JP2023028884A

JP2023028884A - Friction welded joint, tailored blank material, molded article, and method for manufacturing friction welded joint

Info

Publication number: JP2023028884A
Application number: JP2021134850A
Authority: JP
Inventors: 徹岡田; Toru Okada; 博紀富士本; Hironori Fujimoto; 正則泰山; Masanori Taiyama; 真二児玉; Shinji Kodama
Original assignee: Nippon Steel Corp
Current assignee: Nippon Steel Corp
Priority date: 2021-08-20
Filing date: 2021-08-20
Publication date: 2023-03-03

Abstract

To provide a friction welded joint in which one or both of base material steel plates are Al plated and exhibit high joint strength, a tailored blank material, a molded article, and a method for manufacturing the friction welded joint.SOLUTION: A friction welded joint according to one aspect of the present invention comprises: a first steel plate plated with Al; a second steel plate disposed on substantially the same plane as that of the first steel plate; and a friction welded surface that joins the end surfaces of the first and second steel plates. Al plating is discharged from a joint part. A friction welded joint according to another aspect of the present invention comprises a first steel plate plated with Al, a second steel plate disposed on substantially the same plane as that of the first steel plate, and a friction welded surface that joins the end surfaces of the first and second steel plates. An average Al amount in the joint part is less than 1.0 mass%.SELECTED DRAWING: Figure 1

Description

本発明は、摩擦圧接継手、テーラードブランク材、成形品、及び摩擦圧接継手の製造方法に関する。 TECHNICAL FIELD The present invention relates to a friction welded joint, a tailored blank, a molded product, and a friction welded joint manufacturing method.

Ａｌ系めっき鋼板は、優れた耐食性を有するので、様々な機械部品の材料として用いられる。しかしながら、高強度が求められる機械部品の材料としてＡｌ系めっき鋼板を用いる際には、溶接部へのＡｌ濃化に起因する、継手強度の低下が問題となる。 Al-based plated steel sheets have excellent corrosion resistance and are used as materials for various machine parts. However, when using an Al-plated steel sheet as a material for machine parts that require high strength, there is a problem of reduced joint strength due to Al enrichment in the weld zone.

Ａｌ系めっき鋼板を溶接すると、溶接金属中にＡｌ系めっきが取り込まれ、軟質なＡｌ濃化部が形成される。Ａｌ濃化部は、溶接継手に応力が加わった際に破断起点として働くので、継手強度を低下させる。 When Al-plated steel sheets are welded, the Al-based plating is incorporated into the weld metal, forming a soft Al-enriched portion. The Al-enriched portion acts as a fracture starting point when stress is applied to the welded joint, and thus reduces joint strength.

この問題を回避するための手段として、Ａｌ系めっき鋼板の端部からＡｌ系めっきを除去してから、Ａｌ系めっき鋼板を溶接することが挙げられる。例えば、特許文献１には、少なくとも２つの板を突き合わせ溶接することによって得られた溶接された半加工品であって、溶接された接合部が、合金の層が取り除かれた領域に隣接する端面上でもたらされることを特徴とする、溶接された半加工品が開示されている。しかしながら、Ａｌ系めっきを除去する工程は、機械部品の製造コストを増大させる。従って、Ａｌ系めっきを除去することなくＡｌ系めっき鋼板を接合することが好ましい。 As a means for avoiding this problem, the Al-plated steel sheet is welded after removing the Al-based plating from the end of the Al-plated steel sheet. For example, in US Pat. No. 5,400,000, a welded blank obtained by butt-welding at least two plates, the welded joint having an end face adjacent to an area from which a layer of alloy has been removed. A welded blank is disclosed as characterized above. However, the process of removing Al-based plating increases the manufacturing cost of mechanical parts. Therefore, it is preferable to join the Al-plated steel sheets without removing the Al-based plating.

特許文献２には、強度の異なるアルミニウムめっき鋼板を突合せレーザ溶接して形成したホットスタンプ用のテーラードブランクであって、前記突合せレーザ溶接によって形成された溶接金属中のＡｌの平均濃度が０．３質量％以上、１．５質量％以下であり、溶接金属のＡｃ３点が１２５０℃以下であり、さらに、ホットスタンプ後の溶接金属の硬さと溶接金属の最も薄い部分の厚さの積の値が、低強度側の鋼板のホットスタンプ後の硬さと板厚の積の値より高くなるように、前記突合せ溶接する鋼板が組み合わされて溶接されていることを特徴とするテーラードブランクが開示されている。この技術によれば、溶接される部分のめっき層を取り除かずにそのまま突合せレーザ溶接して、十分な継手強度を有するテーラードブランクが得られるとされている。しかしながら、この技術によっても、接合部から十分にＡｌを排出することはできない。 Patent Document 2 discloses a tailored blank for hot stamping formed by butt laser welding aluminum plated steel sheets with different strengths, wherein the weld metal formed by the butt laser welding has an average Al concentration of 0.3. % by mass or more and 1.5% by mass or less, the Ac3 point of the weld metal is 1250° C. or less, and the product of the hardness of the weld metal after hot stamping and the thickness of the thinnest part of the weld metal is , a tailored blank characterized in that the steel plates to be butt-welded are combined and welded so that the value of the product of the hardness after hot stamping of the steel plate on the low strength side and the plate thickness is higher. . According to this technique, it is said that a tailored blank having sufficient joint strength can be obtained by butt laser welding as it is without removing the plating layer of the welded portion. However, even with this technique, Al cannot be sufficiently discharged from the joint.

特許第５２３７２６３号公報Japanese Patent No. 5237263 特許第５３１６６６４号公報Japanese Patent No. 5316664

本発明は、母材鋼板の一方又は両方がＡｌ系めっきを有しながら高い接合強度を有する摩擦圧接継手、テーラードブランク材、成形品、及び摩擦圧接継手の製造方法を提供することを課題とする。 An object of the present invention is to provide a friction welded joint, a tailored blank material, a molded article, and a method for manufacturing a friction welded joint having high joint strength while one or both of the base steel sheets are Al-plated. .

本発明の要旨は以下の通りである。 The gist of the present invention is as follows.

（１）本発明の一態様に係る摩擦圧接継手は、Ａｌ系めっきを有する第１の鋼板と、前記第１の鋼板と実質的に同一平面上に配された第２の鋼板と、前記第１の鋼板の端面と、前記第２の鋼板の端面とを接合する摩擦圧接面と、を備え、前記摩擦圧接面から、前記摩擦圧接面と垂直な方向に０．５ｍｍ以内の領域である接合部の全体にわたり、Ａｌ濃度が、前記第１の鋼板及び前記第２の鋼板のうち母材のＡｌ濃度が高い方のＡｌ濃度の２倍よりも小さい。
（２）本発明の別の態様に係る摩擦圧接継手は、Ａｌ系めっきを有する第１の鋼板と、前記第１の鋼板と実質的に同一平面上に配された第２の鋼板と、前記第１の鋼板の端面と、前記第２の鋼板の端面とを接合する摩擦圧接面と、を備え、前記摩擦圧接面から、前記摩擦圧接面と垂直な方向に０．５ｍｍ以内の領域である接合部における平均Ａｌ量が１．０質量％未満である。
（３）上記（１）又は（２）に記載の摩擦圧接継手では、前記第１の鋼板及び前記第２の鋼板のうち薄い方の板厚が１．０ｍｍ～４．０ｍｍであってもよい。
（４）上記（１）～（３）のいずれか一項に記載の摩擦圧接継手では、前記第１の鋼板の焼入れ後の引張強さと板厚との積が、前記第２の鋼板の焼入れ後の引張強さと板厚との積よりも小さくてもよい。
（５）上記（１）～（４）のいずれか一項に記載の摩擦圧接継手では、前記第１の鋼板のＣ含有量が０．１０質量％以上であってもよい。
（６）上記（１）～（５）のいずれか一項に記載の摩擦圧接継手では、前記第１の鋼板及び前記第２の鋼板がホットスタンプ用鋼板であってもよい。
（７）上記（１）～（６）のいずれか一項に記載の摩擦圧接継手では、前記摩擦圧接継手が、前記摩擦圧接面において前記第１の鋼板及び前記第２の鋼板の表面に垂直に突出したバリを有し、前記バリの表面の一部に、前記第１の鋼板の表面から連続的にＡｌ系めっきが配されてもよい。
（８）本発明の別の態様に係るテーラードブランク材は、上記（１）～（７）のいずれか一項に記載の摩擦圧接継手を含む。
（９）本発明の別の態様に係る成形品は、上記（１）～（７）のいずれか一項に記載の摩擦圧接継手を含む。
（１０）上記（９）に記載の成形品では、前記第１の鋼板の引張強さが１０００ＭＰａ以上であってもよい。
（１１）上記（９）又は（１０）に記載の成形品では、前記第１の鋼板の引張強さと板厚との積が、前記第２の鋼板の引張強さと板厚との積よりも小さくてもよい。
（１２）本発明の別の態様に係る摩擦圧接継手の製造方法は、Ａｌ系めっきを有する第１の鋼板の端面と、第２の鋼板の端面とを突き合せて、線形摩擦接合する工程を備え、前記線形摩擦接合において、印加圧力を５０ＭＰａ以上、周波数を１０Ｈｚ以上、及び振幅を±１ｍｍ以上とし、前記線形摩擦接合を、前記第１の鋼板及び前記第２の鋼板の突き合せ面の全体からバリが排出されるまで継続する。
（１３）上記（１２）に記載の摩擦圧接継手の製造方法では、前記線形摩擦接合の開始の時点において、前記第１の鋼板の前記端面まで、前記Ａｌ系めっきが形成されていてもよい。 (1) A friction welded joint according to an aspect of the present invention includes: a first steel plate having Al-based plating; a second steel plate arranged substantially on the same plane as the first steel plate; a friction-welding surface that joins the end surface of the first steel plate and the end surface of the second steel plate, wherein the area is within 0.5 mm from the friction-welding surface in a direction perpendicular to the friction-welding surface. The Al concentration is less than twice the Al concentration of the first steel sheet and the second steel sheet, whichever has the higher Al concentration in the base material, over the entire portion.
(2) A friction welded joint according to another aspect of the present invention includes a first steel plate having Al-based plating, a second steel plate arranged substantially on the same plane as the first steel plate, and the Equipped with a friction-welding surface that joins the end surface of the first steel plate and the end surface of the second steel plate, and is a region within 0.5 mm from the friction-welding surface in a direction perpendicular to the friction-welding surface. The average amount of Al in the joint is less than 1.0% by mass.
(3) In the friction welded joint described in (1) or (2) above, the thinner one of the first steel plate and the second steel plate may have a thickness of 1.0 mm to 4.0 mm. .
(4) In the friction welded joint according to any one of (1) to (3) above, the product of the tensile strength after quenching of the first steel plate and the plate thickness is equal to the quenching strength of the second steel plate. It may be smaller than the product of the later tensile strength and plate thickness.
(5) In the friction welded joint according to any one of (1) to (4) above, the C content of the first steel sheet may be 0.10% by mass or more.
(6) In the friction welded joint according to any one of (1) to (5) above, the first steel plate and the second steel plate may be steel plates for hot stamping.
(7) In the friction welded joint according to any one of (1) to (6) above, the friction welded joint is perpendicular to the surfaces of the first steel plate and the second steel plate at the friction welded surface. Al-based plating may be provided continuously from the surface of the first steel sheet on a part of the surface of the burr.
(8) A tailored blank according to another aspect of the present invention includes the friction welded joint according to any one of (1) to (7) above.
(9) A molded article according to another aspect of the present invention includes the friction welded joint according to any one of (1) to (7) above.
(10) In the molded product described in (9) above, the tensile strength of the first steel plate may be 1000 MPa or more.
(11) In the molded product according to (9) or (10) above, the product of the tensile strength and the plate thickness of the first steel plate is higher than the product of the tensile strength and the plate thickness of the second steel plate. It can be small.
(12) A method for manufacturing a friction welded joint according to another aspect of the present invention includes a step of butting an end face of a first steel plate having Al-based plating and an end face of a second steel plate and performing linear friction welding. In addition, in the linear friction bonding, the applied pressure is 50 MPa or more, the frequency is 10 Hz or more, and the amplitude is ±1 mm or more, and the linear friction bonding is performed over the entire butt surface of the first steel plate and the second steel plate. continue until the burr is discharged.
(13) In the method for manufacturing a friction welded joint according to (12) above, the Al-based plating may be formed up to the end face of the first steel plate at the start of the linear friction welding.

