Brass alloys usually have excellent corrosion resistance, but inadequate wear resistance due to low hardness, which limits their high-end applications. It is an effective strategy to enhance the wear resistance by significantly refining the brass grains to increase the hardness. Whereas it is still of great challenge for fabricating ultrafinegrained brass alloys via hot working process owing to their quick recrystallization and grain growth. In this study, enhanced grain refinement of CuZn30 brass with trace microalloying elements P, Ni, and Ag (total content of 0.018 wt%) was successfully realized after two-pass continuous extrusion deformation. The microstructure evolution especially the characteristics of dynamic recrystallization and its effect on mechanical properties were then studied. The results showed that the microalloyed CuZn30 alloy achieved a greatly refined microstructure with an average grain size of 0.97 & micro;m after two passes continuous extrusion, compared with 14.33 & micro;m for the normal CuZn30 alloy. It was found that microalloying effectively inhibited the discontinuous dynamic recrystallization behavior, which in turn triggered the continuous dynamic recrystallization during the continuous extrusion process. Such a transition in the dynamic recrystallization mechanism is closely related to the addition of microalloying elements, which alter the dislocation movement behavior, and promote the formation of dense subgrain structures. With enhanced grain refinement, the microhardness increased from 92.96 HV to 180.83 HV correspondingly, with only a slight decrease in electrical conductivity. These results show that the hardness of brass alloys has been significantly improved by microalloying and industrially available deformation processes, which has considerable application potential for improving wear resistance and broadening high-end applications.

Achieving a synergistic enhancement of hardness and electrical conductivity in Cu-Ni-Si alloys requires precise modulation of nanoprecipitation. Although Co and Cr microalloying are established strategies, their underlying mechanisms, particularly the role of chemical short-range order (CSRO), remain unclear. Contrary to expectations, introducing Co and Co-Cr into a Cu-Ni-Si alloy increased hardness but decreased electrical conductivity. Atomic-scale characterization and computational analysis revealed, for the first time, that Co induces a distinct Cu-Co CSRO. This CSRO traps Si solutes, impeding the nucleation and growth of the primary strengthening delta-Ni2Si nanoprecipitates. The retained disordered Ni and Si atoms, along with the CSRO itself, degrade conductivity. Furthermore, Co and Cr regulate nanoprecipitates differently: Co stabilizes the precipitate-matrix interface, refining delta-(Ni,Co)2Si and suppressing coarsening, while Cr segregates at the precipitate core, exerting a kinetic drag effect. Both elements synergistically enhance coarsening resistance. This work clarifies the dual, strengthening-yet-conductivity-limiting role of Co-induced CSRO and the distinct, synergistic mechanisms of Co and Cr in nanoprecipitate modulation.

The structure profile of magnesium alloy tube is difficult to control for complex microstructural evolution under the asymmetric loading of tension and compression induced during tube bending. This study investigates the electro-assisted bending of extruded AZ61 (Mg-6Al-1Zn) magnesium alloy tubes, with particular focus on the influence of pulsed current on microstructure evolution and plastic deformation mechanisms under varying degrees of deformation. The results indicate that pulsed current increases the fraction of {101¯2} tensile twins and effectively regulates twin nucleation positions along the tangential cross-sections on both sides of the bending head. The initially disordered twin distribution is transformed into a more ordered arrangement, thereby enhancing radial microstructural uniformity during bending. The thermal and electromagnetic energy generated by the current promotes the alignment or polarization of twins and dislocations along specific directions. This phenomenon suggests that pulsed current can improve the formability of magnesium alloy tubes through distinctive microstructural modifications. These findings offer valuable insights into microstructure control and bending ability enhancement of magnesium alloy tube.

