Grain size and plastic strain as co-determinants of stress-relaxation process in polycrystalline nickel

Loss of Stress Equivalence in the Strain-Rate Sensitivity of Flow Stress in Fine-Grain Polycrystalline Copper

“…Nevertheless, Hall-Patch curve fitting to the data points can be done in two independent regions; the slope of the Hall-Petch line is smaller in the nanometer range compared with that in the micrometer range. Butt and coworkers [4,5], like El-Sherik et al [6], have recently reported even independence of yield stress of grain size for high-purity aluminium and nickel crystals in the range 250 to 510 and 30 to 75 mm, respectively.…”

“…In the case of stress-relaxation behaviour of polycrystals, Butt et al [5] have found that the stress-relaxation mechanism in A-grade nickel with mean grain diameter D 30, 55 and 65 mm undergoes a change at a critical value of plastic strain e 15, 13 and 4%, respectively. However, for D 75, 163 and 200 mm only one stress-relaxation mechanism remains operative over the entire stress±strain curve.…”

Effect of heat treatment and stress relaxation in 7075 aluminum alloy

“…In the past, stress relaxation has been studied extensively in high purity metals, e.g., copper [8], aluminum [9], nickel [10], tungsten [11], cobalt [12], iron [13], zirconium [14], and niobium [15] etc. from the viewpoint of basic research to develop and test models of relaxation mechanism in terms of dislocation movement in crystals.…”