This research work studies the dynamically recrystallized austenitic grain size (D rec) in a new family of low carbon NiCrCuV advanced ultra-high strength steel (A-UHSS) microalloyed with boron under hot deformation conditions. For this purpose, uniaxial hot-compression tests are carried out in a low carbon A-UHSS microalloyed with different amounts of boron (14, 33, 82, 126 and 214 ppm) over a wide range of temperatures (950, 1000, 1050 and 1100°C) and constant true strain rates (10−3, 10−2 and 10−1 s−1). Deformed samples are prepared and chemically etched with a saturated aqueous picric acid solution at 80°C in order to reveal the D rec and examined by light optical (LOM) and scanning electron microscopy (SEM). The D rec is related to the Zener-Hollomon parameter (Z), and thereafter the D rec divided by Burger's vector (b) is related to the steady state stress (σ ss) divided by the shear modulus (µ) (Derby model). Results shown that the D rec in the current steels is fine (≈ 23 μm) and almost equiaxed, and the recrystallized grain size-flow stress relationship observed after of plastic deformation is consistent with the general formulation proposed by Derby. It is corroborated that boron additions to the current A-UHSS do not have meaningful influence on the D rec.
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