JP5217637B2 - Method for evaluating corrosion resistance of surface-treated steel sheets - Google Patents
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Description
本発明は、自動車クォーターに用いられる表面処理鋼板の耐食性評価方法に関するものである。 The present invention relates to a method for evaluating corrosion resistance of a surface-treated steel sheet used in an automobile quarter.
自動車用表面処理鋼板の開発では、実際に自動車用外板として表面処理鋼板を使用した場合を想定して、塩水噴霧試験（以下、SSTと称す）、複合サイクル腐食試験（以下、CCTと称す）、暴露試験などの腐食試験により、表面処理鋼板の耐食性評価が行われている。しかし、SSTやCCTに代表される腐食促進試験の場合は、塩水濃度、温度、湿度、および時間割合などによって材料間の相対的な耐食性が変化するため、腐食試験結果が実際に自動車用外板として鋼板を用いた場合の耐食性能と異なり、実際の自動車の腐食との相関性が課題とされている。
そこで、上記課題を解決するため、例えば、実際の環境における腐食を再現するために、暴露試験や自動車に試験片を取り付けて走行するOn Vehicle Test などが行われている。
また、環境条件だけでなく、自動車を模擬し加工した試験片を腐食試験に用いる場合もある。例えば、自動車のプレス成形を模擬して、表面処理鋼板に張出し加工や深絞り加工を付与した試験片が腐食試験に供されている（例えば特許文献１）。
さらに、多種多様な試験片が用いられている。例えば、外板向け表面処理鋼板においては、チッピングなどによる塗膜損傷を起点とする外観腐食に対する耐食性が要求されることから、塗装した表面処理鋼板に、人工的に傷を付与した試験片が用いられる。また、鋼板合わせ部の穴あき腐食に対する耐食性は、合わせ内部特有の腐食環境を模擬するために、試験片として、鋼板を重ね合わせた試験片やヘミング形状に加工した試験片が用いられる。
さらに、表面処理鋼板は、製品への成形加工により、めっきや化成処理層が損傷を受けることで耐食性が劣化するので、深絞り成形した試験片や実部品を用いて腐食試験が行われている。
In order to solve the above problems, for example, in order to reproduce corrosion in an actual environment, an exposure test, an on vehicle test in which a test piece is attached to a vehicle, and the like are performed.
In addition to environmental conditions, test pieces that are processed by simulating automobiles may be used for corrosion tests. For example, a test piece obtained by impressing press forming of an automobile and imparting an extension process or a deep drawing process to a surface-treated steel sheet is used for a corrosion test (for example, Patent Document 1).
In addition, a wide variety of test pieces are used. For example, in surface-treated steel sheets for outer panels, corrosion resistance against appearance corrosion starting from coating film damage due to chipping, etc. is required, so test pieces that have been artificially scratched are used on the coated surface-treated steel sheets. It is done. Moreover, in order to simulate the corrosion environment peculiar to the inside of the laminated portion, the corrosion resistance against perforated corrosion of the steel plate mating portion is a test piece obtained by superimposing steel plates or a test piece processed into a hemming shape.
Furthermore, since the corrosion resistance of the surface-treated steel sheet deteriorates due to damage to the plating or chemical conversion treatment layer due to the forming process on the product, a corrosion test is performed using test pieces and actual parts formed by deep drawing. .
現在、自動車用途には様々な種類の亜鉛系めっき鋼板が用いられている。また、摺動性や耐食性の向上を目的として、めっき上に有機、無機皮膜を形成した化成処理鋼板も用いられている。
これらの表面処理皮膜は、製造時においては、比較的均一に鋼板表面に被覆されているが、加工を付与することでめっき皮膜や化成処理皮膜（これらのまとめて表面処理皮膜と称す）が損傷する場合がある。場合によってはパウダリングやフレーキングなどの剥離現象を引き起こす。特に自動車部品の多くは、形状が複雑で難成形な形状のものが多く、加工による変形や摺動が大きいため、めっきや化成処理皮膜は損傷を受け易い。このように、表面処理皮膜が損傷を受けた場合は、該皮膜の防錆効果が損なわれる可能性がある。
Currently, various types of galvanized steel sheets are used for automobile applications. In addition, for the purpose of improving slidability and corrosion resistance, a chemically treated steel sheet in which an organic or inorganic film is formed on the plating is also used.
These surface treatment coatings are coated on the steel sheet surface relatively uniformly at the time of manufacture, but the plating film and chemical conversion treatment film (collectively referred to as the surface treatment film) are damaged by applying the processing. There is a case. In some cases, it causes peeling phenomena such as powdering and flaking. In particular, many automobile parts have many complicated and difficult-to-mold shapes, and are largely deformed and slid by processing, so that plating and chemical conversion coatings are easily damaged. Thus, when the surface treatment film is damaged, the rust prevention effect of the film may be impaired.
