The 800 MPa grade ulra-fine grain steel is a kind of high strength-toughness low carbon(0.05%C) microalloying steel by the rolling technology of multi-directional thermomechanical treatment
large angle cross rolling
heavy deformation strain-introducing ferrite phase transformation
relaxation precipitation controlling transformation and promoting acicular ferrite deformation to decrease grain size of steel to less than 1 μm from 10 μm. The theory research of 800 MPa grade ulra-fine grain steel
recent development and tend in future of production process and welding technology are present- ed in this paper.