20% N is involved in the austenitizing tendency and increase in the hardness of martensite, and has the same effect as G. In order to ensure sufficient hardness through low-temperature quenching, the addition of MO alone is insufficient and the addition of N is essential. To get that effect, N
is 0.02 to 0.0, which is usually included in this type of steel.
It is necessary to add more than 5%. However, if it is contained in too large a quantity, plowholes will occur when the molten steel solidifies.
Since the integrity of the steel ingot would be lost and the retained austenite would be stabilized and the resulting hardness would be low as in the case of Mn, the addition range was limited to 0.06 to 0.20%.

This will be further explained below using examples.

Example First, a material A%a, C, OlE having the composition shown in Table 1.

Melt and cast a 50kJ steel ingot of F%G, H1■, J,
It was hot-rolled into a hot-rolled sheet with a thickness of 3.2 m.

The compositions of these materials are intended to compare the characteristics obtained by the steel of the present invention with conventional steel and comparative steel.
In the table, A to E are the steels of the present invention, Table 1. Each of these materials was further annealed at 820°C sFR, and then cold rolled to a thickness of 0.1 mm with short intermediate annealing at 160°C. To determine whether sufficient hardness as a razor blade could be obtained at a lower quenching temperature than conventional materials, the first barley was heated at 1000°C for 20 seconds, then cooled in oil →
A heat treatment of sub-zero treatment at -70°C for 5 minutes and then tempering at 350°C for 20 minutes was applied.

The hardness of these materials after quenching, sub-zero and tempering was investigated and the hardness was as shown in Table 2. The hardness of the material was evaluated by measuring plane Vickers hardness (load: 1 kq).

Table 2 *As shown in Table 2, there are significantly more giant carbides of 5 μm or more, the steel of the present invention has a hardening temperature of about 50 to 10
It can be seen that even if the quenching temperature is 0°C lower, hardness equivalent to or higher than that obtained when a normal material is quenched from about 1100°C can be obtained. Because it is a thin razor blade of 0.10IIIll,
Being able to lower the quenching temperature in this way is not only a simple energy saving effect, but also facilitates processing during manufacturing, which is a great advantage.

<Effects of the Invention> As explained in detail above, stainless steel for cutlery suitable for thin cutlery such as razor blades, which has hardness and excellent corrosion resistance at a lower quenching temperature by increasing Mn and N than the conventional example, can be obtained. This is not only a simple energy saving effect, but also a great advantage in that it facilitates processing during manufacturing.

[Brief explanation of the drawing]

FIG. 1 shows the relationship between hardness and quenching temperature after sub-zero quenching and tempering of conventional steel, and FIG. 2 shows the relationship between hardness and quenching temperature after sub-zero quenching and after tempering of the steel of the present invention.

Claims (1)

[Claims] Contains C: 0.40-0.80%, Si: 1% or less, Mn: 1-4%, Cr: 11.0-17.0 and N: 0.06-0.20% in weight percentages. The remainder is essentially F
A stainless steel for cutlery characterized by consisting of e.