Influence of Surface Finish on Small Punch Testing of 9Cr Eurofer-97 Steel

Abstract

This study investigated the effect of surface finish on the deformation behavior of Eurofer-97 steel during room-temperature small punch testing. The surface finish of specimens was varied from coarse to fine (ranging from P240-grit silicon carbide paper to a polished finish using 0.06-μm colloidal silica). Testing was conducted on 8-mm diameter by 0.5-mm-thick disks using a 1-mm-radius punch head. No significant change was observed in the elastic-plastic transition load, maximum load, displacement at maximum load, or displacement at failure. Similarly, in all cases, failure occurred in a ductile manner, yielding a dimpled fracture surface. Although friction and surface defects may influence the output of small punch tests, the effect of altering the specimen surface finish alone was negligible in this case, indicating this is not a dominant factor in small punch testing.