Titanium alloys often exhibit mechanical anisotropy depending on their microstructural features, but the underlying mechanism of the strong anisotropy developed after high-temperature annealing remains insufficiently understood. In this study, SP-700 titanium alloy sheets subjected to annealing at 900 degrees C were investigated, and the results revealed significant anisotropy in both yield strength and elongation. Detailed microstructural characterization focusing on phase morphology, crystallographic orientation, and the Burgers orientation relationship demonstrated preferential variant selection of alpha s (the secondary alpha phase) during annealing. Three typical alpha s morphologies were identified along the cylindrical surface: clavate alpha sI, acicular alpha sII, and granular alpha sIII. To quantitatively evaluate their effect on anisotropy, a high-fidelity crystal plasticity finite element method (CPFEM) model was established, which incorporated the specific morphology and orientation of alpha and beta phases after annealing. The simulations successfully captured the experimentally observed anisotropic mechanical behavior. Analysis of the slip system activity and schmid factor (SF) evolution inside alpha sI, alpha sII, and alpha sIII under different tensile directions clarified their respective contributions. Based on these results, an anisotropy equation of yield strength was proposed, relating variant fractions and primary slip system activation. Yield anisotropy between RD and TD was mainly attributed to shifts in dominant slip modes of alpha sI and alpha sIII, together with SF effects. Moreover, fracture surface observations and CPFEM simulations confirmed that Widmannsta & uml;tten alpha colonies composed of alpha sI and alpha sII led to elongation anisotropy through direction-dependent dislocation motion and accumulation. These findings provide new insights into the microstructure-property relationship governing anisotropy in annealed SP-700 titanium alloys.

Bending performance serves as a critical indicator for assessing the formability of copper alloy strip products. This study presents a novel bending test methodology incorporating quantitative evaluation parameters to systematically analyze copper alloy strips deformation behavior. Through comprehensive microstructural characterization of bent specimens, we established a direct correlation between bending surface quality and characteristic features in the force-displacement curve. The investigation further revealed the progressive evolution of surface defects under varying reduction ratios during bending deformation. The developed methodology demonstrates that the bending surface quality can be accurately identified through mechanical curve analysis without requiring microscopic examination, enabling efficient and reliable non-destructive evaluation. This advancement provides an industrially viable solution for real-time quality control of bending performance during production processes.

Mg-11Gd-4Y-2Zn-0.5Zr alloy with long-period stacking ordered (LPSO) phases exhibits excellent high-temperature strength and ductility. In this paper, the influence of compressive stress (hot compression) and shear stress (hot torsion) on the deformation of LPSO phases and dynamic recrystallization (DRX) behavior was investigated at 450 °C and 0.01s−1. Microstructural evolution was characterized using optical microscopy (OM), scanning electron microscopy (SEM), and electron backscattered diffraction (EBSD). The results revealed distinct stress-mode dependencies: DRX area fractions were notably higher under shear stress than under compressive stress. Moreover, the LPSO phases exhibited noticeably different deformation behaviors: intragranular lamellar LPSO phases exhibited weaker kinking deformation with lower kink angles during torsion, while intergranular block LPSO phases suffered more severe fragmentation under shear stress. Theoretical analysis confirmed that the enhanced fragmentation under torsion promotes DRX via particle-stimulated nucleation (PSN) mechanism. Analysis of in-grain misorientation axes (IGMA) and effective Schmid factors (ESF) demonstrated that more pyramidal II slips were preferentially activated under shear stress. Such increased activation of pyramidal II slip facilitates DRX nucleation by generating a higher density of low-angle grain boundaries and sub-grains compared to that under compressive stress.

