JPWO2013047237A1 - Stainless steel for blades and method for producing the same - Google Patents

Abstract

The final objective is to obtain a high hardness and toughness blade having excellent characteristics, and provides a stainless steel intermediate material, an annealed material, a cold rolled steel strip for the purpose, and a method for producing them. . An intermediate material that has been hot-rolled for applying annealing, and the composition is mass%, C: 0.46-0.72%, Si: 0.15-0.55%, Mn: 0.45- 1.00%, Cr: 12.5 to 13.9%, Mo: 0 to 1.5%, B: 0 to 0.012%, the balance is Fe and impurities, fcc phase in X-ray diffraction of longitudinal section Diffraction peak areas (total of diffraction peak areas from (200) plane, (220) plane and (311) plane) and diffraction peak areas from bcc phase (diffraction peaks from (200) plane and (211) plane) An intermediate material of stainless steel for blades having a ratio of (total area) (diffraction peak area from fcc phase / diffraction peak area from bcc phase) of 30 or less.

Description

  The present invention relates to stainless steel for blades used in, for example, razors, cutters, knives, knives, and the like, and a method for manufacturing the same.

Conventionally, martensitic stainless steel has been widely used as a material for blades such as razors, cutters, knives, knives and the like. In particular, it is known that a strip of high carbon martensitic stainless steel containing about 13% Cr and about 0.65% C by mass is optimal as a material for a razor. High carbon martensitic stainless steel (hereinafter referred to as “stainless steel for blades”) used for such applications is usually used after quenching and tempering, and is said to have high hardness and high toughness during use. Characteristics are required.
Stainless steel for blades is usually manufactured through the following manufacturing process.
First, a raw material is melted and cast to produce a raw material. Next, the material is hot-rolled to produce an intermediate material. In some cases, the material is subjected to a lump process by hot forging or hot rolling.
Next, the intermediate material is first annealed to produce an annealed material. Further, cold rolling and subsequent strain relief annealing are repeated as many times as necessary on the annealed material to produce a cold rolled steel strip having the desired thickness. Then, the cold rolled steel strip is quenched and tempered to complete the stainless steel for blades.
Furthermore, the stainless steel for blades becomes a final product through processing steps such as cutting and cutting. In addition, generally the transaction in the stainless steel for blades is often made in the form of either an annealed material or a cold rolled steel strip.
Conventionally, various proposals have been made as techniques for achieving high hardness and high toughness in the above-described stainless steel for blades. For example, as a typical example, Japanese Patent Application Laid-Open No. 5-039547 (Patent Document 1) proposed by the applicant of the present application proposes to increase the carbide density of a cold rolled steel strip of stainless steel for a knife before quenching and tempering. ing. According to this proposal, the short-time hardenability of the cold-rolled steel strip is greatly improved, and the hardness of the stainless steel for the knife after quenching can be increased, and an excellent sharpness as a razor can be obtained. It is possible.

Japanese Patent Laid-Open No. 5-039547

As described above, various proposals have conventionally been made on the technology focusing on the features of the cold-rolled steel strip before quenching and tempering for the stainless steel for blades.
However, it can be said that there has been almost no investigation focusing on the features of the intermediate material after hot rolling and before annealing, and the characteristics of the intermediate material and annealing of stainless steel for blades before quenching after annealing as a semi-finished product. Regarding the relationship between the properties of the material and the properties of the cold-rolled steel strip, it was difficult to say that they were fully elucidated.
For this reason, due to the lack of knowledge on how the intermediate material should be, it is not possible to sufficiently bring out the excellent properties inherent in the stainless steel for blades, particularly to achieve both high hardness and high toughness. There was a problem that it was not possible. In addition, when the identity of the intermediate material has fluctuated for some reason, no means has been known to detect the malfunction at the stage of producing the intermediate material and prevent the occurrence of quality defects in the subsequent process. If a decrease in hardness and toughness becomes apparent for the first time in the lower process without detecting the problems occurring at the intermediate material stage, there is a problem that the processes performed so far become useless and the cost of the product increases. there were.
The present invention is intended to efficiently obtain a high-hardness and high-toughness blade having excellent characteristics by optimizing the intermediate material that affects the structure of the stainless steel for blades before quenching, Therefore, the present invention provides an intermediate material, an annealed material, a cold-rolled steel strip for stainless steel for blades, and a method for producing them.

