METHOD FOR PRODUCING UNIFORM PIPE JOINT OF IRON BASED SHAPE-MEMORY ALLOY

摘要

PROBLEM TO BE SOLVED: To provide a method for producing pipe joints of an iron based shape- memory alloy having substantially uniform columnar crystal rate i.e., shape- memory function over the whole length by a centrifugal casting method.;SOLUTION: The columnar crystal rate exceeds at least 70% of the wall thickness over the whole length of a pipe in any transverse cross section, by beginning casting of molten steel with predetermined composition from the casting point arranged at the one end of the mold rotating at high speed, continuing the casting while moving the casting point to the other end at constant speed in a direction of rotating axis of the mold, and spraying exothermic- insulating flux on the surface of the cast molten steel and moving it to the other end of the mold. Further, it is most desirable to use Ca-Si based flux as the exothermic-insulating flux.;COPYRIGHT: (C)2004,JPO