LASER JOINING METHOD AND LASER JOINT MOLDED BODY

To provide a laser joining method which can suppress deformation of an inner surface of an inside cylindrical member when two cylindrical members are welded and joined to each other with a laser beam.SOLUTION: A laser joining method includes: an insertion step of welding and joining a first cylindrical member 2 having a first inner cavity 21 and a second cylindrical member 3 having a second inner cavity 31 by irradiation of a laser beam L, and inserting at least a part of the second cylindrical member 3 into the first inner cavity 21; a rotation step of integrally rotating the first cylindrical member 2 and the second cylindrical member 3; and a laser irradiation step of irradiating a part where the first cylindrical member 2 and the second cylindrical member 3 overlap each other in the first cylindrical member 2 and the second cylindrical member 3 rotated in the rotation step, with the laser beam L from outside in a radial direction of the first cylindrical member 2. The laser irradiation step radiates the laser beam L at an irradiation angle such that an incident angle θ to the inner periphery of the second cylindrical member 3 is equal to or more than a Brewster's angle between the second cylindrical member 3 and the air.SELECTED DRAWING: Figure 3 【課題】２つの円筒状部材をレーザ光によって溶着して接合する場合に、内側の円筒状部材の内面が変形することを抑制できるレーザ接合方法を提供すること。【解決手段】レーザ接合方法は、第１内腔２１を有する第１円筒状部材２と、第２内腔３１を有する第２円筒状部材３とを、レーザ光Ｌを照射することで溶着して接合し、第２円筒状部材３の少なくとも一部を第１内腔２１に挿入する挿入工程と、第１円筒状部材２及び第２円筒状部材３を一体的に回転させる回転工程と、回転工程において回転されている第１円筒状部材２及び第２円筒状部材３における第１円筒状部材２と第２円筒状部材３とが重なり合った部分に、第１円筒状部材２の径方向の外側からレーザ光Ｌを照射するレーザ照射工程と、を備え、レーザ照射工程において、レーザ光Ｌを、第２円筒状部材３の内周への入射角θが該第２円筒状部材３と空気とのブリュースター角以上となる照射角で照射する。【選択図】図３