PIERCING METAL FOR JOINING DISSIMILAR MATERIAL AND DISSIMILAR MATERIAL JOINING METHOD WITH USE OF PIERCING METAL

To provide a piercing metal for joining dissimilar materials which, in even joining a dissimilar material with an iron-based material component via spot welding, can reliably join both without occurrence of crack in an aluminum die-cast component with low ductility.SOLUTION: A shank 3, which is penetrated through an aluminum die-cast plate A, is so integrally formed from a head 2 with an iron-based material as to project, and on the shank 3, a contact part 7 which contacts a through hole 9 of the aluminum die-cast plate A in the state of penetrating the aluminum die-cast plate A, and a non-contact part 8, which has a diameter smaller than that of the contact part 7 and does not contact the through hole 9 of the aluminum die-cast plate A, are formed. Further, a hollow shape is made from the head 2 to the shank 3 so that welding current concentrates to a central part of an apical surface 4 of the shank 3 even if a contact point of an electrode deviates from a midship part of the head 2.SELECTED DRAWING: Figure 1 【課題】スポット溶接を介した鉄系材料製部材との異材接合でも、展延性の低いアルミダイキャスト製部材にクラックが発生せず、両者を確実に接合することが可能な異材接合用ピアスメタルを提供する。【解決手段】アルミダイキャスト製板材Ａに貫通される軸部３を頭部２から鉄系材料で一体的に突設形成し、その軸部３には、アルミダイキャスト製板材Ａへの貫通状態でアルミダイキャスト製板材Ａの貫通穴９に接触する接触部７と、接触部７よりも小径で且つアルミダイキャスト製板材Ａの貫通穴９に接触しない非接触部８とを形成する。また、電極の当接箇所が頭部２の中央部からずれた場合でも、溶接電流が軸部３の先端面４の中心部に集中するように、頭部２から軸部３にかけて中空形状とする。【選択図】図１