JP2014210954A - Plated sheet steel for truck/bus fuel tank, and fuel tank - Google Patents
Plated sheet steel for truck/bus fuel tank, and fuel tank Download PDFInfo
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- JP2014210954A JP2014210954A JP2013087856A JP2013087856A JP2014210954A JP 2014210954 A JP2014210954 A JP 2014210954A JP 2013087856 A JP2013087856 A JP 2013087856A JP 2013087856 A JP2013087856 A JP 2013087856A JP 2014210954 A JP2014210954 A JP 2014210954A
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/60—Ferrous alloys, e.g. steel alloys containing lead, selenium, tellurium, or antimony, or more than 0.04% by weight of sulfur
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
- C23C2/04—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor characterised by the coating material
- C23C2/12—Aluminium or alloys based thereon
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C28/00—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D
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- Cooling, Air Intake And Gas Exhaust, And Fuel Tank Arrangements In Propulsion Units (AREA)
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Abstract
Description
本発明は、トラック・バス燃料タンク用めっき鋼板及び燃料タンクに関する。 The present invention relates to a plated steel plate for a truck / bus fuel tank and a fuel tank.
自動車の燃料タンクは車体のデザインに合わせて最後に設計されることが多く、その形状は複雑になる傾向にある。自動車燃料タンク材料に要求される特性は、深絞り成形性、成形後の耐衝撃性、耐燃料耐食性、塩害耐食性、シーム溶接性、スポット溶接性等が要求される。これに対応するための材料開発が行われ、多数の技術が開示されている。 The fuel tank of an automobile is often designed last in accordance with the design of the vehicle body, and its shape tends to be complicated. The characteristics required for automobile fuel tank materials include deep drawability, impact resistance after molding, fuel corrosion resistance, salt corrosion resistance, seam weldability, spot weldability, and the like. Material development to cope with this has been performed, and a number of techniques have been disclosed.
これに対してトラックやバスの燃料タンクへの要求特性は少し異なる。まず基本的に成形形状が単純形状であるために、複雑な形状への成形性は必要とされない。トラックやバスの燃料である軽油は比較的酸化劣化し難く、耐燃料耐食性としてもガソリンタンクよりは緩やかとなる。より重要になるのは、燃料タンクの生産効率、つまり低コストで燃料タンクを製造できるような材料が要求されている。このときの生産効率とは、主として溶接性であり、シーム溶接、スポット溶接性に優れた材料が希求されている。 In contrast, the required characteristics of truck and bus fuel tanks are slightly different. First, since the molded shape is basically a simple shape, moldability into a complicated shape is not required. Light oil, which is a fuel for trucks and buses, is relatively less susceptible to oxidative degradation, and its fuel and corrosion resistance is slower than gasoline tanks. More importantly, there is a demand for a material that can produce a fuel tank at a low cost, that is, production efficiency of the fuel tank. The production efficiency at this time is mainly weldability, and a material excellent in seam welding and spot weldability is desired.
これまで自動車の燃料タンク材として特許文献１、２に示すようなＡｌめっき鋼板、Ｓｎ−Ｚｎめっき鋼板が適用されてきた。しかしＡｌ、Ｓｎは共に溶接の電極材質であるＣｕと反応しやすい特性を持ち、一般にシーム溶接性、スポット溶接性には劣る傾向にある。 Until now, Al-plated steel sheets and Sn-Zn plated steel sheets as shown in Patent Documents 1 and 2 have been applied as fuel tank materials for automobiles. However, both Al and Sn have a characteristic of easily reacting with Cu, which is a welding electrode material, and generally tend to be inferior to seam weldability and spot weldability.
更に、最近コモンレール方式と呼ばれる燃料噴射技術が適用されているが、この技術においては、非常に微細な燃料を噴出させるため、噴射孔の目詰まりが問題となる。この目詰まりの原因として一種の金属石鹸が影響するとされている。例えば特許文献３には、脂肪酸亜鉛が原因となり得ることが記載されている。つまり、燃料タンク材として亜鉛を含むめっき材を用いると、この金属石鹸が生成する可能性がある。つまりＺｎめっきは勿論、Ｓｎ−Ｚｎめっきも望ましくなく、Ａｌめっき鋼板の適用が好ましい。 Furthermore, recently, a fuel injection technique called a common rail system has been applied. In this technique, very fine fuel is ejected, and therefore, clogging of the injection holes becomes a problem. It is said that a kind of metal soap influences this clogging. For example, Patent Document 3 describes that fatty acid zinc can be a cause. That is, when a plating material containing zinc is used as the fuel tank material, this metal soap may be generated. That is, not only Zn plating but also Sn—Zn plating is not desirable, and application of an Al plated steel sheet is preferable.
本発明は上記事情に鑑みてなされたもので、トラック・バス燃料タンク用のめっき鋼板として、シーム溶接性、スポット溶接性を向上させ、なおかつ耐燃料、塩害環境での耐食性も確保できるめっき鋼板及びその製造方法の提供を課題とする。 The present invention has been made in view of the above circumstances, and as a plated steel sheet for truck and bus fuel tanks, a plated steel sheet capable of improving seam weldability and spot weldability, and also ensuring fuel resistance and corrosion resistance in a salt damage environment, and It is an object to provide a manufacturing method thereof.
本発明者らは、上記課題を解決するため鋭意研究した結果、シーム溶接性、スポット溶接性を従来より飛躍的に高め、耐燃料、塩害環境における耐食性も確保するためには、鋼板の表裏のめっき付着量を変えることが顕著な効果を有することを見出し、本発明を完成させた。 As a result of diligent research to solve the above problems, the present inventors have dramatically improved seam weldability and spot weldability as compared to conventional techniques, and in order to ensure fuel resistance and corrosion resistance in salt damage environments, The present inventors have found that changing the plating adhesion amount has a remarkable effect, and completed the present invention.
Ａｌめっき鋼板をシーム溶接する際の課題は幾つかあるが、主として２つの課題がある。１つは、シーム溶接時のブローホール欠陥である。この欠陥の発生原因は以下と考えられる。上下の電極輪を用いたシーム溶接において、熱により電極とめっきとが反応し、反応生成物が電極とめっきとの界面に生成する。そうすると反応生成物を介して電極と鋼板との間に密着力が働き、電極輪が鋼板から離れる際に鋼板が電極側に引張られ、その影響でこのような欠陥が生じる。 There are several problems when seam-welding an Al-plated steel sheet, but there are mainly two problems. One is a blowhole defect during seam welding. The cause of this defect is considered as follows. In seam welding using the upper and lower electrode rings, the electrode reacts with the plating due to heat, and a reaction product is generated at the interface between the electrode and the plating. If it does so, adhesive force will act between an electrode and a steel plate via a reaction product, and when an electrode wheel leaves | separates from a steel plate, a steel plate will be pulled to the electrode side and such a defect will arise under the influence.
