Muneaki Shimura

On the Embrittlement and Toughness of High Purity Fe-30Cr-2Mo Alloy

Experiments were conducted to explain unexpected embrittlement phenomena encountered in fabricating a high-purity Fe-30Cr-2Mo alloy. By means of a hydrostatic tension test with a Bridgman-type specimen it was found that the fracture behavior of the alloy is highly dependent on stress state. Under conditions of low triaxial stress, the alloy displays excellent ductility. Under conditions of high triaxial stress, however, it shows less strain to fracture and a transition from ductile to cleavage fracture. The toughness of the Fe-30Cr-2Mo alloy can be significantly improved by thermomechanical processing.

Effects of constituent particles on ductile type striation

Continued from the previous report on fatigue fracture topography in aluminum alloys, this paper discusses on the effects of constituent particles in ductile striation structure on the rate of fatigue crack propagation by the observation of electron fractography.As the results, even if the width of plastic zone at the crack tip was larger than the spacings between the particles arresting effects were observed under various conditions as well as accelerated effects of the constituent particles on the crack propagation, which had been pointed out by Piper3)and Pelloux4).The effects of constituent particles on fatigue crack propagation was so complicated that further systematic investigations are necessary in future in connection with the effects of particles on the formation of substructure in the plastic zone.