本発明によれば、母材鋼板の一方又は両方がＡｌ系めっきを有しながら高い接合強度を有する摩擦圧接継手、テーラードブランク材、成形品、及び摩擦圧接継手の製造方法を提供することができる。 ADVANTAGE OF THE INVENTION According to the present invention, it is possible to provide a friction welded joint, a tailored blank material, a molded article, and a method for manufacturing a friction welded joint having high joint strength while one or both of the base material steel sheets are Al-plated. .

摩擦圧接継手の断面図である。1 is a cross-sectional view of a friction welded joint; FIG. 摩擦圧接継手の摩擦圧接面及び接合部の拡大断面図である。3 is an enlarged cross-sectional view of a friction-welded surface and a joint portion of a friction-welded joint; FIG. バリの表面の一部にＡｌ系めっきが配されている摩擦圧接継手の概略図である。1 is a schematic diagram of a friction welded joint in which Al-based plating is applied to part of the surface of burrs; FIG. 第１の鋼板及び第２の鋼板の板厚が異なる場合の、突出し長さｈを説明する図である。It is a figure explaining protrusion length h in case board thicknesses of a 1st steel plate and a 2nd steel plate differ. 第１の鋼板及び第２の鋼板の板厚が同一である場合の、突出し長さｈを説明する図である。It is a figure explaining protrusion length h when board thickness of a 1st steel plate and a 2nd steel plate is the same.

（第１実施形態に係る摩擦圧接継手）
まず、本発明の第１の実施形態に係る摩擦圧接継手１について、図面を参照しながら説明する。図１は、第１実施形態に係る摩擦圧接継手１を示す断面図であり、図２は、摩擦圧接継手１の摩擦圧接面１３の拡大断面図である。 (Friction welded joint according to the first embodiment)
First, a friction welded joint 1 according to a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing a friction-welding joint 1 according to the first embodiment, and FIG. 2 is an enlarged cross-sectional view of a friction-welding surface 13 of the friction-welding joint 1. As shown in FIG.

図１に示されるように、本実施形態に係る摩擦圧接継手１は、少なくとも２枚の鋼板１１及び１２をこれらの端面において互いに突合せて線形摩擦接合することによって得られる継手である。すなわち、摩擦圧接継手１は、いわゆる突合せ圧接継手である。線形摩擦圧接とは、部材をお互いに接触させながら線形に揺動させて発生する摩擦熱を利用して接合部近傍の温度を上昇させ、加圧して行う圧接のことである（ＪＩＳＺ３０００－２：２０１８参照）。 As shown in FIG. 1, a friction welded joint 1 according to the present embodiment is a joint obtained by linearly friction-welding at least two steel plates 11 and 12 against each other at their end surfaces. That is, the friction welded joint 1 is a so-called butt welded joint. Linear friction welding is pressure welding performed by increasing the temperature in the vicinity of the joint using frictional heat generated by linearly oscillating members while they are in contact with each other (JIS Z 3000- 2:2018).

２枚の鋼板１１及び１２のうち少なくとも一方は、Ａｌ系めっき１１１を有する。Ａｌ系めっき１１１とは、その主成分がＡｌであり、必要に応じてＡｌ以外の元素を含有するめっきを意味する。Ａｌ系めっき１１１に含まれるＡｌ以外の元素とは、例えば３～１５質量％のＳｉである。Ａｌ系めっき１１１は、例えば溶融Ａｌめっき、及び電気Ａｌめっき等である。以下、便宜的に、Ａｌ系めっき１１１を有する鋼板を第１の鋼板１１と称する。また、第１の鋼板１１と接合される鋼板を、第２の鋼板１２と称する。ただし、第１の鋼板１１及び第２の鋼板１２の両方がＡｌ系めっきを有していてもよい。この場合、２枚の鋼板１１及び１２のうち任意のものを、第１の鋼板１１とみなすことができる。また、第２の鋼板１２が、Ａｌ系めっき以外のめっきを有してもよい。 At least one of the two steel plates 11 and 12 has Al-based plating 111 . The Al-based plating 111 means plating whose main component is Al and which contains elements other than Al as necessary. Elements other than Al contained in the Al-based plating 111 are, for example, 3 to 15% by mass of Si. The Al-based plating 111 is, for example, hot-dip Al plating, electric Al plating, or the like. Hereinafter, the steel sheet having the Al-based plating 111 is referred to as the first steel sheet 11 for convenience. A steel plate to be joined to the first steel plate 11 is referred to as a second steel plate 12 . However, both the first steel sheet 11 and the second steel sheet 12 may have Al-based plating. In this case, any one of the two steel plates 11 and 12 can be regarded as the first steel plate 11 . Also, the second steel sheet 12 may have plating other than Al-based plating.

第１の鋼板１１及び第２の鋼板１２の厚さは特に限定されない。図１に例示されるように、第１の鋼板１１及び第２の鋼板１２の厚さが同じであってもよいし、図２に例示されるように、第１の鋼板１１及び第２の鋼板１２の厚さが異なっていてもよい。 The thicknesses of the first steel plate 11 and the second steel plate 12 are not particularly limited. As illustrated in FIG. 1, the first steel plate 11 and the second steel plate 12 may have the same thickness, or as illustrated in FIG. The thickness of the steel plate 12 may be different.

本実施形態に係る摩擦圧接継手はいわゆる突合せ圧接継手であるので、第１の鋼板１１と第２の鋼板１２とは、実質的に同一平面上に配される。ただし、第１の鋼板１１と第２の鋼板１２とが若干の角度をなすことは許容される。本実施形態において、接合部１４の延在方向に垂直な断面において測定される第１の鋼板１１と第２の鋼板１２とがなす角のうち小さい方の角度は、例えば１７０°～１８０°である。 Since the friction welded joint according to this embodiment is a so-called butt welded joint, the first steel plate 11 and the second steel plate 12 are arranged substantially on the same plane. However, it is allowed that the first steel plate 11 and the second steel plate 12 form a slight angle. In the present embodiment, the smaller of the angles formed by the first steel plate 11 and the second steel plate 12 measured in the cross section perpendicular to the extending direction of the joint 14 is, for example, 170° to 180°. be.