The inventors of the present invention have studied focusing on the form of carbide as a factor that affects the hardness and toughness of the features of stainless steel for blades.
First, the carbide distribution is inconsistent due to uneven distribution of carbides in the structure of the cold rolled steel strip of the stainless steel for blades, or a mixture of carbides with coarse crystal grains and carbides with fine crystal grains. In the case of being uniform, it was confirmed that the hardness and toughness when the cold-rolled steel strip was quenched and tempered were reduced as compared with the case where the carbide was uniformly distributed.
Next, it has been determined that the composition and the amount of the fcc phase, among the features of the intermediate material of stainless steel for blades, affect the distribution of carbides in the structure of the cold-rolled steel strip obtained from the intermediate material. It was.
And while optimizing the composition of the intermediate material of the stainless steel for blades and suppressing the amount of the fcc phase, the distribution of carbides in the cold rolled steel strip can be made uniform. The inventors have found that the characteristics of a certain blade can be greatly improved and have reached the present invention.
That is, the present invention is an intermediate material of stainless steel for blades after hot rolling and before annealing, and the composition is mass%, C: 0.46 to 0.72%, Si: 0.15 to 0.55%, Mn: 0.45 to 1.00%, Cr: 12.5 to 13.9%, Mo: 0 to 1.5%, B: 0 to 0.012%, the balance consisting of Fe and impurities, longitudinal section Of X-ray diffraction from the fcc phase (the sum of diffraction peak areas from the (200) plane, (220) plane and (311) plane) and the diffraction peak area from the bcc phase ((200) plane and (211) ) The intermediate material of the stainless steel for blades having a ratio of the total diffraction peak area from the surface) (diffraction peak area from the fcc phase / diffraction peak area from the bcc phase) of 30 or less.
The aforementioned B is preferably contained in the range of 0.0005 to 0.0050%.

Moreover, this invention is a manufacturing method of the intermediate material of the above-mentioned stainless steel for blades, Comprising: The material for hot rolling adjusted to the above-mentioned composition is heated to 1100-1250 degreeC, and hot rolling completion temperature is 700- Performing hot rolling at 1000 ° C., the diffraction peak area from the fcc phase (the sum of the diffraction peak areas from the (200) plane, (220) plane and (311) plane) in the X-ray diffraction of the longitudinal section and the bcc phase Stainless steel for blades having a ratio of diffraction peak areas from (total of diffraction peak areas from (200) plane and (211) plane) (diffraction peak area from fcc phase / diffraction peak area from bcc phase) to 30 or less This is a method for producing an intermediate material for steel.
In this invention, it is a manufacturing method of the annealing material of the stainless steel for blades which anneals for 1 to 100 hours at 800-860 degreeC after the above-mentioned hot rolling.
Moreover, this invention is a manufacturing method of the cold rolled steel strip of the stainless steel for blades which performs the process of cold rolling and annealing using the above-mentioned annealing material, and makes thickness less than 1.0 mm.

  Since the blade manufactured using the stainless steel for blades of the present invention can achieve both high hardness and high toughness, it is particularly suitable for applications such as a thin razor. Further, according to the present invention, quality control can be performed at the stage of the intermediate material instead of the final product, so that the occurrence of defects can be suppressed and the manufacturing cost can be reduced.

