ULTRAFINE-GRAINED LOW CARBON STEELS BY SEVERE PLASTIC DEFORMATION

摘要

The structure and properties of 0,14 percent C and 0,1 percent C - B low-carbon steels taken in two initial states, martensitic and ferritic-pearlitic, were studied after cold equal-channel angular (ECA) pressing. ECA pressing leads to the formation of only partially submicrocrystalline structure with a grain size of 150 - 300 nm, depending on the steel alloying and initial state. The finest structure with the elements of 190 nm in size is obtained in the 0,1 percent C - B steel microalloyed with boron. The strength of the 0,1 percent C - B steel after cold ECA pressing (R_m = 805-1235 MPa) meets the specifications of fasteners of the R80 - R120 strength grade. The strength of the deformed 10,14 percent C steel is close to the R80 strength grade.