摩擦圧接継手１は、第１の鋼板１１の端面と、第２の鋼板１２の端面とを接合する摩擦圧接面１３を有する。溶接継手とは異なり、固相接合によって形成される摩擦圧接継手１の接合部には溶融凝固部が形成されない。溶接継手の断面をピクリン酸で腐食させて観察すると、溶融凝固痕であるデンドライトが明瞭に確認されるが、摩擦圧接継手１の腐食断面にはデンドライトが含まれず、その代わりに、摩擦圧接面１３が筋状に存在する様子を確認することができる。 The friction welded joint 1 has a friction welded surface 13 that joins the end surface of the first steel plate 11 and the end surface of the second steel plate 12 . Unlike welded joints, no melt-solidified portion is formed in the joined portion of the friction welded joint 1 formed by solid phase welding. When the cross section of the welded joint is corroded with picric acid and observed, dendrites, which are traces of molten solidification, are clearly observed. It is possible to confirm the existence of streaks.

摩擦圧接面１３は、線形摩擦圧接によって形成される。適切な線形摩擦圧接によって得られた、第１実施形態に係る摩擦圧接継手１の接合部１４においては、Ａｌ濃度が、第１の鋼板１１及び第２の鋼板１２のうち母材のＡｌ濃度が高い方のＡｌ濃度の２倍よりも小さい。ここで接合部１４とは、摩擦圧接面１３から、摩擦圧接面１３と垂直な方向に０．５ｍｍ以内の領域のことである。例えば、図２に示される摩擦圧接継手１の断面においては、破線Ａ～破線Ｄに囲まれた領域が接合部１４である。 The friction contact surface 13 is formed by linear friction contact. In the joint 14 of the friction welded joint 1 according to the first embodiment obtained by appropriate linear friction welding, the Al concentration of the base material of the first steel plate 11 and the second steel plate 12 is less than twice the higher Al concentration. Here, the joint portion 14 is a region within 0.5 mm from the friction contact surface 13 in the direction perpendicular to the friction contact surface 13 . For example, in the cross section of the friction welded joint 1 shown in FIG.

上述の通りＡｌ濃度が抑制された接合部１４を有する摩擦圧接継手においては、第１の鋼板１１及び第２の鋼板１２の端面に存在する物質が、摩擦圧接面１３の外部に排出されている。端面に存在する物質とは、例えば酸化物や、Ａｌ系めっき１１１のダレである。換言すると、第１実施形態に係る摩擦圧接継手１においては、接合部１４からＡｌ系めっき１１１が排出されているのである。通常の溶接継手においては、溶接金属にＡｌ系めっきが取り込まれ、継手強度を低下させる軟質なＡｌ濃化部が形成される。一方、Ａｌ系めっき１１１が接合部１４から排出されている場合、接合部に軟化部が形成されないので、高い接合強度が確保される。 In the friction welded joint having the welded portion 14 with the Al concentration suppressed as described above, substances present on the end faces of the first steel plate 11 and the second steel plate 12 are discharged to the outside of the friction welded surface 13. . The substance existing on the end face is, for example, an oxide or sagging of the Al-based plating 111 . In other words, in the friction welded joint 1 according to the first embodiment, the Al-based plating 111 is discharged from the joint portion 14 . In a normal welded joint, the Al-based plating is incorporated into the weld metal, forming a soft Al-enriched portion that reduces the strength of the joint. On the other hand, when the Al-based plating 111 is discharged from the joint 14, a softened portion is not formed in the joint, ensuring high joint strength.

なお、摩擦圧接面１３の近傍に、第１の鋼板１１及び第２の鋼板１２の表面から垂直に突出したバリ１５が形成されていてもよい。バリ１５は、第１の鋼板１１及び第２の鋼板１２の端面に存在する物質が、摩擦圧接面１３の外部に排出されて形成されたものである。バリ１５には、Ａｌ系めっき１１１が含まれていてもよい。バリ１５は、摩擦圧接継手１の接合強度に影響しないからである。一方、摩擦圧接継手１の美観確保等の目的で、バリ１５が摩擦圧接継手１から除去されていてもよい。 A burr 15 projecting vertically from the surfaces of the first steel plate 11 and the second steel plate 12 may be formed in the vicinity of the friction contact surface 13 . The burrs 15 are formed by substances existing on the end faces of the first steel plate 11 and the second steel plate 12 being ejected to the outside of the friction contact surface 13 . The burr 15 may contain Al-based plating 111 . This is because the burr 15 does not affect the joint strength of the friction welded joint 1 . On the other hand, the burrs 15 may be removed from the friction welded joint 1 for the purpose of ensuring the appearance of the friction welded joint 1 or the like.

また、バリ１５は、その表面の一部に、第１の鋼板１１の表面から連続的に形成されたＡｌ系めっきを有していてもよい。バリ１５は、図３に示されるように、摩擦圧接面１３の近傍において昇温によって軟化した金属が盛り上がることによって生じる。端面までＡｌ系めっきが配された鋼板を線形摩擦接合に供した場合、端面の近傍に配されていたＡｌ系めっきは、バリ１５の盛り上がりに追従してめくれあがる。従って、端面までＡｌ系めっきが配された鋼板を線形摩擦接合に供した場合、バリ１５の表面の一部に、第１の鋼板１１の表面から連続的にＡｌ系めっきが配されることになる。このようなバリ１５を有する摩擦圧接継手は、線形摩擦接合の際に端面からＡｌ系めっきを除去する工程が省略されていたと推定される。従って、このようなバリ１５を有する摩擦圧接継手は、製造コストの面で優れている。 Moreover, the burr 15 may have Al-based plating continuously formed from the surface of the first steel sheet 11 on a part of its surface. As shown in FIG. 3, the burr 15 is caused by the swelling of metal softened by the temperature rise in the vicinity of the friction contact surface 13 . When a steel plate having Al-based plating applied to the end faces is subjected to linear friction welding, the Al-based plating disposed near the end faces curls up following the swelling of the burrs 15 . Therefore, when a steel plate with Al-based plating applied to the end face is subjected to linear friction welding, the Al-based plating is continuously applied to a part of the surface of the burr 15 from the surface of the first steel plate 11. Become. It is presumed that the friction welded joint having such burrs 15 did not have the step of removing the Al-based plating from the end faces during linear friction welding. Therefore, a friction welded joint having such burrs 15 is excellent in terms of manufacturing cost.

接合部１４からＡｌ系めっき１１１が排出されているか否かは、ＥＰＭＡを用いて摩擦圧接継手１の断面の元素分布を測定することにより判別可能である。図２に、摩擦圧接継手１の断面拡大図を示す。図２における破線Ａ及び破線Ｃは、第１の鋼板１１及び第２の鋼板１２のうち薄い方（図２においては第１の鋼板１１）の、塑性変形を受けていない表面を延長した線である。第１の鋼板１１と第２の鋼板１２との界面であって、破線Ａ及び破線Ｃよりも板厚方向内側にある領域を、摩擦圧接面１３とみなす。図２における破線Ｂ及び破線Ｄは、摩擦圧接面１３に平行であって、摩擦圧接面１３から０．５ｍｍ離れた線である。破線Ａ～破線Ｄに囲まれた領域が、摩擦圧接面１３から摩擦圧接面１３に垂直な方向に０．５ｍｍ以内の領域、即ち接合部１４である。破線Ａ～破線Ｄに囲まれた領域におけるＡｌ濃度を、摩擦圧接面１３に沿った方向、及び摩擦圧接面１３に垂直な方向に沿って１００μｍ間隔で測定する。これにより、接合部１４のＡｌ濃度の測定点は１００μｍ間隔の格子状に配列されることになる。そして、破線Ａ～破線Ｄに囲まれた領域において、鋼板のＡｌ濃度の２倍以上のＡｌ濃度である測定点が存在しない摩擦圧接継手は、接合部１４からＡｌ系めっき１１１が排出された継手であるとみなされる。第１の鋼板１１のＡｌ濃度と第２の鋼板１２のＡｌ濃度とが相違する場合は、Ａｌ濃度が高い方の鋼板のＡｌ濃度を上述の「鋼板のＡｌ濃度」として用いる。 Whether or not the Al-based plating 111 is discharged from the joint 14 can be determined by measuring the elemental distribution of the cross section of the friction welded joint 1 using EPMA. FIG. 2 shows an enlarged sectional view of the friction welded joint 1. As shown in FIG. Broken lines A and C in FIG. 2 are lines extending the surface of the thinner one of the first steel plate 11 and the second steel plate 12 (the first steel plate 11 in FIG. 2) that has not undergone plastic deformation. be. An interface between the first steel plate 11 and the second steel plate 12 and located inside the broken lines A and C in the plate thickness direction is regarded as a friction contact surface 13 . Broken lines B and D in FIG. 2 are lines parallel to the friction contact surface 13 and separated from the friction contact surface 13 by 0.5 mm. A region surrounded by dashed lines A to D is a region within 0.5 mm from the friction contact surface 13 in the direction perpendicular to the friction contact surface 13 , that is, the joint portion 14 . The Al concentration in the area surrounded by dashed lines A to D is measured at intervals of 100 μm along the direction along the friction contact surface 13 and the direction perpendicular to the friction contact surface 13 . As a result, the measurement points of the Al concentration of the junction 14 are arranged in a lattice pattern with an interval of 100 μm. In the area surrounded by the dashed lines A to D, the friction welded joint where there is no measurement point where the Al concentration is twice or more the Al concentration of the steel plate is a joint in which the Al-based plating 111 is discharged from the joint 14. is considered to be When the Al concentration of the first steel sheet 11 and the Al concentration of the second steel sheet 12 are different, the Al concentration of the steel sheet with the higher Al concentration is used as the "Al concentration of the steel sheet".