It is a schematic diagram which shows a test piece collection position and an evaluation surface. It is a drawing substitute photograph which shows an example of the metal structure of the intermediate material of the stainless steel for blades of this invention. It is a drawing substitute photograph which shows an example of the metal structure of the intermediate material of the stainless steel for blades of a comparative example. It is a drawing substitute photograph which shows an example of the metal structure of the intermediate material of the stainless steel for blades of this invention. It is a drawing substitute photograph which shows an example of the metal structure of the intermediate material of the stainless steel for blades of a comparative example. It is a drawing substitute photograph which shows an example of the metal structure of the intermediate material of the stainless steel for blades of this invention. It is a drawing substitute photograph which shows an example of the metal structure of the intermediate material of the stainless steel for blades of this invention. It is a drawing substitute photograph which shows an example of the metal structure after performing quenching-subzero-tempering to the annealing material of the stainless steel for blades of this invention. It is a drawing substitute photograph which shows an example of the metal structure after performing quenching-subzero-tempering to the annealing material of the stainless steel for blades of a comparative example. It is a drawing substitute photograph which shows an example of the metal structure after performing quenching-subzero-tempering to the annealing material of the stainless steel for blades of this invention. It is a drawing substitute photograph which shows an example of the metal structure after performing quenching-subzero-tempering to the annealing material of the stainless steel for blades of a comparative example. It is a drawing substitute photograph which shows an example of the metal structure after performing quenching-subzero-tempering to the annealing material of the stainless steel for blades of this invention. It is a drawing substitute photograph which shows an example of the metal structure after performing quenching-subzero-tempering to the annealing material of the stainless steel for blades of this invention. It is a drawing substitute photograph which shows an example of the metal structure of the cold rolled steel strip of the stainless steel for blades of this invention. It is a drawing substitute photograph which shows an example of the metal structure after performing quenching-subzero-tempering to the cold rolled steel strip of the stainless steel for blades of this invention. It is a drawing substitute photograph which shows an example of the metal structure of the cold rolled steel strip of the stainless steel for blades of this invention. It is a drawing substitute photograph which shows an example of the metal structure after performing quenching-subzero-tempering to the cold rolled steel strip of the stainless steel for blades of this invention.

As noted above, an important feature of the present invention is the final product by controlling the amount of fcc phase in the intermediate material prior to annealing, in addition to optimizing the alloy composition that affects the morphology of the carbide. The achievement of both high hardness and high toughness for the blade.
First, the alloy composition that gives the basic characteristics defined in the present invention will be described. In addition, content of each element is the mass%.
C: 0.46-0.72%
The reason why C is set to 0.46 to 0.72% is to achieve sufficient hardness as a blade and to suppress crystallization of eutectic carbide during casting and solidification to a minimum. If C is less than 0.46%, sufficient hardness as a blade cannot be obtained. On the other hand, if it exceeds 0.72%, the crystallization amount of the eutectic carbide increases due to the balance with the Cr amount, which causes chipping at the time of cutting. The lower limit of the preferable amount of C is 0.50%, more preferably 0.65%. Moreover, the upper limit of the preferable amount of C is 0.70%.
Si: 0.15-0.55%
Si is added as a deoxidizer during refining. In order to obtain a sufficient deoxidation effect, 0.15% or more of Si remains. On the other hand, if it exceeds 0.55%, the amount of inclusions increases and causes chipping during cutting. Therefore, Si is 0.15 to 0.55%. Si also has the effect of increasing the temper softening resistance. Addition of 0.20% or more of Si can obtain sufficient hardness as a blade. Therefore, the lower limit of the preferable Si amount is 0.20%. Moreover, the upper limit of the preferable Si amount is 0.35%.
Mn: 0.45 to 1.00%
Mn is also added as a deoxidizer during refining in the same manner as Si. If an attempt is made to obtain a sufficient deoxidation effect, 0.45% or more of Mn will remain. On the other hand, when it exceeds 1.00%, hot workability will fall. Therefore, Mn is set to 0.45 to 1.00%. The minimum of the preferable amount of Mn is 0.65%. Moreover, the upper limit of the preferable amount of Mn is 0.85%.

