Comments on the paper entitled “Microstructural features of a type 304L stainless steel deformed at 1473 K in the strain rate interval 10−3 to 102 s−1”

On the relationship between the intrinsic hot workability parameters of DMM and PRM

“…It should be noted that η in terms of m is valid only if the test data of σ versus for a constant T and ɛ obeys the power law (). Prasad et al [18–31] were evaluating η by computing m as the slope of ) curve, which varies with . Although η varies with ɛ, and T in their calculations, usage of the slope of curve for evaluating η is erroneous because of their assumption of power law for the flow stress holding good from 0 to each strain rate while evaluating the integral for J .…”

“…The test data of for several materials reported by Prasad and his research team [18–31] are for , whereas the integration for G in needs the input from . To overcome this difficulty, the integral for G is split as where which can be obtained by finding the slope ( m ) of curve close to the point, .…”

“…To bring out the differences in evaluating the efficiency of power dissipation (η), between the methods adopted in [18–31] and in the present study, the flow stress data (namely, the flow stress (σ) and the effective strain rate at a constant temperature, T = 450°C and strain (ɛ) = 0.3) of 3–9 pure aluminum as given in Table 1, are considered. The intrinsic hot workability parameter, ς, is also computed.…”

“…The Dynamic Material Model (DMM), proposed by Gegel and coworkers [14] and followed by Prasad and coworkers [15, 16] arose from considerations of physical systems modeling of Wellstead [17]. This model has been extensively used to study the hot working characteristics of several materials [18–31]. The Polar Reciprocity Model (PRM) by Rajagopalachary & Kutumbarao [32–35] has adopted Hill's associated flow rule of plasticity [36].…”