JPH10259418A - Grinding finished stainless steel sheet excellent in strain removability and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve strain removability in the surface of a steel sheet by specifying the surface roughness in final grinding finish of a stainless steel sheet and regulating the atomic concn. ratio of Cr, Si and Al as the components in surface oxidized coating to specified value or above. SOLUTION: In a state in which a stainless steel sheet is finally subjected to grinding finish, the atomic concn. ratio of Cr, Si, Al and Fe (Cr+Si+Al)/Fe in surface oxidized coating is regulated to >=0.4. Also, the surface grinding is executed so as to regulate the center line average roughness Ra in a direction rectangular to the grinding streak to <=0.30 μm. Successively, bright annealing is executed under the conditions satisfying two inequalities of 750<=T1<=5×T2+1250 and -70<=T2<=-30. Furthermore, in the inequalities, T1 denotes the annealing temp. ( deg.C), and T2 denotes the dew point ( deg.C) of the annealing atmosphere. The bright annealing is executed generally in a reducing atmosphere in which hydrogen and nitrogen are mixed in a ratio of H2 :N2 =(1 to 9):1. The annealing temp. in the bright annealing is preferably regulated to 800 to 1050 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the interior of vehicles such as trains, the exterior and interior walls of doors and buildings such as buildings, building materials such as doors, the exterior of commercial refrigerators, doors and other kitchen equipment, etc. The present invention relates to a polished stainless steel sheet having excellent dirt removal properties used in the present invention.

[0002]

2. Description of the Related Art Polished stainless steel sheets are often used in vehicle materials, building materials, kitchen appliances and the like in order to impart corrosion resistance and design. Conventionally, a polished stainless steel plate is manufactured by rotating a polishing belt, a polishing disk, or the like, and bringing the polished surface into contact with the polished steel plate. HL finishing, N depending on the size of abrasive grains, etc.
o. 3, No. There are various polishing finishes, such as 4 polishing finishes, buffing finishes, and mirror finishes.

[0003] These polished finishes are used as final finishes, and are applied after bright rolling or atmospheric annealing after cold rolling, pickling after tempering rolling and tension leveler to adjust the material and shape.

However, when the above-mentioned polished stainless steel sheet is used in a place where it comes into contact with human hands, such as vehicle materials, building materials, kitchen equipment, etc., dirt such as hand marks, fingerprints, or oils and fats remains, and the appearance is beautiful. Had been a problem.

[0005] As a method of preventing these, it has been proposed to apply a fluorine-based clear or to perform a silicon-fluorine-based treatment, or to be disclosed in JP-A-6-335705, JP-A-7-9003, As described in Japanese Unexamined Patent Publication No. Hei 7-9006 and Japanese Unexamined Patent Publication No. Hei 7-9007, it has been proposed to make the fingerprint inconspicuous or easy to remove by controlling the shape of the irregularities with a laser dull roll. ing. However, these methods have problems such as an increase in cost industrially and the inability to impart a design characteristic of a polished stainless steel material.

In the production of a polished stainless steel sheet as disclosed in JP-A-59-197524 and JP-A-59-215418, after cold rolling, polishing with a two-stage abrasive belt, and bright annealing. Alternatively, a production method in which temper rolling is performed after annealing and pickling is described, but the relationship between the surface characteristics and fingerprint resistance or stain resistance is not clearly described.

[0007]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and has as its object to improve the stain removal property of a polished stainless steel plate.

[0008]

Means for Solving the Problems The present inventors have studied the components in the oxide film formed on the surface of the polished stainless steel plate, the surface roughness, and the dirt-removing property, and have found that the polished stainless steel is excellent in the dirt-removing property. The steel sheet and its manufacturing method were established. That is, according to the present invention, a stainless steel plate is finally polished and finished, and has a surface roughness Ra of 0.3.
0 μm or less and Cr, Si, A of the surface oxide film component
A material having a surface oxide film with a high concentration of 1 and a manufacturing method have been developed.

