A thermo-mechanical correlation with driving forces for hcp martensite and twin formations in the Fe-Mn-C system exhibiting multicomposition sets

作者：Nakano Jinichiro^*

来源：Science and Technology of Advanced Materials, 2013, 14(1): 014207.

DOI：10.1088/1468-6996/14/1/014207

• stacking fault energy
• high manganese steel
• TWIP
• TRIP
• shape memory alloys

The thermodynamic properties of the Fe-Mn-C system were investigated by using an analytical model constructed by a CALPHAD approach. The stacking fault energy (SFE) of the fcc structure with respect to the hcp phase was always constant at T-0, independent of the composition and temperature when other related parameters were assumed to be constant. Experimental limits for the thermal hcp formation and the mechanical (deformation-induced) hcp formation were separated by the SFE at T-0. The driving force for the fcc to hcp transition, defined as a dimensionless value -dG(m)/(RT), was determined in the presence of Fe-rich and Mn-rich composition sets in each phase. Carbon tended to partition to the Mn-rich phase rather than to the Fe-rich phase for the compositions studied. The results obtained revealed a thermo-mechanical correlation with empirical yield strength, maximum true stress and maximum true strain. The proportionality between thermodynamics and mechanical properties is discussed.

• 出版日期2013-2