軟鋼変質部の切欠き疲れ強さに関する研究

概要

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In a fillet weld, it is well known that the heat affected zone is generally the most critical part for fatigue fracture. Many factors seem to play important parts in determining its fatigue strength. In this report, basic experiments were made about the effect of a notch on the fatigue strength of H.A.Z. in a mild steel (SS 41). Fatigue tests were performed using small notched bar specimens subjected to rotary bending. The notch was located at the H.A.Z. of welded bead, deposited manually (in one pass or two pass) or by unionmelt method (in one pass). A special double notch was machined in a specimen, in order to assure the initiation of a fatigue crack at the H.A.Z. of weld. The tip radius of the notch was changed in series, and the notched fatigue strength was determined for 2×(10)^6 cycles of loading. Also the stress distributions were estimated for double notched specimens applying Neuber's calculation. Test data were analysed under the conception of the ε_0 value proposed by Ishibashi, referring to the calculated stress distribution. As the result, it was revealed that the ε_0 value of H.A.Z. in mild steel was about 0.05mm, regardless of the notch sharpness and welding conditions.
社団法人溶接学会の論文
1963-04-25