JPH061348A - Can with welded body - Google Patents

Abstract

PURPOSE:To improve the adhesion and reliability of coating film by a method wherein a specified amount of chromium metal layer is formed on the surface of a steel plate containing a specified percent of carbon in a granular form with a specified density of the chromium metal particles, a chromium hydrate oxide layer is formed on the chromium metal layer and the steel plates are formed into a can body, which is welded at specified nugget pitches. CONSTITUTION:A chromium layer is formed on the surface of a steel plate containing 0.01-0.2wt.% of carbon in an amount of at most 300mg/m<2>. On this chromium metal layer, a chromium hydrate oxide layer is formed in an amount of at most 30mg/m<2> based on the converted weight of chromium metal. This chromium metal layer is deposited on one side of the steel plate in a granular form in a manner wherein the density of the chromium metal particles present is set at 10<10>-10<15>/m<2> per chromium metal particle having a base bottom diameter of at least 10nm. Two of such steel plates are arranged with their side edges parallel to each other and the inner and outer steel plates 1 and 2 are welded together at the welding parts 3 spaced at the nugget pitches at most eight times the thickness of the steel plate. The welding parts 3 are pre-treated to improve the weldability.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal can body used as a container. More specifically, a container having a can body formed by welding a Cr-plated steel sheet, which causes metal powder contamination of the can contents and the can making environment, and which is applied to the can body by welding repair coating. It does not require pre-welding treatment such as mechanical grinding or chemical treatment of the steel plate for welding, which becomes a factor that hinders the adhesion of the coating, and the necessary and sufficient strength of the welded part and excellent coating adhesion In addition, the present invention relates to a can body having corrosion resistance, high productivity, and excellent economical efficiency.

[0002]

2. Description of the Related Art Conventionally, gallon cans have been formed such that the rolling direction of the steel strip is perpendicular to the can height direction. this is,
When the can body is welded along the rolling direction, the carbon content of the conventional steel sheet for cans is not low enough to suppress the increase in hardness that occurs in the weld heat affected zone of the can body. Since the anisotropy of the rolling texture near the welded part and the anisotropy of the rupture strength resulting from the increase in the hardness of the heat-affected zone of the welded part cause cracks in the flange forming part for the can lid wrapping, which is not practical. Met.

A gallon can used for a container for oils and fats is made of tin-free steel (hereinafter referred to as "TFS"). However, the TFS is used as it is, and a commonly used mash seam type canning machine ( Welding was not possible by using the "welding machine"). This is because the surface of TFS is covered with Cr hydrate oxide having high electrical resistance, as described by the present inventors in "Materials and Processes", Vol. 4, p. This is because continuous welding is difficult with a seam welder. Therefore, conventional TF
When welding S, a method of grinding and removing the welded portion immediately before the welding operation has been generally used.

However, according to this method, there is a fear that the contents of the can are damaged due to deterioration of the working environment due to the grinding powder, mixing of the grinding powder into the product can, and the like. Further, the ground iron is exposed in the ground portion or the ground iron is further partially oxidized, and the adhesion of the coating film in the subsequent repair coating is not as good as TFS.

Therefore, even when repair coating is performed, problems such as peeling of the coating film and corrosion under the coating film are always included.
In addition, as a matter of course, when the repair coating was not performed, the ground portion was corroded extremely quickly.

Attempts to impart weldability to TFS have been made by Cr
The plating layer is deposited in a granular form, and the Sn plating layer is TFS.
Methods such as precipitation on the top are known.

A method of improving weldability using a granular Cr layer is as follows.
The method is typified by the inventors' proposal, for example, Japanese Patent Laid-Open No. 3-229897, and is excellent in cost because it can be realized only by the Cr plating step, that is, it does not require a separate treatment with a dissimilar metal. However, the relationship between the nugget pitch, the density of the granular Cr layer and the weldability has not been clarified.

Further, when Sn is deposited on the Cr plating, a special treatment is required to remove the Cr hydrated oxide layer, and the adhesion of the coating film on the Sn plating layer is likely to decrease. Due to problems in operation and quality control, it is not widely used in gallon can applications that are often used in clear coating.