Laser heat treatment (LHT) was employed to achieve rapid quenching of an Al-Cu-Mg alloy. The mechanical properties, microstructural evolution, and precipitate characteristics under different LHT conditions were systematically investigated. The results showed that LHT with peak temperatures above 450 °C significantly improved the mechanical strength of the alloy but not exceeding 580 °C to avoid grain boundary melting. With increasing laser temperature, no obvious changes in grain orientation, texture, or grain size were observed, whereas the morphology and distribution of precipitates evolved considerably. Unlike conventional furnace heat treatment, which predominantly produced uniformly dispersed nanoscale S′ precipitates within grains, LHT generated fewer intragranular S′ precipitates but induced a unique continuous chain-like S′ phase along grain boundaries, accompanied by the formation of precipitation-free zones. The volume fraction of these grain-boundary precipitates increased markedly with rising laser temperature. This distinctive precipitation behavior contributed to a novel strengthening mechanism. Quantitative analysis based on theoretical models revealed that the chain-like S′ phases contributed up to approximately 18.3

As a light rare earth element, La element is primarily selected microalloying element in aging strengthened copper alloy. In this study, the La added Cu-Ni-Si alloy is studied for clarifying structure and type of the second phase formed by La element and other elements. The Cu-Ni-Si alloy with addition of La exhibits different texture types and stronger interaction between Ni2Si phase and nano-twins compared to the alloy without La element. Such difference contributes the excellent resistance to over-aging of the La contained Cu-Ni-Si alloy. Meanwhile, the structure of the La-rich phase was explored using a transmission electron microscope with multiple probes and a fast imageable X-ray energy spectrum analysis probe as well as first-principle calculations. The addition of La element in the alloy formed two kinds of rich La phases, LaNi9Si4 and LaNi2Si2, which both show incoherent relationship with the matrix. Specially, a new kind of core-shell structure is found with shell of LaNi9Si4 and core of LaNi2Si2. This characteristic can be used as a dispersion strengthening phase in the subsequent design of Cu-Ni-Si alloys, providing a new idea for the research and development of new high-performance Cu-Ni-Si alloys.

An unexpected increase in the electrical conductivity of Cu-Cr-Zr alloy was identified during solid solution treatment, with the conductivity rising from the typical 42.11 % IACS to as high as 88.95 % IACS. Such a significant enhancement in conductivity is driven by oxygen diffusion at 950 °C, where oxygen primarily reacts with dissolved Cr in the matrix, not with primary Cr phases. Specifically, oxygen-driven dissolution of primary Cr phases forms a ring-like structure that further promotes reactions. These reactions result in formation of nano-sized Cr₂O₃ precipitates, thereby contributing to the improved conductivity. These findings suggest a potential method for optimizing copper alloys' microstructure and properties by controlling oxygen content.

Little is known about the mechanical property and formability of CZ1 zirconium alloy sheet. In this study, tensile tests of CZ1 sheet were carried out along rolling direction (RD), diagonal direction (DD) and transverse direction (TD). Nakazima tests were conducted to construct the forming limit diagram (FLD) for CZ1 sheet. Three anisotropic yield criteria including Hill48, Barlat89 and BBC2003 were chosen to calibrate the anisotropic coefficients in order to compare the accuracy for anisotropy description. The classical Marciniak-Kuczynski (M-K) model and different yield criteria are applied to predict the forming limit strains theoretically. After comparison, BBC2003+M-K model predicted FLD is in good agreement with the experimental result. Then the effects of material parameters including hardening exponents (n value) and Lankford coefficients (r-values) on the FLD are analyzed with this approach. Furthermore, the relationship between material parameters and formability can be unveiled aiming at providing an optimized direction for formability.

The Zr-1.0Sn-1.0Nb-0.1Fe alloy sheet with a typical double-peak basal texture was rolled up to 70 % thickness reductions at room temperature to follow its textural evolution. An unusual weakened basal texture under increasing rolling strain is found for cold rolled Zr alloy sheets. Specifically, basal pole is changing from transverse direction (TD) to normal direction (ND) resulting in a stronger basal texture under small deformation amount. For heavy deformation, the maxima of texture components spread from ND to TD. This spreading of the texture change is primarily related to a certain amount activation of pyramidal (c + a) slip, which inhibited the formation of basal texture. In-grain misorientation axes analysis and visco-plastic self-consistent simulation jointly suggested that the distinctive tendency of texture evolution is mainly derived from the competition between basal (a) slip and pyramidal (c + a) slip.

