Production manner null of the spring which is superior in dimensional stability at the time of the low temperature

摘要

PURPOSE:To obtain a spring stainless steel wire excellent in dimensional stability at the time of low temp. annealing by specifying the compsn. of a mixed structure of an austenite phase and a ferrite phase and regulating the rate of change in its outside dimension at the time of low temp. annealing. CONSTITUTION:In a stainless steel wire constituted of a dual phase mixed structure having two-phases of an austenite phase and a ferrite phase, the ferrite content in the above structure is regulated to 30 to 70%. In this way, by the combination of the austenite phase by which outer diameter expands at the time of heating with the ferrite phase by which the outer diameter contracts, the rate of change in the outer diameter of the stainless steel wire at the time of low temp. annealing can be set to =0.25%. In this way, the spring stainless steel wire having an extremely low rate of dimensional change at the time of low temp. annealing after the forming of a coil spring can be obtd.