もう一つの課題は、電極表面にめっきと電極との反応生成物が生成し、これが欠落することで溶接品位が低下することである。 Another problem is that a reaction product between the plating and the electrode is generated on the surface of the electrode, and the lack of this results in a reduction in weld quality.
これらの課題はいずれも、電極とめっき中のＡｌとの反応が原因であるため、めっき付着量を低下させることが有効と考えられる。 Since all of these problems are caused by the reaction between the electrode and Al during plating, it is considered effective to reduce the plating adhesion amount.
更に本発明者らは、鋼中のＰによりシーム溶接性が向上するとの知見を得た。特にめっき付着量が低い時にＰによるシーム溶接性の向上が顕著であった。鋼中のＰが合金層に拡散し、表面でＡｌＰを形成してＣｕとの反応を抑制しているものと推定している。 Furthermore, the present inventors have obtained knowledge that seam weldability is improved by P in steel. In particular, when the amount of plating was low, the seam weldability was significantly improved by P. It is presumed that P in the steel diffuses into the alloy layer and AlP is formed on the surface to suppress the reaction with Cu.
本発明は、上記知見に基づいてなされたもので、その要旨は、以下の通りである。
（１） 質量％で、Ｃ：０．０００５〜０．０８％、Ｓｉ：０．００３〜０．５％、Ｍｎ：０．０５〜０．８％、Ｐ：０．００５〜０．０５％、Ｓ：０．１％以下を含有し、残部Ｆｅ及び不可避的不純部物からなる鋼板の一方の面及び他方の面に、Ａｌ−Ｆｅ−Ｓｉ合金層とＡｌ−Ｓｉ層とを有する溶融Ａｌめっき層が備えられ、前記一方の面と前記他方の面のめっき付着量がそれぞれ異なり、前記一方の面のめっき付着量が３０〜６０ｇ/ｍ２の範囲であり、前記他方の面のめっき付着量が５〜３０ｇ/ｍ２の範囲であることを特徴とするトラック・バス燃料タンク用めっき鋼板。
（２） 質量％で、Ｃ：０．０００５〜０．０８％、Ｓｉ：０．００３〜０．５％、Ｍｎ：０．０５〜０．８％、Ｐ：０．００５〜０．０５％、Ｓ：０．１％以下を含有し、残部Ｆｅ及び不可避的不純部物からなる鋼板の一方の面に、Ａｌ−Ｆｅ−Ｓｉ合金層とＡｌ−Ｓｉ層とを有し、めっき付着量が３０〜６０ｇ/ｍ２である溶融Ａｌめっき層が備えられ、前記鋼板の他方の面には、Ａｌ−Ｆｅ−Ｓｉ合金層からなり、めっき付着量が５〜３０ｇ/ｍ２である溶融Ａｌめっき層が備えられていることを特徴とするトラック・バス燃料タンク用めっき鋼板。
（３） 前記鋼板が更に、質量％で、Ｔｉ：０．００１〜０．１％、Ｎｂ：０．００１〜０．０５％またはＢ：０．０００３％〜０．０１％の１種又は２種以上を含むことを特徴とする（１）または（２）に記載のトラック・バス燃料タンク用めっき鋼板。
（４） 前記溶融Ａｌめっき層の表面に、Ｃｒ、Ｚｒ、Ｔｉ、Ｓｉ、Ｖの１種または２種以上の化合物を含有する皮膜が片面当たり５０〜１０００ｍｇ/ｍ２の付着量で形成されていることを特徴とする（１）〜（３）の何れか一項に記載のトラック・バス燃料タンク用めっき鋼板。
（５） （１）〜（４）の何れか一項に記載のトラック・バス燃料タンク用めっき鋼板によって製造され、めっき付着量の少ない面が外面側とされていることを特徴とするトラック・バス用燃料タンク。
This invention was made | formed based on the said knowledge, The summary is as follows.
(1) By mass%, C: 0.0005 to 0.08%, Si: 0.003 to 0.5%, Mn: 0.05 to 0.8%, P: 0.005 to 0.05% , S: Molten Al containing 0.1% or less and having an Al—Fe—Si alloy layer and an Al—Si layer on one side and the other side of the steel sheet comprising the remaining Fe and inevitable impure parts A plating layer is provided, the plating adhesion amount of the one surface and the other surface is different, the plating adhesion amount of the one surface is in a range of 30 to 60 g / m 2 , and the plating adhesion of the other surface is A plated steel sheet for truck and bus fuel tanks, characterized in that the amount is in the range of 5 to 30 g / m 2 .
(2) By mass%, C: 0.0005 to 0.08%, Si: 0.003 to 0.5%, Mn: 0.05 to 0.8%, P: 0.005 to 0.05% , S: containing 0.1% or less, and having an Al—Fe—Si alloy layer and an Al—Si layer on one surface of a steel plate made of the remaining Fe and inevitably impure parts, and having a coating adhesion amount The molten Al plating layer which is 30-60 g / m < 2 > is provided, The other surface of the said steel plate consists of an Al-Fe-Si alloy layer, and the molten Al plating whose plating adhesion amount is 5-30 g / m < 2 > A plated steel sheet for truck and bus fuel tanks, characterized in that a layer is provided.
(3) The steel plate is further mass%, Ti: 0.001 to 0.1%, Nb: 0.001 to 0.05%, or B: 0.0003% to 0.01%, or 1 or 2 The plated steel sheet for a truck / bus fuel tank according to (1) or (2), which contains more than seeds.
(4) A film containing one or more compounds of Cr, Zr, Ti, Si, and V is formed on the surface of the molten Al plating layer with an adhesion amount of 50 to 1000 mg / m 2 per side. The plated steel sheet for a truck / bus fuel tank according to any one of (1) to (3), wherein:
(5) A truck / truck manufactured by the plated steel sheet for a truck / bus fuel tank according to any one of (1) to (4), wherein a surface with a small amount of coating is the outer surface. Fuel tank for buses.
本発明によれば、コモンレール方式等を用いた場合にも噴射孔目詰まりを起こすことが無く、特にシーム溶接、スポット溶接等の生産性に優れたトラック・バス燃料タンク用めっき鋼板を提供できる。また、本発明に係るトラック・バス燃料タンク用めっき鋼板によれば、ユーザーにおける燃料タンクの生産性が向上するため、廉価なタンクを市場に供給できることが期待される。 According to the present invention, a plated steel sheet for a truck / bus fuel tank can be provided which does not cause clogging of injection holes even when a common rail system or the like is used, and is particularly excellent in productivity such as seam welding and spot welding. Further, according to the plated steel sheet for truck / bus fuel tank according to the present invention, the productivity of the fuel tank for the user is improved, and it is expected that an inexpensive tank can be supplied to the market.
