PSI - Issue 19

Motoki Nakane et al. / Procedia Structural Integrity 19 (2019) 284–293 Author name / Structural Integrity Procedia 00 (2019) 000–000

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5. Conclusions For the purpose of investigating the effect of disk grinding surface finish on fatigue strength of the nuclear component materials, fully reversed tension-compression strain-controlled fatigue tests of disk grinding finished austenitic stainless steel SUS316L plate were performed at RT in air. The fatigue strength of parallel and random grinding scratch directions to the cyclic loading direction were almost the same as those of emery polished specimens. On the other hand, specimen which has grinding scratch directions perpendicular to the cyclic loading decreases fatigue strength of the material, and fatigue strength is much lower than that of lathe machining finish specimen even if maximum roughness height is 1/10 of lathe machining finish specimen. By measurements and FEA, it was found that hardness, residual stress and local strain at bottom of grinding scratch were not essential cause of fatigue strength reduction of grinding finish materials. Microscopic observations for ground surface and fracture surface of the fatigue test specimen revel that local plastic deformation of the material surface due to the multiple grinding work at same place, same direction generates very sharp and long ‘groove-like scratches’, and these groove-like scratchs could lead to fatigue reduction of the materials. Asada, S., Hirano, A., Saito, T., Takada, Y., Kobayashi, H., 2018. Development of New Design Fatigue Curve in Japan – Proposal of a New Fatigue Evaluation Method −, ASME 2018 Pressure Vessels and Piping Conference, PVP2018-84432., ASME. ASME Boiler and Pressure Vessel Code, Section III, 2007 Ed.-2009 Ad., Rules for Construction of Nuclear Power Plant Components, ASME. JIS G 4304, 2010. Hot-rolled stainless steel plate, sheet and strip. (2010). JSME Data book, Fatigue of Metals (II), 2 nd Edition, The Japan Society of Mechanical Engineers, 1984. (in Japanese) JSME S NC1-2016, Codes for Nuclear Power Generation Facilities, Rules on Design and Construction for Nuclear Power Plants, The First Part : Light Water Reactor Structural Design Standard, JSME. (in Japanese). Nakane, M., Wang, Y., Hatoh, H., Yamamoto, M., Hirano, A., Hayashi, K., 2019. Development of New Design Fatigue Curves in Japan – Discussion of Effect Surface Finish on Fatigue Strength of Nuclear Component Materials –, ASME 2019 Pressure Vessels and Piping Conference, PVP2019-93167, ASME. Fukuta, Y., Kanasaki, H., Asada, S., Sera, T., 2014. Proposal of Surface Finish Factor on Fatigue Strength in Design Fatigue Curve, ASME 2014 Pressure Vessels and Piping Conference, PVP2014-28601, ASME. Le Duff, J. A., Lefrançois, A., Vernot, J. P., 2009. Effects of Surface Finish and Loading Conditions on the Low Cycle Fatigue Behavior of Austenitic Stainless Steel in PWR Environment for Various Strain Amplitude Levels, ASME 2009 Pressure Vessels and Piping Conference, PVP2009-78129, ASME. NUREG/CR-6909, ANL-06/08 , Effect of LWR Coolant Environments on Fatigue Life of Reactor Materials (Final Report), ANL-06/08, U.S. Nuclear Regulatory Commission, 2007. Siebel, E., Gaier, M., 1957. Influence of surface roughness on the fatigue strength of steels and non-ferrous alloys, Engineers Digest, pp. 18 109– 112, Translation from VDI Zeitschrift 98 (30), pp.1715–1723, (1956). References