In-situ neutron diffraction during tensile under low temperature in low alloy steel containing metastable austenite

Yamashita, Takayuki; Morooka, Satoshi  ; Harjo, S.   ; Koga, Norimitsu*; Umezawa, Osamu*

Volume fraction, phase stresses and crystal orientation in low alloy steel containing metastable austenite were investigated using by in-situ neutron diffraction during tensile under low temperatures. The martensite showed much higher phase stress than the other phases at each test temperatures. The phase stresses of ferrite matrix plus bainite and martensite increased as decreasing test temperature. The austenite phase stress was constant as increased applied true stress at low temperatures. It's suggested that austenite transformed to martensite prior to plastic deformation. The austenite which 111 direction parallel to tensile direction (111-A) is most stable at 293 K. At low temperatures, the 111-A transformed to martensite at early stage of deformation. The relative integrated intensity of 111-A was constant at later stage of deformation. It means that stable 111-A do not transformed to martensite during homogeneous deformation also at low temperatures.