本発明の実施形態であるトラック・バス燃料タンク用めっき鋼板は、鋼板と、鋼板の一方の面及び他方の面に形成された溶融Ａｌめっき層とからなる溶融Ａｌめっき鋼板である。本実施形態のトラック・バス燃料タンク用めっき鋼板では、一方の面と他方の面のめっき付着量の範囲が異なっており、一方の面に付着量が比較的大きな溶融Ａｌめっき層が形成され、他方の面に付着量が比較的小さな溶融Ａｌめっき層が形成される。 A plated steel sheet for truck / bus fuel tanks according to an embodiment of the present invention is a hot-dip Al plated steel sheet comprising a steel plate and a hot-dip Al plated layer formed on one surface and the other surface of the steel plate. In the plated steel sheet for truck and bus fuel tanks of this embodiment, the range of the plating adhesion amount on one surface and the other surface is different, and a molten Al plating layer having a relatively large adhesion amount is formed on one surface, A molten Al plating layer having a relatively small amount of adhesion is formed on the other surface.
以下、本発明の限定要件について説明する。まず、鋼の成分組成を限定する理由について説明する。なお、成分組成に係る％は、質量％を意味する。 Hereinafter, the limitation requirement of this invention is demonstrated. First, the reason for limiting the component composition of steel will be described. In addition,% concerning a component composition means the mass%.
鋼板のＰ含有量は０．００５〜０．０５％とする。Ｐは固溶強化元素で、比較的安価に鋼板の強度を高めることができるが、粒界に偏析し易いために、鋼板の強度が高い場合に低温脆化を引き起こす元素である。本発明において、Ｐがめっき付着量が少ない場合にシーム溶接性の向上に寄与することを見出した。この効果を得るためには鋼板中のＰが０．００５％以上であることが必要である。一方、鋼板中のＰ量を増大させると鋼板の靭性が低下するため望ましくない。このため上限を０．０５％とする。 The P content of the steel sheet is 0.005 to 0.05%. P is a solid solution strengthening element, which can increase the strength of the steel sheet relatively inexpensively, but is an element that causes low temperature embrittlement when the strength of the steel sheet is high because it easily segregates at the grain boundaries. In this invention, it discovered that P contributed to the improvement of seam weldability, when there is little plating adhesion amount. In order to obtain this effect, it is necessary that P in the steel sheet is 0.005% or more. On the other hand, increasing the amount of P in the steel sheet is not desirable because the toughness of the steel sheet decreases. For this reason, the upper limit is made 0.05%.
Ｃは、鋼板の強度を決める元素である。トラック・バスの燃料タンクは先述したように特に複雑な形状に成型される訳ではない。しかし部位によっては延性を要求されることもあり得るため、鋼板中のＣ量は０．０００５〜０．０８％程度が好ましい。更に好ましくは０．００１〜０．０５％である。 C is an element that determines the strength of the steel sheet. The truck and bus fuel tanks are not molded into a particularly complex shape as described above. However, since ductility may be required depending on the part, the C content in the steel sheet is preferably about 0.0005 to 0.08%. More preferably, it is 0.001 to 0.05%.
Ｓｉも鋼板の強度を高める元素であり、必要に応じて０．００３％以上を添加する。Ｓｉ量が０．５％を超えるとめっき性が劣化するので、Ｓｉ量は０．００３〜０．５％が好ましい。 Si is also an element that increases the strength of the steel sheet, and 0.003% or more is added as necessary. If the Si content exceeds 0.5%, the plating properties deteriorate, so the Si content is preferably 0.003 to 0.5%.
Ｍｎも鋼板の強度を上げる働きがある。また、Ｍｎは、熱延工程時においてＳに起因する熱間脆性の抑制にも有効であり、０．０５％以上の添加が望ましい。一方で過剰に添加すると鋼板の加工性を低下させるため０．８％以下が好ましい。 Mn also works to increase the strength of the steel sheet. Mn is also effective in suppressing hot brittleness caused by S during the hot rolling step, and it is desirable to add 0.05% or more. On the other hand, if added excessively, the workability of the steel sheet is lowered, so 0.8% or less is preferable.
Ｓは、熱間加工性を劣化させる元素であり、また、鋼板の加工性を劣化させる元素である。本発明において、Ｓ量は限定しないが、０．１％以下が好ましい。また、Ｓは少ない方が好ましいが、０．００１％未満とすることは、脱硫コストの上昇を招くので、０．００１％以上が好ましい。 S is an element that degrades hot workability, and is an element that degrades the workability of a steel sheet. In the present invention, the amount of S is not limited, but is preferably 0.1% or less. Further, it is preferable that the S content is small, but if it is less than 0.001%, the desulfurization cost is increased, so 0.001% or more is preferable.
鋼板は、上記の元素以外に不可避的不純物及び残部鉄からなる。不可避的不純物として例えばＡｌやＮを含有しうる。Ａｌは、通常、脱酸のために添加する元素である。本発明においてＡｌ量は限定しないが、０．００５％未満の鋼板は、製鋼工程において脱酸が不十分であり、その結果、鋼板中に酸化物が多量に残存して局部変形能の劣化を招く場合がある。従って、Ａｌを０．００５％以上含有する鋼板が好ましい。一方、鋼板中のＡｌが０．０８％を超えると、鋼板中にアルミナを主体とする酸化物が多量に残存して、局部変形能の劣化を招くので、０．０８％以下が好ましい。 A steel plate consists of an unavoidable impurity and remainder iron other than said element. For example, Al or N may be contained as an inevitable impurity. Al is an element usually added for deoxidation. In the present invention, the amount of Al is not limited, but a steel sheet of less than 0.005% is insufficiently deoxidized in the steel making process, and as a result, a large amount of oxide remains in the steel sheet, resulting in deterioration of local deformability. May invite. Therefore, a steel plate containing 0.005% or more of Al is preferable. On the other hand, if the Al content in the steel sheet exceeds 0.08%, a large amount of oxide mainly composed of alumina remains in the steel sheet, leading to deterioration of local deformability, so 0.08% or less is preferable.
Ｎは不可避的不純物であり、少ないほど好ましい元素である。本発明において、Ｎ量は限定しないが、Ｎ量を０．００１％未満に低減することは、精錬コストの上昇を招くので、Ｎ量は０．００１％以上が好ましい。一方、Ｎ量が０．００５％を超える鋼板には析出物が生成し、焼入れ後の靭性が劣化するので、Ｎ量は０．００５％以下が好ましい。 N is an inevitable impurity, and the smaller the amount, the more preferable element. In the present invention, the amount of N is not limited, but reducing the amount of N to less than 0.001% leads to an increase in refining costs, so the amount of N is preferably 0.001% or more. On the other hand, precipitates are generated on a steel sheet having an N content exceeding 0.005%, and the toughness after quenching deteriorates. Therefore, the N content is preferably 0.005% or less.
本発明においては、上記の元素以外にＴｉ、Ｎｂ、Ｂの１種または２種以上を鋼板に含有させることができる。以下、添加理由と添加量について述べる。 In this invention, 1 type, or 2 or more types of Ti, Nb, and B other than said element can be contained in a steel plate. Hereinafter, the reason for addition and the addition amount will be described.
