206 SUS304鋼母材および溶接材の疲労き裂近傍における塑性誘起マルテンサイト変態(セッション7)

概要

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The present study investigates plasticity-induced martensitic transformation around fatigue cracks in single V-groove butt-welded SUS304 plates at room temperature in air. Distributions of α' phase volume fraction V_<α'> around fatigue cracks were measured with ferrite scope. The results were compared with the distributions of vertical magnetic flux density B_z above fatigue cracks in welded specimens magnetized by a strong electromagnet. It was revealed that the B_z distributions reflected the spatial distributions of pre-existing ferrite phase and plasticity-induced martensite phase around the weldment and fatigue cracks: i.e., the distance between the points where B_z reached the maximum and the minimum values B_<zmax> and B_<zmin> had linear correlations with real crack length 2a. The B_<zmax> and the B_<zmin> values also showed linear relations with applied maximum stress intensity factor value K_<max>. These results imply that the measurement of the vertical magnetic flux density above fatigue cracks located near weldments can estimate 2a and K_<max> values.
社団法人日本機械学会の論文
2005-03-13