なお、破線Ａ及び破線Ｃよりも板厚方向外側にある領域（例えばバリ１５）は評価対象とはされない。また、第１の鋼板１１と第２の鋼板１２とが同一平面上にある図２において、接合部１４の断面は、長方形形状となっているが、第１の鋼板１１と第２の鋼板１２とが若干の角度をなしていてもよい。この場合、破線Ａ及び破線Ｃと、破線Ｂ及び破線Ｄとがなす角度が９０°ではなく、約８０°～１００°の範囲で変動しうる。しかし、この場合も、上述の通り１００μｍ間隔の格子状に測定点を配置すればよい。 Note that regions outside the dashed lines A and C in the plate thickness direction (for example, burrs 15) are not evaluated. In addition, in FIG. 2 in which the first steel plate 11 and the second steel plate 12 are on the same plane, the cross section of the joint portion 14 has a rectangular shape. and may form a slight angle. In this case, the angle formed by the dashed lines A and C and the dashed lines B and D may vary from about 80° to 100° instead of 90°. However, in this case as well, the measurement points may be arranged in a grid pattern with intervals of 100 μm as described above.

（第２実施形態に係る摩擦圧接継手）
次に、本発明の第２の実施形態に係る摩擦圧接継手１について説明する。第２実施形態に係る摩擦圧接継手１は、第１実施形態と同様に、Ａｌ系めっき１１１を有する第１の鋼板１１と、第１の鋼板１１と実質的に同一平面上に配された第２の鋼板１２と、第１の鋼板１１の端面及び第２の鋼板１２の端面を接合する摩擦圧接面１３と、を有する。第１の鋼板１１、第２の鋼板１２、及びＡｌ系めっき１１１の構成は、第１実施形態と同様のものとすることができる。また、第２実施形態に係る摩擦圧接継手１は、第１実施形態と同様にバリ１５を有してもよい。 (Friction welded joint according to the second embodiment)
Next, a friction welded joint 1 according to a second embodiment of the present invention will be described. A friction welded joint 1 according to the second embodiment includes, as in the first embodiment, a first steel plate 11 having an Al-based plating 111 and a second steel plate 11 arranged substantially on the same plane as the first steel plate 11 . 2 steel plate 12 and a friction welding surface 13 that joins the end face of the first steel plate 11 and the end face of the second steel plate 12 . The configurations of the first steel plate 11, the second steel plate 12, and the Al-based plating 111 can be the same as those in the first embodiment. Further, the friction welded joint 1 according to the second embodiment may have burrs 15 as in the first embodiment.

第２実施形態に係る摩擦圧接継手１は、第１の鋼板１１の端面と、第２の鋼板１２の端面とを接合する摩擦圧接面１３を有し、摩擦圧接面１３から摩擦圧接面１３に垂直な方向に０．５ｍｍ以内の領域である接合部１４における平均Ａｌ量が１．０質量％未満である。接合部１４とは、第１実施形態と同じく、図２の破線Ａ～破線Ｄに囲まれた領域のことである。接合部１４の平均Ａｌ量が１．０質量％未満である場合、摩擦圧接継手１の接合部においてＡｌに起因する軟化が生じず、高い接合強度が確保される。 The friction-welding joint 1 according to the second embodiment has a friction-welding surface 13 that joins the end surface of the first steel plate 11 and the end surface of the second steel plate 12, and from the friction-welding surface 13 to the friction-welding surface 13 The average amount of Al in the joint 14 within 0.5 mm in the vertical direction is less than 1.0% by mass. The joint portion 14 is a region surrounded by dashed lines A to D in FIG. 2, as in the first embodiment. When the average amount of Al in the joint portion 14 is less than 1.0% by mass, softening due to Al does not occur in the joint portion of the friction welded joint 1, and high joint strength is ensured.

接合部１４における平均Ａｌ量は、接合部１４からＡｌ系めっき１１１が排出されているか否かの判別方法と同様の方法で、特定することができる。具体的には、摩擦圧接継手１の断面において、ＥＰＭＡを用いて摩擦圧接継手１の断面の元素分布を測定することにより、接合部１４における平均Ａｌ量を求める。即ち、図２に示される破線Ａ～破線Ｄに囲まれた領域におけるＡｌ濃度を、摩擦圧接面１３に沿った方向、及び摩擦圧接面１３に垂直な方向に沿って１００μｍ間隔で測定する。これにより、接合部１４のＡｌ濃度の測定点は１００μｍ間隔の格子状に配列されることになる。そして、これらの測定点におけるＡｌ濃度の平均値を算出し、これを、接合部１４における平均Ａｌ量とみなす。 The average amount of Al in the joint portion 14 can be specified by the same method as the method for determining whether the Al-based plating 111 is discharged from the joint portion 14 . Specifically, the average amount of Al in the joint 14 is obtained by measuring the element distribution of the cross section of the friction welded joint 1 using EPMA. That is, the Al concentration in the area surrounded by the broken lines A to D shown in FIG. As a result, the measurement points of the Al concentration of the junction 14 are arranged in a lattice pattern with an interval of 100 μm. Then, the average Al concentration at these measurement points is calculated and regarded as the average Al amount in the joint 14 .

接合部１４からＡｌ系めっき１１１が排出されているか否かの判断、及び接合部１４における平均Ａｌ量の測定のいずれにおいても、ＥＰＭＡ測定条件は以下の通りとする。
・加速電圧１５ｋＶ
・ビーム径１００ｎｍ
・１点あたりの照射時間１０００ｍｓ EPMA measurement conditions are as follows for both the determination of whether the Al-based plating 111 is discharged from the joint 14 and the measurement of the average Al amount in the joint 14 .
・Acceleration voltage 15 kV
・Beam diameter 100 nm
・Irradiation time per point: 1000ms

摩擦圧接継手１は、第１実施形態に係る構成、及び第２実施形態に係る構成の両方を兼備してもよい。また、上述の要件が満たされる限り、第１実施形態、及び第２実施形態に係る摩擦圧接継手１の構成は特に限定されない。これら実施形態に係る摩擦圧接継手１の一層好適な形態に関し、以下に例示的に説明する。特に断りが無い限り、以下に説明される構成は、第１実施形態に係る摩擦圧接継手１、及び第２実施形態に係る摩擦圧接継手１の両方に適用可能である。 The friction welded joint 1 may have both the configuration according to the first embodiment and the configuration according to the second embodiment. Moreover, as long as the above requirements are satisfied, the configuration of the friction welded joint 1 according to the first embodiment and the second embodiment is not particularly limited. A further preferred form of the friction welded joint 1 according to these embodiments will be exemplified below. Unless otherwise specified, the configuration described below is applicable to both the friction welded joint 1 according to the first embodiment and the friction welded joint 1 according to the second embodiment.

（板厚）
第１の鋼板１１及び第２の鋼板１２のうち、少なくとも薄い方の鋼板の板厚が４．０ｍｍ以下であってもよい。両方の鋼板の板厚を４．０ｍｍ以下としてもよい。鋼板の板厚を４．０ｍｍ以下とすることにより、摩擦圧接継手１をプレス成形部品の材料として用いることが可能となる。これにより、例えば自動車部品などの幅広い薄板構造部材に、本実施形態に係る摩擦圧接継手１を適用することが可能となる。第１の鋼板１１及び第２の鋼板１２の一方又は両方の板厚を、３．５ｍｍ以下、３．０ｍｍ以下、又は２．８ｍｍ以下としてもよい。 (Thickness)
Of the first steel plate 11 and the second steel plate 12, at least the thinner steel plate may have a thickness of 4.0 mm or less. The plate thickness of both steel plates may be 4.0 mm or less. By setting the plate thickness of the steel plate to 4.0 mm or less, the friction welded joint 1 can be used as a material for press-formed parts. This makes it possible to apply the friction welded joint 1 according to the present embodiment to a wide range of thin plate structural members such as automobile parts. The plate thickness of one or both of the first steel plate 11 and the second steel plate 12 may be 3.5 mm or less, 3.0 mm or less, or 2.8 mm or less.

一方、少なくとも薄い方の鋼板の板厚を１．０ｍｍ以上とすることにより、第１の鋼板１１及び第２の鋼板１２の摩擦圧接の際に座屈が生じることを効果的に防止可能となる。薄い方の鋼板の板厚を１．２ｍｍ以上、１．５ｍｍ以上、又は２．０ｍｍ以上としてもよい。厚い方の鋼板の板厚の下限値に、上述の値を適用することも妨げられない。 On the other hand, by setting the plate thickness of at least the thinner steel plate to 1.0 mm or more, it is possible to effectively prevent buckling from occurring during friction welding of the first steel plate 11 and the second steel plate 12. . The plate thickness of the thinner steel plate may be 1.2 mm or more, 1.5 mm or more, or 2.0 mm or more. It is also possible to apply the above values to the lower limit of the plate thickness of the thicker steel plate.