Cr: 12.5 to 13.9%
The reason why Cr is set to 12.5 to 13.9% is to achieve sufficient corrosion resistance and to suppress crystallization of eutectic carbide during casting and solidification to a minimum. If Cr is less than 12.5%, sufficient corrosion resistance as stainless steel cannot be obtained, and if it exceeds 13.9%, the amount of eutectic carbides crystallizes and causes chipping during cutting. The lower limit of the preferable Cr amount is 13.0%. Moreover, the upper limit of the preferable Cr amount is 13.6%.
Mo: 0 to 1.5%
Since Mo is an element that improves the corrosion resistance, 1.5% can be added as the upper limit if necessary. However, if Mo exceeds 1.5%, the solid solution strengthening becomes strong, the deformation resistance becomes high, and the hot workability is deteriorated, so the content of Mo is made 0 to 1.5%.
B: 0 to 0.012%,
B is an effective element for improving hardness and toughness. In the present invention, the toughness can be improved also by adjusting the strength ratio of the X-ray described later, but the effect of improving the toughness can be surely obtained by adding B in advance. Therefore, about B, you may add 0.012% to an upper limit. However, if B exceeds 0.012%, the ductility is remarkably reduced as hot workability. Therefore, the upper limit of B is set to 0.012%. In addition, if it is going to acquire the hardness and toughness improvement effect by B addition more reliably, since the effect of B addition will not be enough if it is less than 0.0005%, B is 0.0005 to 0.0050% of range It is good to be inside.
The elements other than those described above are Fe and impurities.
Typical impurity elements include P, S, Ni, W, V, Cu, Al, Ti, N, and O. These elements are preferably regulated to the following ranges.
P ≦ 0.03%, S ≦ 0.005%, Ni ≦ 0.15%, W ≦ 0.05%, V ≦ 0.2%, Cu ≦ 0.1%, Al ≦ 0.01%, Ti ≦ 0.01%, N ≦ 0.05% and O ≦ 0.05%.

According to the study of the present inventors, diffraction peak areas from the fcc phase (diffraction from the (200) plane, (220) plane, and (311) plane) in the X-ray diffraction of the intermediate material of the stainless steel for blades having the above-described composition. (The sum of peak areas) and the ratio of the diffraction peak areas from the bcc phase (the sum of diffraction peak areas from the (200) plane and (211) plane) (diffraction peak area from the fcc phase / diffraction peak area from the bcc phase) ) Was found to correlate with the toughness of the stainless steel for blades obtained through the manufacturing steps such as annealing, cold rolling, quenching, and tempering using the intermediate material.
Specifically, when the ratio of the diffraction peak area from the fcc phase to the diffraction peak area from the bcc phase in the X-ray diffraction of the stainless steel intermediate material for blades exceeds 30, the amount of the fcc phase becomes too large. . Then, when annealing is performed after hot working, carbide having a high aspect ratio is likely to precipitate at the grain boundaries. As a result, for example, the toughness significantly decreases after quenching and tempering when used for a blade. Therefore, the ratio of the diffraction peak area from the fcc phase / the diffraction peak area from the bcc phase needs to be 30 or less. Preferably it is 20 or less, More preferably, it is 5 or less. The lower limit may be zero.
In the present invention, the fcc phase (200) plane, (220) plane and (311) plane and the bcc phase (200) plane and (211) plane were selected because of the alloy having the composition defined in the present invention. This is because, in the system, the above-mentioned orientation is a main peak in X-ray diffraction. Except for the main peak, since the peak intensity is low, the influence of the ratio of the diffraction peak area from the fcc phase / the diffraction peak area from the bcc phase is small. Therefore, the measurement of the main peak is sufficient.
Since the ratio of the diffraction peak area from the fcc phase / the diffraction peak area from the bcc phase described above has a correlation with the actual volume ratio of each phase, it can be evaluated as a value corresponding to the ratio of the constituent phases. it can.

