Deformation mechanisms in 316 stainless steel irradiated at 60 degrees C and 330 degrees C

Plastically deformed microstructures in neutron-irradiated austenitic stain less steel were investigated by transmission electron microscopy (TEM). Neu tron irradiation at 60 degreesC and 330 degreesC to about 7 dpa induced a h igh number density of faulted loops and black dots, which resulted in irrad iation-induced hardening. In the specimen irradiated at 60 degreesC and ten sile tested at 25 degreesC at a strain rate of 4x10(-4) s(-1), the deformat ion microstructure consisted of twins, elongated faulted loops, and lath an d twin martensite phase. In the specimens irradiated and tested at 330 degr eesC at a strain rate of 4x10(-4) and 4x10(-6) s(-1), in addition to these features, dislocation channeling was also observed. The TEM examination sug gests that lath and twin martensite can form during tensile testing at both of these temperatures. Examination of the specimens irradiated and tensile tested at 330 degreesC indicated that twinning was the predominant deforma tion mode at slower strain rate and dislocation channeling was favored at h igher temperature. From the micrographs taken from the {111} plane streak i n a diffraction pattern, it is suggested that faulted loops could be the pr incipal twin initiation site during deformation. (C) 2000 Elsevier Science B.V. All rights reserved.