[0009]

DISCLOSURE OF THE INVENTION The present invention eliminates the problems derived from the above-mentioned conventional gallon can forming method, specifically, there is no contamination of the can making environment and the contents of the can due to the scattering of grinding powder.
An object of the present invention is to provide a highly reliable can having a high adhesion of a coating film on a welding repair coating part.

[0010]

DISCLOSURE OF THE INVENTION The inventors of the present invention intend to solve the problems of the welding method by the conventional pre-grinding of the can body formed by welding the can body using chrome-plated steel sheet as a material. As a result of intensive research on the relationship between the plate thickness and the nugget pitch, focusing on the nugget pitch of the welded part, a can body was formed by the welding method using a low carbon steel plate that has been used as a steel plate for cans. In the can body, a sound weld appearance can be obtained by defining the size and density of the granular precipitated Cr in the Cr plating layer of the steel sheet and controlling the weld nugget pitch of the can body within a certain range with respect to the plate thickness. It was found that a can body having sufficient welding strength and excellent coating film adhesion and corrosion resistance after coating can be obtained, and the present invention has been completed.

That is, according to the present invention, a steel sheet shear-formed so that two facing sides are substantially parallel to each other is deformed into a tubular shape with the two parallel sides facing each other, and the two stacked sides are overlapped. A can body having a welded can body formed by welding, wherein the carbon content of the steel sheet is in the range of 0.01 to 0.2% by weight, and the basis weight of the steel sheet surface is 300 mg / m ² or less. Amount of metal chrome layer is further provided, and a hydrated chromium oxide layer having an adhesion amount of 30 mg / m ² or less in terms of the amount of metal chrome is provided thereon, and the metal chrome layer is granular at least on one side of the steel sheet. The density of metal chrome particles present in the chrome is 1 for metal chrome particles with a base diameter of 10 nm or more.
It is 0 ¹⁰ to 10 ¹⁵ pieces / m ² , the nugget pitch of the can body weld portion is 8 times or less of the plate thickness, and the weld portion of the steel plate is not subjected to welding pretreatment for improving weldability. A can body having a welding can body characterized by the above is provided, and the above object is achieved.

[0012]

[Function] When chrome seamed steel sheet is used to perform can body welding similar to tinplate by using a mash seam welding machine, the minimum welding current value at which joining at the material interface begins and the welded portion is melted and scattered. It was extremely difficult to obtain a sound weld by reversing the welding upper limit current at which a so-called splash occurs, which is a welding defect of whiskers formed by rapid cooling. The difference between the maximum value and the minimum value of the welding current is the weldable current range (ACR).
In the conventional Cr-plated steel sheet in which the plating layer does not have granular precipitation, this is very small or could not be obtained at all. Further, in the case where the Cr plating layer is deposited in granular form,
The amount of deposited metal Cr and Cr hydrated oxide and the numerical range of the granular precipitated metal Cr layer were extremely limited.

Mash seam welding utilizes Joule heat at the material interface as a heat source for the welding. Therefore, the ACR of the material depends on the interfacial contact resistance between the materials to be welded and the weld overlap. It also varies greatly depending on the accuracy of the overlap width of. Since this ACR varies slightly depending on the manufacturing lot of steel sheet, the ACR of a certain material
If it is very narrow, the welding conditions such as welding current must be changed for each incoming lot in the welding process, and the production must be stopped during that time, so that it cannot be practically used for commercial production. This is the reason why materials with wide ACR are required.

Splash is generated by excessive heat generation due to the welding current and melting of the material in the vicinity of the weld interface. At that time, the molten metal is extruded to the outside and rapidly solidified, mainly due to the pressure applied to the electrodes. .

Due to the characteristics of the plating reaction, a chromium hydrated oxide layer having a high electric resistance is always present on the surface of the chromium-plated steel sheet, so that the interfacial contact resistance is higher than that of tinplate and the like. The amount of heat generated per current increases.

