Towards Bridging the Experimental Length-Scale Gap for Tensile Tests on Structural Materials: Lessons Learned from an Initial Assessment of Microtensile Tests and the Path Forward

Abstract

Microtensile testing of structural materials offers several advantages over conventional mesoscale tests, including the ability to target specific areas of interest and directly correlate the mechanical response to the microstructure of the material. As this technique becomes more widely adopted, it has the potential to have a tremendous impact in the nuclear materials field. However, further work on establishing appropriate testing parameters, unifying testing procedures, and demonstrating the effectiveness of the methodology is required before microtensile tests can be used to replace mesotensile tests for the qualification of materials for use in reactor environments. As a first step towards bridging the experimental length-scale gap for tensile tests, we conducted micro- and mesotensile tests on polycrystalline 304 stainless steel and directly compared the test data to identify the size scaling behavior in such material. Comparison of the results obtained on these two length scales clearly illustrates the specimen size effect, with smaller being stronger. The paper discusses the limitations of microtensile testing, outlines the challenges involved in interpretation of its results, and lists the lessons learned through the process.