自溶性合金を溶射した鋼の高温疲労特性

抄録

Low cycle fatigue tests were performed at room temperature and at 673 K for 1%Cr-Mo steel coated with self fusing alloy by gas spraying. The fatigue properties of self fusing alloy-sprayed steel and the mechanism of fatigue-fracture were discussed comparing to those of ceramic-sprayed steel. Following observations and conclusions were obtained.
(1) The fatigue life of the self fusing-sprayed steel at 673 K was shorter than that at RT, while the fatigue lives at RT and 673 K almost coincided with those of base metal, respectively.
(2) The crack initiation in the self fusing layer did not occurred in the early stage of fatigue lives, which was observed in the ceramic coated layer.
(3) Fusing heat treatment did not improve the fatigue life of the self fusing alloy-sprayed steel remarkably.
(4) The fatigue-fracture process of the ceramic-sprayed steel is considered that in the early stage of fatigue life, a fatigue crack initiates at the surface of the ceramic layer and propagates quickly to the substrate metal. On the other hand, the above phenomena is not observed in the self fusing alloy-sprayed steel, whose behavior is more like that of the base metal.