3%Ni-Mo-V鋼の高温性質に及ぼす硫化物の影響

抄録

The effects of sulfides on the high temperature strength of the twelve 3%Ni-Mo-V steels having four different sulfur contents and subjected to forging at three different rates were studied. The test results were as follows: (1) The creep-rupture strength (plain specimen) at 500°C was not affected by sulfides, but the steels which contain 0.048 and 0.090%S ruptured showing low ductility. (2) Sulfides have the similar effect on the strength against the cyclic thermal stress as on the tensile ductility, and the crack depth observed by the author’s cyclic thermal stressing method has the following relation to the fracture ductility,
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where h_max: maximum crack depth measured after 1000 cycles (mm), ε_f: fracture ductility.