Influence of refined hierarchical martensitic microstructures on yield strength and impact toughness of ultra-high strength stainless steel

Study on hot deformation behavior and workability of squeeze-cast 20 vol%SiCw/6061Al composites using processing map

A novel medium-Mn steel with superior mechanical properties and marginal oxidization after press hardening

Hot deformation characterization of as-homogenized Al-Cu-Li X2A66 alloy through processing maps and microstructural evolution

Hot deformation of a cast-homogenized ZK60 magnesium alloy was studied in terms of dynamic recrystallization (DRX) kinetics. The alloy was isothermally compressed under uniaxial loading at 400 °C and 450 °C with varying strain rates of 0.001, 0.01 and 0.1 s−1. The DRX fraction of each deformation condition was determined via electron backscatter diffraction (EBSD) analysis. DRX kinetics during hot deformation was investigated using an Avrami-DRX equation. For the sake of comparison, Avrami-SRX (static recrystallization) modeling was also employed. Both models were calibrated and validated for hot deformation of the alloy. It was observed that the Avrami-DRX model could be successfully used to predict the DRX kinetics except for the lowest DRX fraction (i.e., deformation at 400 °C/0.1 s−1). Moreover, the Avrami-SRX model was in good agreement with the Avrami-DRX model for deformation at the lowest strain rate (i.e., 0.001 s−1). With increasing strain rate, Avrami-SRX model became increasingly less viable. This was mainly attributed to the smaller than 50% recrystallized fractions at 0.01–0.1 s−1.

Modeling dynamic recrystallization during hot deformation of a cast-homogenized Mg-Zn-Zr alloy

Hot deformation characterization of ultrahigh strength stainless steel through processing maps generated using different instability criteria

A new ultrahigh-strength stainless steel was compressed at the temperature range of 1273 K to 1423 K (1000 °C to 1150 °C) with a strain rate varying from 0.01 to 10 s−1 using a thermomechanical simulator. The microstructures quenched after hot deformation were examined. It was found that dynamic recrystallization (DRX) could occur in this heavily alloyed steel during the entire studied deformation condition. In contrast, dynamic precipitation only takes place at temperatures below 1373 K (1100 °C) and its influence on DRX depends on both deformation temperature and strain rate. The critical strain for the onset of DRX increases as usual with the decreasing temperature or the increasing strain rate; however, it decreases with the increase of strain rate from 1 to 10 s−1 at the temperatures of 1273 K and 1323 K (1000 °C and 1050 °C). This is attributed to the complicated interaction of DRX and dynamic precipitation when both can occur during deformation. On the one hand, dynamic precipitation could occur during deformation below 1373 K (1100 °C) and then suppress DRX due to the pinning of migrating boundaries. On the other hand, such a suppression shall decrease when not enough particles could dynamically precipitate during the short period of deformation at a high strain rate, which should facilitate DRX. Therefore, strain rate has a complicated influence on DRX kinetics. Finally, we developed quantitative models, which can successfully predict the critical strain for DRX, the recrystallized fraction, and grain sizes using the Zener–Holloman parameter as a mere input. Moreover, this model can also simulate the unusual acceleration of DRX at the high strain rate, resulting from the above-stated complicated interaction of dynamic precipitation and DRX.

Complicated Interaction of Dynamic Recrystallization and Precipitation During Hot Deformation of Ultrahigh-Strength Stainless Steel

Enhanced strength-ductility synergy in a new 2.2 GPa grade ultra-high strength stainless steel with balanced fracture toughness: Elucidating the role of duplex aging treatment

Zhenbao Liu

Papers

Influence of refined hierarchical martensitic microstructures on yield strength and impact toughness of ultra-high strength stainless steel

Hot deformation characterization of ultrahigh strength stainless steel through processing maps generated using different instability criteria

Complicated Interaction of Dynamic Recrystallization and Precipitation During Hot Deformation of Ultrahigh-Strength Stainless Steel

Enhanced strength-ductility synergy in a new 2.2 GPa grade ultra-high strength stainless steel with balanced fracture toughness: Elucidating the role of duplex aging treatment

Effect of Aging on Transformation Behavior of Reverted Austenite and Toughness in Co-Free Maraging Stainless Steel