Microstructure evolution and static recrystallization kinetics in hot-deformed austenite of coarse-grained Mo-free and Mo containing low-carbon CrNiMnB ultrahigh-strength steels

Ali, Mohammed; Seppälä, Oskari; Fabritius, Timo; Kömi, Jukka

doi:10.1016/j.mtcomm.2022.104676

Cited by 9 publications

(6 citation statements)

References 45 publications

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“…This localized heating, along with plastic deformation and the presence of dislocations, facilitates the occurrence of static recrystallization (SRX) in the vicinity of the intermetallic layers. [ 51 ] This leads to the observed higher percentage of recrystallized grains near the intermetallic layers, as shown in the GOS maps.…”

Section: Resultsmentioning

confidence: 92%

Microstructural Evolution, Intermetallic Formation, and Mechanical Performance of Dissimilar Al6061–Ti6Al4V Static Shoulder Friction Stir Welds

Sundar. A,

Mugada,

Kumar

2023

Adv Eng Mater

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The present study focuses on achieving microstructural uniformity in dissimilar Al–Ti joints through static shoulder friction stir welding (SSFSW). This method restricts material mixing at the Al–Ti interface due to reduced shoulder action, resulting in peak temperatures of 317 °C (SSFSW) and 491 °C in conventional friction stir welding (CFSW). This reduction in heat input during SSFSW leads to decreased mechanical mixing, resulting in a thinner 2.169 μm intermetallic layer at interface of SSFSW compared to 5.485 μm in CFSW. The resulting weld nugget (WN) microstructure reveals the presence of Ti particles, intermetallic compounds, and fine Al‐associated grains. Rearrangement of dislocations through slip‐and‐climb mechanisms, along with distinct recrystallization processes in SSFSW, significantly reduces grain size within WN. The kernel average misorientation map highlights the presence of nonuniform dislocation concentrations at the interface of CFSW, attributed to the large Ti particles that impede the mobility of dislocations. As a result, the interface of CFSW is found to be the weakest among all the zones, eventually leading to the failure of the CFSW joint near the Ti interface after reaching an ultimate tensile strength of 259 MPa. In contrast, SSFSW welds achieve a higher tensile strength of 289 MPa.

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Section: Resultsmentioning

confidence: 92%

Microstructural Evolution, Intermetallic Formation, and Mechanical Performance of Dissimilar Al6061–Ti6Al4V Static Shoulder Friction Stir Welds

Sundar. A,

Mugada,

Kumar

2023

Adv Eng Mater

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“…The corresponding morphology of each stage is shown in black boxes I, II, and III in Figure 16b, which is the most important feature of DDRX. [ 40,41 ] In the mechanism of strain‐induced grain boundary migration, the migration and bulging of HAGBs provide favorable conditions for the nucleation of DDRX grains; thus, it fully shows that the sawtooth grain boundary is the nucleation site of the DDRX mechanism.…”

Section: Discussionmentioning

confidence: 97%

Study on Hot Deformation Behavior and Dynamic Recrystallization Mechanism of Cu‐Ti‐Fe Alloy

Wang,

Ren,

Wang

et al. 2023

Adv Eng Mater

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Hot compression experiments with the deformation temperatures of 750‐950 °C and the strain rates of 0.01‐10 s‐1 were carried out on a Gleeble‐3500 thermal‐mechanical simulator. The flow behavior and dynamic recrystallization (DRX) mechanism of the Cu‐Ti‐Fe alloy were systematically studied under different hot deformation conditions. According to the curves of flow stress and work hardening rate, the DRX critical condition of the alloy is obtained, and the critical stress value of DRX is small under high‐temperature and low‐strain rate. After fitting, the logarithmic values of the critical stress and critical strain have a linear relationship with lnZ, which indicates that the alloy is more prone to DRX at high temperatures and low strain rates. The Arrhenius constitutive model of the alloy was established, the linear correlation coefficient (R2) was 0.984. Combined with the microstructure of Cu‐Ti‐Fe alloy, the microstructure evolution characteristics and DRX mechanism were elucidated. The dominant mechanism of the alloy under the deformation temperature of 750–950 °C is the DRX mechanism. The LAGBs transform into HAGBs and continuous dynamic recrystallization (CDRX) grains form. Abundant dislocations gather near the HAGBs, causing grain boundaries to protrude. High‐temperature conditions make the dislocations disappear, forming discontinuous dynamic recrystallization (DDRX) grains.This article is protected by copyright. All rights reserved.