Ｔｉ及びＮｂは、微細な炭化物を形成させて鋼板の加工性を向上させることができる。このためにはそれぞれ、０．００１％以上の添加が好ましいが、過度の添加は、添加効果が飽和し、製造コストが上昇する。従って、Ｔｉの添加量は０．１％以下、Ｎｂの添加量は０．０５％以下とすることが好ましい。 Ti and Nb can form fine carbides and improve the workability of the steel sheet. To this end, addition of 0.001% or more is preferable, but excessive addition will saturate the addition effect and increase the production cost. Therefore, the addition amount of Ti is preferably 0.1% or less, and the addition amount of Nb is preferably 0.05% or less.
Ｂは、鋼板の二次加工性を向上させる元素である。この効果を得るためにはＢを０．０００３％以上とすることが好ましい。一方、Ｂの過剰添加は鋼板の加工性を阻害するため、０．０１％以下とすることが好ましい。 B is an element that improves the secondary workability of the steel sheet. In order to obtain this effect, B is preferably 0.0003% or more. On the other hand, since excessive addition of B inhibits the workability of the steel sheet, it is preferably made 0.01% or less.
なお、本発明に係る鋼板は、製鋼段階においてスクラップ等から混入するＣｕ、Ｃｒ、Ｓｎ、Ｎｉ等を、本発明の効果を損なわない範囲で含有してもよい。また、脱酸元素として使用したＣａや、Ｃｅ等を含むＲＥＭを、本発明の効果を損なわない範囲で含有してもよい。 In addition, the steel plate which concerns on this invention may contain Cu, Cr, Sn, Ni etc. which mix from scraps etc. in the steelmaking stage in the range which does not impair the effect of this invention. Moreover, you may contain REM containing Ca used as a deoxidation element, Ce, etc. in the range which does not impair the effect of this invention.
上記の鋼板は、鋼スラブを熱間圧延することにより製造される。また、本発明に係る鋼板を得るために、熱間圧延後に、冷間圧延及び焼鈍を行ってもよい。 Said steel plate is manufactured by hot-rolling a steel slab. Moreover, in order to obtain the steel plate which concerns on this invention, you may perform cold rolling and annealing after hot rolling.
熱間圧延に供する鋼スラブを製造する方法は、連続鋳造方法に限定されるものではない。通常の連続鋳造方法や、厚さ１００ｍｍ以下の薄スラブを鋳造する方法を採用することができる。 The method for producing a steel slab for hot rolling is not limited to the continuous casting method. A normal continuous casting method or a method of casting a thin slab having a thickness of 100 mm or less can be employed.
熱間圧延条件は特に規定するものでない。例えば加熱温度は１４００℃以下とし、好ましくは１２５０℃以下とする。また、最終圧延終了温度はＡr3点以上が好ましく、巻き取り温度は６００〜７５０℃が好ましい。 The hot rolling conditions are not particularly specified. For example, the heating temperature is 1400 ° C. or lower, preferably 1250 ° C. or lower. The final rolling end temperature is preferably Ar3 or higher, and the winding temperature is preferably 600 to 750 ° C.
冷間圧延、焼鈍、及び、めっきの各条件は、特に規定されるものではなく、通常の条件でよい。冷間圧延は、通常の冷延圧下率の範囲、例えば、４０〜８０％で実施すればよい。めっきは、熱間圧延後、冷間圧延後、又は、再結晶焼鈍後に実施するが、加熱条件や冷却条件は、特に規定されるものではない。 The conditions for cold rolling, annealing, and plating are not particularly defined, and may be ordinary conditions. Cold rolling may be performed in a range of a normal cold rolling reduction ratio, for example, 40 to 80%. Plating is performed after hot rolling, after cold rolling, or after recrystallization annealing, but heating conditions and cooling conditions are not particularly defined.
熱間圧延後または冷間圧延後に、Ａｌめっきを付与するものとする。先述したように、コモンレール方式のエンジンにおいてＺｎを含有するめっきは使用が制限されるので、工業的にはＡｌめっきが最も有利である。Ａｌめっきは通常５〜１５％のＳｉを添加したＡｌめっき浴を用いて溶融めっき法で行われるが、本発明は溶融めっき法に限定するものでなく、溶融塩電解法、蒸着法等も適用することができる。これらの方法の中で工業的に最も安価に製造できるのは溶融めっき法であり、本発明でもこの方法を適用することが望ましい。 Al plating is applied after hot rolling or after cold rolling. As described above, in a common rail engine, plating containing Zn is restricted in use, and therefore, aluminum plating is most advantageous from an industrial viewpoint. Al plating is usually performed by a hot dipping method using an Al plating bath to which 5 to 15% Si is added. However, the present invention is not limited to the hot dipping method, and a molten salt electrolysis method, a vapor deposition method, etc. are also applicable. can do. Among these methods, the one that can be manufactured industrially at the lowest cost is the hot dipping method, and it is desirable to apply this method also in the present invention.
溶融Ａｌめっき法で溶融Ａｌめっき鋼板を製造する際に、Ａｌめっき浴のＡｌ及びＳｉと鋼板のＦｅとが反応して、溶融Ａｌめっき層と鋼板との界面に、金属間化合物からなるＡｌ−Ｆｅ−Ｓｉ合金層が形成される。このＡｌ−Ｆｅ−Ｓｉ合金層の上に、Ａｌめっき浴とほぼ同一組成のＡｌ―Ｓｉ層が形成される。 When producing a hot-dip Al-plated steel sheet by hot-dip Al plating, Al and Si in the Al-plating bath react with Fe of the steel sheet, and an Al- consisting of an intermetallic compound is formed at the interface between the hot-dip Al plating layer and the steel sheet. An Fe—Si alloy layer is formed. An Al—Si layer having almost the same composition as the Al plating bath is formed on the Al—Fe—Si alloy layer.
Ａｌめっき浴は、Ａｌを８５％以上含有することが望ましく、また、Ｓｉを５〜１５％含有することが好ましい。Ｓｉ量が５％未満ではめっき後にＡｌ−Ｆｅ−Ｓｉ合金層が成長し過ぎて加工性を低下させ、Ｓｉが１５％超含有させるような場合にはＡｌめっきの耐食性が低下するため好ましくない。更に好ましいＳｉ量は６〜１２％である。 The Al plating bath desirably contains 85% or more of Al, and preferably contains 5 to 15% of Si. If the amount of Si is less than 5%, the Al—Fe—Si alloy layer grows too much after plating to deteriorate workability, and if Si is contained in an amount exceeding 15%, the corrosion resistance of Al plating is lowered, which is not preferable. A more preferable Si amount is 6 to 12%.