このような加工による表面処理皮膜への影響をシミュレートする方法として、深絞り加工などの加工を付与した試験片を用いて評価することもできるが、実際の自動車の腐食箇所と加工様式は必ずしも一致していていない。また、同じ目的で実プレス加工した自動車部品が耐食性評価に用いられる場合もあるが、実際の自動車成形部品は寸法が大きく、サンプル調達性の面、腐食試験機のスペースの面からも、一様に評価することは困難であった。このように、現在の耐食性評価方法では、表面処理鋼板を適用する部材の実際の皮膜損傷とそれに伴う耐食性劣化の程度を再現できておらず、従って、適正な耐食性を評価することが困難であった。 As a method of simulating the effect of such processing on the surface treatment film, it can also be evaluated using a test piece with processing such as deep drawing, but the actual corrosion location and processing mode of an automobile are not necessarily the same. Does not match. In addition, automotive parts that have been actually pressed for the same purpose may be used for corrosion resistance evaluation, but actual automotive molded parts are large in size, uniform in terms of sample availability and corrosion tester space. It was difficult to evaluate. As described above, the current corrosion resistance evaluation method cannot reproduce the actual film damage of the member to which the surface-treated steel sheet is applied and the degree of the corrosion resistance deterioration associated therewith. Therefore, it is difficult to evaluate the appropriate corrosion resistance. It was.
本発明は、かかる事情に鑑みなされたもので、実際の自動車クォーター材の腐食に対して相関性が高い、表面処理鋼板の耐食性評価方法を提供することを目的とする。 The present invention has been made in view of such circumstances, and an object thereof is to provide a method for evaluating the corrosion resistance of a surface-treated steel sheet, which has a high correlation with the corrosion of an actual automobile quarter material.
本発明者らは、上記課題を解決すべく検討を重ねた。その結果、以下の知見を得た。 The present inventors have repeatedly studied to solve the above problems. As a result, the following knowledge was obtained.
自動車は部位毎に異なる様式でプレス成形されるため、ひずみの変形分布が異なる。したがって表面処理鋼板が受ける損傷の形態や程度もそれぞれの部位によって異なる。ゆえに、自動車クォーターなどの腐食の厳しい部位に用いられる表面処理鋼板の耐食性を評価するにあたっては、各部位の特徴的な成形様式の加工を表面処理鋼板に付与したものを試験片として、前記試験片を腐食環境に供して耐食性を評価することが重要となる。
さらに、自動車において、腐食が激しい代表的な部位としては、フード、ドア、クオーター、ホイールハウス、サイドシルなどの鋼板合わせ部が挙げられることから、合わせ部形状で評価することが必要となる。
Since an automobile is press-molded in a different manner for each part, the strain distribution differs. Therefore, the form and degree of damage that the surface-treated steel sheet undergoes vary depending on each part. Therefore, in evaluating the corrosion resistance of the surface-treated steel sheet used in the severely corroded part such as an automobile quarter, the test piece is obtained by giving the surface-treated steel sheet the processing of the characteristic forming mode of each part. It is important to evaluate the corrosion resistance by subjecting to a corrosive environment.
Furthermore, typical parts of automobiles that are severely corroded include steel plate mating parts such as hoods, doors, quarters, wheel houses, and side sills. Therefore, it is necessary to evaluate the shape of the mating parts.
本発明は、以上の知見に基づき、鋭意研究を重ねた結果完成されたもので、その要旨は以下のとおりである。
［１］自動車クォーターに用いられる表面処理鋼板の耐食性評価方法であって、表面処理鋼板に深絞り加工、一軸引張り加工、平面摺動加工のいずれか１種類以上の加工を付与し、前記加工付与後の異種又は同種の表面処理鋼板を重ね合わせて鋼板合わせ部を形成し、次いで、前記鋼板合わせ部を形成した鋼板を試験片として腐食環境に供して耐食性を評価することを特徴とする自動車クォーター用表面処理鋼板の耐食性評価方法。
［２］前記［１］において、前記鋼板合わせ部は、前記異種又は同種の表面処理鋼板を接合して形成されることを特徴とする自動車クォーター用表面処理鋼板の耐食性評価方法。
［３］前記［２］において、前記接合が、抵抗溶接による接合であることを特徴とする自動車クォーター用表面処理鋼板の耐食性評価方法。
［４］前記［１］〜［３］のいずれかにおいて、前記試験片は、前記鋼板合わせ部を形成した後、化成処理および電着塗装を施したものであることを特徴とする自動車クォーター用表面処理鋼板の耐食性評価方法。
The present invention has been completed as a result of intensive studies based on the above findings, and the gist thereof is as follows.
