Effect of refining with synthetic slags on the resistance to fracture of low-alloy steel
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In studying the component parts of the fracture toughness of normalized steel. 14G2-SAFB from a converter heat that was treated with synthetic slags in comparison with the standard steel we used nonstandard characteristics:ap=aT−aP.D. (whereaP.D. is the work of macroplastic deformation of samples with a fatigue crack that precedes crack propagation) and also the critical size of the stable crack 1st, which characterizes the reliability of the material. Parameter 1st characterizes the resistance to brittle fracture, in contrast toap, which determines the resistance to ductile fracture.
Treatment of normalized steel 14G2SAFB with synthetic slags leads to an increase of the fracture toughnessan at all notch radii, an increase in the length of the stable crack (critical size of the defect), an increase in the work of plastic deformation preceding crack movement, and a higher value ofai. The ductile-brittle transition temperature determined from 50% ductile components in the fracture and the work of crack propagation do not change as the result of treatment with synthetic slag, which must be associated with the reduction of the oxygen content in this case.
KeywordsFatigue Brittle Fracture Toughness Fatigue Crack Oxygen Content
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