Ni基鍛造材,鋳造材からなる摩擦圧接材の強度特性

概要

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To develop a compact and highly reliable micro gas turbine rotor, a turbine wheel and rotor-stacking shaft were integrated by friction weld. The characteristic strength of a friction-welded (FW) joint made of Ni-based cast alloy, MM247, and Ni-based forged alloy, IN718, was investigated. The 0.2% proof strength of MM247 was lower than that of IN718. The FW joint showed the same tensile strength as MM247 and the same creep rupture strength as IN718. The low cycle fatigue strength of the joint was lower than that of MM247 under a large strain load or low strain rate, but the joint showed the same fatigue strength as MM247 under other conditions. The creep fatigue strength of the FW joint was lower than that of MM247 and of IN718. Four mechanisms were considered to explain this deterioration: elastic follow up in IN7l8 due to low creep strength, a high triaxiality factor in IN718, anisotropic behaviors in MM247 due to a large grain size, and secondary stress at the interface due to different resistances to deformation.
2013-11-20