구형나노압입시험을 이용한 고강도 이상조직강의 유동특성 예측 연구

Abstract

An attempt is made to predict the macroscopic plastic flow behavior of ultra-high performance pipeline steel consisting of dual phase (ferrite and bainite) by performing nanoindentation experiments on each constituent micro-phase with two spherical indenters having different radii (550 nm and 3.3 mm). Based on the well-known concepts of indentation stress-strain and constraint factor, the nanoindentation hardness values are converted to macroscopic strengths in consideration of the size effect for spherical indentation. Finally, the applicability of ‘rule-of-mixture’ to estimation of the flow properties of the dual-phase steel using the properties of the micro-phases is examined by comparison with the result from conventional tensile test.