To solve problems that it takes time in measuring a shape memory function of a shape memory alloy, and a load on the quality control for individual products is heavy.
When a ferrous shape memory alloy is manufactured by a centrifugal casting method, the quality control of individual products is important. A plurality of test pieces are sampled from one or a plurality of samples belonging to the same composition range and manufactured under the same condition, the tensile strength or proof stress is detected for each test piece, a predetermined stress is exerted in each test piece to give a strain, and the test piece is heated to a predetermined temperature to measure the shape recovery ratio. A primary function to correlate individual results of the tensile strength or proof stress and each shape recovery ratio is specified, and the shape memory function of every pipe joint to be manufactured with the same composition and under the same manufacturing condition is individually estimated from the primary function to considerably save the load.
MAEDONO HIROAKI
YAMAMOTO MASAAKI