Ａｌ−Ｆｅ−Ｓｉ合金層の厚みは通常２〜５μｍであるが、浴温、浴組成、侵入板温、冷却速度及びラインスピードにより変化する。一般に板厚が薄い時にはラインスピードを上昇させることができ、合金層厚みは薄くなる傾向となる。本発明においてＡｌ−Ｆｅ−Ｓｉ合金層の厚みは規定しないが、この層は硬質で脆いために、厚過ぎると鋼板の加工性を阻害する。このためＡｌ−Ｆｅ−Ｓｉ合金層は４μｍ以下とすることが望ましい。
なお、Ａｌ−Ｓｉ層とＡｌ−Ｆｅ−Ｓｉ合金層については、断面検鏡より確認するものとする。図１に断面組織の写真の一例を示す。Ａｌ−Ｓｉ層とＡｌ−Ｆｅ−Ｓｉ合金層とは、図１に示すように光学顕微鏡で明確に区別できる。当然ＳＥＭ−ＥＤＳ、ＥＰＭＡ等の元素分析によっても確認可能である。
The thickness of the Al—Fe—Si alloy layer is usually 2 to 5 μm, but varies depending on the bath temperature, bath composition, penetration plate temperature, cooling rate, and line speed. Generally, when the plate thickness is thin, the line speed can be increased, and the alloy layer thickness tends to be thin. In the present invention, the thickness of the Al—Fe—Si alloy layer is not specified, but since this layer is hard and brittle, if it is too thick, the workability of the steel sheet is hindered. For this reason, the Al—Fe—Si alloy layer is desirably 4 μm or less.
In addition, about an Al-Si layer and an Al-Fe-Si alloy layer, it shall confirm with a cross-sectional microscope. FIG. 1 shows an example of a photograph of a cross-sectional structure. The Al—Si layer and the Al—Fe—Si alloy layer can be clearly distinguished by an optical microscope as shown in FIG. Naturally, it can also be confirmed by elemental analysis such as SEM-EDS and EPMA.
本発明では、めっき付着量を一方の面と他方の面とで異なる値となるよう制御し、一方の面のめっき付着量を３０〜６０ｇ/ｍ２とし、他方の面のめっき付着量を５〜３０ｇ/ｍ２とすることが好ましい。 In the present invention, the plating adhesion amount is controlled to be different between one surface and the other surface, the plating adhesion amount on one surface is set to 30 to 60 g / m 2, and the plating adhesion amount on the other surface is set to 5 it is preferable that the to 30 g / m 2.
燃料タンクの外面となる他方の面は、良好なシーム溶接性、スポット溶接性を得るために、めっき付着量を少なくすることが望ましい。特に鋼板のＰ量を制御することでより良好な溶接性が得られる。その一方で、溶融Ａｌめっき層は合金層を含むため、めっき付着量の下限には限度があり、事実上５ｇ／ｍ２未満とすることは不可能である。このため下限を５ｇ／ｍ２とする。めっき付着量が増大すると塩害環境の外面環境における耐食性は増大するが、溶接性が低下する。めっき付着量が３０ｇ／ｍ２を超えるとシーム溶接性及びスポット溶接性が低下するため、上限を３０ｇ／ｍ２とする。 In order to obtain good seam weldability and spot weldability, it is desirable that the other surface, which is the outer surface of the fuel tank, be reduced in the amount of plating. In particular, better weldability can be obtained by controlling the P content of the steel sheet. On the other hand, since the molten Al plating layer includes an alloy layer, there is a limit to the lower limit of the plating adhesion amount, and it is virtually impossible to make it less than 5 g / m 2 . Therefore, the lower limit is 5 g / m 2 . As the amount of plating increases, the corrosion resistance in the outer environment of the salt damage environment increases, but the weldability decreases. If the plating adhesion amount exceeds 30 g / m 2 , the seam weldability and spot weldability deteriorate, so the upper limit is made 30 g / m 2 .
なおめっき付着量の測定方法については、通常の方法でよい。すなわち重量法でめっき付着量を測定し、蛍光Ｘ線強度との間に検量線を作成して蛍光Ｘ線で付着量を測定することが望ましい。 In addition, about the measuring method of plating adhesion amount, a normal method may be sufficient. In other words, it is desirable to measure the amount of plating adhesion by the gravimetric method, create a calibration curve between the intensity of fluorescent X-rays and measure the amount of adhesion by fluorescent X-rays.
燃料タンクの内面となる一方の面は、燃料タンクの内面環境、すなわち軽油やガソリンに対する耐食性、あるいはこれらが酸化劣化した際に生成する有機酸（蟻酸、酢酸等）に対する耐食性を確保する必要がある。一方の面のめっき付着量が３０ｇ/ｍ２未満では十分な耐燃料耐食性が得られない。また本発明は鋼板の一方の面と他方の面とで差厚めっきとするものであるが、溶融めっき法の場合は、鋼板の両面でめっき付着量に差を持たせるには限度があり、他方の面のめっき付着量が３０ｇ／ｍ２のときに、一方の面のめっき付着量を６０ｇ／ｍ２超とすることは困難なために、上限を６０ｇ／ｍ２とする。 One surface, which is the inner surface of the fuel tank, needs to ensure the inner surface environment of the fuel tank, that is, corrosion resistance to light oil and gasoline, or corrosion resistance to organic acids (formic acid, acetic acid, etc.) generated when these deteriorate by oxidation. . If the amount of plating on one surface is less than 30 g / m 2 , sufficient fuel corrosion resistance cannot be obtained. In addition, the present invention is a differential thickness plating on one side and the other side of the steel plate, but in the case of the hot dipping method, there is a limit to making a difference in the amount of plating on both sides of the steel plate, When the plating adhesion amount on the other surface is 30 g / m 2 , it is difficult to make the plating adhesion amount on one surface more than 60 g / m 2 , so the upper limit is set to 60 g / m 2 .
溶融めっき法において、めっき付着量を制御するために、通常はガスワイピング法が用いられる。めっき付着量の制御因子として、一般的にガス圧、ラインスピード、鋼板−ノズル間距離、ノズルギャップ、ノズル形状等がある。本発明は鋼板の表裏面のめっき付着量を異ならせるものであり、このため表裏面でガス圧、鋼板−ノズル間距離、ノズルギャップ等を変えることが有効である。鋼板の表裏面でめっき付着量が同一の品種と、鋼板の表裏面でめっき付着量が異なる品種とを、同一のめっき製造ラインで製造することを考慮すると、鋼板−ノズル間距離を変化させることや、ガス圧を表裏で可変とすることでめっき付着量を調整することが望ましい。 In the hot dipping method, a gas wiping method is usually used to control the amount of plating adhesion. As control factors for the amount of plating, there are generally gas pressure, line speed, steel plate-nozzle distance, nozzle gap, nozzle shape, and the like. In the present invention, the amount of plating adhesion on the front and back surfaces of the steel sheet is made different. For this reason, it is effective to change the gas pressure, the distance between the steel sheet and the nozzle, the nozzle gap, and the like on the front and back surfaces. The distance between the steel plate and the nozzle can be changed considering that the same plating production line is used to produce a product with the same coating weight on the front and back surfaces of the steel plate and a product with a different plating coverage on the front and back surfaces of the steel plate. In addition, it is desirable to adjust the plating adhesion amount by making the gas pressure variable on both sides.
