Abstract：In vacuum conditions, micron-grade ZrC particles were added into a low-carbon microalloy steel as deformation center and recrystallization center of austenite and deformation-induced ferrite during hot-rolling to refine grains. A low-carbon microalloy high strength steel of yield strength 518 MPa was obtained in the laboratory. Composition，quantity and particle size distribution of the precipitated phase in the test steel were studied by chemical phase analysis and small-angle X-ray scattering method; morphology of the second phase particles and microstructure of the steel were also examined by SEM and TEM. It was found that there was less content of MC precipitated phase with size less than 18nm and there was no MC precipitated phase with size less than 10nm. The strengthening effect of the second phase particles including carbide precipitated phase and the added ZrC particles on the steel was discussed. Refinement strengthening is the primary strengthening mode. Dislocation strengthening is the second, precipitation strengthening and solution strengthening are less. The added ZrC particles play an important role in the course of refinement strengthening and dislocation strengthening.
2010, Vol. 45 