When the above X-ray diffraction is performed, the X-ray is irradiated on the longitudinal section of the intermediate material. In the present application, the “longitudinal section” means a section corresponding to the evaluation surface 2 shown in FIG. 1 among the surfaces of the test piece collected from the vicinity of the center of the width of the intermediate material 1 of the stainless steel for blades as shown in FIG. That is, a cross section perpendicular to the width direction of the intermediate material. The reason why the longitudinal section is used for the evaluation is that the rolled material has anisotropy depending on the rolling direction, so that the evaluation can be performed under the same conditions by fixing the evaluation surface. Moreover, when it is set as a cutting tool, it is because a vertical cross section often corresponds to the cutting edge most required to achieve both high strength and toughness.
The test piece used for X-ray diffraction is adjusted to a test piece for X-ray diffraction by mirror-polishing the longitudinal section and further performing electrolytic polishing. Then, X-ray diffraction is performed using the above-described electropolished surface as a measurement surface, and then the sum of the areas of diffraction peaks from the (200), (220), and (311) planes of the fcc phase and (200) of the bcc phase. The ratio of the total area of diffraction peaks from the (211) plane is calculated. When obtaining the area of each diffraction peak, the area of the diffraction peak obtained by subtracting the intensity of the background is obtained.

Next, the manufacturing method of the intermediate material of the stainless steel for blades of this invention, an annealing material, and a cold-rolled steel strip is demonstrated.
First, a stainless steel material for blades is manufactured by melting and casting. For melting, methods such as vacuum melting, atmospheric melting, vacuum arc remelting, electroslag remelting and the like can be applied. For casting, a material can be obtained by casting into a mold or continuous casting. You may perform the homogenization heat processing to the raw material obtained as needed. Furthermore, you may add the lump process by hot forging or hot rolling.
Then, the intermediate material of the stainless steel for blades is manufactured by hot-rolling the said raw material. In hot rolling, heating is performed to 1100 to 1250 ° C., hot rolling is performed, and an intermediate material of stainless steel for blades is manufactured by setting the end temperature of hot rolling to 700 to 1000 ° C.
The reason for setting the heating temperature to 1100 to 1250 ° C. is that this temperature range has a relatively low deformation resistance and has excellent hot workability. When it exceeds 1250 ° C., it becomes a temperature range in which the ductility is extremely lowered, and cracking is likely to occur during hot working. On the other hand, if it is less than 1100 ° C., the deformation resistance of the material during hot rolling is large, and it becomes difficult to process at a high processing rate, and it is necessary to repeat reheating during hot processing. A preferred lower limit of the heating temperature is 1150 ° C.

In the present invention, the end temperature of hot rolling is set to 700 to 1000 ° C., phase control and metal structure control are performed in consideration of hot workability when an intermediate material of stainless steel for blades is used. Because. When the end temperature of hot rolling exceeds 1000 ° C., the ratio of the diffraction peak area from the fcc phase to the diffraction peak area from the bcc phase in X-ray diffraction exceeds 30 and the amount of the fcc phase increases. When the amount of the fcc phase is too large, carbides are likely to precipitate at the fcc phase grain boundary in the annealing performed thereafter. Further, when the processing end temperature is high, the residual strain is small and the crystal grain size tends to be large, so that carbides precipitated at the fcc phase grain boundary during annealing tend to form a network.
On the other hand, when the end temperature of hot rolling is less than 700 ° C., deformation resistance increases and hot rolling becomes difficult. Therefore, the heating temperature of the hot rolling process is set to 1100 to 1250 ° C., and the end temperature of the hot rolling is set to 700 to 1000 ° C. The lower limit of the preferable heating temperature is 1150 ° C., the upper limit of the preferable end temperature is 950 ° C., the upper limit of the more preferable end temperature is 900 ° C., and the lower limit of the preferable end temperature is 750 ° C.

In the above-mentioned hot rolling, the intermediate material of the stainless steel for blades having a hot working finish temperature of 700 to 1000 ° C. is wound in the plate on the runout table and / or by the winding device. In the middle, it is good to cool with water. Cooling may be performed within a period of 5 minutes from the end of the final pass of hot rolling with an amount of water such that a cooling speed capable of cooling the coiled coil to 600 ° C. or less is obtained.
This is because, in the wound coil, although the cooling once proceeds on the surface where the coil is in contact with the atmosphere, the coil surface once cooled is heated again by the retained heat of the coil itself, and the coil tip region, This is because the metal structures may be different from each other in the vicinity of the center and in the rear end region. If a part of the wound coil exceeds 600 ° C. within 5 minutes from the end of the final pass of hot rolling, the toughness as a blade may be lowered.
Therefore, it is preferable that the wound coil is cooled with water so that the coil temperature is 600 ° C. or less within 5 minutes from the end of the final pass of the hot rolling.
When the above hot rolling process is completed, an intermediate material of stainless steel for blades having a structure defined in the present invention can be obtained.

