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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 T 0, 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 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 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:
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 Lab. (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
OSTI Identifier:
1124598