7mass%Cr系ニハード鋳鉄の破壊靱性と疲労き裂伝ぱ特性に及ぼす黒鉛の影響

概要

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The influence of graphite volume on fracture toughness and fatigue crack propagation had been studied in 7 mass% chromium Ni-hard cast iron with 0.57〜4.52% graphite for the purpose of improving the wear and crack resistance as steel rolling mill roll materials. The main experimental results are shewn as follows ; (1) Fracture toughness (K_<IC>) increases with an increase in graphite volume and shows the maximum K_<IC≫ value of 25.7 MPa・m^<0.5> at 1.90% graphite, and then it decreases as the graphite volume rises over 1.90%. (2) Threshold stress intensity factor range for fatigue crack propagation (ΔK_<th>) varies in the same manner as fracture toughness and it shows the maximum ΔK_<th> value of 8.5 MPa・m^<0.5> at 1.90% graphite. (3) Paris-Erdogan equation da/dN= C (ΔK_1)^m holds good between crack propagation rate and stress intensity factor range, and there is a constant relation of C=3.89×10^<-4>/15.8^m. (4) Existence of adequate graphite volume restrains crack propagation and improves K_<IC> and ΔK_<th>. (5) Heat-treatment of hardening-tempering deteriorates ΔK_<th> and hastens crack propagation.
一般社団法人日本機械学会の論文
2001-08-25