By performing the first annealing at 700 ° C. to 860 ° C. for 1 to 100 hours on the intermediate material of the stainless steel for blades manufactured by the above-described manufacturing method, the annealed material for stainless steel for blades in which carbides are precipitated is manufactured.
Furthermore, in the case of obtaining a cold rolled steel strip of stainless steel for blades having a thickness of 1.0 mm or less using the stainless steel annealed material for blades described above, the manufacturing can be performed by repeating cold rolling and annealing. It becomes possible.
When the above-described cold rolled steel strip of stainless steel for blades is subjected to quenching, tempering, and blade cutting to make a blade, subzero treatment is performed after quenching or coating is performed on the surface after tempering as necessary. Sometimes.

The following examples further illustrate the present invention.
Six 10 kg steel ingots (materials) A to F were produced by vacuum melting. Table 1 shows chemical components of the steel ingots A to F.

A material for hot rolling having a width of 45 mm, a length of 1000 mm, and a thickness of 20 mm was produced from the steel ingots A to D described above. Using these hot rolling materials, hot rolling was performed under the following three conditions to obtain an intermediate material of stainless steel for blades.
(1) A to D materials: a process of heating to 1180 ° C. and terminating hot rolling at 850 ° C.
(2) A to C materials: a process of heating to 1200 ° C. and finishing hot rolling at 1050 ° C.
(3) E and F materials: Step of heating to 1180 ° C. and finishing hot rolling at 900 ° C.
In addition, since the C alloy which performed the hot rolling of said (2) had a crack generate | occur | produced during hot rolling, the operation | work was interrupted.
Also, in this test, the length required to wind the coil was not obtained, but within 5 minutes from the end of the final hot rolling pass, the intermediate material of the stainless steel for blades was cooled to 600 ° C. I confirmed.

A test piece was collected from the vicinity of the center of the width of the stainless steel intermediate material for the blade. The sampling position of the test piece was the position shown in FIG. 1, and the longitudinal section described as the evaluation surface 2 was used as the evaluation surface for metallographic observation, X-ray diffraction and hardness.
The ratio of the diffraction peak area from the fcc phase to the diffraction peak area from the bcc phase and the hardness in observation of the metal structure and X-ray diffraction in the longitudinal section of the collected specimen were measured. In addition, the test piece used for X-ray diffraction prepared the test piece for X-ray diffraction by carrying out the mirror surface grinding | polishing of the longitudinal section, and also performing electrolytic polishing.
The material No. which performed the metal structure observation. Drawing substitute photographs showing the metal structures of 1 to 6 are shown in FIGS. Table 2 shows the ratio and hardness of the diffraction peak area from the fcc phase and the diffraction peak area from the bcc phase in X-ray diffraction. Table 3 shows the diffraction peak areas from the fcc phase and the bcc phase for each plane index.

In the metal structure observation described above, the longitudinal section of the test piece was polished to a mirror surface, then corroded with an aqueous ferric chloride solution, and observed using a scanning electron microscope.
The ratio of the diffraction peak area from the fcc phase to the diffraction peak area from the bcc phase in X-ray diffraction is the diffraction peak area from the fcc phase in X-ray diffraction (diffraction from the (200) plane, (220) plane, and (311) plane). (The sum of the peak areas) and the diffraction peak area from the bcc phase (the sum of the diffraction peak areas from the (200) plane and the (211) plane)) (diffraction peak area from the fcc phase / diffraction peak area from the bcc phase) I asked for it. For the X-ray diffraction measurement, RINT2500V manufactured by Rigaku Corporation was used, and Co was used as the radiation source.
The hardness was measured with a load of 98.1 (N) using a Vickers hardness meter after the cut specimen was paper-polished to # 1200 abrasive paper. The hardness is an average of 5 points.

