Stress partitioning behavior of duplex alloys consisting of BCC and FCC phases at low temperature

Yamashita, Takayuki; Tomono, Shohei*; Morooka, Satoshi  ; Harjo, S.   ; Kawasaki, Takuro   ; Nameki, Tatsuya*; Koga, Norimitsu*; Umezawa, Osamu*

The tensile deformation and stress partitioning behavior of duplex phase alloys consisting of FCC and BCC at low temperatures were investigated using in-situ neutron diffraction during deformation. Cu-40mass%Fe alloy rolled sheet and JIS SUS329J4L duplex stainless steel were used. Both alloys showed a good balance of strength and elongation at low temperatures. In Cu-40mass%Fe alloy, the BCC phase stress at yield point increased by decreasing test temperature. The FCC phase stress at yield point was almost constant regardless of test temperature. The FCC phase started plastic deformation at a low applied true stress. When the BCC phase yielded, phase stress of FCC increased drastically at beginning, then, it increased to applied true stress with the same rate of BCC phase stress at latter regime. On the other hand, both BCC and FCC phase stresses in SUS329J4L increased by decreasing temperature.