An Experimental Study of TRIP Behavior in a Cr-Ni-Mo-Al-Ti Maraging Steel -Quantitative Identification of Backstress Evolution and Iso-Volume Fraction Lines-
Kiyokazu NAGAYAMA, Shinnosuke GOTO, Takaki TERASAKI, Kikuaki TANAKA, F.D. FISCHER and G. CAILLETAUD
Abstract:The quantitative identification of the backstress evolution is carried out in a Cr-Ni-Mo-Al-Ti maraging steel under thermomechanical loading conditions. The evolution depends on the direction of the applied stress; tensile, compressive or shear. The iso-volume fraction lines (the iso-x lines) are determined between the transformation-start line and the transformation-finish line on the applied hold stress-temperature plane. The iso-x lines are composed of a tensile-branch and a compressive-branch, each of which is parallel to the martensite-start line. The cross point of the tensile- and compressive-branches of the iso-x line shifts to the direction of backstress evolution. The almost hold stress-independent martensite-finish line is proved to be attributed to the backstress evolution. Key Words:Transformation-Induced Plasticity (TRIP), Backstress evolution, Iso-x lines, TRIP strain, Greenwood-Johnson effect, Magee effect