It is required a function that the compressor of a car air conditioner in case overloaded will be disconnected from the engine power. Presented here is the development of a mechanical fuse part having such function. This part can be realized by satisfying two functions simultaneously; (1) the part has sufficient fatigue strength to transmit power without breaking, and (2) it breaks promptly to disconnect the power if an overload occurs. This can be realized by developing a material having high fatigue limit ratio (fatigue strength/tensile strength). Such material was investigated and was found that a high fatigue limit ratio is achieved by steam treating a Fe-Cu-C material sintered compact with a decreased amount of carbon. This newly developed material has recently been applied to such required mechanical fuse parts.
