Optimization of strength and ductility in Fe--Mn trip steels
A series of Fe--Mn alloys containing 16 to 20 percent Mn, 0 to 0.15 percent C, and 0 to 1.0 percent Mo were designed to illustrate the effect of balanced chemistry and heat treatment for the optimization of the mechanical properties of a class of materials known as TRIP steels. The mechanical properties of TRIP steels in a room temperature test depends on the position of the M/sub s/ and M/sub d/ temperatures, which are controlled by the chemical composition, with respect to room temperature. In general, the strength and ductility of the 16 percent Mn steels improved with increasing alloy content while the 20 percent Mn alloys were less sensitive to increased alloy content. As the chemical composition was increased, the phase composition tended toward more epsilon martensite. This increase in the epsilon martensite content indicated that the M/sub d/ temperature was decreasing towards room tempeature, and the effect of the decreasing M/sub d/ temperature showed itself in the variation of the mechanical properties. The 16 percent Mn alloy showed a 30 ksi yield strength and 30 percent elongation while the 16 percent Mn-0.08 percent C-1.0 percent Mo alloy had a 46 ksi yield strength and 46 percent elongation. Thermal cycling was used to increase the epsilon martensite content further to increase he strength and ductility. The 16 percent Mn-0.08 percent C-1.0 percent Mo alloy after thermal cycling had a 60 ksi yield strength and 53 percent elongation. The ductile-brittle transition temperature (DBTT) of these alloys were also controlled by the chemical composition. The 16 percent Mn alloy had a DBTT of -160/sup 0/C while the 16 percent Mo-0.13 percent C alloy had a DBTT of -80/sup 0/C. The addition of a carbide forming element and the reduction of carbon caused the DBTT to decrease. The 16 percent Mn-0.08 percent C-1.0 percent Mo alloy had a DBTT of -140/sup 0/C.
- Research Organization:
- California Univ., Berkeley (USA). Lawrence Berkeley Lab.
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 7336892
- Report Number(s):
- LBL-3986
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360103* -- Metals & Alloys-- Mechanical Properties
ALLOYS
CARBON ADDITIONS
CHEMICAL COMPOSITION
DUCTILE-BRITTLE TRANSITIONS
DUCTILITY
ELONGATION
IRON ALLOYS
IRON BASE ALLOYS
MANGANESE ALLOYS
MARTENSITE
MECHANICAL PROPERTIES
MEDIUM TEMPERATURE
MOLYBDENUM ADDITIONS
MOLYBDENUM ALLOYS
STEELS
TENSILE PROPERTIES
YIELD STRENGTH