Effects of <I>In Situ</I> Irradiation by 20 MeV Protons on the Fatigue Properties of 316 Stainless Steel

Abstract

The effects of irradiation on the fatigue properties of stainless steel were studied under the condition of in situ irradiation or after irradiation using 20 MeV protons. Strain controlled fatigue tests using a resonant and a drive force DF at constant were measured in situ during the test. Whereas the present damage rate was very low, the apparent effects of in situ irradiation on the fatigue properties were observed, e.g. the elongation

Effects of In-Situ Proton-Irradiation and Thermal-Pulse on the High-Cycle Fatigue Properties of Low Carbon 316 Stainless Steels

“…As a matter of fact, the work hardening exponent n [8] estimated fiom the line 1 shown in Fig.1 is as high as n=l (see [6] [4] in which the work hardening exponent n is as low as about 0.2 and fatigue induced precipitates can be observed as black dots in TEM observation [5]. Shortening of Nf for the higher (Ph-PO)IPO range and elongation of Nf for the lower (Ph-Po)IPo range are observed for 3 16F in [5] in which the work hardening exponent n is about 0.33 and the fatigue induced precipitation is intermediate between 316(ST-1) and 3 16SI.…”

“…Understanding of the high cycle fatigue property itself may also be important, because the most of the structural reactor materials is expected to be subjected to the high cycle fatigue stresses during the reactor operation. The preliminary work on the Ti-modified AISI 316L stainless steel (see [4] and 316(ST-1) below) indicates that the effect of radiation damage on the fatigue life Nf in the %-controlled tests at 333 K, here elongation in Nf, is much larger under irradiation than after irradiation, where is the total strain amplitude. The firther study on the various modified-3161 stainless steels [5,6] shows that the fatigue hardening mainly governs Nf of the solution treated specimens and in situ radiation damage or thermal pulse modities the fatigue hardening process.…”

“…The fatigue tests were carried out using the flexural vibrations of a U-shaped reed specimen, where the middle of the U-shape forms a composite reed with thickness of 0.12 mm and a gage length of 16 mm and two open ends of the U-shape are thick for clamping. Excitation of the flexural vibrations was made electromagnetically and the fatigue tests were conducted in the atmosphere of 102 Pa He to suppress a heat-up of a specimen (see [4,6] for details). Period P of the resonant flexural vibrations of a specimen in the elastic range will be referred to as Po below, where l/Po here is about 200 Hz.…”

High Cycle Fatigue Properties of Type 316 Stainless Steel

“…2 in ref. [3]). An external current applid to the half coil gives a drive force (DF) to the specimen, and an excited flexural resonant vibration of the specimen generates an electrical signal between two ends of the specimen which is proportionl to the amplitude of the resonant vibration.…”

Fatigue Behavior of Cold-Worked 304 Stainless Steels under <I>In-Situ</I> Irradiation at 300&deg;C

“…In the course of extensive efforts to accumulate the available experimental data on in-situ irradiation fatigue tests, some essential differences in fatigue behavior between in-situ irradiation and post-irradiation conditions have been demonstrated in some works. [1][2][3][4] In a previous paper, 4) stresscontrolled fatigue tests were conducted for 20% cold-worked 316 stainless steel under 17 MeV proton irradiation at 300 C. Substantial increase of fatigue life with prolonged crack propagation was detected in the in-situ irradiation condition. The in-situ irradiation effect on fatigue behavior has been discussed based on the interaction between radiation-induced defect (RID) clusters and moving dislocations.…”