In normal mash seam welding using an AC power source, when the welding current is small, the fusion or forged area per individual nugget is small, and as shown in FIG.
Unwelded parts tend to remain between adjacent nuggets. In such a state, a macroscopically continuous welded portion cannot be obtained, and naturally a sound product as a can cannot be obtained.

Further, when the welding current is increased with the same nugget pitch to obtain a continuous welded portion between nuggets, heat generation at the interface abruptly increases, causing a splash as shown in FIG. This phenomenon is basically the same even when the Cr plating layer is granularly deposited,
In particular, when the plate thickness is small, welding is easier than when the plating layer is flat, but the current range that can be welded is narrowed, and it was difficult to obtain a can body without splash.

Therefore, in the present invention, the welding heat per nugget is reduced, and in order to obtain a continuous and sound weld, the nugget pitch of the can body weld is 8 times or less the plate thickness, preferably. Defined as 6 times or less. This nugget pitch is considered to be determined by the balance between fusion or forge welding of the superposed materials due to heat generation at the interface and heat propagation inside the materials and heat absorption by the electrodes and atmosphere.

That is, in a region where the nugget pitch is 8 times the plate thickness or less, sufficient forging or fusion due to heat generation due to contact resistance at the interface occurs, and at the same time, diffusion and absorption of excess heat due to heat conduction inside the material is sufficient. Therefore, no splash occurs. Instead of a short fusion length per nugget, the adjacent nuggets are sufficiently close to each other, and as a result, the welded part is continuous in a sound state. In this area, when forming a can body using a chrome-plated steel sheet as a material, there is no need for pretreatment such as grinding of the welded part prior to the welded part, the splash of the welded part is minimal, and it is beautiful and strong. A welded portion can be formed and sufficient strength can be obtained.

[0020]

[Structure] The structure of the present invention will be described in detail below.

In the can body of the present invention, steel plates shear-formed so that the two sides facing each other as a can body are substantially parallel are deformed into a cylindrical shape with the two parallel sides facing each other, and are laminated together. Welding can bodies whose sides are formed by welding are used. This is a method generally used in the past as a method of welding and forming a can body, and the cross-section at the time of tubular molding referred to here includes various shapes such as a circle, an ellipse, and a polygon. In addition, the fact that the two opposite sides are substantially parallel means that they are formed into a tubular shape prior to welding,
This means that when the two sides to be welded face each other, they are parallel to each other so that welding is possible.

The carbon content of the steel sheet of the present invention is 0.01 to.
The range of 0.2% by weight, preferably 0.01 to 0.1% by weight, is because this is a region generally manufactured as a can material. If the carbon content is higher than this range, the formability is likely to be significantly impaired due to the increase in steel plate hardness, and control is difficult.

In the present invention, the most important thing is to obtain a robust can body whose sealing property is sufficiently ensured, but to secure the moldability in various processes by the conventionally known can body molding method. In order to do so, it is sufficient if the carbon content is in this region.

Further, in the present invention, if it is possible to apply a predetermined chrome plating as the plated steel plate original plate, for example, Ni plating is applied to the outermost surface of the steel plate and then a Ni diffusion layer is formed by thermal diffusion treatment. It is also possible to use such a surface adjustment original plate, and similarly, between the chromium plating layer and the original plate, a metal such as Ni, Zn, Sn, or Fe or an alloy plating of these metals or an alloy plating of the metal and P or the like is simply applied. It is also possible to insert layers or multiple layers.

The surface of the steel sheet in the present invention 300 mg / m ² or less, preferably a metal layer of Cr 30 to 200 mg / m ^2, further 30 mg / m ² or less of metal Cr terms thereon, preferably 2 to 2
The reason why the Cr hydrated oxide layer having a deposition amount of 0 mg / m ² is provided is to obtain sufficient coating film adhesion and corrosion resistance for the applications where the chromium-plated steel cans have been conventionally used.

