Development and validation of processing maps for nickel based powder metallurgy superalloys

Abstract

A simple instability condition based on Ziegler's continuum principles as applied to large plastic flow is extended to define the deformation processing maps that delineate 'safe' and 'non-safe' hot working conditions. Processing maps were developed utilising the measured flow stress data of nickel based powder metallurgy superalloys in a constitutive equation. The applicability of the processing maps developed has been examined by comparing with the reported microstructural observations of deformed compression specimens. Optimum hot working conditions for the materials are suggested, based on the maximum values of the strain rate sensitivity index.

Effect of processing parameters on hot compressive deformation behavior of a new Ni–Cr–Co based P/M superalloy

“…Srinivasan et al [15] studied the hot working characteristic of Nimonic 75, 80A and 90 using processing map in the ranges of temperature 850-1200 • C and strain rate 0.001-100 s −1 . Babu et al [16] did the work on development and validation of processing maps for nickel based P/M superalloys IN 100, MA754 and AP-1. Cai et al [17] developed the processing maps for GH708 in deformation temperature range 1050-1180 • C and strain rate range 0.01-10 s −1 , and pointed out that the strain had a slight effect on the processing maps.…”

“…Processing map was developed on the basis of the dynamic material model (DMM), which aimed to correlate the constitutive behavior with microstructure evolution, flow instability and hot workability [13][14][15][16][17][18][19]. Briefly, the work-piece undergoing hot deformation was considered to be a dissipater of power supplied by a particular source.…”