Abstract
The grain boundary misorientation distributions associated with the development of dynamic recrystallization were studied in a high-nitrogen austenitic stainless steel subjected to hot working. Under conditions of discontinuous dynamic recrystallization, the relationships between the grain or subgrain sizes and flow stresses can be expressed by power law functions with different grain/subgrain size exponents of about −0.76 (for grain size) or −1.0 (for subgrain size). Therefore, the mean grain size being much larger than the subgrain size under conditions of low flow stress gradually approaches the size of the subgrains with an increase in the flow stress. These dependencies lead to the fraction of high-angle boundaries being a function of the flow stress. Namely, the fraction of ordinary high-angle boundaries in dynamically-recrystallized structures decreases with a decrease in the flow stress. On the other hand, the fraction of special boundaries, which are associated with annealing twins, progressively increases with a decrease of the flow stress.
Highlights
Dynamic recrystallization (DRX) is a very effective tool to obtain a desirable microstructure in various metallic materials [1,2,3,4]
It should be noted that previous studies dealt with continuous post-dynamic recrystallization after large strain deformation by multiple warm forgings at differentMetals temperatures, whereas the present study considers conventional DRX microstructures
The deformation microstructures that developed in a high-nitrogen austenitic stainless steel during hot working accompanied by dynamic recrystallization (DRX) were studied
Summary
Dynamic recrystallization (DRX) is a very effective tool to obtain a desirable microstructure in various metallic materials [1,2,3,4]. The DRX microstructures depend sensitively on the deformation ·. One of the most important structural parameters is grain size, which significantly affects properties of metals and alloys; especially, their mechanical/deformation behavior [7]. The grain size in DRX microstructures can be controlled by deformation conditions, e.g., it increases with an increase in the deformation temperature and/or a decrease in the strain rate [8,9]. The flow stress during hot deformation of various metals and alloys depends on the deformation conditions and can be expressed by a power law function of Z. A power law generally holds between the flow stress and the DRX grain size with a grain size exponent of about −0.7 for hot working conditions [10,11,12]
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