Precipitation Behavior of Wrought Fe-Ni-Based Alloy HR6W

Abstract

Age hardening behavior of Fe Ni based alloy HR6W was investigated at the temperature range between 973 K and 1073 K. Two step increase in hardness is detected for the alloy at each temperature; the rst increase in hardness results from the precipitation of M 23 C 6 phase and the second one corresponds to that of Laves phase. The TTP time temperature precipitation diagram for the alloy is established based on the results of hardness measurement and microstructure observation, where the precipitation of Laves phase is slower than that of M 23 C 6 phase by three orders of magnitude and the nose temperature of Laves phase is above 1073 K. The M 23 C 6 phase precipitates with plate like morphology along grain boundaries at the early stage of aging, followed by the precipitation of Laves phase with granular morphology with increasing aging time. It is found that the M 23 C 6 and Laves phases are aligned under stress condition, due to their precipitation on the dislocations introduced during creep deformation.

Evaluation of Cleavage Fracture Behavior of C14 Fe₂W Laves Phase by First-principles Calculations and Crystal Orientation Analysis

“…In recent years, heatresistant steels that utilize Laves phases as strengthening particles have been developed, and it has been reported that these steels have both superior high-temperature strength and good ductility compared with conventional steels. [20][21][22][23][24][25] Takeyama 25) reported that creep strength can be enhanced without loss of ductility by densely surrounding the grain boundaries with the Fe 2 Nb Laves phase. Thus, unified knowledge on the effect of the Laves phase in heat-resistant steels on the ductility and toughness of steels is required.…”