熱延鋼板、冷延鋼板、焼鈍鋼板、及び、めっき鋼板の調質圧延は、形状を適切に調整するために、適宜実施すればよい。 What is necessary is just to implement suitably the temper rolling of a hot-rolled steel plate, a cold-rolled steel plate, an annealed steel plate, and a plated steel plate, in order to adjust a shape appropriately.
また、めっき後の溶融Ａｌめっき層の表面に、化成処理皮膜を形成してもよい。化成処理皮膜は、シーム溶接性やスポット溶接性を更に向上させる効果があり、また、塗料膜との密着性を向上させる効果もある。化成処理皮膜としては、Ｃｒ、Ｚｒ、Ｔｉ、Ｓｉ、Ｖの１種または２種以上の化合物を含有する皮膜がよい。化成処理皮膜の付着量は片面当たり皮膜として５０〜１０００ｍｇ／ｍ２が望ましい。付着量が５０ｍｇ／ｍ２以下ではシーム溶接性及びスポット溶接性の向上効果が十分でなく、一方、付着量を多くしすぎても鋼板の表面抵抗が大きくなりすぎてシーム溶接性やスポット溶接性が低下する。このため付着量は片面当たり５０〜１０００ｍｇ／ｍ２が望ましい。これら化成処理皮膜の付着量測定についても、原則はめっき付着量と同様で、重量法で測定した皮膜量と蛍光Ｘ線強度との間に検量線を作成し、蛍光Ｘ線で測定するものとする。 Moreover, you may form a chemical conversion treatment film on the surface of the hot-dip Al plating layer after plating. The chemical conversion treatment film has an effect of further improving seam weldability and spot weldability, and also has an effect of improving adhesion with the paint film. As the chemical conversion film, a film containing one or more compounds of Cr, Zr, Ti, Si, and V is preferable. As for the adhesion amount of a chemical conversion treatment film, 50-1000 mg / m < 2 > is desirable as a film | membrane per single side | surface. When the adhesion amount is 50 mg / m 2 or less, the effect of improving the seam weldability and spot weldability is not sufficient. On the other hand, even if the adhesion amount is too large, the surface resistance of the steel sheet becomes too large and the seam weldability and spot weldability are increased. Decreases. For this reason, the adhesion amount is desirably 50 to 1000 mg / m 2 per side. The adhesion amount measurement of these chemical conversion coatings is basically the same as the coating adhesion amount, and a calibration curve is created between the coating amount measured by the gravimetric method and the fluorescent X-ray intensity, and measured with fluorescent X-rays. To do.
本発明では、鋼板の一方の面及び他方の面のそれぞれの溶融Ａｌめっき層に、Ａｌ−Ｆｅ−Ｓｉ層とＡｌ−Ｓｉ層とが形成される場合と、一方の面の溶融Ａｌめっき層にＡｌ−Ｆｅ−Ｓｉ層とＡｌ−Ｓｉ層とが形成され、他方の面の溶融Ａｌめっき層にＡｌ−Ｆｅ−Ｓｉ層のみが形成される場合とがある。すなわち、本発明の一実施形態として、他方の面にＡｌ−Ｓｉ層が無く、全てＡｌ−Ｆｅ−Ｓｉ層となっている場合がある。このような場合には、シーム、スポット溶接性が極めて向上することに加えて外面塗装との密着性も改善する。Ａｌ−Ｓｉ層を確実になくすためには、めっき後に溶融Ａｌめっき層を再加熱する必要がある。あるいはめっき付着量をできるだけ小さくしてめっき浴の浴温を高目にしておき、めっき浴の予熱でＡｌ−ＳｉとＦｅとの反応を促進する方法を採用してもよい。 In the present invention, when the Al-Fe-Si layer and the Al-Si layer are formed on each of the molten Al plating layers on one surface and the other surface of the steel plate, and on the molten Al plating layer on one surface. In some cases, an Al—Fe—Si layer and an Al—Si layer are formed, and only the Al—Fe—Si layer is formed in the molten Al plating layer on the other surface. That is, as an embodiment of the present invention, there is a case where there is no Al—Si layer on the other surface and all are Al—Fe—Si layers. In such a case, in addition to the seam and spot weldability being greatly improved, the adhesion with the outer surface coating is also improved. In order to eliminate the Al—Si layer without fail, it is necessary to reheat the molten Al plating layer after plating. Alternatively, a method may be employed in which the plating adhesion amount is made as small as possible to keep the bath temperature of the plating bath high, and the reaction between Al—Si and Fe is promoted by preheating the plating bath.
本実施形態のトラック・バスの燃料タンクは、例えば以下の手順で製造される。まず、本実施形態に係るめっき鋼板に曲げ加工を施して四角筒とし、この四角筒の両端開口部に鏡板を突合せ溶接してタンク本体を製造する。四角筒を製造する際は、めっき付着量が小さな他方の面を外面側とする。また、タンク内部に燃料の流通孔を複数有する複数の仕切板を配置し、仕切板とタンク本体とをスポット溶接してタンク本体の内部を複数の分割室に仕切る。更に、タンク本体の上面に給油口を設ける。燃料タンクの内面（一方の面）は通常無塗装とし、めっき付着量が小さな外面（他方の面）は塗装することが多い。外面の塗装種、塗装膜厚については特に限定されない。例えばメラミン系の水溶性樹脂を適用し、膜厚１０〜１００μｍ程度が望ましい。当然膜厚が厚い方が外面の防錆性は優れるがコストも増大するので、燃料タンク材が置かれる車体の位置等によって適正な膜厚を選定することとなる。 The truck / bus fuel tank of the present embodiment is manufactured, for example, by the following procedure. First, the plated steel sheet according to the present embodiment is bent to form a square cylinder, and a tank body is manufactured by butt welding end plates to both ends of the square cylinder. When manufacturing a square cylinder, let the other surface with small plating adhesion amount be an outer surface side. In addition, a plurality of partition plates having a plurality of fuel flow holes are disposed inside the tank, and the partition plate and the tank body are spot welded to partition the inside of the tank body into a plurality of divided chambers. Furthermore, an oil filler opening is provided on the upper surface of the tank body. The inner surface (one surface) of the fuel tank is usually unpainted, and the outer surface (the other surface) with a small amount of plating is often painted. There are no particular restrictions on the type of coating on the outer surface and the coating film thickness. For example, a melamine-based water-soluble resin is applied, and a film thickness of about 10 to 100 μm is desirable. Naturally, the thicker the film, the better the rust prevention of the outer surface, but the cost also increases. Therefore, an appropriate film thickness is selected depending on the position of the vehicle body on which the fuel tank material is placed.