Next, quenching, sub-zero treatment, and tempering applied when using the intermediate material of the stainless steel for blades shown in Table 2 as a blade were performed.
An intermediate material for specimen collection having a width of 40 mm, a length of 100 mm, and a thickness of 1 mm was cut out from the stainless steel intermediate material for blades. At this time, the test piece collection intermediate material was cut out so as to include the vicinity of the center of the width of the rolled material shown in FIG.
The above-mentioned intermediate material for collecting specimens was annealed at 840 ° C. for 5 hours to obtain an annealed material, and then quenched as it was kept at 1100 ° C. for 3 minutes and then cooled with water. Further, after the quenching, sub-zero treatment was performed at -75 ° C for 30 minutes, and tempering was performed at 150 ° C for 3 minutes after the sub-zero treatment.
Five test pieces for a three-point bending test having a width of 5 mm, a length of 70 mm, and a thickness of 0.5 mm were prepared from each of the test piece collection intermediate materials subjected to the heat treatment.
Further, another test piece is taken from a position corresponding to the position shown in FIG. 1 (near the center of the width of the rolled material), and the test is performed so that the longitudinal section described as the evaluation surface 2 becomes the metal structure observation and hardness evaluation surface. Pieces were collected. The metallographic photographs (Nos. 1 to 6) are shown in Tables 4 to 13 and the hardness, absorbed energy, bending strength and deflection by a three-point bending test are shown in Table 4.
In the metal structure observation, the evaluation surface was polished to a mirror surface, then corroded with an aqueous ferric chloride solution, and observed using a scanning electron microscope. In the three-point bending test, a test piece having a width of 5 mm, a length of 70 mm, and a thickness of 0.5 mm was measured with a span of 50 mm. The hardness and the three-point bending test are average data for five points.

From Tables 2 and 4, the ratio of the diffraction peak area from the fcc phase to the diffraction peak area from the bcc phase in X-ray diffraction in which annealing, quenching, sub-zero treatment, and tempering heat treatment were performed on the stainless steel intermediate material for blades was 30 or less. In this case, it is confirmed that the toughness evaluated by the absorbed energy of the three-point bending test is excellent while maintaining high hardness even after the annealing-quenching-sub-zero treatment-tempering heat treatment.
This can be considered to be due to the difference in the metal structure after the heat treatment of annealing, quenching, sub-zero treatment, and tempering. Specifically, when the ratio of the diffraction peak area from the fcc phase to the diffraction peak area from the bcc phase in the X-ray diffraction of the stainless steel rolled material for blades exceeds 30, as confirmed from FIG. 9 and FIG. It is considered that carbide with a high aspect ratio of the stainless steel rolled material for blades after heat treatment is connected to the grain boundary, resulting in a decrease in toughness.
On the other hand, when the ratio of the diffraction peak area from the fcc phase to the diffraction peak area from the bcc phase in X-ray diffraction is 30 or less, as confirmed from FIG. 8, FIG. 10, FIG. 12, and FIG. This is considered to be because the carbides of the above are more uniformly dispersed and have a more preferable structure in terms of toughness.
From these results, it is confirmed that the stainless steel intermediate material for blades of the present invention has high hardness and high toughness as a blade by performing annealing-quenching-sub-zero treatment-tempering heat treatment.
In addition to the ratio of the diffraction peak area from the fcc phase to the diffraction peak area from the bcc phase in X-ray diffraction, it can be seen that the balance between hardness and toughness is further improved by containing 0.0050% or less of B.

