A Stacking Fault Energy Perspective into the Uniaxial Tensile Deformation Behavior and Microstructure of a Cr-Mn Austenitic Steel

作者：Barman H^*; Hamada A S; Sahu T; Mahato B; Talonen J; Shee S K; Sahu P; Porter D A; Karjalainen L P

来源：Metallurgical and Materials Transactions A-Physical Metallurgy and Materials Science, 2014, 45A(4): 1937-1952.

DOI：10.1007/s11661-013-2175-z

A Cr-Mn austenitic steel was tensile strained in the temperature range 273 K (0 A degrees C) a parts per thousand currency sign T a parts per thousand currency sign 473 K (200 A degrees C), to improve the understanding on the role of stacking fault energy (SFE) on the deformation behavior, associated microstructure, and mechanical properties of low-SFE alloys. The failed specimens were studied using X-ray diffraction, electron backscatter diffraction, and transmission electron microscopy. The SFE of the steel was estimated to vary between similar to 10 to 40 mJ/m(2) at the lowest and highest deformation temperatures, respectively. At the ambient temperatures, the deformation involved martensite transformation (i.e., the TRIP effect), moderate deformation-induced twinning, and extended dislocations with wide stacking faults (SFs). The corresponding SF probability of austenite was very high (similar to 10(-2)). Deformation twinning was most prevalent at 323 K (50 A degrees C), also resulting in the highest uniform elongation at this temperature. Above 323 K (50 A degrees C), the TRIP effect was suppressed and the incidence of twinning decreased due to increasing SFE. At elevated temperatures, fine nano-sized SF ribbons were observed and the SF probability decreased by an order (similar to 10(-3)). High dislocation densities (similar to 10(15) m(-2)) in austenite were estimated in the entire deformation temperature range. Dislocations had an increasingly screw character up to 323 K (50 A degrees C), thereafter becoming mainly edge. The estimated dislocation and twin densities were found to explain approximately the measured flow stress on the basis of the Taylor equation.

• 出版日期2014-4