“…This phenomenon occurs, because multiple-twin boundaries (Σ9) are produced when Σ3 grain boundaries encounter different {111} faces and the Σ9 grain boundary is at 40°. In general, the internal driving force of the alloy reached the critical value required for twin deformation due to the Cu–Sn alloy's face-centered-cubic structure and low stacking fault energy, which render Cu–Sn prone to twinning (Humphreys & Hatherly, 2004; Debin et al, 2009; Gholinia & Brough, 2012; Xiao & Xia, 2014). Fig.…”
A thin-walled copper (Cu)–tin (Sn) alloy cylinder was treated after spinning at 200–400°C for 0.5 h. The characteristics of the alloy microstructure under different temperatures were analyzed through electron back-scattered diffraction. The results were as follows. The grain size at 200–300°C decreases as the heat treatment temperature rises, but the grain size at 400°C increases. At 200–300°C, the microstructure primarily consists of deformed grains. It is found that the main reason for the formation of high-angle grain boundaries (HAGBs) is static recrystallization. For the grain boundary orientation differential, the low-angle sub-grain boundary gradually grows into the HAGB, and multiple annealing twin Σ9 boundaries appear. Grain orientation is generally random at any temperature range. The mechanical property test indicated that, at the upper critical recrystallization temperature of 300°C, the elongation of the Cu–Sn alloy gradually increases, and its yield strength and ultimate tensile strength rapidly decrease.
“…This phenomenon occurs, because multiple-twin boundaries (Σ9) are produced when Σ3 grain boundaries encounter different {111} faces and the Σ9 grain boundary is at 40°. In general, the internal driving force of the alloy reached the critical value required for twin deformation due to the Cu–Sn alloy's face-centered-cubic structure and low stacking fault energy, which render Cu–Sn prone to twinning (Humphreys & Hatherly, 2004; Debin et al, 2009; Gholinia & Brough, 2012; Xiao & Xia, 2014). Fig.…”
A thin-walled copper (Cu)–tin (Sn) alloy cylinder was treated after spinning at 200–400°C for 0.5 h. The characteristics of the alloy microstructure under different temperatures were analyzed through electron back-scattered diffraction. The results were as follows. The grain size at 200–300°C decreases as the heat treatment temperature rises, but the grain size at 400°C increases. At 200–300°C, the microstructure primarily consists of deformed grains. It is found that the main reason for the formation of high-angle grain boundaries (HAGBs) is static recrystallization. For the grain boundary orientation differential, the low-angle sub-grain boundary gradually grows into the HAGB, and multiple annealing twin Σ9 boundaries appear. Grain orientation is generally random at any temperature range. The mechanical property test indicated that, at the upper critical recrystallization temperature of 300°C, the elongation of the Cu–Sn alloy gradually increases, and its yield strength and ultimate tensile strength rapidly decrease.
“…The tubular blank in the FE model of the process, which is presented in Figure 4, was meshed with a C3D8R element. 10 Owing to large contact interfaces in the flow-forming process, surface to surface contact was applied in this model. 9 Owing to using lubricant oil during the process, a frictionless interface mode was selected.…”
Section: Solving Methodsmentioning
confidence: 99%
“…They showed that the S/L ratio (ratio of the contact length in the circumferential direction to the contact length in the longitudinal direction in the interface area between pre-form and roller) increases while the values of attack angle and feed rate increase. Debin et al 10 Simulated backward flow forming by the FEM and investigated the dependency of microstructure and texture to deformation records.…”
Flow forming as a precise locally plastic deformation is applied to fabricate thin-walled seamless tubes. Diametral growth as a dimensional defect that occurrs in a flow-formed tube is studied numerically and experimentally in this article. Flow forming of an AISI 321 steel tube is investigated using a finite element method with a dynamic explicit approach. The efficient parameters on the diametral growth are determined using experimental outcomes. The parameters considered are the thickness reduction (%), the feed rate of the roller (mm/min) and the roller nose radius (mm). Response surface methodology is employed to draw out a mathematical model of the diametral growth with regard to the significant parameters. The gained equation reveals that the thickness reduction is the most significant parameter and feed rate has the slightest effect on the diametral growth. The diametral growth increases with the rise in the thickness reduction and the roller nose radius and it leads to a decrease with a high value of feed rate. The innovation point of view is related to the fact that the high level of roller nose radius covers the efficiency of feed rate.
“…For the area near the groove vertex, at c = 0.2, some grains showed a change in morphology, where their long axis formed a smaller angle with RD; at c = 0.3, many grains displayed a wavy morphology as they continued to elongate at the RD direction. The formation of complex grain shapes in TCR may be due to two reasons: firstly, due to the three-axis compressive stress state in the deformation zone, as shown in figure 5, some grains bend to adapt to the compressive stress [26]. Secondly, under small deformation, local uneven stress fields in the thickness direction of the tube may lead to the formation of wavy grains.…”
Tube continuous rolling (TCR) is a beneficial method for the production of titanium pipes due to its high efficiency and shorter process, with the mandrel playing a crucial role. In this study, the mechanism of the mandrel and its influence on the TCR process were investigated in detail through numerical simulations and experimental tests. The analysis included a detailed examination of metal slip, tension, stress-strain field, temperature field, metal flow, and microstructure evolution for various mandrel diameter coefficient. As the mandrel diameter coefficient increases, the grains at the groove vertex are elongated and recrystallized grains appear. At the same time, the quantity of twins at the groove taper initially increases and then decreases. Therefore, the deformation mechanism at the groove taper changes from twinning to slip.
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