[1] A method for evaluating the corrosion resistance of a surface-treated steel sheet used in an automobile quarter, wherein the surface-treated steel sheet is subjected to at least one of deep drawing, uniaxial tension processing, and plane sliding processing, and the processing is applied. An automobile quarter characterized by forming a steel plate mating portion by superimposing different types or the same kind of surface-treated steel plates, and then evaluating the corrosion resistance by using the steel plate on which the steel plate mating portion is formed as a test piece in a corrosive environment. For evaluating corrosion resistance of surface-treated steel sheets.
[2] The method for evaluating corrosion resistance of a surface-treated steel sheet for automobile quarters , wherein the steel sheet mating portion is formed by joining the different or the same kind of surface-treated steel sheets.
[3] The method for evaluating corrosion resistance of a surface-treated steel sheet for automobile quarters according to [2], wherein the joining is joining by resistance welding.
[4] In any of the above [1] to [3], the test piece is formed with the steel plate mating portion and then subjected to chemical conversion treatment and electrodeposition coating . Corrosion resistance evaluation method for surface treated steel sheet.
本発明の表面処理鋼板の耐食性評価方法によれば、実際の自動車クォーター材の腐食に対して相関性が高い評価を簡便に実施することができる。その結果、材料開発の効率化および腐食試験による材料選定の精度向上が期待される。 According to the corrosion resistance evaluation method for a surface-treated steel sheet according to the present invention, it is possible to easily perform an evaluation having a high correlation with the corrosion of an actual automobile quarter material. As a result, it is expected to improve the efficiency of material development and improve the accuracy of material selection through corrosion tests.
本発明は実際の自動車部位に即して自動車用表面処理鋼板の耐食性評価を行う方法であり、本発明では自動車クォーターに用いられる表面処理鋼板を対象とする。そして、その特徴は、自動車クォーターの成形様式で表面処理鋼板を加工した試験片を腐食が発生しやすい合わせ部形状にし、腐食試験に供する耐食性評価方法である。
本発明の耐食性評価の対象である自動車クォーター材（クォーターに相当するサイドパネルの外板でホイールハウス外板と重なる部分またはリヤフェンダー）の場合は、材料の深絞り加工の要素が強く、鋼板合わせ部になるフランジ部分は引張りと圧縮の変形を同時に受ける。また、材料の流入に伴い、金型との摺動を受けた部分がパネル部品の一部を形成する。ゆえに、クォーター材の耐食性評価試験を行うに際し、実際の自動車クォーター材の腐食に対して相関性が高い評価結果を得るためには、自動車クォーター材の特徴的な成形様式の加工、すなわち、深絞り加工、一軸引張り加工、平面摺動加工のいずれか１種類以上の加工を表面処理鋼板に付与したものを試験片とすることが重要となる。特に好ましいのは、表面処理鋼板に、2種類の加工を付与する場合であり、例えば深絞り加工または一軸引張り加工を付与した後にさらに平面摺動加工を付与する、あるいは、平面摺動加工を付与した後にさらに例えば深絞り加工または一軸引張り加工を付与するものである。そして、このように、自動車クォーター材の加工を模擬して、事前に表面処理鋼板を加工しておき、加工後の表面処理鋼板を試験片として腐食試験を行うことにより、実際の自動車クォーター材の腐食を高い精度で再現することができる。
具体的には、まず、表面処理鋼板に深絞り加工、一軸引張り加工、平面摺動加工のいずれか１種類以上の加工を付与し、前記加工付与後の異種又は同種の表面処理鋼板を重ね合わせて鋼板合わせ部を形成する。次いで、前記鋼板合わせ部を形成した鋼板を試験片として腐食環境に供して耐食性を評価することを特徴とする。
この時、鋼板合わせ部は、前記異種又は同種の表面処理鋼板を接合して形成されることが好ましい。また、特に抵抗溶接により接合されることが好ましい。
また、前記試験片は、鋼板合わせ部を形成したのち、化成処理および電着塗装を施したものであることが好ましい。
以下、詳細に説明する。
The present invention is a method for evaluating the corrosion resistance of a surface-treated steel sheet for automobiles in accordance with an actual automobile part. In the present invention, a surface-treated steel sheet used for automobile quarters is an object. And the characteristic is the corrosion-resistance evaluation method which makes the test piece which processed the surface treatment steel plate with the shaping | molding style of the automobile quarter into the joint part shape which is easy to generate | occur | produce corrosion, and uses for a corrosion test.
