3506 高強度鋼SCM435のΔK_<th>近傍における疲労き裂進展挙動に及ぼす水素の影響(S20-2 水素チャージ材の強度特性,S20 材料強度特性に及ぼす水素の影響)

概要

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The effects of hydrogen on the near threshold fatigue crack growth behavior was studied on a high-strength steel SCM435. The crack growth rate of hydrogen-charged specimens was faster than that of uncharged specimens. Hydrogen decreased threshold stress intensity factor range ΔK_<th> in specimens with low residual stress. However, there was no clear difference in ΔK_<th> between the hydrogen-charged specimen and uncharged the specimen with high residual stress. The fracture surface near ΔK_<th> of hydrogen-charged specimen with low residual stress was flatter than that of uncharged specimen with that. The crack in the hydrogen-charged specimen was thinner than that in the uncharged specimen. The crack in the hydrogen-charged specimen was less zigzag. Transgranular fracture caused by fatigue was dominant and intergranular fracture was little in specimens with low residual stress. It is presumed that the effects of hydrogen is related to crack closure and plastic deformation of the crack tip.
社団法人日本機械学会の論文
2006-09-15