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“…To examine the effects of temperature, prestrain, and strain rate on the microstructure following the stress relaxation test, EBSD measurements were conducted on the specimens under various deformation conditions, specifically with respect to the plastic strain, strain rate, and temperature: 0.03/0.01 s −1 /1000 • C, 0.03/0.01 s −1 /1050 • C, 0.03/ 0.8 s −1 /1050 • C, and 0.05/0.01 s −1 /1000 • C. To maintain consistency, it is worth noting that the same 300 s relaxation time was applied to all conditions, as illustrated in Figure 3. It should be mentioned that the holding time has a significant influence on both the grain size distribution and the average PAG size [31]. Representative sections for orientation mapping under different deformation conditions are displayed in Figure 12a-d.…”

Section: Effect Of Srx On Martensite Morphologymentioning

confidence: 99%

Investigating the Static Recrystallization Behavior of 22MnB5 Manganese–Boron Steel through Stress Relaxation Analysis

Birnbaum,

Pilz,

Neufeld

et al. 2023

Metals

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A constitutive model was developed to characterize the static recrystallization (SRX) and evolution of the grain size of the industrially relevant press-hardening steel, 22MnB5, subsequent to the hot forming of sheet metal. Isothermal stress relaxation tests were conducted using the BAEHR 805 A/D thermomechanical simulator, encompassing a temperature range of 950 to 1050 °C, prestrain levels ranging from 0.01 to 0.1, and strain rates spanning from 0.01 to 0.8 s−1. The results obtained from the isothermal stress relaxation tests facilitated the formulation of an Avrami equation-based model, which aptly describes the kinetics of SRX in relation to the temperature, prestrain, and strain rate. Notably, an increase in temperature led to accelerated recrystallization kinetics, signifying temperature-dependent behavior. When the temperature increased from 950 to 1050 °C, the recrystallization time was reduced to approximately one-third. Additionally, the prestrain exhibited a positive influence on the acceleration of SRX kinetics. A quintupling of the prestrain from 0.01 to 0.05 resulted in a reduction of the static recrystallization duration to approximately one-fifth. Among the parameters studied, the strain rate had the least impact on the SRX kinetics, as doubling the strain rate from 0.01 to 0.8 only resulted in a halving of the recrystallization duration. Moreover, an analysis of the microstructural evolution in response to the forming parameters was undertaken. While the grain-size investigation post-isothermal stress relaxation tests provided results in line with the SRX kinetics calculations, the observed effects were comparatively subdued. Furthermore, a comprehensive examination was conducted using electron backscatter diffraction (EBSD) analysis, aiming to explore the effects of specific stress relaxation states on the morphology of martensite. The findings reveal fully recrystallized globulitic microstructures, characterized by relatively minor differences among them.

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Microstructure evolution and static recrystallization kinetics in hot-deformed austenite of coarse-grained Mo-free and Mo containing low-carbon CrNiMnB ultrahigh-strength steels

Cited by 9 publications

References 45 publications

Microstructural Evolution, Intermetallic Formation, and Mechanical Performance of Dissimilar Al6061–Ti6Al4V Static Shoulder Friction Stir Welds

Microstructural Evolution, Intermetallic Formation, and Mechanical Performance of Dissimilar Al6061–Ti6Al4V Static Shoulder Friction Stir Welds

Study on Hot Deformation Behavior and Dynamic Recrystallization Mechanism of Cu‐Ti‐Fe Alloy

Investigating the Static Recrystallization Behavior of 22MnB5 Manganese–Boron Steel through Stress Relaxation Analysis

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