In the case of automotive quarter materials (parts of side panels corresponding to quarters that overlap the wheel house outer plate or rear fender) that are subject to the corrosion resistance evaluation of the present invention, the elements of deep drawing of the material are strong, and the steel plate matching The flange part which becomes a part receives the deformation | transformation of tension and compression simultaneously. Further, with the inflow of the material, the portion that has been slid with the mold forms a part of the panel component. Therefore, in order to obtain an evaluation result that is highly correlated with the corrosion of the actual automobile quarter material when performing the corrosion resistance evaluation test of the quarter material, the processing of the characteristic molding mode of the automobile quarter material, that is, deep drawing It is important to use a test piece obtained by applying one or more types of processing, uniaxial tension processing, and plane sliding processing to the surface-treated steel sheet. Particularly preferred is the case where two types of processing are applied to the surface-treated steel sheet. For example, after applying deep drawing processing or uniaxial tension processing, plane sliding processing is further applied, or plane sliding processing is applied. Then, for example, deep drawing or uniaxial tensile processing is applied. And, in this way, by simulating the processing of the automobile quarter material, by processing the surface-treated steel sheet in advance, and performing the corrosion test using the processed surface-treated steel sheet as a test piece, Corrosion can be reproduced with high accuracy.
Specifically, first, any one or more of deep drawing, uniaxial tension processing, and plane sliding processing is applied to the surface-treated steel sheet, and the different or the same type of surface-treated steel sheets after the processing are superimposed. The steel plate mating part is formed. Next, the steel plate on which the steel plate mating portion is formed is used as a test piece in a corrosive environment to evaluate the corrosion resistance.
At this time, it is preferable that the steel plate mating portion is formed by joining the different or same kind of surface-treated steel plates. Moreover, it is preferable to join especially by resistance welding.
Moreover, it is preferable that the test piece is subjected to chemical conversion treatment and electrodeposition coating after forming a steel plate mating portion.
Details will be described below.
表面処理鋼板に深絞り加工、一軸引張り加工、平面摺動加工のいずれか１種類以上の加工を付与する。
自動車クォーター材を模擬するために、例えば、表面処理鋼板に対して円筒状に深絞り加工、若しくは一軸引張り加工を行う。加工の方法はコニカルカップ試験機や通常の引張り試験機など成形性能を評価するための試験機を使用してもよい。
また、表面処理鋼板に対して平面摺動加工を行うこともできる。加工の方法は、摺動試験機により、材料のしごきと変形を付与することで、クォーター、またはそれに相当するサイドパネルやリヤフェンダーの摺動加工が厳しい部位を模擬することができる。
上記加工は１回だけでなく、複数種、複数回の加工を付与することができ、この時の加工方法、回数等は特に限定されず、実際に用いられる自動車クォーター材の加工方式を考慮して選択することが好ましい。
Any one or more of deep drawing, uniaxial tension, and plane sliding is applied to the surface-treated steel sheet.
In order to simulate an automobile quarter material, for example, a deep drawing process or a uniaxial tension process is performed in a cylindrical shape on a surface-treated steel sheet. The processing method may use a testing machine for evaluating molding performance such as a conical cup testing machine or a normal tensile testing machine.
Moreover, a plane sliding process can also be performed with respect to a surface treatment steel plate. The processing method can simulate a part where the sliding processing of the quarter or the corresponding side panel or rear fender is severe by applying ironing and deformation of the material by a sliding tester.
The above-mentioned processing can be applied not only once but also multiple types and multiple times, and the processing method, number of times, etc. at this time are not particularly limited, considering the processing method of the automobile quarter material actually used. Are preferably selected.
加工付与後の異種又は同種の表面処理鋼板を重ね合わせて鋼板合わせ部を形成する。
自動車では、完全に塗装された外面よりも、複数の鋼板が重なり合った鋼板合わせ部の方が穴あき腐食が発生し易く、防錆対策の中心となっている。このため、自動車クォーターに用いられる表面処理鋼板の耐食性を評価するにあたっては、クォーター内外板の合わせ部やクォーターと他の部品とで構成される合わせ部における腐食を再現するため、表面処理鋼板に加工を付与した後、表面処理鋼板を重ね合わせて鋼板合わせ部を形成することとする。この時の鋼板合わせ部を形成する鋼板は同種であっても異種であってもどちらでもよい。
また、鋼板合わせ部は、異種又は同種の表面処理鋼板を接合して形成することができる。例えば、スポット溶接等の抵抗溶接で接合して形成することができる。抵抗溶接は自動車の製造工程で使用されている接合方法であり、実験室においても溶接機を用いることにより簡便に接合することができる方法のため、鋼板合わせ部の形成に際し、好適に使用される。しかし、鋼板合わせ部の接合方法は上記に限定されず、他には、シーム溶接等の抵抗溶接の他に、トックス接合などのかしめ、ロウ付け、摩擦攪拌接合等が挙げられる。
The different or the same kind of surface-treated steel sheets after processing are overlapped to form a steel sheet mating portion.