次に、本発明の実施例について説明するが、実施例での条件は、本発明の実施可能性及び効果を確認するために採用した一条件例であり、本発明は、この一条件例に限定されるものではない。本発明は、本発明の要旨を逸脱せず、本発明の目的を達成する限りにおいて、種々の条件を採用し得るものである。 Next, examples of the present invention will be described. The conditions in the examples are one example of conditions used for confirming the feasibility and effects of the present invention, and the present invention is based on this one example of conditions. It is not limited. The present invention can adopt various conditions as long as the object of the present invention is achieved without departing from the gist of the present invention.
（実施例１）
表１に示す成分組成の溶鋼を転炉から出鋼し、スラブとした後、加熱温度：１２２０℃、仕上げ温度：８７０℃、巻取温度：６３０℃で熱間圧延した。熱延鋼板を冷延率７０％で厚さ１ｍｍになるように冷間圧延し、その後、連続溶融めっきラインにて焼鈍、Ａｌめっきした。このときの焼鈍温度は７８０℃、めっき浴温６６０℃、めっき浴組成はＡｌ−９％Ｓｉとし、更にめっき浴には鋼帯等から溶解したＦｅが約２．５％混入していた。めっき後、めっき付着量の調整をガスワイピング法にて行った。表裏面のガスワイピング条件を独立に制御して、それぞれの付着量を調整した。
Example 1
The molten steel having the component composition shown in Table 1 was removed from the converter and made into a slab, and then hot rolled at a heating temperature of 1220 ° C, a finishing temperature of 870 ° C, and a winding temperature of 630 ° C. The hot-rolled steel sheet was cold-rolled to a thickness of 1 mm at a cold rolling rate of 70%, and then annealed and Al-plated in a continuous hot dipping line. At this time, the annealing temperature was 780 ° C., the plating bath temperature was 660 ° C., the plating bath composition was Al-9% Si, and about 2.5% Fe dissolved from the steel strip was mixed in the plating bath. After plating, the amount of plating adhesion was adjusted by a gas wiping method. The amount of adhesion was adjusted by independently controlling the gas wiping conditions on the front and back surfaces.
こうして製造したＡｌめっき鋼板のシーム溶接性、スポット溶接性を評価した。シーム溶接については、１００×５００ｍｍの試験片を２枚合わせ、このときめっき付着量の少ない面を外面側とした。電極径は２５０ｍｍ、電極先端Ｒは８ｍｍ、加圧力は５００ｋｇｆ、溶接電流は１５ｋＡ、２ｏｎ−１ｏｆｆとし（６０Ｈｚ）、溶接速度は４ｍ／分とした。連続的に１０００枚溶接し、１０００枚目のナゲット形成状況を観察した。電極と鋼板との反応が激しい場合には、電極と鋼板が溶着気味となり、鋼板を引き剥がす力が生じる。この力のためブローホールが生成したものを×とし、ブローホールのないものを○としてシーム溶接性を評価した。 The seam weldability and spot weldability of the thus produced Al-plated steel sheet were evaluated. For seam welding, two 100 × 500 mm test pieces were put together, and at this time, the surface with a small amount of plating adhesion was defined as the outer surface side. The electrode diameter was 250 mm, the electrode tip R was 8 mm, the applied pressure was 500 kgf, the welding current was 15 kA, 2 on-1 off (60 Hz), and the welding speed was 4 m / min. 1000 pieces were continuously welded, and the formation state of the 1000th nugget was observed. When the reaction between the electrode and the steel plate is intense, the electrode and the steel plate are slightly welded, and a force to peel off the steel plate is generated. The seam weldability was evaluated by assuming that a blowhole was generated due to this force as x and a blowhole-free one as ○.
またスポット溶接性についても評価した。２３０×３２０ｍｍの試験片２枚合わせて、めっき付着量の少ない面を外面側とした。先端６φ−４０ＲのＤＲ電極を用いて、加圧力２５０ｋｇｆ、通電１２サイクル（６０Ｈｚ）、溶接電流８ｋＡで１０００点溶接し、１０００点目のナゲット形成状況を観察した。ナゲット径が４ｍｍ以上あるものを○、４ｍｍ未満であるものを×としてスポット溶接性を評価した。 The spot weldability was also evaluated. Two test pieces of 230 × 320 mm were combined, and the surface with a small amount of plating adhesion was defined as the outer surface side. Using a DR electrode with a tip 6φ-40R, 1000 points were welded at a pressure of 250 kgf, energization 12 cycles (60 Hz), and a welding current of 8 kA, and the nugget formation state at the 1000th point was observed. Spot weldability was evaluated by making a nugget diameter of 4 mm or more ○ and a nugget diameter of less than 4 mm x.
また内面側の評価として、有機酸を含有する燃料に対する耐食性を評価した。ガソリンをＪＩＳ Ｋ２２８７に従って酸化劣化させた。この劣化ガソリンと通常のガソリンの混合物に対して水を１０体積％混合し、水中の蟻酸約１００ｐｐｍ、酢酸約２００ｐｐｍとなるように調整した。この腐食液５００ｍＬ中に３０×４０ｍｍに剪断し、端面シールした試験片を浸漬させ、４５℃で１０００時間腐食試験し、試験後の腐食深さを測定した。最大腐食深さが０．２ｍｍよりも大きいものは×、０．２ｍｍ未満を○とした。 Moreover, corrosion resistance with respect to the fuel containing an organic acid was evaluated as evaluation of an inner surface side. Gasoline was oxidized and deteriorated according to JIS K2287. 10% by volume of water was mixed with the mixture of this deteriorated gasoline and normal gasoline, and adjusted so that the formic acid in water was about 100 ppm and the acetic acid was about 200 ppm. A test piece that had been sheared to 30 × 40 mm and end-face sealed in 500 mL of this corrosive solution was immersed and subjected to a corrosion test at 45 ° C. for 1000 hours, and the corrosion depth after the test was measured. The case where the maximum corrosion depth was larger than 0.2 mm was evaluated as x, and the case where the maximum corrosion depth was smaller than 0.2 mm was evaluated as ◯.
表２に、鋼成分と、内面側及び外面側のめっき付着量と、シーム溶接性と、スポット溶接性と、耐食性とを示す。
表２に示す試験例の内面側及び外面側のめっき層は、いずれも、Ｆｅ−Ｓｉ−Ａｌ合金層上Ｓｉ−Ａｌ合金層があるめっき層であった。
番号４では、外面側のめっき付着量が多いため、シーム溶接性、スポット溶接性が低下した。
また番号９は内面側のめっき付着量を大きくしたものであるが、このときには外面側もある程度めっき付着量が大きくなり、やはり溶接性に劣った。
番号５は内面側のめっき付着量が少ない場合で、内面環境における耐食性が低下した。
番号１２は鋼板中のＰ量が低い場合であり、この場合にも溶接性の低下が認められた。
番号１５については、シーム溶接及びスポット溶接のナゲット断面において割れが認められた。これは、鋼板中のＰ量が高いためと考えられ、このようなナゲットは望ましくない。
一方、本発明例では、鋼成分と内面側、外面側のめっき付着量を適正化することで良好な溶接性、内面耐食性が達成されることが確認された。
Table 2 shows the steel components, the plating adhesion amounts on the inner surface side and the outer surface side, seam weldability, spot weldability, and corrosion resistance.