Next, the above-mentioned No. 1 and no. An intermediate material for specimen collection having a width of 40 mm, a length of 100 mm, and a thickness of 1.5 mm was cut out from the intermediate material of the stainless steel for blades shown in FIG. At this time, the test piece collection intermediate material was cut out so as to include the vicinity of the center of the width of the intermediate material shown in FIG.
The intermediate material for collecting specimens described above was annealed at 840 ° C. for 10 hours, and then cold-rolled with a small cold rolling mill, and was cooled without breaking until the thickness reached 0.075 mm. It was possible to obtain a hot rolled material. Thereby, it was confirmed that it is possible to use a cold-rolled steel strip.
Next, the above-mentioned cold-rolled material was quenched and held at 1100 ° C. for 40 seconds, followed by water cooling. Further, after the above quenching, sub-zero treatment was performed at -75 ° C for 30 minutes, and tempering was performed at 150 ° C for 30 seconds after the sub-zero treatment.
Using the above-mentioned cold-rolled material and annealing-quenching-sub-zero treatment-tempered test piece collection material after heat treatment, the test is performed from the position corresponding to the position shown in FIG. 1 (near the center of the width of the rolled material). A piece was taken and a test piece was taken so that the vertical cross section shown as the evaluation surface 2 was a metal structure observation and hardness evaluation surface. Drawing substitute photographs showing the metal structures (Nos. 1 and 3) before and after the heat treatment are shown in FIGS.

From the results of FIGS. 14 to 17 and Table 5, the cold-rolled material of the present invention and the stainless steel for blades after quenching, sub-zero treatment and tempering did not show carbide with high aspect ratio that deteriorates toughness, and good toughness. It turns out that the spherical carbide | carbonized_material obtained from is disperse | distributing finely. Further, the hardness after quenching, sub-zero treatment, and tempering is as high as 790 HV or higher.
From the above results, it is possible to realize a metal structure and hardness suitable for a blade by performing annealing and cold rolling using the intermediate material of the stainless steel for blades of the present invention, and further quenching, subzero treatment and tempering. confirmed.

  Since the blade manufactured using the intermediate material of the stainless steel for blades of the present invention and the cold rolled steel strip is excellent in hardness and toughness, application to a razor or the like can be expected.

1 Intermediate material of stainless steel for blades 2 Longitudinal section

Claims (6)

  It is an intermediate material of stainless steel for blades after hot rolling and before annealing, and the composition is mass%, C: 0.46-0.72%, Si: 0.15-0.55%, Mn: 0.45 1.00%, Cr: 12.5 to 13.9%, Mo: 0 to 1.5%, B: 0 to 0.012%, the balance is Fe and impurities, and fcc in X-ray diffraction of the longitudinal section. Diffraction peak area from phase (sum of diffraction peak areas from (200) plane, (220) plane and (311) plane) and diffraction peak area from bcc phase (diffraction from (200) plane and (211) plane) An intermediate material for stainless steel for blades, characterized in that the ratio of the sum of peak areas (diffraction peak area from fcc phase / diffraction peak area from bcc phase) is 30 or less.   The intermediate material for stainless steel for blades according to claim 1, wherein B is contained in a range of 0.0005 to 0.0050%.   It is a manufacturing method of the intermediate material of the stainless steel for blades after a hot rolling and before annealing, Comprising: The composition is mass%. C: 0.46-0.72%, Si: 0.15-0.55%, Mn: 0.45 to 1.00%, Cr: 12.5 to 13.9%, Mo: 0 to 1.5%, B: 0 to 0.012%, the balance being Fe and impurities 1100 to 1250 The film is heated to 0 ° C. and subjected to hot rolling with a hot rolling end temperature of 700 to 1000 ° C., and diffraction peak areas ((200) plane, (220) plane and (311) from the fcc phase in X-ray diffraction of the longitudinal section are obtained. ) The ratio of the diffraction peak area from the plane) to the diffraction peak area from the bcc phase (the sum of the diffraction peak areas from the (200) plane and (211) plane) (from the diffraction peak area from the fcc phase / bcc phase) The diffraction peak area) is 30 or less. Intermediate material manufacturing method of the cutlery stainless steel characterized by and.   B is contained in 0.0005 to 0.0050% of range, The manufacturing method of the intermediate material of the stainless steel for blades of Claim 3 characterized by the above-mentioned.   An intermediate for stainless steel for blades manufactured by the manufacturing method according to claim 3 or 4 is annealed at 800 to 860 ° C for 1 to 100 hours. Production method.   Cold-rolling and annealing are performed on the annealed stainless steel material for blades manufactured by the manufacturing method according to claim 5 to make the thickness less than 1.0 mm. A method of manufacturing a cold rolled steel strip.

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