In automobiles, the perforated corrosion is more likely to occur in the steel plate mating portion where a plurality of steel plates overlap than the completely painted outer surface, which is the center of rust prevention measures. For this reason, when evaluating the corrosion resistance of surface-treated steel sheets used in automobile quarters, the surface treated steel sheets are processed to reproduce the corrosion at the mating parts of the quarter inner and outer plates and the mating parts composed of quarters and other parts. Then, the surface-treated steel sheets are overlapped to form a steel sheet mating portion. The steel plates forming the steel plate mating portion at this time may be the same type or different types.
Moreover, the steel plate mating portion can be formed by joining different or the same type of surface-treated steel plates. For example, it can be formed by joining by resistance welding such as spot welding. Resistance welding is a joining method used in the manufacturing process of automobiles, and it is a method that can be easily joined by using a welding machine even in a laboratory, so it is preferably used when forming a steel sheet mating part. . However, the joining method of the steel sheet mating portion is not limited to the above, and other than resistance welding such as seam welding, caulking such as Tox joining, brazing, friction stir welding, and the like can be given.
鋼板合わせ部を形成した鋼板を試験片として腐食環境に供して耐食性を評価する。
試験片を、例えば、複合サイクル試験などの腐食環境に供し、所定期間後の腐食の状態を観察する、若しくは塗膜の膨れ幅、赤錆の発生頻度などを定量的に測定することによって耐食性を評価する。
耐食性を評価する方法は特に限定しない。自動車用外観腐食試験法として国内外で規格化されている試験法、例えば、国内では、JASO M 609-91で規格された試験法、米国では、Society of Automotive Engineers（自動車技術者協会）で定めたSAE J2334などの複合サイクル試験法を用いることができる。
また、自動車の生産工程に従い、鋼板合わせ部を形成した鋼板に対して、化成処理および電着塗装を施し試験片として、この試験片を腐食環境に供して耐食性を評価することが好ましい。このように鋼板合わせ部に対して電着塗装までの一連の処理を施した試験片を用いることで、より実際の自動車構造を模擬することができる。
なお、化成処理および電着塗装の条件は特に限定しないが、以下に化成処理および電着塗装の条件の一例を示す。
日本パーカラインジング（株）製PB-3080りん酸塩化成処理液を用いて、りん塩皮膜量が1.8〜2.2ｇ/ｍ2になるように化成処理を行った後、関西ペイント（株）製自動車用電着塗料を用いて、焼付け後の膜厚が18〜24μｍになるように塗装する。その後、170℃の雰囲気で20分間焼付け処理する。また、化成処理前に脱脂処理、表面調整処理を行ってもよい。
試験片には、鋼板合わせ内部だけを腐食させ、外面からの腐食の影響を除くために、合わせ部を形成した鋼板の外表面（合わせ開口部を除く）にシールを施すことが好ましい。
The steel plate on which the steel plate mating part is formed is subjected to a corrosive environment as a test piece to evaluate the corrosion resistance.
Evaluate the corrosion resistance by subjecting the test piece to a corrosive environment such as a combined cycle test and observing the state of corrosion after a predetermined period of time, or by quantitatively measuring the swelling width of the coating film, the occurrence frequency of red rust, etc. To do.
The method for evaluating the corrosion resistance is not particularly limited. Test methods standardized at home and abroad as exterior corrosion test methods for automobiles, for example, in Japan, the test method standardized by JASO M 609-91, in the United States established by Society of Automotive Engineers (Automotive Engineers Association) Combined cycle testing methods such as SAE J2334 can be used.
Moreover, it is preferable to evaluate the corrosion resistance by subjecting the steel sheet on which the steel sheet mating portion is formed according to the automobile production process to chemical conversion treatment and electrodeposition coating as a test piece and subjecting the test piece to a corrosive environment. Thus, the actual vehicle structure can be simulated more by using the test piece that has been subjected to a series of processes up to electrodeposition coating on the steel sheet mating portion.
In addition, although the conditions of chemical conversion treatment and electrodeposition coating are not specifically limited, an example of the conditions of chemical conversion treatment and electrodeposition coating is shown below.