（鋼板の引張強さ及び板厚）
鋼板の焼入れ硬化能（熱処理による焼入れ硬化のしやすさを示す合金の性質であり、焼入れた時にどれだけ深く硬い組織が得られるかを示す性質）及び厚さを規定することにより、先行技術に対する本実施形態に係る摩擦圧接継手１の優位性が一層顕著となる。一般的に用いられる焼入れ硬化能の評価指標の一例は、炭素当量（鋼材の合金元素の含有量を炭素量に換算した値）であるが、本実施形態に係る摩擦圧接継手１においては、焼入れ性の評価指標として、「焼入れ後の引張強さ」を用いる。鋼板の焼入れ後の引張強さとは、鋼板を８００～１０００℃に加熱して、次いで金型冷却や水冷により急冷した後で測定される、鋼板の引張強さを意味する。急冷の際、８００℃から５００℃まで鋼板の温度が低下するのに要する時間が、下記式１～４によって算出される値ｔ_Ｍよりも小さくなるようにする。
ｌｏｇ_１０ｔ_Ｍ＝４．６×ＣＥＩ－２．０８（式１）
ＣＥＩは、下記式によって算出される値である。
ＣＥＩ＝Ｃｐ＋Ｓｉ／２４＋Ｍｎ／６＋Ｃｕ／１５＋Ｎｉ／１２＋Ｃｒ×（１－０．１６√Ｃｒ）／８＋Ｍｏ／４＋０．０９（式２）
Ｃｐ＝Ｃ（Ｃ≦０．３％）（式３）
Ｃｐ＝Ｃ／６＋０．２５（Ｃ＞０．３％）（式４）
なお、式２～式４に記載の元素記号は、鋼板における、この記号に係る合金元素の質量％での含有量を意味する。 (Tensile strength and plate thickness of steel plate)
By stipulating the quench hardenability of the steel plate (a property of the alloy that indicates the ease of quench hardening by heat treatment, and indicates how deep and hard the structure can be obtained when quenched) and thickness, The superiority of the friction welded joint 1 according to this embodiment becomes even more remarkable. An example of a commonly used evaluation index of hardenability is carbon equivalent (a value obtained by converting the content of alloying elements of steel materials into carbon content). As a property evaluation index, "tensile strength after quenching" is used. The tensile strength of a steel sheet after quenching means the tensile strength of the steel sheet measured after the steel sheet is heated to 800 to 1000° C. and then quenched by die cooling or water cooling. During quenching, the time required for the temperature of the steel sheet to drop from 800° C. to 500° C. is set to be smaller than the value t _M calculated by the following equations 1-4.
log ₁₀ t _M =4.6×CEI−2.08 (equation 1)
CEI is a value calculated by the following formula.
CEI=Cp+Si/24+Mn/6+Cu/15+Ni/12+Cr×(1−0.16√Cr)/8+Mo/4+0.09 (Formula 2)
Cp=C (C≦0.3%) (Formula 3)
Cp=C/6+0.25 (C>0.3%) (Formula 4)
Incidentally, the elemental symbols described in Formulas 2 to 4 mean the content in mass % of the alloying element according to this symbol in the steel sheet.

鋼板に上記条件で焼入れをしてから引張強さを測定することにより、鋼板の焼入れ硬化能を評価することができる。ただし、「焼入れ後の引張強さ」を用いて鋼板の焼入れ硬化能を規定した場合であっても、摩擦圧接継手１の鋼板が焼入れされている必要はない。焼入れ前の摩擦圧接継手１も、所定の要件を満たす限り、本実施形態に係る摩擦圧接継手１であるとみなされる。 By measuring the tensile strength after quenching the steel sheet under the above conditions, the quench hardenability of the steel sheet can be evaluated. However, even if the "tensile strength after quenching" is used to define the quench hardenability of the steel sheet, the steel sheet of the friction welded joint 1 need not be quenched. The friction welded joint 1 before quenching is also regarded as the friction welded joint 1 according to the present embodiment as long as it satisfies predetermined requirements.

本実施形態に係る摩擦圧接継手１では、Ａｌ系めっき１１１を有する第１の鋼板１１の、焼入れ後の引張強さと板厚との積が、第２の鋼板１２の焼入れ後の引張強さと板厚との積よりも小さくてもよい。この場合、摩擦圧接継手１は、通常の溶接継手に対する一層の優位性を発揮する。 In the friction welded joint 1 according to the present embodiment, the product of the tensile strength after quenching and the plate thickness of the first steel plate 11 having the Al-based plating 111 is the tensile strength after quenching of the second steel plate 12 and the plate thickness. It may be smaller than the product with the thickness. In this case, the friction welded joint 1 exhibits a further advantage over the normal welded joint.

通常の溶接継手において、上述の母材条件は、接合強度の確保の観点からは極めて不利である。その理由として、（１）溶接金属に取り込まれたＡｌ系めっき１１１は、母材と溶接金属との境界である溶融境界部の近傍に濃化すること、（２）薄い鋼板の溶融境界部には応力集中が生じやすいこと、及び（３）高強度鋼板の溶融境界部に軟質なＡｌ濃化部が存在すると、Ａｌ濃化部とそれ以外の部位との間の硬度差が著しくなること、が挙げられる。 In a normal welded joint, the above-mentioned base material conditions are extremely disadvantageous from the viewpoint of ensuring joint strength. The reasons for this are that (1) the Al-based plating 111 incorporated into the weld metal concentrates in the vicinity of the fusion boundary, which is the boundary between the base metal and the weld metal, and (2) the fusion boundary of the thin steel plate is likely to cause stress concentration, and (3) if there is a soft Al-enriched part in the fusion boundary of the high-strength steel sheet, the difference in hardness between the Al-enriched part and other parts becomes significant. is mentioned.

しかしながら、本実施形態に係る摩擦圧接継手１においては、摩擦圧接面及びその近傍からＡｌ系めっき１１１が排出されているか、又はこの領域における平均Ａｌ濃度が極めて低く抑えられている。そのため、上述の焼入れ後の引張強さ、及び板厚を有する場合であっても、本実施形態に係る摩擦圧接継手１は高い接合強度を確保することができる。 However, in the friction-welding joint 1 according to the present embodiment, the Al-based plating 111 is discharged from the friction-welding surface and its vicinity, or the average Al concentration in this region is kept extremely low. Therefore, even if the friction welded joint 1 according to the present embodiment has the above-described tensile strength and plate thickness after quenching, high joint strength can be ensured.

（鋼板のＣ含有量）
Ａｌ系めっき１１１を有する第１の鋼板１１のＣ含有量は、例えば０．１０質量％以上であってもよい。Ｃ含有量が多く、従って高強度を有するＡｌ系めっき鋼板を溶接することによって得られる突合せ継手は、接合強度の低下が極めて生じやすいことが知られている。その理由は、Ａｌ濃化部とその他の部分との硬度差が著しい点にある。しかしながら、本実施形態に係る摩擦圧接継手１においては、摩擦圧接面及びその近傍からＡｌ系めっき１１１が排出されているか、又はこの領域における平均Ａｌ濃度が極めて低く抑えられている。そのため、Ａｌ系めっき１１１を有する第１の鋼板１１のＣ含有量が０．１０質量％以上であっても、本実施形態に係る摩擦圧接継手１は高い接合強度を確保することができる。 (C content of steel plate)
The C content of the first steel sheet 11 having the Al-based plating 111 may be, for example, 0.10% by mass or more. It is known that butt joints obtained by welding Al-plated steel sheets, which have a high C content and therefore high strength, are extremely susceptible to a decrease in joint strength. The reason for this is that there is a significant difference in hardness between the Al-enriched portion and other portions. However, in the friction-welding joint 1 according to the present embodiment, the Al-based plating 111 is discharged from the friction-welding surface and its vicinity, or the average Al concentration in this region is kept extremely low. Therefore, even if the C content of the first steel sheet 11 having the Al-based plating 111 is 0.10% by mass or more, the friction welded joint 1 according to this embodiment can ensure high joint strength.

（鋼板の種類）
本実施形態に係る摩擦圧接継手１の用途は特に限定されず、これを構成する鋼板の種類は、用途に応じて適宜選択することができる。例えば摩擦圧接継手１を自動車部品として用いる場合、第１の鋼板１１及び第２の鋼板１２をホットスタンプ用鋼板とすることが好ましい。ホットスタンプ用鋼板とは、ホットスタンプに適した板厚、及び焼入れ性を有する鋼板のことである。ホットスタンプ用鋼板の成分は、例えば、質量％で、Ｃ：０．０５～０．５５％、Ｓｉ：０．０１～２．０％、Ｍｎ：０．２～３．０％、Ｃｒ：０．０１～０．５％、Ｂ：０．１％以下（０％を含む）、及びＡｌ：０．００５～０．１％を含有し、残部がＦｅ及び不純物からなる。不純物とは、例えば鋼材を工業的に製造する際に、鉱石若しくはスクラップ等のような原料、又は製造工程の種々の要因によって混入する成分であって、本実施形態に係る摩擦圧接継手に悪影響を与えない範囲で許容されるものを意味する。Ｔｉ、Ｍｏ、Ｎｂの１種または２種以上がさらに鋼板に含有されてもよい。上に列記された各合金元素の含有量の数値範囲のうち、一部のみが第１の鋼板１１及び／又は第２の鋼板１２に適用されてもよい。例えば、第１の鋼板１１及び第２の鋼板１２が、Ａｌ：０．００５～０．１％を含有し、残りが鉄及び任意の合金元素である鋼板であってもよい。 (type of steel plate)
The application of the friction welded joint 1 according to the present embodiment is not particularly limited, and the type of steel plate forming it can be appropriately selected according to the application. For example, when the friction welded joint 1 is used as an automobile part, it is preferable that the first steel plate 11 and the second steel plate 12 are steel plates for hot stamping. A steel sheet for hot stamping is a steel sheet having a thickness and hardenability suitable for hot stamping. The components of the steel plate for hot stamping are, for example, in mass%, C: 0.05 to 0.55%, Si: 0.01 to 2.0%, Mn: 0.2 to 3.0%, Cr: 0 0.01% to 0.5%, B: 0.1% or less (including 0%), and Al: 0.005% to 0.1%, the balance being Fe and impurities. Impurities are raw materials such as ores or scraps, or components that are mixed due to various factors in the manufacturing process when steel materials are industrially manufactured, for example, and have an adverse effect on the friction welded joint according to the present embodiment. It means what is permissible within the range not given. One or more of Ti, Mo and Nb may be further contained in the steel sheet. Only some of the numerical ranges of the content of each alloying element listed above may be applied to the first steel sheet 11 and/or the second steel sheet 12 . For example, the first steel sheet 11 and the second steel sheet 12 may be steel sheets containing 0.005 to 0.1% Al, with the balance being iron and optional alloying elements.

