球状黒鉛鋳鉄の弾塑性破壊靱性

概要

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In the nodular cast iron and the compacted vermicular cast iron with a ferrite matrix, the elastic-plastic fracture toughness J_<IC> was evaluated by means of acoustic emission, electric potential and R-curve method based on ASTM E 813. J_<in>(AE) and J_<in>(EP), estimated from rapid increasing points in cumulative number of AE events and electric potential difference respectively, correspond with a small amount of crack extension in the mid-thickness of specimen. J_<in>(R), on the other hand, estimated from R-curve method, corresponds with an appropriate amount of crack extension which is nearly equal to 2δ_c. In the present analysis, J_<IC> was optimized from J_<in>(R). Dependence of J_<IC> on graphite nodularity n was represented by J_<IC>=62-14.7(n^<-1/2>-n^<3/2>) (kJ/m^2) using the critical condition of void coalescence that R^^-=X^^- where R^^- is a mean radius of voids developed around graphite nodules and X is an inter-nodule spacing, respectively.
社団法人日本鉄鋼協会の論文
1983-04-01