To solve the difficulty of forming complex parts of aluminium alloy, a method was proposed using local hardening by laser heat treatment (LHT) to improve the formability of the Al alloy sheet. In order to explore the influence of laser local hardening on deep drawing forming performance, the temperature field of laser treatment was simulated based on the measured data, and a sheet model coupled with mechanical property gradient was established. In addition, the mechanism of the improvement of material formability by the change of constitutive parameters was revealed by the combination of simulation and experiment. The results show that laser scanning can generate a stable gradient temperature field with little influence on the surrounding area. Furthermore, the multi-pass scanning allows for the design of property gradient differential sheets with varying ranges. It is proved that the LHT can effectively improve the plastic strength and the local hardening ability of Al alloy. The results of deep drawing simulations and tests show that the LHT mainly affects the forming ability of differential aluminium alloy sheets by regulating the gradient distribution of strain hardening exponent n and strain hardening coefficient k. The gradient decreasing distribution of n value from the heat treatment center to the surrounding area can not only improve the forming ability of the core area, but also alleviate the strain concentration in the periphery, so as to achieve a more uniform strain distribution in the large deformation zone. The gradient distribution of k can change the position and order of the yield behavior of the plate, and then change the material flow sequence, thus slowing down the material flow at the bottom fillet with higher k value and reducing the tendency of thinning and cracking. In particular, it is found that the gradient distribution of k value is the dominant factor to improve the forming ability of poor aluminium alloy sheet. When the gradient of k value distribution between the laser strengthening area and the surrounding material reaches the critical value, the fracture position of the deep drawing part will shift, which greatly delays the occurrence of necking and cracking processes and improves the overall forming ability of the sheet.

This work examines the micromechanical deformation of GH4169 superalloy, focusing on how & ouml; phase characteristics, including content (area fraction), morphology, and distribution, affect grain scale stress/strain partitioning. By combining microstructural characterization with crystal plasticity finite element modeling, we elucidate the mechanisms behind the unusual mechanical evolution after cold rolling (0-70%) and solution treatment. The results show that higher cold rolling reduction not only raises the area fraction of the & ouml; phase from 0.27% to 4.56% but also alters its morphology and size. The coexisting spheroidal, short-rod-like, and needle-like particles evolve primarily via elongation along the long axis and dissolution along the short axis, resulting in overall coarsening. Concurrently, the distribution shifts from intragranular sites toward grain boundaries and triple junctions. These microstructural evolutions result in hard-soft grain strain partitioning, where strain localizes in hard grains but spreads extensively in soft grains. The significant strength degradation observed at 70% deformation is primarily due to excessive & ouml; phase precipitation, which weakens solid-solution strengthening. Compared to morphology, the distribution of the & ouml; phase exerts a more pronounced influence on slip activation and local stress evolution. Uniformly dispersed intragranular & ouml; particles promote multi-slip activity and effectively regulate matrix stress distribution.

Zircaloy-4 (Zr-4) sheets used in fuel assembly structural parts are subjected to high temperatures, stresses, corrosive environments, and radiation. Due to the poor formability of Zr-4, cracks usually occur during the fabrication of spacer grids at room temperature. In this research, annealed Zr-4 sheets with two distinct initial textures were studied during stamping. Experimental results showed that the sheet with higher normal Kearns factors exhibited weaker formability, leading to cracking at the punch radius under the same punching depth. Electron backscatter diffraction (EBSD) observations revealed discrepancies in texture evolution under different strain paths during plastic deformation. A multi-scale simulation was conducted to elucidate the deformation mechanisms. Modeling accuracy was validated by comparing crack locations, thickness distributions, and post-deformation textures with experimental results. The contribution of slip and twinning to crack formation was quantified. The simulation indicated that Zr-4 sheets with weaker textures exhibited better deformation compatibility, primarily due to enhanced activation of prismatic slip, whereas sheets with stronger textures showed dominant basal slip activity, which promoted cracking.