ここまで、２枚の鋼板１１及び１２を端面において突き合せて接合した摩擦圧接継手１について説明した。しかしながら、摩擦圧接継手１が３枚以上の鋼板を有していてもよい。全ての鋼板が摩擦圧接面１３によって接合されていてもよいし、一部の鋼板のみが摩擦圧接面１３によって接合され、他の鋼板が溶接等の別の手段によって接合されていてもよい。例えば、１枚のＡｌ系めっき鋼板と、２枚のめっき無し鋼板とを接合して継手を製造する場合、Ａｌ系めっき鋼板とめっき無し鋼板との接合に対してのみ摩擦圧接を適用し、めっき無し鋼板同士の接合には別の接合手段（例えばレーザ溶接等）を適用してもよい。 So far, the friction welded joint 1 in which the two steel plates 11 and 12 are butted and joined at their end surfaces has been described. However, the friction welded joint 1 may have three or more steel plates. All the steel plates may be joined by the friction-welding surfaces 13, or only some of the steel plates may be joined by the friction-welding surfaces 13 and the other steel plates may be joined by another means such as welding. For example, when manufacturing a joint by joining one Al-plated steel sheet and two non-plated steel sheets, friction welding is applied only to the joining of the Al-plated steel sheet and the non-plated steel sheet, and the plating is performed. Another joining means (for example, laser welding, etc.) may be applied to joining the bare steel sheets.

（第３実施形態に係るテーラードブランク材）
次に、本発明の第３の実施形態に係るテーラードブランク材について説明する。テーラードブランク材とは、プレス成形部品の材料であって、溶接等の手段を用いて複数の鋼板を接合することによって製造されたものである。テーラードブランク材は、自動車のサイドパネル及びフロアパネル等のような、様々な材質及び板厚の鋼板をつなぎ合わせて製造される機械部品の材質として極めて好適である。 (Tailored blank material according to the third embodiment)
Next, a tailored blank material according to a third embodiment of the present invention will be described. Tailored blanks are materials for press-formed parts, and are manufactured by joining a plurality of steel plates using means such as welding. Tailored blanks are extremely suitable as materials for machine parts, such as automobile side panels and floor panels, which are manufactured by connecting steel plates of various materials and plate thicknesses.

本発明の第３実施形態に係るテーラードブランク材は、上述された第１実施形態又は第２実施形態に係る摩擦圧接継手１を含む。従って、第３実施形態に係るテーラードブランク材は、Ａｌ系めっき鋼板を構成部品として有するにもかかわらず、高い接合強度を確保することができる。 A tailored blank according to the third embodiment of the present invention includes the friction welded joint 1 according to the first or second embodiment described above. Therefore, the tailored blank material according to the third embodiment can ensure high bonding strength in spite of having Al-plated steel sheets as constituent parts.

（第４実施形態に係る成形品）
次に、本発明の第４の実施形態に係る成形品について説明する。成形品とは、テーラードブランク材にプレス加工、好ましくはホットスタンプ加工をすることにより得られる部品である。 (Molded product according to the fourth embodiment)
Next, a molded product according to a fourth embodiment of the invention will be described. A molded product is a part obtained by pressing, preferably hot stamping, a tailored blank.

第４実施形態に係る成形品は、第３実施形態に係るテーラードブランク材と同様に、上述された第１実施形態又は第２実施形態に係る摩擦圧接継手１を含む。第４実施形態に係る成形品は、Ａｌ系めっき鋼板を構成部品として有するにもかかわらず、高い接合強度を確保することができる。なお、テーラードブランク材と成形品との相違は、プレス加工前の状態であるか、プレス加工後の状態であるか、という点にある。第４実施形態に係る成形品は、例えば第３実施形態に係るテーラードブランク材をホットスタンプすることによって製造可能である。成形品の用途は特に限定されないが、例えば自動車部品とすることができる。 The molded article according to the fourth embodiment includes the friction welded joint 1 according to the above-described first or second embodiment, like the tailored blank material according to the third embodiment. The molded product according to the fourth embodiment can ensure high bonding strength in spite of having Al-plated steel sheets as components. The difference between the tailored blank material and the molded product is whether it is in a state before press working or after press working. A molded product according to the fourth embodiment can be manufactured, for example, by hot stamping the tailored blank material according to the third embodiment. The use of the molded product is not particularly limited, but it can be used as, for example, automobile parts.

プレス加工前のテーラードブランク材は、加工を容易にする目的で、焼入れされていないことが通常である。一方、第４実施形態に係る成形品は、焼入れされていることが好ましい。例えば、第１の鋼板１１の引張強さが１０００ＭＰａ以上とされていることが好ましい。これにより、成形品の強度を飛躍的に高めることができる。なお、引張強さが１０００ＭＰａ以上のＡｌ系めっき鋼板を溶接すると、溶接部におけるＡｌ濃化によって、接合強度が低下することがある。一方、第４実施形態に係る成形品は、摩擦圧接面１３から０．５ｍｍ以内の領域からＡｌ系めっき１１１が排出されているか、又は摩擦圧接面１３から０．５ｍｍ以内の領域における平均Ａｌ量が１．０質量％未満であるので、たとえＡｌ系めっき鋼板の引張強さが１０００ＭＰａ以上であっても接合強度を確保することができる。 Tailored blanks before press working are usually not quenched for the purpose of facilitating working. On the other hand, the molded product according to the fourth embodiment is preferably quenched. For example, it is preferable that the tensile strength of the first steel plate 11 is 1000 MPa or more. As a result, the strength of the molded product can be dramatically increased. It should be noted that, when welding Al-plated steel sheets having a tensile strength of 1000 MPa or more, the joint strength may decrease due to Al enrichment in the weld zone. On the other hand, in the molded product according to the fourth embodiment, the Al-based plating 111 is discharged from the region within 0.5 mm from the friction contact surface 13, or the average Al amount in the region within 0.5 mm from the friction contact surface 13 is less than 1.0% by mass, the joint strength can be ensured even if the tensile strength of the Al plated steel sheet is 1000 MPa or more.

また、第４実施形態に係る成形品においては、Ａｌ系めっき鋼板である第１の鋼板１１の引張強さと板厚との積が、第２の鋼板１２の引張強さと板厚との積よりも小さくてもよい。このようなＡｌ系めっき鋼板から構成される成形品は、接合強度の低下が極めて生じやすいことが知られている。その理由は、Ａｌ濃化が極めて生じやすく、さらにＡｌ濃化部とその他の部分との硬度差が著しい点にある。しかしながら、第４実施形態に係る成形品においては、摩擦圧接面１３から摩擦圧接面１３に垂直な方向に０．５ｍｍ以内の領域である接合部１４からＡｌ系めっき１１１が排出されているか、又は接合部１４における平均Ａｌ量が１．０質量％未満である。そのため、Ａｌ系めっき鋼板が上述の引張強さ、及び板厚を有する場合であっても、第４実施形態に係る成形品は高い接合強度を確保することができる。 In addition, in the molded product according to the fourth embodiment, the product of the tensile strength and the plate thickness of the first steel plate 11, which is an Al-plated steel plate, is higher than the product of the tensile strength and the plate thickness of the second steel plate 12. may be smaller. It is known that a molded article composed of such an Al-plated steel sheet is extremely susceptible to deterioration in bonding strength. The reason for this is that Al concentration is very likely to occur, and that there is a significant difference in hardness between the Al-enriched portion and other portions. However, in the molded product according to the fourth embodiment, the Al-based plating 111 is discharged from the joint 14 within 0.5 mm in the direction perpendicular to the friction contact surface 13 from the friction contact surface 13, or The average amount of Al in the joint 14 is less than 1.0% by mass. Therefore, even if the aluminum-based plated steel sheet has the above-described tensile strength and thickness, the molded article according to the fourth embodiment can ensure high bonding strength.

