中・高温大気中における炭素綱STS42の疲労き裂進展特性

概要

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Fatigue crack growth characteristics and the fatigue crack closure in a STS42 steel for nuclear piping were investigated at temperatures around 288℃ (from room temperature up to 400℃). Within the temperature range tested, the crack growth rate, da/dN, was well described in terms of the effective stress intensity factor range. An apparent difference in da/dN-ΔK relation is due to the crack closure. At 100℃, a thin stable oxide film (Fe_3O_4) on the fracture surfaces works as wear protection and the production of fretting oxide debris (Fe_2O_3) is prevented. As a result, da/dN at 100℃ is faster than those at room temperature and at 288℃ due to the lack of crack closure. The resistance to oxidation at 288℃ for STS42 was inferior to those for A508-3 and 304. However, such characteristic in STS42 promotes an occurrence of crack closure which has a favorable effect on fatigue crack growth resistance.
社団法人日本材料学会の論文
1992-01-15