Rolling Deformation Research Articles

Study on Softening Resistance of Cu-Sn-Fe-P alloy for Advanced Electrical Connectors

The effect of adding iron element in tin bronze on the microstructure and properties of Cu-Sn-Fe-P alloy is studied by means of phase diagram calculation and microstructure observation. The work hardening curve of Cu-Sn-Fe-P alloy is plotted by cold deformation of the alloy with different reduction rates. The test and microstructure observation are conducted for tensile strength and ductility of the alloy sample annealed at different temperatures, so as to determine the recrystallization temperature of the alloy. The results show that the addition of iron element plays a significant role in grain refinement and improves the subsequent working performance. After the cold rolling deformation, an obvious work hardening effect is imposed on the alloy. With the increase of the deformation, the alloy presents a trend of increasing first and then becoming stable in the tensile strength, while a reverse trend in ductility. Cu-Sn-Fe-P alloy has a softening resistance equivalent to that of QSn6.5-0.1 high-tin bronze, both of which will be softened at 400ºC; therefore, Cu-Sn-Fe-P alloy can replace QSn6.5-0.1 alloy at high temperature.The present study proposes how to maintain the original properties of the tin-phosphorous bronze alloy while reducing the content of the tin, and achieve the more effective industrialized production.

Modeling of layer thickness and strain for the two-layered metal clad plate rolling with the different roll diameters

The realization of online prediction in rolling production line is an innovative breakthrough in key rolling technology. The deformation behavior of metal clad plate in the deformation zone under different roll diameters is modeled and analyzed in this paper based on the flow function method. The volume flow through the unit section at the rolling inlet is maximum. The maximum volume flow of carbon steel layer occurs at the near bonding surface. The maximum volume flow of stainless steel layer occurs near the top surface. The strong shear effect caused by the velocity break mainly occurs on the side of the carbon steel layer, which plays a decisive role in the composite of metal plate. Meanwhile, the position of the maximum shear stress has a tendency to move towards the outlet of the deformation zone with the increase of the reduction rate, contained within the rolling zone. According to the flow function field, the velocity field model of the clad plate in the rolling deformation zone is established. Based on the upper bound method, the layer thickness and every power proportion can be obtained by the principle of minimum energy. Further, the equivalent strain model of the element is established based on the velocity field and strain rate field models. The accuracy of the model is verified by rolling simulation, experiments and microscopic characterization under different working conditions. The model can provide theoretical guidance and technical support for the online prediction and control of deformation behavior in the rolling process.

Enhanced formability of Al–Mg–Si–Zn alloy sheet via dislocation structure and texture during cold rolling

The effects of cold rolling deformation on microstructure, texture, and formability of Al–Mg–Si–Zn alloy were systematically investigated using OM, SEM, TEM, XRD, and tensile tests. The results indicated that the effect of cold rolling deformation on the recrystallized microstructure and texture of the sheets mainly depended on the differences in dislocation structure and texture distribution. With the increase of cold rolling deformation, the dislocation structure gradually changed from a mixture of density dislocation walls and microbands to a lamellar bands structure, the large-angle boundary gradually increased, and the size of dislocation cells gradually decreased, which indicated a gradual increase of the stored deformation energy. In addition, the deformation texture increased gradually with the raise of cold rolling deformation. After T4P treatment, the recrystallized grain size gradually reduced with the increase of cold rolling deformation. The main recrystallization textures in the sheets with 41 % and 55 % deformation were Cube {001}<100> and CubeRD {310}<001> textures, respectively. The CubeND {001}<310> texture was predominantly present in the sheets with 69 % and 82 % deformation, meanwhile some P {011}<233> texture was also observed in the sheets with 82 % deformation. It was found that the dislocation structure and deformation texture distribution formed in the sheet with 82 % cold rolling deformation contributed to smaller recrystallized grains and weaker P texture after solution heat treatment, which enhanced the average plastic strain ratio r value and improved the formability.

Analysis of Microstructure, Texture Evolution, and the Mechanism of Grain Refinement of Commercially Pure Titanium During Cold Rolling: Experiment and Simulation

A comprehensive understanding of the microstructures and texture evolutions during the rolling process is of great significance for the preparations of high‐quality commercially pure titanium (CP‐Ti) sheets. Therefore, in the present work, the effects of rolling reductions on the microstructures and textures of CP‐Ti are investigated by optical microscope, electron backscatter diffraction, and X‐ray diffraction. A crystal plasticity finite element model (CPFEM) is developed to accurately predict the rolling deformation behaviors of CP‐Ti sheets. The results show that the slip and twinning including , compression twins and extension twins are prone to plastic deformations during the whole rolling process. The c‐axes of grains gradually tilt toward the transverse direction and the grains gradually deviate from the original //rolling direction (RD) to //RD. As a result, the mixed textures of and are developed in the specimen. The grain refinements are closely linked with the developments of and twins. In addition, the twin fractions and texture evolutions are well predicted by the CPFEM model. These results documented in this work should not only help to elucidate the microstructures and texture evolutions of CP‐Ti, but also shed important light on improving its properties.

Texture evolution and strengthening mechanism of CuCrZr alloys during cold rolling

The evolution of microstructure and crystallographic texture in Cu–1Cr-0.061Zr alloy strips during multi-pass cold rolling deformation was studied. The results showed that the tensile strength of Cu–1Cr-0.061Zr alloy increased from 507 MPa to 683 MPa with increasing rolling strain, while the conductivity decreased from 84.1 to 68.1 of the International Annealed Copper Standard. When the strain is 1.86–3.85, the elongation is effectively stable at 7.5%–8.5%. The local strain and grain dislocation angle inside the alloy gradually increase with the increase in strain, and the grain orientation distribution becomes more uniform and stronger. The dislocation slip generated during the rolling process leads to the concentration of grain orientation toward the <11−1> direction, causing the Goss texture ({110}<001>) to gradually transform into a Copper texture ({112}<11−1>) with relatively stable grain orientation, which significantly improves the mechanical properties at the macro level. In addition, the heat generated during the cold rolling process causes the cancellation of heterologous dislocations on a certain slip surface, resulting in a decreased dislocation density and a slight growth of nanoprecipitates. Nanoprecipitation strengthening and grain boundary strengthening are the main strengthening mechanisms in the Cu–1Cr-0.061Zr alloy, while the strength contribution of banded Cr phase dispersion is relatively small.

