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

Thermodynamic properties of the Fe-Mn-C system were investigated by using an analytical model constructed by a CALPHAD approach. Stacking fault energy (SFE) of the fcc structure with respect to the hcp phase was always constant at T0, independent of composition and temperature when the 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 T0. The driving force for the fcc to hcp transition, defined as a dimensionless value –dGm/(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 studied compositions. The obtained results 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.
Authors:
 [1]
  1. National Energy Technology Lab., Albany, OR (United States); URS Corp., Albany, OR (United States)
Publication Date:
OSTI Identifier:
1124598
Report Number(s):
A-CONTR-PUB--005
Journal ID: ISSN 1468-6996
Grant/Contract Number:
FE0004000
Type:
Accepted Manuscript
Journal Name:
Science and Technology of Advanced Materials
Additional Journal Information:
Journal Volume: 14; Journal Issue: 1; Journal ID: ISSN 1468-6996
Publisher:
IOP Publishing
Research Org:
National Energy Technology Laboratory (NETL), Pittsburgh, PA, and Morgantown, WV (United States)
Sponsoring Org:
USDOE Office of Fossil Energy (FE)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; CARBON; DEFORMATION; FCC LATTICES; HCP LATTICES; MARTENSITE; STACKING FAULTS; STRAINS; STRESSES; THERMODYNAMIC PROPERTIES; THERMODYNAMICS; YIELD STRENGTH stack fault energy; high manganese steel; TWIP; TRIP; shape memory alloys; high performance steels