JOINT METHOD OF TITANIUM MATERIAL AND STEEL MATERIAL

PROBLEM TO BE SOLVED: To provide a joint method capable of joining titanium material and a steel material without causing the deterioration of strength on a joint part.SOLUTION: A joint method of titanium material and steel material is characterized in that, in the method for subjecting a frictional stir joint tool having a probe on a tip of a shoulder to high speed rotation to cause the frictional stir joint tool to contact with/insert to a material to be joined, the titanium material and the steel material as the material to be joined are arranged on such a position that the titanium material and the steel material are overlapped, thereafter, such a probe that a probe length is 0.1 to 1.5 mm-longer than a thickness of the material to be joined which is overlapped on the upper side is subjected to high-speed rotation to cause the frictional stir joint tool to contact with/insert to an upper side material to be joined, and an indentation depth of the shoulder is set to be less than A-value of the following equation (1) and, according to such a frictional stir joint method that the joint is performed by softening and plastic flowing with frictional heat such that the sum of the probe length and the indentation depth does not exceed 1.5 mm more than the thickness of the upper side plate material, the titanium material and the steel material are overlapped and joined: A=T-{(D×ST×L)/(D×ST+D×ST)}...(1).SELECTED DRAWING: Figure 2 【課題】チタン材と鉄鋼材料とを、接合部の強度低下を招くことなく接合することができる接合方法を提供する。【解決手段】ショルダーの先端にプローブを有する摩擦攪拌接合工具を高速回転させて被接合材に接触・挿入して接合する方法であって、被接合材としてチタン材と鉄鋼材料を重ねた位置に配置したのち、プローブ長さが上側に重ねた被接合材の厚さより0.1〜1.5mm長いプローブを高速回転させて上側の被接合材に接触・挿入し、かつ、ショルダーの押し込み深さを下記(1)式のA値より小さくし、プローブ長さと押し込み深さの合計が上側板材の厚さより1.5mmを超えないように、摩擦熱にて軟化・塑性流動させて接合する摩擦攪拌接合法により、チタン材と鉄鋼材料を重ね接合することを特徴とするチタン材と鉄鋼材料との接合方法。A=TU-{(Dp×STL×Lp)/(Dp×STL+ Ds×STU)}・・・(1)【選択図】図２