（第５実施形態に係る摩擦圧接継手の製造方法）
次に、本発明の第５の実施形態に係る摩擦圧接継手の製造方法について説明する。本発明の第５実施形態に係る摩擦圧接継手の製造方法は、Ａｌ系めっきを有する第１の鋼板の端面と、第２の鋼板の端面とを突き合せて、線形摩擦接合する工程を有する。線形摩擦接合とは、部材をお互いに接触させながら、通常は片側だけを線形に揺動させて発生する摩擦熱を利用して接合部近傍の温度を上昇させ、加圧して行う圧接のことである（ＪＩＳＺ３０００－２：２０１８参照）。 (Method for manufacturing a friction welded joint according to the fifth embodiment)
Next, a method for manufacturing a friction welded joint according to the fifth embodiment of the present invention will be described. A method for manufacturing a friction welded joint according to the fifth embodiment of the present invention includes a step of butting an end face of a first steel plate having Al-based plating and an end face of a second steel plate and performing linear friction welding. Linear friction welding is a pressure welding method in which the temperature in the vicinity of the joint is raised by using the frictional heat generated by linearly oscillating normally only one side while the members are brought into contact with each other. Yes (see JIS Z 3000-2:2018).

線形摩擦接合においては、印加圧力を５０ＭＰａ以上とし、周波数を１０Ｈｚ以上とし、振幅を±１ｍｍ以上とする。印加圧力とは、第１の鋼板と第２の鋼板との間にかけられる加圧力のことである。周波数とは、１秒間に第１の鋼板と第２の鋼板とを線形に揺動させる回数である。振幅とは、第１の鋼板と第２の鋼板とを線形に揺動させる際の変位量の最大値である。これにより、第１の鋼板１１及び第２の鋼板１２を十分に加熱し、摩擦圧接面１３を形成することができる。 In linear friction welding, the applied pressure is set to 50 MPa or more, the frequency is set to 10 Hz or more, and the amplitude is set to ±1 mm or more. Applied pressure is the pressure applied between the first steel plate and the second steel plate. The frequency is the number of times the first steel plate and the second steel plate are linearly oscillated per second. The amplitude is the maximum value of the amount of displacement when the first steel plate and the second steel plate are linearly oscillated. Thereby, the first steel plate 11 and the second steel plate 12 can be sufficiently heated to form the friction-welded surfaces 13 .

さらに、線形摩擦接合は、第１の鋼板１１及び第２の鋼板１２の突き合せ面の全体からバリが排出されるまで継続される必要がある。「突き合せ面の全体からバリが排出される」とは、昇温によって軟化した材料を、被接合界面全体からバリとして排出するという意味である。なお、この状態が達成されているか否か、摩擦圧接継手１を破壊せずに確認することは困難である。そのため、製造しようとする摩擦圧接継手１と同じ素材を用いて、摩擦圧接試験を予め行い、上述の状態を達成可能な接合時間を予め求めておけばよい。この接合時間よりも長く摩擦圧接を実施することにより、第１の鋼板１１及び第２の鋼板１２の突き合せ面の全体からバリを排出することができる。 Furthermore, linear friction welding needs to be continued until burrs are removed from the entire butting surfaces of the first steel plate 11 and the second steel plate 12 . The phrase "flash is discharged from the entire butting surfaces" means that the material softened by the temperature rise is discharged as burrs from the entire interface to be joined. It is difficult to confirm whether or not this state has been achieved without destroying the friction welded joint 1 . Therefore, the same material as the friction-welding joint 1 to be manufactured is used, and a friction-welding test is performed in advance to determine in advance the bonding time that can achieve the above-described state. By performing friction welding for a longer time than this joining time, burrs can be removed from the entire butting surfaces of the first steel plate 11 and the second steel plate 12 .

線形摩擦接合において、その他の接合条件は特に限定されず、線形摩擦接合を適切に完了させて、接合不良がない摩擦圧接継手を得ることができる範囲内で、種々の条件を採用することができる。好適な製造条件として、例えば、板厚等に応じて突出し長さを設定することが好ましい。具体的には、摩擦圧接継手１を構成する鋼板１１及び１２のうち薄い方の板厚ｔ（ｍｍ）が１．０ｍｍ～４．０ｍｍである場合、板厚ｔと、線形摩擦接合における突出し長さｈ（ｍｍ）と、線形摩擦接合における印加圧力σ_ｃ（ＭＰａ）とが、下記式５の関係を満たすことが好ましい。すなわち、印加圧力σ_ｃが下記式５で規定される上限値（１００×ｔ／ｈ）^２（ＭＰａ）以下であることが好ましい。
σ_ｃ≦（１００×ｔ／ｈ）^２（式５）
ここで突出し長さとは、図４Ａのように第１の鋼板１１及び第２の鋼板１２の板厚が異なる場合は、第１の鋼板１１及び第２の鋼板１２のうち薄い方の、チャックＣから鋼板の端面側に突き出している部分の長さのことであり、図４Ｂのように第１の鋼板１１及び第２の鋼板１２の板厚が同一である場合は、第１の鋼板１１及び第２の鋼板１２のうち、チャックＣからの突出し量が大きい方の、チャックＣから鋼板の端面側に突き出している部分の長さのことである。第１の鋼板１１及び第２の鋼板の厚さ、並びに突出し量が同一である場合は、いずれの突出し量を突出し長さｈとして用いても同一の結果が得られる。 In linear friction welding, other welding conditions are not particularly limited, and various conditions can be adopted within a range in which linear friction welding can be properly completed to obtain a friction welded joint with no joint failure. . As a suitable manufacturing condition, for example, it is preferable to set the protrusion length according to the plate thickness and the like. Specifically, when the plate thickness t (mm) of the thinner one of the steel plates 11 and 12 constituting the friction welded joint 1 is 1.0 mm to 4.0 mm, the plate thickness t and the protrusion length in linear friction welding It is preferable that the height h (mm) and the applied pressure σ _c (MPa) in the linear friction welding satisfy the relationship of the following formula 5. That is, the applied pressure σ _c is preferably equal to or less than the upper limit (100×t/h) ² (MPa) defined by Equation 5 below.
σ _c ≦(100×t/h) ² (Formula 5)
Here, when the thicknesses of the first steel plate 11 and the second steel plate 12 are different as shown in FIG. 4A, the protrusion length is the chuck C is the length of the portion protruding from the end face side of the steel plate, and when the plate thickness of the first steel plate 11 and the second steel plate 12 are the same as in FIG. 4B, the first steel plate 11 and the It is the length of the portion of the second steel plate 12 that protrudes from the chuck C toward the end surface of the steel plate, the portion that protrudes from the chuck C by a larger amount. When the first steel plate 11 and the second steel plate have the same thickness and the same protrusion amount, the same result can be obtained regardless of which protrusion amount is used as the protrusion length h.

鋼板の摩擦圧接においては、溶接とは異なり、鋼板の厚さ方向と垂直に、鋼板に加圧する必要がある。そのため、鋼板の厚さに対して印加圧力が大きすぎると、鋼板が座屈する場合がある。一方、印加圧力が小さすぎると、圧接に要する時間が長くなって生産性が落ちる場合がある。また、圧接に要する時間が長くなると、摩擦熱によって接合界面から離れた箇所の温度が上昇し、軟化し、座屈が生じやすくなる場合がある。本発明者らの実験結果によれば、上述の通り印加圧力の下限値を５０ＭＰａとし、印加圧力の上限値σ_ｃを鋼板の板厚に応じて定めることにより、鋼板の座屈を一層効果的に抑制可能である。なお、突出し長さｈは、座屈を抑制する観点からは小さいほど好ましいが、突出し長さｈが小さすぎると十分な接合時間を確保することが難しくなることに留意する必要がある。 In friction welding of steel plates, unlike welding, it is necessary to apply pressure to the steel plates perpendicularly to the thickness direction of the steel plates. Therefore, if the applied pressure is too large relative to the thickness of the steel plate, the steel plate may buckle. On the other hand, if the applied pressure is too low, the time required for press contacting will become longer, which may reduce productivity. In addition, when the time required for pressure welding becomes longer, the temperature of a portion remote from the joint interface rises due to frictional heat, softening, and buckling may easily occur. According to the experimental results of the present inventors, as described above, the lower limit of the applied pressure is set to 50 MPa, and the upper limit of the applied pressure σ _c is determined according to the thickness of the steel plate, whereby the buckling of the steel plate is more effective. can be suppressed to From the viewpoint of suppressing buckling, it is preferable that the protrusion length h is as small as possible.

Ａｌ系めっき鋼板を溶接する場合は、Ａｌによる接合部の脆化を避けるために、鋼板の表面に配されたＡｌ系めっきを除去することが通常である。一方、本実施形態に係る摩擦圧接継手の製造方法では、摩擦圧接によってＡｌ系めっきが接合部から排出されるので、鋼板の摩擦圧接においては、Ａｌ系めっき１１１を鋼板から除去する必要はない。換言すると、本実施形態に係る摩擦圧接継手の製造方法においては、線形摩擦接合の開始の時点において、第１の鋼板１１の端面まで、Ａｌ系めっき１１１が形成されていてもよい。これにより、Ａｌ系めっき１１１を第１の鋼板１１から除去する工程を省略して、摩擦圧接継手の製造コストを一層低減することができる。 When welding Al-plated steel sheets, it is common to remove the Al-based plating on the surface of the steel sheet in order to avoid embrittlement of the joint due to Al. On the other hand, in the method for manufacturing a friction welded joint according to the present embodiment, since the Al-based plating is discharged from the joint portion by friction welding, it is not necessary to remove the Al-based plating 111 from the steel sheet in the friction welding of the steel sheet. In other words, in the method of manufacturing a friction welded joint according to the present embodiment, the Al-based plating 111 may be formed up to the end face of the first steel plate 11 at the start of linear friction welding. As a result, the process of removing the Al-based plating 111 from the first steel sheet 11 can be omitted, and the manufacturing cost of the friction welded joint can be further reduced.