The forming quality of metal bipolar plate(BPP)flow channels in proton exchange membrane fuel cells(PEMFCs)is a key factor affecting battery performance.A flow channel with straight sidewalls and a low thinning rate can enhance battery output.Roll forming,as a new technology for BPP production,offers advantages such as a low thinning rate and high efficiency.However,existing roll curve design methods struggle to accommodate both low thinning rates and straight sidewall angles simultaneously.This study aims to develop flow channels with right-angled sidewalls,which provide benefits such as a low thinning rate,reduced residual stress,and high accuracy.A roller tooth profile was designed to achieve a flow channel with right-angled sidewalls and minimal thinning.Simula-tions and experiments were conducted to validate the feasibility of this novel design method for the roll forming process.The study investigated the effects of roller tooth parameters on sidewall angle,thinning rate,and residual stress.A multifactor evaluation method was developed to optimize the tip fillet radius and the tooth profile backlash of the roller.The results indicated that the tip fillet radius and the tooth profile backlash were negatively correlated with the sidewall angle.As the tip fillet radius and tooth profile backlash increased,the thinning rate and residual stress decreased.With a tip fillet radius of 0.25 mm and a tooth profile backlash of0.1 9 mm,the flow channel achieved an approximately right-angled sidewall,a maximum thinning rate of 7.7％,a 29.6％reduction in maximum residual stress,and maximum and average residual stress imbalance values of 7.1％and 3.2％,respectively.This study proposes a new design method for a right-angled sidewall runner roller gear profile,facilitating the roll forming of metal BPPs with right-angled sidewalls and minimal thinning.This method provides theoretical support for the large-scale appli-cation of roll forming in the manufacture of PEMFC BPPs.

The equal channel angular bending (ECAB) of AZ31 magnesium alloy rolled sheet (2 mm) under different paths was conducted at 150 degrees C. The evolutions of microstructure and mechanical properties of the sheet were investigated after 5-pass ECAB along the same path, normal direction rotation path and rolling direction (RD) rotation path. The results show that after 5-pass ECAB, a large amount of extension twinning (ETW) and a certain amount of contraction twinning (CTW) and double twinning (DTW) are introduced into the sheet, which can effectively improve the basal texture of the base plane. After annealing treatment, the elongation of the sheets undergone ECAB is obviously improved. In particular, the area fraction of ETW in the deformed sheet rotated 5 passes around the rolling direction (RD) can reach 28.74%, and after annealing, the elongation can reach 28.8% with a tensile strength of 235.7 MPa. Compared with the original sheet, the relative increase ratio of the elongation is 57.4%, while the tensile strength is only 3.8% lower.

The forming quality of flow channels on metallic bipolar plates significantly impacts the performance of hydrogen fuel cells. The roll forming process offers a promising, efficient method for producing these plates due to its continuous nature. Understanding the uniformity and dimensional accuracy of roll-formed bipolar plate channels is essential for enhancing forming quality and facilitating mass production. This study focuses on 0.1-mm-thick 316L roll-formed microchannels, establishing evaluation criteria based on channel depth uniformity, tilt angle, wall thickness, residual stress, and dimensional accuracy. We analyze how roll forming mold parameters like fillet radius and side gap influence channel characteristics. Results indicate that increasing the fillet radius or side gap enhances uniformity in depth, tilt angle, thickness, and residual stress but decreases dimensional accuracy. To resolve the conflict between channel uniformity and dimensional accuracy, a cooperative game model based on a combined weighting method was proposed, optimizing the fillet radius and side gap to achieve the best coupling solution. The optimal fillet radius and side gap were determined to be r=0.25 mm and e=0.27 mm, respectively, resulting in a comprehensive channel score of F_h=0.669 . Experimental validation confirmed that the formed channels exhibit good uniformity and high dimensional accuracy.