In the present invention, at least one side of the steel sheet has metallic Cr deposited in a granular form, and the presence density of the granular precipitated metallic Cr is such that the base portion diameter is 10 nm or more.
About 10 ¹⁰ to 10 ¹⁵ particles / m ² , preferably 1 × 1
The range of 0 ¹¹ to 8 × 10 ¹⁴ pieces / m ² is that if the range is exceeded, the effect of the granular metal Cr is lost due to the flattening of the unevenness of the Cr layer due to the depopulation or overdense of the granular precipitation Cr. This is because the effects of suppressing the generation of splash and improving the adhesion of the coating film are not exhibited.

The Cr plating layer having the density of the metallic Cr grains as described above can be provided by a method known per se. For example, it is disclosed in the specification of JP-A-3-229897.

In the present invention, the nugget pitch of the welded portion of the can body is defined to be 8 times or less, preferably 6 times or less of the plate thickness in this region when forming a can body using a chrome-plated steel sheet as a material. This is because pretreatment such as grinding of the welded portion prior to the welded portion is not required, the occurrence of splash in the welded portion is slight, a beautiful and strong welded portion can be formed, and sufficient strength can be obtained. This is because the input heat amount per individual unit nugget is small, the spread of the weld heat affected zone is minimized, and at the same time, the distance between the nuggets is sufficiently close, so that a macroscopically continuous weld portion is obtained. This is because.

As described above, control of the nugget pitch can be achieved by means such as appropriately combining the wire electrode feed speed during welding and the AC welding power source frequency.

As long as the chromium-plated steel sheet as the material in the present invention satisfies the performance matching the use as the can body, the Cr-plated steel sheet is provided between the Cr-plated layer and the base steel sheet layer.
Other than simple metals or non-metal elements other than simple substance, multiple layers, alloys, dispersion plating layers, and those and underlying iron or surface Cr
A diffusion layer with the layer may be formed. Regarding the coating on the uppermost layer of the outermost Cr plating layer of the present invention, any surface treatment may be performed on the portion where direct welding is not performed. Further, here, the portions other than the welded portion may be painted or unpainted. The nature of the paint and the means of painting or coating may be of any kind.

[0031]

EXAMPLES The present invention will be described more specifically below based on examples. Manufacturing method of can body plate thickness 0.14 to 0.32 mm, carbon content 0.02
0.25 wt% of aluminum killed cold-rolled steel sheet, per side metallic chromium 87~320mg / m ^2, and further 6~31mg / m ² adhered to hydrated chromium oxide thereon with the metal chromium amount in terms, can inner-corresponding portion Epoxy phenolic resin and chrome-plated steel sheet with 60 mg / m ² of epoxy ester resin coated on the outer surface of the can are used by various wire seam welders manufactured by Sudronic Co., Ltd. Welded and molded. Table 1 shows the steel plates used and the welding conditions.

[0032]

[Table 1]

Evaluation Method The above cans were evaluated by the following methods. Nugget pitch: The center-to-center distance of each nugget was measured from the micrograph of the longitudinal cross section of the weld. Flange crack: In the welding process, the can body after flange formation by the flanger was pulled out, and the state of crack generation near the weld was visually determined. If there is no crack, ◎,
When the occurrence of cracks was recognized, it was evaluated as x. Weld strength (peel test): At one end of the weld on the can body,
Make a 3 cm incision at each side of the welded part at an angle of 45 ° from the edge of the steel plate, grasp that part with pliers, and peel the welded part from the can body by a peel test to ensure continuity of the welded part. investigated. It was evaluated as ⊚ when the welded part was continuously torn to the end, and as × when it was broken in the middle. Contamination of metal powder in cans: Cellophane tape with a width of 15 mm was applied to the left and right 4 cm of the center of the welded part in the body of the can after welding, and immediately peeled off, then 0.1 N HCl 50c
Put in c, boil for 10 minutes, by atomic absorption analysis,
Fe and Cr in the leachate were measured. F above the measurement limit
When e and Cr were detected, it was evaluated as ×, and when not detected, it was evaluated as ⊚. Splash generation: Visually, the splash generated on the inner surface and the outer surface of the can during welding at the center value of the weldable current range was determined as follows. ◎ No splash occurs ○ Cover can be covered by repair painting, and there is no problem with sealing property and strength. × Cannot be covered by repair painting Salt spray test: Using 5% NaCl aqueous solution, spray salt water on the weld repair coating part with a salt spray tester, measure the red rust occurrence area after 20 days, and compare it to the reference value Within ± 20%, it was evaluated as ◯, when it exceeded 20%, it was evaluated as x, and when it was less than -20%, it was evaluated as ⊚.