実施例により本発明の一態様の効果を更に具体的に説明する。ただし、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に過ぎない。本発明は、この一条件例に限定されない。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、種々の条件を採用し得る。 The effect of one embodiment of the present invention will be described more specifically with reference to examples. However, the conditions in the examples are only one example of conditions adopted for confirming the feasibility and effects of the present invention. The present invention is not limited to this one conditional example. Various conditions can be adopted for the present invention as long as the object of the present invention is achieved without departing from the gist of the present invention.

表１に示すホットスタンプ用鋼板Ａ及びＢの端面を突き合せて、表２に示す接合法で接合して、種々の突き合せ継手を製造した。なお、２枚の鋼板のうち、引張強さと板厚との積が小さい方を鋼板ａとした。具体的な接合条件は、以下の通りとした。なお、全ての発明例及び比較例において、Ａｌめっきの除去をすることなく鋼板ａ及び鋼板ｂを接合した。 The end faces of hot stamping steel plates A and B shown in Table 1 were butted and joined by the joining method shown in Table 2 to produce various butt joints. Of the two steel plates, the one having the smaller product of tensile strength and plate thickness was designated as steel plate a. Specific bonding conditions were as follows. In all the invention examples and comparative examples, the steel sheets a and b were joined without removing the Al plating.

（レーザ溶接条件）
・レーザ種類：焦点径φ０．６ｍｍのファイバーレーザ
・レーザ出力：４～６ｋＷ（板組に応じて調整）
・溶接速度：３ｍ／ｍｉｎ
・シールドガス種：Ａｒ
・シールドガス流量：２０ｌ／ｍｉｎ (Laser welding conditions)
・Laser type: Fiber laser with a focal diameter of φ0.6mm ・Laser output: 4 to 6kW (adjusted according to the board assembly)
・Welding speed: 3m/min
・Shield gas type: Ar
・Shielding gas flow rate: 20 l/min

（線形摩擦圧接条件）
・印加圧力：１００ＭＰａ
・周波数：１５Ｈｚ
・振幅：±２ｍｍ
・突出し長さ：鋼板Ａ及び鋼板Ｂともに、７ｍｍ（発明例）又は３０ｍｍ（参考例） (Linear friction welding conditions)
・ Applied pressure: 100 MPa
・Frequency: 15Hz
・Amplitude: ±2mm
・Protrusion length: Both steel plate A and steel plate B are 7 mm (invention example) or 30 mm (reference example)

得られた種々の突き合せ継手に、平板金型を用いて焼入れをした。焼入れ条件は、加熱温度９００℃、加熱時間４ｍｉｎ、及び下死点保持時間１ｍｉｎとした。焼入れ後の試験片からＪＩＳ５号引張試験片を切り出した。切り出しの際には、引張試験片の長手方向が、接合界面に垂直となるようにした。そして、引張試験片を静的引張試験に供し、破断形態を確認した。引張試験の際の引張速度は１０ｍｍ／ｍｉｎとした。母材で破断が生じた継手は、良好な接合強度を有する継手であると判断し、表２の「破断形態」の列に「〇」と記載した。 The various butt joints obtained were quenched using a flat plate mold. The quenching conditions were a heating temperature of 900° C., a heating time of 4 minutes, and a bottom dead center holding time of 1 minute. A JIS No. 5 tensile test piece was cut out from the quenched test piece. When cutting out, the longitudinal direction of the tensile test piece was made perpendicular to the joint interface. Then, the tensile test piece was subjected to a static tensile test to confirm the rupture mode. The tensile speed during the tensile test was 10 mm/min. Joints in which the base material was fractured were judged to be joints having good bonding strength, and were marked with "○" in the column of "fracture form" in Table 2.

さらに、接合部からＡｌめっきが排出されているか否かを、上述した方法によって確認し、その結果も表２に記載した。レーザ溶接部の平均Ａｌ濃度は、溶接前の突合せ界面から０．５ｍｍ範囲から求めた。 Furthermore, whether or not the Al plating was discharged from the joint was confirmed by the method described above, and the results are also shown in Table 2. The average Al concentration of the laser-welded portion was obtained from the range of 0.5 mm from the butt interface before welding.

レーザ溶接によって製造された比較例１～５の継手は、その接合部に溶接金属を有しており、溶接金属中にはＡｌめっきに起因するＡｌ濃化部が確認された。これらを破断試験に供したところ、接合部（溶接金属）で破断が発生した。 The joints of Comparative Examples 1 to 5 manufactured by laser welding had weld metal at their joints, and Al-enriched portions due to Al plating were confirmed in the weld metal. When these were subjected to a breaking test, breakage occurred at the joint (weld metal).

参考例１では、接合方法が線形摩擦接合とされたが、これにより得られた摩擦圧接継手には接合不良が生じた。即ち、線形摩擦接合する工程を適切に完了することができなかった。これは、板厚に対して印加圧力が大きすぎたからであると推定される。 In Reference Example 1, linear friction welding was used as the joining method, but the resulting friction welded joint had poor joining. That is, the process of linear friction welding could not be properly completed. It is presumed that this is because the applied pressure was too large for the plate thickness.

発明例１～６は、印加圧力が適切な線形摩擦圧接によって形成された継手であった。これら発明例の継手の接合部（摩擦圧接面から０．５ｍｍ以内の領域）からは、Ａｌめっきが排出されていた。また、これら発明例の継手を破断試験に供したところ、摩擦圧接面ではなく鋼板Ａにおいて破断が生じた。即ち、発明例１～６の継手は、母材鋼板の一方又は両方がＡｌ系めっきを有しながら、優れた接合強度を具備していた。 Invention Examples 1 to 6 were joints formed by linear friction welding with an appropriate applied pressure. Al plating was expelled from the joint portion (region within 0.5 mm from the friction-welding surface) of the joints of these invention examples. Further, when the joints of these invention examples were subjected to a fracture test, fracture occurred at the steel sheet A, not at the friction welded surfaces. That is, the joints of Invention Examples 1 to 6 had excellent bonding strength while one or both of the base steel sheets had Al-based plating.

１摩擦圧接継手
１１第１の鋼板
１１１Ａｌ系めっき
１２第２の鋼板
１３摩擦圧接面
１４接合部
１５バリ
Ｃチャック 1 friction welded joint 11 first steel plate 111 Al-based plating 12 second steel plate 13 friction welded surface 14 joint 15 burr C chuck

Claims

a first steel plate having Al-based plating;
a second steel plate arranged substantially on the same plane as the first steel plate;
a friction welding surface that joins the end face of the first steel plate and the end face of the second steel plate;
with
The Al concentration of the base metal of the first steel plate and the second steel plate over the entire joint, which is a region within 0.5 mm in the direction perpendicular to the friction welding surface from the friction welding surface Friction welded joints with less than twice the Al concentration of the higher concentration.

a first steel plate having Al-based plating;
a second steel plate arranged substantially on the same plane as the first steel plate;
a friction welding surface that joins the end face of the first steel plate and the end face of the second steel plate;
with
A friction welded joint, wherein the average amount of Al in a joint area within 0.5 mm from the friction welded surface in a direction perpendicular to the friction welded surface is less than 1.0% by mass.

3. The friction welded joint according to claim 1, wherein the thinner one of the first steel plate and the second steel plate has a thickness of 1.0 mm to 4.0 mm.

The product of the tensile strength and thickness of the first steel sheet after quenching is smaller than the product of the tensile strength and thickness of the second steel sheet after quenching. The friction welded joint according to any one of claims 1 to 3.

The friction welded joint according to any one of claims 1 to 4, wherein the C content of the first steel plate is 0.10% by mass or more.

The friction welded joint according to any one of claims 1 to 5, wherein the first steel plate and the second steel plate are steel plates for hot stamping.

The friction welded joint has burrs protruding perpendicularly to the surfaces of the first steel plate and the second steel plate on the friction welded surface,
The friction welded joint according to any one of claims 1 to 6, wherein part of the surface of the burr is continuously plated with Al-based plating from the surface of the first steel plate.

A tailored blank material comprising the friction welded joint according to any one of claims 1 to 7.

A molded article comprising the friction welded joint according to any one of claims 1 to 7.

10. The molded product according to claim 9, wherein the tensile strength of said first steel plate is 1000 MPa or more.

The molded product according to claim 9 or 10, wherein the product of tensile strength and thickness of said first steel plate is smaller than the product of tensile strength and thickness of said second steel plate.

A step of butting the end face of the first steel plate having Al-based plating and the end face of the second steel plate and performing linear friction bonding,
In the linear friction welding, the applied pressure is 50 MPa or more, the frequency is 10 Hz or more, and the amplitude is ±1 mm or more,
A method for manufacturing a friction welded joint, wherein the linear friction welding is continued until burrs are removed from the entire butting surfaces of the first steel plate and the second steel plate.

13. The method of manufacturing a friction welded joint according to claim 12, wherein the Al-based plating is formed up to the end surface of the first steel plate at the start of the linear friction welding.