The effect of microstructure on superplasticity of W-containing duplex stainless steels

Conference · Sat Dec 30 23:00:00 EST 1995

OSTI ID:194190

Han, Y S; Hong, S H ^[1]

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1. Korea Advanced Inst. of Science and Technology, Taejon (Korea, Republic of). Dept. of Materials Science and Engineering

The superplasticity of Fe-25Cr-7Ni-3Mo, Fe-25Cr-7Ni-1Mo-2W and Fe-22Cr-5Ni-1Mo-2W duplex stainless steels was investigated by the tensile test at 850 C with the strain rate ranged from 10{sup {minus}3} s{sup {minus}1} to 10{sup {minus}1} s{sup {minus}1}. The tensile elongations of the alloys were strongly dependent on the formation of {sigma} phase through eutectoid decomposition at 850 C. The substitution of W for Mo retarded the formation of {sigma} phase due to the lower diffusivity of W compared to Mo. The tensile elongation of Fe-25Cr-7Ni-3Mo alloy was larger than those of Fe-25Cr-7Ni-1Mo-2W and Fe-22Cr-5Ni-1Mo-2W alloys. A maximum elongation of 750% was obtained in Fe-25Cr-7Ni-3Mo alloy at 850 C with an initial strain rate of 3.16 {times} 10{sup {minus}3} s{sup {minus}1}. Dynamic recrystallization was not observed, while a significant strain induced grain growth of {sigma} phase was observed during the tensile deformation at 850 C. The interphase sliding at {sigma}/{gamma} boundaries in duplex microstructure is suggested as a controlling mechanism for the superplasticity of duplex stainless steel at 850 C.

• OSTI ID: 194190
• Report Number(s): CONF-950201--; ISBN 0-87339-300-7
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CHEMICAL COMPOSITION
CHROMIUM ALLOYS
ELONGATION
FLOW STRESS
GRAIN GROWTH
GRAIN SIZE
IRON BASE ALLOYS
MICROSTRUCTURE
MOLYBDENUM ALLOYS
NICKEL ALLOYS
PLASTICITY
SCANNING ELECTRON MICROSCOPY
STRAIN RATE
TENSILE PROPERTIES
TRANSMISSION ELECTRON MICROSCOPY
TUNGSTEN ALLOYS
X-RAY DIFFRACTION