After performing chemical conversion treatment using PB-3080 phosphate chemical treatment solution manufactured by Nippon Parker Lines Co., Ltd. so that the amount of the phosphate film is 1.8 to 2.2 g / m 2 , manufactured by Kansai Paint Co., Ltd. Using an electrodeposition paint for automobiles, the film thickness after baking is 18-24 μm. Thereafter, baking is performed for 20 minutes in an atmosphere of 170 ° C. Moreover, you may perform a degreasing process and a surface adjustment process before chemical conversion treatment.
It is preferable to seal the test piece on the outer surface (excluding the mating opening) of the steel plate on which the mating portion is formed in order to corrode only the inner portion of the steel plate and eliminate the influence of corrosion from the outer surface.
なお、本発明で用いる表面処理鋼板とは、特に限定されず、使用される目的に応じて適宜選択することができる。中でも、電気亜鉛めっき鋼板、溶融亜鉛めっき鋼板および合金化溶融亜鉛めっき鋼板は好適に使用される。 The surface-treated steel sheet used in the present invention is not particularly limited and can be appropriately selected depending on the purpose of use. Among these, an electrogalvanized steel sheet, a hot dip galvanized steel sheet, and an alloyed hot dip galvanized steel sheet are preferably used.
試験片の作製
板厚0.75mmでめっき付着量45g／m2、及び60g／m2の合金化溶融亜鉛めっき鋼板（GA45およびGA60）2種と、板厚0.75mmでめっき付着量50g／m2の電気亜鉛めっき鋼板（EG50）ならびに冷延鋼板の計4種に対して、図１に示す深絞り加工と図２に示す一軸引張り加工をそれぞれ施した。深絞り加工後の鋼板各２枚はそのままサンプルとした。一方、一軸引張り加工を受けた鋼板は加工を受けた箇所からサンプルとして各２枚切り出し採取した。次いで、同種の鋼板の上記サンプルをスポット溶接で接合して合わせ部を形成し、図３に示す深絞り加工による試験片（参考例１；ｎ＝３）と図４に示す一軸引張り加工による試験片（参考例２；ｎ＝３）を作製した。次いで、作製した試験片の評価面の腐食に影響を及ぼす部位にポリエステル製粘着テープ（日東電工（株）製リビック（登録商標））でシールした。なお、上記一軸引張り加工は、引張り速度1m/minの条件にて行い、上記深絞り加工は、ブランク径100mmφ、ポンチ径50mmφ、しわ押さえ29420N（3tf）、速度2mm/secの条件にて深さ30mmの深絞り加工を行った。
Coating weight 45 g / m 2 by making thickness 0.75mm the test piece, and the 60 g / m 2 galvannealed steel sheet (GA45 and GA 60) 2 species and, coating weight 50 g / m in thickness 0.75mm for two of the electro-galvanized steel sheet (EG50) and four kinds of cold rolled steel sheets were subjected respectively uniaxial tension process are shown in deep drawing and 2 shown in FIG. Two steel plates after deep drawing were used as samples. On the other hand, two steel plates that were subjected to uniaxial tensile processing were cut out and sampled as samples from the processed portions. Next, the above-mentioned samples of the same type of steel plates were joined by spot welding to form a mating portion, and a test piece by deep drawing shown in FIG. 3 ( Reference Example 1; n = 3) and a test by uniaxial tension shown in FIG. A piece ( Reference Example 2; n = 3) was produced. Subsequently, the part which affects the corrosion of the evaluation surface of the produced test piece was sealed with a polyester adhesive tape (Ribik (registered trademark) manufactured by Nitto Denko Corporation). The uniaxial tension processing is performed under the conditions of a pulling speed of 1 m / min, and the deep drawing processing is performed under the conditions of a blank diameter of 100 mmφ, a punch diameter of 50 mmφ, a wrinkle presser 29420N (3 tf), and a speed of 2 mm / sec. 30mm deep drawing was performed.
比較試験片の作製
比較サンプルとして、上記本発明と同様に4種の鋼板を用いて、加工を行わず、それ以外は上記本発明２と同じ方法で作製した試験片(比較例１；ｎ＝３)を準備した。また、上記本発明の加工方法（一軸引張り加工および深絞り加工）の代わりに図５に示す張出し加工を行ない、図６に示す試験片とした以外は上記本発明と同じ方法で作製した試験片(比較例２；ｎ＝３)を準備した。なお、上記張出し加工は、しわ押さえ147100N（15tf）、速度1m/minの条件にて高さ20mmの張り出し加工を行った。
Production of comparative test specimens As comparative samples, four types of steel plates were used in the same manner as in the present invention, and the other specimens were processed in the same manner as in the present invention 2 except that no processing was performed (Comparative Example 1; n = 3) was prepared. Moreover, the test piece produced by the same method as the said invention except having performed the overhang | projection process shown in FIG. 5 instead of the processing method (uniaxial tension process and deep drawing process) of the said invention, and making it the test piece shown in FIG. (Comparative Example 2; n = 3) was prepared. The overhanging process was carried out with a height of 20 mm under the conditions of a wrinkle presser 147100N (15 tf) and a speed of 1 m / min.
