HIGH-TEMPERATURE SENSITIVITY OF NOTCHED AISI 304L STAINLESS-STEEL TESTS

Experiments were designed to determine the failure characteristics of AISI 304L stainless steel under different stress triaxialities and tem peratures up to 70% of melt. The data show that as temperature increas es the displacement to failure of notched tensile specimens increases. The complex interaction of deformation mechanisms, such as twinning a nd dynamic recrystallization, appears to negate the damage accumulatio n at higher temperatures. Microstructural analyses and finite element simulations indicate that voids nucleate, grow, and coalesce more rapi dly as temperature and triaxiality increase. Finite element simulation s were performed to analyze temperature dependence on the Cocks-Ashby void growth model. The finite element simulations qualitatively show a double-knee that was observed in the notched experimental specimens a fter loading. The combined experimental-numerical study indicates that failure can be defined at several points in the notch tests when: (1) macrovoids starts to form, (2) the load drop-off occurs, and (3) tota l perforation of the specimen occurs. These three points occur simulta neously in ambient conditions but occur at different displacements at higher temperatures. (C) 1998 Elsevier Science Ltd. All rights reserve d.