That is, the present invention is as follows. (1) The surface oxide film has a surface oxide film in which the atomic concentration ratio of Cr, Si, Al, and Fe (Cr + Si + Al) / Fe is 0.4 or more, and the center line average roughness Ra in the direction perpendicular to the polishing eye. A polished stainless steel sheet excellent in stain removal properties, characterized by having a particle size of 0.30 μm or less. (2) The stainless steel plate is mechanically polished so that the center line average roughness Ra in the direction perpendicular to the polished eye is 0.30 μm or more, and then bright annealing is performed under the conditions satisfying the following expressions (1) and (2). Polished stainless steel sheet with excellent stain removal characteristics. 750 ≦ T1 ≦ 5 × T2 + 1250 (1) −70 ≦ T2 ≦ −30 (2) where T1 is the annealing temperature (° C.) T2 is the dew point of the annealing atmosphere ( ℃)

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION As a result of various studies, the present inventors have found that there is a close relationship between the stain removal property of a polished stainless steel plate, the composition of the surface oxide film formed on the surface, and the surface roughness. In order to improve the stain removal property, Cr, S
It has been found that it is effective to form a surface oxide film rich in i and Al and to reduce the surface roughness.

For this reason, Cr, Si, Al, F in the surface oxide film formed on the surface of the polished stainless steel plate.
e as an atomic concentration ratio (Cr + Si
+ Al) / Fe, and in the SUS430 and SUS304 steel sheets, the atomic concentration ratio (Cr + Si + Al) / Fe is 0.2 to 3 and the center line average roughness Ra is 0.05 to 0.
The test materials adjusted to 4 μm were compared for dirt removal. The components in the surface oxide film are analyzed by AES (Auger electron spectroscopy), and the atomic concentration ratio (Cr + Si + Al) / Fe at the point where the oxygen concentration is the highest is determined. The surface roughness is the center line average roughness of JIS B0601. The stain removal was evaluated by measuring the color difference ΔE ^* (= (ΔL ^{* 2} + Δa ^*) between the surface after applying yellow petrolatum to the surface of the stainless steel plate, wiping with a cloth, and ultrasonically cleaning in acetone ^{. Two}
+ Δb ^{* 2} ) ^1/2 ; JIS Z8730, hereinafter ΔE).

As a result, as shown in FIG. 1, when the atomic concentration ratio (Cr + Si + Al) / Fe in the surface oxide film is large and 0.4 or more, ΔE is less than 0.15, so that the dirt is not conspicuous and the dirt removability is poor. It turned out good. As described below, when the color difference ΔE is 1.5 or more, the residual stain is conspicuous as discoloration, and in order for the residual stain not to be conspicuous as discoloration, it is necessary that ΔE is less than 1.5. 0.0 ≦ ΔE <1.5: Residual stains are not noticeable as discoloration ΔE ≧ 1.5: Residual stains are noticeable as discoloration Atomic concentration ratio (Cr + Si + Al) / Fe in conventional polished surface oxide film Is inferior in stain removal property at about 0.2.

Next, the influence of the surface roughness will be described.
As shown in FIG. 2, the smaller the center line average roughness Ra, the smaller the Δ
It became clear that E was small and the stain removal property was good.
However, (Cr + Si + Al) / Fe in the surface oxide film
Is less than 0.4, ΔE is 2 even at the same level of roughness.
It is clearly about twice as large, and the stain removability is poor.
As a result, in order to obtain ΔE of less than 1.5 at which the stain is not conspicuous as discoloration, as shown in FIG.
It has become clear that the ratio of (+ Si + Al) / Fe needs to be 0.4 or more and Ra is 0.3 μm or less.

Next, a method of manufacturing a polished stainless steel sheet having excellent stain removal properties will be described. From the relationship between the surface oxide film and the surface roughness, mechanical polishing is performed so that the center line average roughness Ra in the direction perpendicular to the polished eye is 0.30 μm or less, and bright annealing is performed. Regarding the bright annealing conditions, bright annealing is generally performed in a reducing atmosphere in which hydrogen and nitrogen are mixed at a ratio of H ₂ : N ₂ = (1 to 9): 1. (° C.) and the atmosphere dew point T 2 (° C.) change the components in the surface oxide film after annealing.

FIG. 4 shows the results of mechanical polishing of SUS430 and SUS304 steel plates with Ra = 0.1 μm and bright annealing at various annealing temperatures T1 (° C.) and atmospheric dew points T2 (° C.). The horizontal axis represents the annealing temperature, and the vertical axis represents the atmospheric dew point. The atomic concentration ratios of Cr, Si, Al, and Fe (Cr + Si) at the depth where oxygen in the oxide film is the highest, respectively.
+ Al) / Fe is determined, and the range where the atomic concentration ratio is 0.4 or more is as follows: 750 ≦ T1 ≦ 5 × T2 + 1250 (1) −70 ≦ T2 ≦ −30 (1)・ (2)

If the bright annealing temperature T1 (° C.) is lower than 750 ° C., the diffusion rate of the effective elements Si and Al centered on Cr becomes slow, and a surface oxide film having a sufficient atomic concentration ratio cannot be obtained. On the other hand, when the temperature exceeds (5 × T2 + 1250) ° C., the condition for reducing Cr is satisfied, so that the oxidation and diffusion and movement of Cr are suppressed and the diffusion and movement of other elements are also suppressed. However, since the annealing temperature under the Cr reduction condition is determined by the relationship with the dew point, the annealing temperature T1 (° C.) of the bright annealing is preferably in the range of the above equation (1), and is preferably 800 ° C. or higher.
0 ° C or less is good.