The plating layers on the inner surface side and the outer surface side in the test examples shown in Table 2 were both plating layers having a Si—Al alloy layer on the Fe—Si—Al alloy layer.
In No. 4, seam weldability and spot weldability deteriorated due to the large amount of plating on the outer surface side.
No. 9 is an increase in the amount of plating deposited on the inner surface side. At this time, the amount of plating deposited on the outer surface side also increased to some extent, and the weldability was also inferior.
No. 5 is a case where the amount of plating on the inner surface side is small, and the corrosion resistance in the inner surface environment is lowered.
No. 12 is a case where the amount of P in the steel sheet is low, and in this case, a decrease in weldability was also observed.
For number 15, cracks were observed in the nugget cross sections of seam welding and spot welding. This is thought to be because the amount of P in the steel sheet is high, and such a nugget is not desirable.
On the other hand, in the example of the present invention, it was confirmed that good weldability and inner surface corrosion resistance were achieved by optimizing the steel component and the amount of plating adhesion on the inner surface side and outer surface side.
（実施例２）
表１の鋼Ｂ（板厚１ｍｍ）を用いて溶融Ａｌめっきした。付着量は厚目付側で４０ｇ／ｍ２、薄目付側で１９ｇ／ｍ２とした。溶融Ａｌめっき後、表３に示す薬液を両面に塗布し、８０℃で焼き付けた。このようにして製造したＡｌめっき鋼板のスポット溶接性を評価した。評価方法は実施例１とほぼ同じであるが、打点数は１５００点とし、１５００点後のナゲット形成状況を断面観察し、４ｍｍ以上を○、４ｍｍ未満を△とした。
(Example 2)
Hot dip Al plating was performed using steel B shown in Table 1 (plate thickness: 1 mm). The amount of adhesion was 40 g / m 2 on the thick side and 19 g / m 2 on the thin side. After the molten Al plating, the chemicals shown in Table 3 were applied on both sides and baked at 80 ° C. The spot weldability of the Al-plated steel sheet thus manufactured was evaluated. The evaluation method is almost the same as in Example 1. However, the number of hit points is 1500, and the nugget formation state after 1500 points is cross-sectionally observed.
表３にスポット溶接性の評価結果を示す。皮膜の無い例が番号３３であり、皮膜が厚い場合が番号３２であり、番号２４〜３１はいずれも皮膜を適正量付与した例である。皮膜を適正量付与することで、スポット溶接の連続打点は１５００点以上になることが示された。番号３２、３３はここでの評価は△であるが、実施例１の評価では○となっていた。 Table 3 shows the evaluation results of spot weldability. An example without a film is No. 33, a case where the film is thick is No. 32, and Nos. 24-31 are examples in which an appropriate amount of film is applied. It was shown that by applying an appropriate amount of the film, the number of continuous spot welding spots is 1500 or more. Numbers 32 and 33 were evaluated as “Δ”, but were evaluated as “good” in Example 1.
（実施例３）
表１の鋼Ｆ（板厚１．６ｍｍ）を用いて溶融Ａｌめっきした。付着量は厚目付側で３３ｇ／ｍ２とし、薄目付側で８ｇ／ｍ２とした。浴温を６９０℃とし、めっき後の冷却装置を使用せず、空冷としたところ、薄目付側の面ではＡｌ−Ｓｉ層がなくなり、外観は黒色を呈するようになった。このようにして製造したＡｌめっき鋼板のスポット溶接性を評価した。評価方法は実施例１とほぼ同じであるが、打点数は２０００点とし、２０００点後のナゲット形成状況を断面観察し、５．１ｍｍ以上を○、５．１ｍｍ未満を△としたところ、○の評価となった。すなわち、Ａｌ−Ｓｉ層が無くなることで連続打点は２０００点以上となることが示された。
Example 3
Using the steel F shown in Table 1 (plate thickness 1.6 mm), hot dip Al plating was performed. The amount of adhesion was 33 g / m 2 on the thick side and 8 g / m 2 on the thin side. When the bath temperature was set to 690 ° C. and the cooling device after plating was not used, and air cooling was performed, the Al—Si layer disappeared on the light-weighted surface, and the appearance became black. The spot weldability of the Al-plated steel sheet thus manufactured was evaluated. The evaluation method is almost the same as in Example 1. However, the number of hit points was 2000, and the cross-sectional observation of the nugget formation state after 2000 points was made. It became evaluation of. That is, it is shown that the continuous hitting point becomes 2000 points or more by eliminating the Al-Si layer.
前述したように、本発明によれば、シーム溶接性、スポット溶接性に優れためっき鋼板を提供するもので、本鋼板を適用することでこれら溶接を高生産で実行することが可能となる。これにより低廉なトラック・バス用燃料タンクを供給することが可能となり、産業上の利用可能性が高いものである。 As described above, according to the present invention, a plated steel sheet having excellent seam weldability and spot weldability is provided. By applying this steel sheet, it is possible to execute these weldings with high production. As a result, inexpensive fuel tanks for trucks and buses can be supplied, and industrial applicability is high.
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| JPS62161944A (en) * | 1986-01-13 | 1987-07-17 | Nisshin Steel Co Ltd | Aluminized steel sheet |
| JPH11152555A (en) * | 1997-11-20 | 1999-06-08 | Nippon Steel Corp | Rust preventive steel sheet for fuel tank excellent in corrosion resistance and weldability |
| JP2003221660A (en) * | 2002-01-31 | 2003-08-08 | Nisshin Steel Co Ltd | Fuel tank for vehicle made from hot-dip aluminized stainless steel sheet |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JPS62161944A (en) * | 1986-01-13 | 1987-07-17 | Nisshin Steel Co Ltd | Aluminized steel sheet |
| JPH11152555A (en) * | 1997-11-20 | 1999-06-08 | Nippon Steel Corp | Rust preventive steel sheet for fuel tank excellent in corrosion resistance and weldability |
| JP2003221660A (en) * | 2002-01-31 | 2003-08-08 | Nisshin Steel Co Ltd | Fuel tank for vehicle made from hot-dip aluminized stainless steel sheet |
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| WO2016059678A1 (en) * | 2014-10-14 | 2016-04-21 | 新日鐵住金株式会社 | Plated steel sheet and fuel tank |
| JPWO2016059678A1 (en) * | 2014-10-14 | 2017-08-31 | 新日鐵住金株式会社 | Plated steel sheet and fuel tank |
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