Evolution of Twin Boundaries and Contribution to Dynamic Recrystallization and Grain Growth of Inconel 625

Abstract

Dynamic recrystallization (DRX) and grain growth behaviors of Inconel 625 alloy are investigated via hot compression test in the temperature range of 900–1200 °C and strain rate range of 0.01–10 s−1. The electron backscatter distribution technique is an effective method for identifying twin boundary evolution on the basis of temperature and strain rate; this approach is applied in this study to investigate the effects of twins on the DRX process and grain growth. The fraction of DRX increases with temperature under all strain rates, but the strain rate exerts a complex effect on DRX. Grain size variation with temperature follows a similar trend of declining and then increasing, whereas no apparent trend is observed at various strain rates. The DRX mechanism of the Inconel 625 alloy shifts from discontinuous DRX to continuous DRX with a reduction in deformation temperature and increase in strain rate. The fraction of Σ3n (n = 1, 2, 3) boundaries (twin boundaries) increases with increasing temperature at low temperatures (<1100 °C), but declines with increasing temperature at high temperatures (≥1100 °C). At low temperatures (<1100 °C), the fraction of Σ3n (n = 1, 2, 3) boundaries declines with an increasing strain rate up to 1 s−1 and then increases.

Hot Deformation Behavior and Dynamic Recrystallization Nucleation Mechanisms of Inconel 625 during Hot Compressive Deformation

“…The CDRX nucleation mechanism is characterized by progressive subgrain rotation, and 10°–15° misorientation angles often indicate the occurrence of CDRX in subgrain substructure. [ 43 ] To evaluate the DRX mechanism of the Inconel 625 alloy during high‐temperature compression, the point to origin misorientation and point to point misorientation were analyzed along the eight lines (A 1 , A 2 , B 1 , B 2 , C 1 , C 2 , D 1 , D 2 ) marked in Figure 6a,c,e,g. As shown in Figure a–d, the point to point misorientation angle cannot exceed 4°, and the point to origin misorientation angle exceeds 10° within the grain and along the initial grain boundary, indicating the progressive subgrain rotation characterization of CDRX is well developed.…”

“…It involves the procedures of LAGB array and rearrangement of dislocations during hot deformation. [43,44] The process of DDRX features bulging grain boundaries. Grain boundary bulging is an extension of the DRX process, which is caused by the twin and dislocation contribution to stress concentration on the grain boundary at high temperature.…”

The Effect of the Strain Rate on the Fretting Wear Properties of Thermally Compressed Inconel 625 Alloy

“…The detailed evolution of the microstructure and mechanism of Inconel 625 can be found in the existing literature. [1,22] The preceding information indicates that when the strain rates were 0.1 and 1 s À1 , the thermally compressed Inconel 625 not only had higher hardness and www.advancedsciencenews.com www.aem-journal.com better plasticity, but also a lower friction coefficient and better wear resistance. The characteristics of the wear surface and materials of the thermally compressed Inconel 625 were analyzed.…”

“…The composition of commercial Inconel 625 alloy is shown in Table 1 . Previous research [ 22 ] has found that Inconel 625 thermally compressed in the range of 1000–1100 °C has good strength and a relatively small average grain aspect ratio. To study the properties of fretting wear formed at different strain rates (deformation speeds), an as‐cast Inconel 625 cylinder (φ8 × 12 mm) was subjected to thermal compression with a deformation amount of 50% at temperatures of 1000 and 1100 °C and strain rates of 0.01, 0.1, 1, and 10 s −1 using a Gleeble‐3800 thermal simulation testing machine to obtain fretting wear samples ( Figure a).…”

Modeling the Rheological Behavior of a Novel Hot Isostatic Pressed Powder Metallurgy Superalloy

“…Recently, many scholars have developed the phenomenological, physical mechanism, and machine learning models to depict the deformation behavior of Ni-based alloys. [17][18][19][20][21] Tan et al [22] predicted the flow behavior of Inconel718 superalloy by strain-compensated Arrhenius constitutive equation. Zhang et al [23] established the artificial intelligence and phenomenological models to describe the rheological behavior of a hot extruded P/M alloy.…”