Abstract
The flow stress behavior of high-strength low-alloy (HSLA) steel at different true strains was studied using a hot compression test. The effect of dynamic recrystallization (DRX) on the transformed ferrite microstructures was investigated with electron backscatter diffraction (EBSD). The EBSD analysis indicated that the fraction of high-angle grain boundaries (HAGBs) and DRX increased with increasing true strain. The low-angle grain boundaries (LAGBs) were gradually transformed into HAGBs with increasing DRX degree. When the true strain was increased to 0.916, the fraction of HAGBs increased to 85% and the fraction of DRX increased to 80.3%. The relatively high fraction of HAGBs was related to the complete DRX. The dislocations and substructures in the tested steel at different true strains were characterized by transmission electron microscopy (TEM). TEM observation shows that the nucleation of the dynamically recrystallized grains occurred by the bulging of the original grain boundaries. The DRX nucleation mechanism of the HSLA steel is the strain-induced grain boundary migration mechanism.
Highlights
High-strength low-alloy (HSLA) steel is broadly applied in construction, ship building and automobile manufacturing due to its weldability, corrosion resistance and specific strength [1,2,3,4]
high-strength low-alloy (HSLA) steel ingot is obtained by melting in a vacuum induction furnace
When the temperature was higher than 870.4 °C, the microstructure of the tested steel was single
Summary
High-strength low-alloy (HSLA) steel is broadly applied in construction, ship building and automobile manufacturing due to its weldability, corrosion resistance and specific strength [1,2,3,4]. The isothermal hot compression process of HSLA steel has been studied to understand its dynamic recrystallization behavior under different conditions [9,10]. Metals 2020, 10, 817 the effect of deformation parameters on the DRX behavior of austenite in a Nb-Ti microalloyed steel They reported that DRX occurred more readily with increasing temperature and decreasing strain rate. Shen et al [15] researched the effect of deformation conditions on the microstructure evolution of ferrite during intercritical deformation in low-carbon microalloyed steels, and the study showed that continuous DRX was induced by a small strain of 0.25 when the temperature was 750 ◦ C and the strain rate was 0.1 s−1. The DRX nucleation mechanism in the HSLA steel was determined by TEM analysis
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