The above results are shown in Table 2. From this result, it is clear that the intended purpose is achieved by the contents of the present invention.

[0035]

[Table 2]

[0036]

As described above, according to the present invention, there can be obtained a highly reliable can, which is free from the contamination of the can making environment and the contents of the can due to the scattering of the grinding powder, and the high adhesion of the coating film at the weld repair coating part.

[Brief description of drawings]

FIG. 1 is a schematic view of a longitudinal cross section of a welded portion in the case of insufficient welding strength in conventional Cr-plated steel plate welding.

FIG. 2 is a schematic view of a vertical cross section of a welded portion when a splash occurs in conventional welding.

FIG. 3 is a schematic view of a longitudinal cross section of a welded portion in the case of proper welding of a Cr-plated steel sheet according to the present invention.

[Explanation of symbols]

 1 Outer Steel Plate 2 Inner Steel Plate 3 Fused, Forged or Weld Heat Affected Zone 4 Splash 5 Blowhole

[Procedure amendment]

[Submission date] April 15, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0031

[Correction method] Change

[Correction content]

[0031]

EXAMPLES The present invention will be described more specifically below based on examples. Manufacturing method of can body plate thickness 0.14 to 0.32 mm, carbon content 0.02
0.25 wt% of aluminum killed cold-rolled steel sheet, per side metallic chromium 87~320mg / ^{m 2,} and further 6~31mg / ^{m 2} adhered to hydrated chromium oxide thereon with the metal chromium amount in terms, can inner-corresponding portion Epoxy phenolic resin and 60 mg / epoxy ester resin on the outer surface of the can
Using a chrome-plated steel sheet coated with dm ^2, a can body was weld-formed by changing the nugget pitch with various wire seam welders manufactured by Sudronic. Table 1 shows the steel plates used and the welding conditions.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor, Hajime Ogata 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Kawasaki Steel Corporation Technical Research Division (72) Inventor Morito Extension Kawasaki, Chuo-ku, Chiba, Chiba Town No. 1 Kawasaki Iron & Steel Co., Ltd. Technical Research Division (72) Inventor Hideo Kuminato No. 1 Kawasaki-cho, Chuo-ku, Chiba, Chiba Prefecture Kawasaki Steel Co., Ltd. Chiba Iron Works (72) Inventor Ichiro Kondo Itami Hyogo City Aramaki 10 Shimogita, Itami Plant, Kawatetsu Container Co., Ltd. (72) Inventor Shinya Miura, 1 Niihamacho, Chuo-ku, Chiba City, Chiba Kawatetsu Container Co., Ltd., Chiba Plant

Claims (1)

[Claims] 1. A steel sheet shear-formed so that two facing sides are substantially parallel to each other, the two parallel sides are opposed to each other, the steel sheets are deformed into a tubular shape, and the two overlapped sides are welded to each other. A can body having a welded can body, wherein the steel sheet has a carbon content of 0.01.
~ 0.2% by weight and 300 on the surface of the steel sheet.
mg / m ² or less of the weight per unit area of the metal chromium layer is provided further thereon hydrated chromium oxide of 30 mg / m ² or less of coating weight as metal chromium amount in terms layer is provided, and the metal chromium layer is At least on one side of the steel sheet, it is precipitated in a granular form,
The existence density of the metal chrome particles is 10 ¹⁰ to 10 ¹⁵ pieces / m ² for the metal chrome particles having a base diameter of 10 nm or more, and the nugget pitch of the can body welded portion is 8 times or less the plate thickness, and A can body having a welding can body, characterized in that the welded portion of the steel sheet has not been subjected to welding pretreatment for improving weldability.