Cross wedge rolling enables the reallocation of axial volume for long parts due to the way of rotational forming. It can not only process finished products, but also provide semi-finished products for subsequent processes. In this paper, a novel forming sequence plan containing cross wedge rolling and die forging was proposed to manufacture GH4169 superalloy blade with double-mounting plates efficiently. Microstructure of the alloy is inheritably transmitted during multi-pass heat and plastic deformation processes, thereby achieving the prediction of grain size throughout the entire preparation process, which is ultimately verified by experiments. The results indicate that the rationality of the novel forming sequence plan manufacturing blades has been preliminarily demonstrated by the load variation, temperature history, as well as effective strain field in the thermomechanical processing. Then, to prove the predictive accuracy and reliability of established microstructure model, a comparison was made between experimental cross wedge rolled part and counterpart in simulation. Specially, the half-length of grain refinement region and volume fraction of recrystallization in mixed crystal region were introduced as evaluation indicators. Model predictions showed good agreement with microstructures obtained in actual rolled part. Finally, the predicted grain size of the blade, relied on previous processes, shows a similar variation trend along the axis of the blade to the actual one. The mixed crystal structure generated by cross wedge rolling on the rolled part is further refined in the subsequent die forging. And grain size in different regions of blade all meets the standard requirements.

In the brief preparation process of copper materials, cast billets undergo critical thermomechanical deformation and annealing steps, where understanding recrystallization behavior is essential for microstructure control. Hot deformation behavior and the metadynamic recrystallization (MDRX) characteristics of cast TP2 copper has been investigated by double-pass thermal compression tests in the temperature range of 700 similar to 800 degrees C, strain rate range of 0.1 similar to 10s(-1), strain range of 0.51 similar to 0.92 and inter-pass time of 0 similar to 60 s. Key findings reveal that the microstructural evolution of columnar-grained TP2 copper during thermal deformation and high-temperature holding processes exhibits pronounced differences compared to that of homogeneous equiaxed-grained copper typically employed in general studies. Discontinuous dynamic recrystallization (DDRX) and continuous dynamic recrystallization (CDRX) are the primary mechanisms governing microstructural evolution during hot deformation. The initial refinement of the average grain size followed by subsequent coarsening during the temperature maintenance process. The softening behaviors of MDRX are significantly accelerated with increasing compression temperature, strain rate, or first-pass strain. A kinetic model for MDRX, developed based on parameter-dependent softening fractions, demonstrates excellent agreement with experimental data. By manipulating the aforementioned parameters, the behavior of MDRX can be modulated to influence the microstructure following dynamic recrystallization (DRX) during hot deformation. This is particularly significant in facilitating secondary refinement, which is crucial for improving the microstructure and properties of TP2 tube products.

The ultrafine copper wire with a diameter of 18 µm is prepared via cold drawing process from the single crystal downcast billet (Φ8 mm), taking a drawing strain to 12.19. In this paper, in-depth investigation of the microstructure feature, texture evolution, mechanical properties, and electrical conductivity of ultrafine wires ranging from Φ361 µm to Φ18 µm is performed. Specially, the microstructure feature and texture type covering the whole longitudinal section of ultrafine wires are elaborately characterized. The results show that the average lamella thickness decreases from 1.63 µm to 102 nm during the drawing process. Whereas, inhomogeneous texture evolution across different wire sections was observed. The main texture type of copper wires are components of <111>, <001> and <112> orientations. Specifically, the peripheral region is primarily dominated by <111> and <112>, while the central region is <001> and <111>. As the drawing strain increases, the volume fraction of hard orientation <111> with low Schmid factor increase, where notably higher fraction of <111> is result from the consumption of <112> and <001> for the wire of Φ18 µm. For drawn copper wire of 18 µm, superior properties are obtained with a tensile strength of 729.8 MPa and an electrical conductivity of 86.9