Analysis of the ground surface finish effect on the LCF life of a 304L austenitic stainless steel in air and in PWR environment

Influence of Strain Rate and Waveshape on Environmentally-Assisted Cracking during Low-Cycle Fatigue of a 304L Austenitic Stainless Steel in a PWR Water Environment

“…The surface of the fatigue samples were thereafter mirror-polished by mechanical polishing down to 1 µm grade diamond paste. The specimen geometry and tensile mechanical properties were described in more details elsewhere [9]. In addition, flanges were machined on both specimen shoulders in order to fix the strain measurement system described in the next section, which requires a calibration to relate the elongation applied between flanges to the strain amplitude targeted in the gauge length.…”

“…-Dissolved oxygen content: lower than 0.01 ppm; -Hydrogen: 25-35 cc (STP)/kg PWR water; -Cl and F: lower than 0.05 ppm; -B:~1000 ppm (adjusted by boric acid additions); -Li: quantity needed for adjustment of pH (~2 ppm); -PH: [7][8][9][10]; and -Conductivity: 2-40 µS/cm. FOR PEER REVIEW 4 of 20 Eden Prairie, MN, USA) servohydraulic loadframe equipped with a pressure vessel which enables a maximum pressure of 140 bars and a temperature of 300 °C was used (Figure 2a).…”

“…More precisely, the material cyclic stress-strain (CSS) behavior and fatigue lives with complex signals were first determined in PWR medium and then compared to data obtained using triangular signals in the same environment, but also to data obtained in air in similar loading conditions at total strain amplitude of 0.6%. Furthermore, previous studies have shown that in the PWR environment the initiation stage is very short [9]. This is the reason why a special attention has been paid here to a fine analysis of the propagation stage, by combining measurements of striation spacing with crack growth data derived from interrupted tests, using a methodology explained in [9].…”

“…Furthermore, previous studies have shown that in the PWR environment the initiation stage is very short [9]. This is the reason why a special attention has been paid here to a fine analysis of the propagation stage, by combining measurements of striation spacing with crack growth data derived from interrupted tests, using a methodology explained in [9]. The objective is to identify a parameter that can account for the crack growth behavior under different strain rates and loading signals.…”

“…While this work is a part of a more comprehensive study, encompassing the examination of the effect of surface finishing, only results obtained on polished samples are considered here for the sake of clarity. The aspects peculiar to the ground surface finishing, which is also representative of some actual surface conditions in a component, were addressed in another paper [9].…”