Mechanical properties of a Cr-Ni-Mo-Al-Ti maraging steel in the process ofmartensitic transformation

Mechanical properties of a Cr-Ni-Mo-Al-Ti maraging steel are studied experi mentally in the process of martensitic transformation. The transformation-s tart and -finish temperatures are determined from the dilatometric curves u nder a tensile, compressive or shear hold stress. An anomalous temperature- dependence of the yield stress is investigated. By checking the closing of the dilatometric loop in a full heating-annealing-cooling thermal cycle und er the applied hold stress, a back stress is confirmed to exist in both the axial and radial directions in the thin-walled tubular specimen, and its i nitial value is identified. The annealing condition is proved to have a mar ked effect on the initial value of the back stress. The back stress is show n to evolve in the progress of transformation. The evolution of the TRIP st rain is evaluated under the hold stress in both the axial and shear directi on. Especially when the hold stress is removed in the process of transforma tion, a backflow, due to the Magee effect, is observed. (C) 2001 Elsevier S cience B.V. All rights reserved.