1990 Volume 76 Issue 1 Pages 89-96
The heavy-gauge HSLA steel plates with low yield ratio have been applied to the steel-frames of high-rise buildings to utilize the benefits of their high strength and uniform deformability. The yielding behavior of steels relates to the microstructural morphologies such as microstructure, volume fraction and shape of each phase, dislocation, grain size and so on. In the present paper, appropriate microstructural morphology for low YR HSLA steel was investigated by FEM analysis. The influence of shape, volume fraction and mechanical properties of each phase on yielding behavior were analyzed by dual-phase and tri-phase models. From a series of FEM analysis, it is clarified that the appropriate microstructural morphologies to decrease the YRare as follows. (1) Uniform distribution of spherical high-hardness phase in low-hardness phase (2) Around 50% volume fraction of low-hardness phase (3) Increase of the ratio of yield strength of high-hardness phase to that of low-hardness phase.
