This article uses the compressive split-Hopkinson pressure bar to compare the dynamic flow behaviors of S15C mild steel and S50C medium alloy heat-treatable steel (abbreviated hereafter to medium steel) at temperatures ranging from 25 °C to 800 °C. The effects of carbon content, strain rate, and temperature on the mechanical responses of the two metals are evaluated. The microstructures of both steels are studied using a transmission electron microscopy (TEM) technique. The flow stress of both carbon steels is found to increase with strain rate, but to decrease with temperature. Furthermore, the deformation resistance and the work-hardening rate both increase with increasing carbon content. The activation energy, ΔG*, of the two metals varies as a function of the strain rate and temperature, but is virtually unaffected by the carbon content. The present study identifies a maximum ΔG*, value of 58 kJ/mol for the S15C mild steel and 54.9 kJ/mol for the S50C medium steel. A Zerilli-Armstrong bcc constitutive model using appropriate coefficients applied to describe the high-strain-rate plastic behaviors of the S15C and S50C carbon steels. The errors between the calculated stress and the measured stress are found to be less than 5 pct. Transmission electron microscopy microstructural observations reveal that the dislocation density and the degree of dislocation tangling increase with increasing strain rate in both steels. Additionally, the TEM observations indicate that a higher strain rate reduces the size of the dislocation cells. Furthermore, it is shown that the annihilation of dislocations occurs more readily at elevated temperatures. The current results provide a valuable reference for the application of S15C mild steel and S50C medium steel in high-speed plastic forming processes.
|Number of pages||12|
|Journal||Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science|
|Publication status||Published - 2005 Nov|
All Science Journal Classification (ASJC) codes
- Condensed Matter Physics
- Mechanics of Materials
- Metals and Alloys