材料期刊网

The documented experimental results show that grain refinement can not substantially improve the elongation but the strength of low carbon steels, particularly when the grain size is smaller than 1 mum. A simple model of geometrically necessary dislocations and statistically-stored dislocations is proposed to account for the effects of grain refinement on the yield strength and uniform elongation of ultrafine grained low carbon steels. In this model, both grain boundary and precipitate strengthening mechanisms were considered. It is shown that both grain and precipitate refinements are necessary to improve the strength and elongation of materials.