以上により得られた、参考試験片と比較試験片をSAE J2334腐食試験に供した。
また、本試験の評価のために、各めっきをクォーターに使用し、北米を8〜12年走行した車両（各めっきについて3台）のクォーターの鋼板合わせ部の腐食深さ測定データを用いた。なお、これら車両のクォーターの鋼板合わせ部には、シーラー、ワックス等の副資材は使用されていない。
腐食試験の終了は、上記の冷延鋼板と実車データの最大腐食深さの比が約１になるサイクルで全てのサンプルの試験を終了させた。試験後、鋼板合わせ部の溶接部に穴をあけて分解し、内部の腐食生成物を除錆剤により溶解除去した後、ポイントマイクロメーターを用いて板厚を測定し、各試験片の健全部に対する板厚減少値（腐食深さ）の最大値を求めた。また、各試験片の最大腐食深さ（ｎ＝３）は、同種のめっき材を使用した実車クォーター材の最大腐食深さ（ｎ＝３）それぞれを1とした場合の比を求めて評価した（全評価値としてｎ＝９となる）。
以上の方法により得られた結果を図７に示す。
The reference test piece and the comparative test piece obtained as described above were subjected to the SAE J2334 corrosion test.
In addition, for the evaluation of this test, the corrosion depth measurement data of the steel sheet mating part of the quarter (three for each plating) of a vehicle (three for each plating) that used each plating for the quarter and traveled in North America for 8 to 12 years was used. In addition, secondary materials such as sealers and waxes are not used in the steel plate mating portions of the quarters of these vehicles.
The end of the corrosion test was completed for all samples in a cycle in which the ratio of the maximum corrosion depth of the cold-rolled steel sheet to the actual vehicle data was about 1. After the test, a hole was made in the welded part of the steel plate mating part to disassemble and the internal corrosion products were dissolved and removed with a rust remover, then the plate thickness was measured using a point micrometer, and the healthy part of each test piece The maximum value of the thickness reduction value (corrosion depth) with respect to was obtained. Moreover, the maximum corrosion depth (n = 3) of each test piece was evaluated by determining the ratio when the maximum corrosion depth (n = 3) of an actual vehicle quarter material using the same kind of plating material was set to 1. (The total evaluation value is n = 9).
The results obtained by the above method are shown in FIG.
図７より、加工せずに鋼板合わせ部を形成した試験片（比較例１）、および張出し加工して鋼板合わせ部を形成した試験片（比較例２）では、冷延鋼板が実際の自動車と同じ程度の腐食深さに達しても、めっき鋼板（GA45、EG50、GA60）では、実際の自動車の腐食深さと大きく異なり、傾向が一致していないことがわかる。
これに対して、参考の深絞り加工または一軸引張り加工を付与し鋼板合わせ部を形成した試験片（参考例１および２）では、全てのめっき鋼板（GA45、EG50、GA60）について冷延鋼板と同様に実際の自動車との腐食比が0.5〜1.5の範囲であり、実際の自動車におけるクォーターの耐食性を高い精度で再現した。
From FIG. 7, in the test piece (Comparative Example 1) in which the steel sheet mating part was formed without processing, and in the test piece (Comparative Example 2) in which the steel sheet mating part was formed by overhang processing, Even when the corrosion depth reaches the same level, it can be seen that the plated steel sheets (GA45, EG50, GA60) differ greatly from the actual automobile corrosion depth, and the trends do not match.
On the other hand, in the test pieces ( Reference Examples 1 and 2) in which the reference deep drawing or uniaxial tension processing was applied to form the steel sheet mating portion, all the plated steel sheets (GA45, EG50, GA60) Similarly, the corrosion ratio with an actual automobile is in the range of 0.5 to 1.5, and the quarter corrosion resistance of an actual automobile is reproduced with high accuracy.
