Abstract
Abstract
The tensile strength of a micro‐alloyed carbon steel in the mushy zone is investigated as well as the influence of temperature, strain rate and thermal histories. The parameters varied comprised thermal histories of both solidifying and reheating type and strain rates from 1 × 10−4 to 1 × 10−2 s−1 were tested using the physical simulation system Gleeble‐1500D. The measured results showed that tensile strength decreased with increasing test temperature in the mushy zone. The tensile strength with solidified type thermal history was lower than that with the reheated type, and the difference of tensile strength derived from the two thermal histories decreased with increasing cooling rate and increasing temperature. The tensile strength decreased with decreasing strain rate in the mushy zone. A viscoplastic constitutive equation with variables of deformation temperature, stress, strain rate, solid fraction and deformation activation energy was constructed. Moreover, the measured thermo‐mechanical parameters, such as zero strength temperature (ZST) and zero ductility temperature (ZDT), were consistent with those predicted according to the corresponding solid fractions.