If the dew point T2 (° C.) of the bright annealing exceeds −30 ° C., the oxidation of Fe becomes intense, and the Fe on the surface oxide film is increased.
Inevitably thickens and further causes bluing, lowering the commercial value of the polished stainless steel plate. In addition, a gas dew point below -70 ° C is very difficult industrially. Therefore, the dew point of the bright annealing is preferably in the range of the above formula (2), and more preferably -60 ° C or more and less than -35 ° C.

[0018]

EXAMPLES Table 1 shows examples of the present invention and comparative examples. Using various steel types, after performing cold rolling on the material that has undergone the steps of refining-casting-hot rolling-annealing and pickling, mechanical polishing is performed,
Finally, bright annealing was performed. The atomic concentration of Cr, Si, Al, and Fe in the oxide film of each steel sheet was measured by AES (Auger electron spectroscopy), and the atomic concentration ratio (Cr + S
i + Al) / Fe was determined. The surface roughness was determined by the center line average roughness Ra of JISB0601 in the direction perpendicular to the direction of the polished line. The stain removal property was evaluated by applying the color difference ΔE between the surface after the yellow vaseline was applied to the surface of the steel sheet, wiped off with a cloth and ultrasonically cleaned in acetone, and the original surface.

The examples of the present invention have good stain removal properties in which the atomic concentration ratio is 0.4 or more and the roughness Ra is 0.3 μm or less, and the stain removal property and the color difference ΔE are less than 1.5. On the other hand, the comparative example is a polished stainless steel sheet having an atomic concentration ratio of less than 0.4 or a roughness Ra of more than 0.3 μm and having poor stain removal properties.

[0020]

[Table 1]

[0021]

As is apparent from the above, according to the present invention, it is possible to produce a polished stainless steel sheet excellent in stain removal properties.

[Brief description of the drawings]

FIG. 1 shows an atomic concentration ratio (Cr + Si + A) in a surface oxide film of an abrasive having a center line average roughness Ra = 0.25 to 0.3 μm.
l) Diagram showing the relationship between / Fe and the color difference ΔE after yellow petrolatum application, wiping, and ultrasonic cleaning in acetone.

FIG. 2 is a graph showing the relationship between the center line average roughness Ra and the color difference ΔE after yellow petrolatum coating, wiping, and ultrasonic cleaning in acetone.

FIG. 3 shows a center line average roughness Ra having a color difference ΔE of less than 1.5 after application of yellow petrolatum, wiping, and ultrasonic cleaning in acetone, and an atomic concentration ratio (Cr + Si +) in a surface oxide film.
FIG. 3 is a diagram showing a range of Al) / Fe.

FIG. 4 shows an annealing temperature T1 (° C.) and a dew point T in bright annealing.
The figure which shows the relationship of 2 (degreeC) and atomic concentration ratio (Cr + Si + Al) / Fe of Cr, Si, Al, Fe in a surface oxide film.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI C23C 8/18 C23C 8/18

Claims (2)

[Claims] 1. Cr, Si, A in a surface oxide film
It has a surface oxide film having an atomic concentration ratio of 1 and Fe (Cr + Si + Al) / Fe of 0.4 or more, and a center line average roughness Ra in a direction perpendicular to a polished eye is 0.30 μm or less. Polished stainless steel sheet with excellent stain removal. 2. A stainless steel plate is mechanically polished to a center line average roughness Ra perpendicular to the polished eye of 0.30 μm or less,
Subsequently, a method for producing a polished stainless steel sheet having excellent stain removal properties, characterized by performing bright annealing under conditions satisfying the following equations (1) and (2). 750 ≦ T1 ≦ 5 × T2 + 1250 (1) −70 ≦ T2 ≦ −30 (2) where T1 is the annealing temperature (° C.) T2 is the dew point of the annealing atmosphere ( ℃)