板厚0.75mmでめっき付着量45g／m2の合金化溶融亜鉛めっき鋼板（GA45）に対して、図８に示す平面摺動加工を付与した後、図2と同様に一軸引張り加工を施し、加工を受けた箇所からサンプルを切断採取した。平面摺動加工は、ビードの先端5mmr、平工具の肩5mmRとし、潤滑油に一般洗浄油（スギムラＲ325Ｌ）を使用し、押し付け圧2452N（250kgf）とし、引き抜き速度を1mm/minとした。次いで、同種の鋼板の上記サンプルをスポット溶接で接合して合わせ部を形成し、試験片（本発明例３；ｎ＝３）を作製した。また、試験片に、アルカリ脱脂を行い、以下に示すように化成処理および電着塗装を施した後、さらに、本発明例１と同様に、評価面の腐食に影響を及ぼす部位にシールした。
リン酸塩化成処理液（日本パーカライジング（株）製ＰＢ−３０８０）を用いて、りん酸塩皮膜量が１．８〜２．２g/m2となるように化成処理を行った後、関西ペイント（株）製自動車用電着塗料を用いて電着塗装した。その後、１７０℃の雰囲気で20分間焼付け処理し、膜厚が１８〜２４μmの電着塗膜を形成した。
After applying the flat sliding process shown in FIG. 8 to the alloyed hot-dip galvanized steel sheet (GA45) with a plate thickness of 0.75 mm and a coating weight of 45 g / m 2 , the same uniaxial tensile process as in FIG. A sample was cut and collected from the processed part. In the flat sliding process, the tip of the bead was 5 mmr, the flat tool shoulder was 5 mmR, general cleaning oil (Sugimura R325L) was used as the lubricating oil, the pressing pressure was 2452 N (250 kgf), and the drawing speed was 1 mm / min. Next, the above-mentioned samples of the same type of steel plate were joined by spot welding to form a mating portion, and a test piece (Invention Example 3; n = 3) was produced. Further, the test piece was subjected to alkali degreasing and subjected to chemical conversion treatment and electrodeposition coating as shown below, and then, in the same manner as in Example 1 of the present invention, the test piece was sealed to a site that affected the corrosion of the evaluation surface.
After performing chemical conversion treatment using a phosphate chemical treatment solution (PB-3080 manufactured by Nihon Parkerizing Co., Ltd.) so that the amount of phosphate film is 1.8 to 2.2 g / m 2 , Kansai Paint Electrodeposition coating was performed using an electrodeposition paint for automobiles. Then, it baked for 20 minutes in 170 degreeC atmosphere, and formed the electrodeposition coating film with a film thickness of 18-24 micrometers.
上記のようにして、平面摺動加工および一軸引張り加工後、化成処理、電着塗装した試験片（本発明例３；ｎ＝３）を作製した。これを試験片としてSAE J2334腐食試験に供し、実施例１と同じ試験期間で試験片を取り出した。取り出した試験片は、実施例１と同様の方法により各試験片の健全部に対する板厚減少値（腐食深さ）の最大値を求めた。また、各試験片の最大腐食深さ（ｎ＝３）は、同種のめっき材を使用した実車クォーター材の最大腐食深さ（ｎ＝３）それぞれを1とした場合の比を求めて評価した（全評価値としてｎ＝９となる）。
以上の方法により得られた結果を実施例1の結果と併せて図７に示す。
As described above, a test piece (Invention Example 3; n = 3) prepared by chemical conversion treatment and electrodeposition coating after plane sliding and uniaxial tension was prepared. This was subjected to SAE J2334 corrosion test as a test piece, and the test piece was taken out in the same test period as in Example 1. The taken-out test piece calculated | required the maximum value of the plate | board thickness reduction | decrease value (corrosion depth) with respect to the healthy part of each test piece by the method similar to Example 1. FIG. Moreover, the maximum corrosion depth (n = 3) of each test piece was evaluated by determining the ratio when the maximum corrosion depth (n = 3) of an actual vehicle quarter material using the same kind of plating material was set to 1. (The total evaluation value is n = 9).
The results obtained by the above method are shown in FIG. 7 together with the results of Example 1.
図７より、本発明の平面摺動加工後一軸引張り加工を付与し鋼板合わせ部を形成した試験片（本発明例３）では、冷延鋼板と同様に実際の自動車との腐食比が0.5〜1.5の範囲であり、実際の自動車におけるクォーターの耐食性を高い精度で再現した。 From FIG. 7, in the test piece (invention example 3) in which the uniaxial tension processing is applied after the plane sliding processing of the present invention to form the steel sheet mating portion, the corrosion ratio with the actual automobile is 0.5 to 5 like the cold rolled steel sheet. In the range of 1.5, the corrosion resistance of the quarter in an actual car was reproduced with high accuracy.
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