623 高強度鋼のギガサイクル疲労特性 : その 3 : 介在物と組織割れ起点内部破壊における水素脆化の影響

概要

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The effect of hydrogen embrittlement on internal fracture of giga-cycle fatigue was investigated for the spring steel SUP12 of heats A and D1 with Vickers hardness HV=520 and 518,where Al_2O_3 inclusions and matrix cracks were observed at the fracture sites, respectively. Fatigue tests were conducted after specimens were heated up to 300℃ in the high vacuum of 2x(10)^2 pa. The treatment did not give the intemal fracture originated at Al_2O_3 inclusions, whereas matrix cracks were eliminated and fatigue strength σ_w=874 MPa from the empirical equationσ_w=1.6HV for the surface fracture. It is suggested from these results that the hydrogen embrittlement influences the matrix crack-originated internal fracture and that the creation of tempered martensite with high resistance to hydrogen emnbrittlement in heat D1 makes the fatigue strengthσ_w estimated for the surface fracture possible.
社団法人日本機械学会の論文
2000-07-31