8 research outputs found
Structural and magnetic transformations in the Fe-Mn binary system
No full textThe phase transformations of five binary iron-manganese (Fe-Mn) alloys with manganese contents ranging from 1 to 21 weight percent have been characterized in the temperature range between room temperature and 1250 degrees C. Differential scanning calorimetry and dilatometry were used to experimentally characterize both the phases and magnetic transformation temperatures. X-ray diffraction and light optical microscopy were employed for the room temperature microstructure characterization. Depending on the manganese content of the alloy, three different crystal structures can be found: body centered cubic (bcc) (alpha/alpha '), face centered cubic (fcc) (gamma), and hexagonal compact (hcp) (epsilon). At manganese contents lower than 10% the phases present are the alpha/alpha ' (bcc) and gamma (fcc). Above similar to 10 weight percent manganese increasing amounts of epsilon (hcp) is formed at the expense of the body centered cubic structures, and no alpha/alpha ' (bcc) is observed for the 21 weight-percent manganese alloy
Impact toughness properties of nickel-free austenitic stainless steels
No full textThe Charpy-V impact toughness of six interstitially-alloyed nickel-free austenitic stainless steels was investigated in the temperature range between -196 and 150 degrees C. Unlike traditional face-centered-cubic steels, the investigated alloys show a marked decrease in impact toughness with decreasing temperature and cleavage-like fracture surfaces at low temperatures. The decrease in impact toughness is due to the combined effects of high strain rate and temperature sensitivity of plastic flow and the strong planarity of the deformation mechanisms of nitrogen-alloyed nickel-free alloys at low temperatures. The effects of the high strain rate and temperature sensitivity of the flow stress on the fracture behavior are discussed based on an analysis of the critical stress for fracture and plastic flow
