Paper presented at the 7th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Turkey, 19-21 July, 2010.
This paper employs a compressive split-Hopkinson pressure bar to investigate the impact deformation and fracture behaviour of 304L stainless steel. Annealed 304L stainless steel bars are pre-strained to strains of 0.15 or 0.5 and are machined into cylindrical compression specimens. Impact tests are then performed at strain rates ranging from 2000 to 6000 s-1 at temperatures of 300oC, 500oC and 800oC. The experimental results show that the flow stress increases with increasing pre strain and strain mte, but decreases with increasing temperature. Negative and near-zero work hardening rates are found in the specimens pre-strained to 0.5 and then deformed at 300°C and 500oC, respectively. The strain rate sensitivity of the pre strained specimens increases with increasing strain rate, but decreases with increasing temperature. The highest strain rate sensitivity is found in the specimen pre-strained to 0.5 and then tested at a temperature of 300°C under a strain rate of 6000 s-1. OM and SEM observations of the fracture surfaces show that the formation of adiabatic shear bands is the dominant fracture
mechanism in 304L stainless steel specimens pre-strained to 0.5 and then deformed at temperatures of 300oC or 500oC.