Effect of cold rolling deformation on the microstructure and mechanical properties of spray-formed Al–Zn–Mg–Cu alloy

Effect of cold rolling deformation on the microstructure and mechanical properties of spray-formed Al–Zn–Mg–Cu alloy

Processing of an as-cast Al-7.5 wt%Y eutectic alloy by rolling and annealing to improve the tradeoff between strength and electrical conductivity

This paper describes insights from an experimental investigation into tailoring microstructure of an Al–Y eutectic alloy to improve its trade-off between strength and electrical conductivity via casting, cold rolling, and annealing. Mechanical testing, ex-situ microscopy, and in-situ synchrotron X-ray diffraction were employed to characterize microstructural evolution as well as strengthening and conduction mechanisms. The as-rolled alloy exhibited substantially improved strength and electrical conductivity compared to the as-cast alloy. The rolling deformation induced a lamellar structure in the alloy consisting of coarse primary α-Al grains organized into fibers floating within ultrafine eutectic matrix of α-Al grains and β-Al3Y particles. Subsequent annealing at 280 °C for 1-h caused partial recrystallization of the primary α-Al phase, while annealing at 400 °C for 1 h cause both α-Al and β-Al3Y phases to undergo recrystallization with coarsening of α-Al but reduction in size of β-Al3Y. Interestingly, stacking faults were observed to be thermally stable during the annealing processing contributing to the heat resistance of the alloy. Relative to the cold-rolled state, the alloy after annealing at 280 °C for 1 h retained a tensile strength of 90 % with improved ductility and electrical conductivity. Furthermore, the alloy after annealing at 400 °C for 1 h lost some strength but electrical conductivity further increased. The effects of cold rolling on the lamellar-structure creation and subsequent annealing on the microstructural changes and resulting strength and electrical conductivity of the alloy are discussed in this paper.

Revealing the precipitation kinetics of multi-stage and multi-scale Ti-bearing precipitation in a 460 MPa grade HSLA steel

The multi-stage and multi-scale Ti-bearing precipitates, containing TiN, Ti(C, N), Ti4C2S2 and TiC, were systematically examined through experimental observations and our modified precipitation kinetic analyses. The result showed that cubic TiN (several microns) mainly precipitated in molten steel. After continuous casting, Ti(C, N) and Ti4C2S2 primarily precipitated in austenite, spanning 100–1000 nm in size. Upon subjected to severe rough rolling deformation, further precipitation of Ti(C, N) and Ti4C2S2 (tens of nanometers) appeared, accompanying with austenite recrystallization. During finishing rolling, recrystallized austenite grains were subdivided into multiple microbands, leading to an accumulation of deformation stored energy (DSE). The strain-induced precipitation (SIP) of spherical TiC particles (10–20 nm) distributed along microband walls, prior austenite grain boundaries, and even within the microbands. Subsequently, sequential matrix transformations, specifically ferrite (γ → α) and pearlite (γ → α + θ), were initiated during coiling. High-density TiC interphase precipitation occurred during the γ → α transformation, while a more dispersed, low-density TiC precipitation was observed after the γ → α + θ transformation. Kinetic analyses revealed that the nose temperature for Ti(C, N) precipitation in austenite was a minimum of 200 °C higher than that of Ti4C2S2. The DSE accelerated the TiC SIP with higher nose temperature in austenite during hot rolling. Moreover, kinetic analyses also implied that the migrating γ/α interface promoted faster TiC nucleation and growth relative to dislocation nucleation, and the relative precipitation time shortened more than 20 orders of magnitude. Furthermore, both the γ/α interface migrating velocity and the interface carbon content exhibited weak influence on the kinetics of interphase precipitation. However, the pearlite formation reduced the driving force of TiC precipitation, resulting in the TiC dispersed precipitation rather than TiC interphase precipitation.

Exceptionally flexible and stable quasi-solid-state supercapacitors via salt-in-polyampholytes electrolyte with non-freezable properties

Hydrogel electrolytes have been intensively studied for a decade, due to their outstanding intrinsic physical properties, such as good flexibility, high stretchability, and high ionic conductivity. However, due to their low mechanical strength (<103 Pa) and poor ionic conductivity (<1 mS/cm) at low temperatures, many researchers have been focusing on improving these issues. Thus, in our study, we prepared salt-in-polyampholytes (SIPAs) that have two different counterions (Li+ and Cl-) in an aqueous medium via facile one-step UV radical polymerization. Polyampholyte (PA) improves the toughness and elongation by inducing strong ionic interactions between opposite charges in the polymer chains, but also exhibits excellent recovery ability under periodically changing strain and strong adhesion with electrodes. Furthermore, the incorporation of LiCl salt into our PA results in SIPA with high ionic conductivity at 25 °C (134 mS/cm) and even at sub-zero temperatures (15 mS/cm). Consequently, the non-freezable SIPA-based quasi-solid-state supercapacitor (QSS), assembled with activated carbon electrodes, exhibits a wide operating voltage window as high as 2.0 V, a high specific capacitance of 241 F/g, and high energy (34 Wh/kg) and power (598 W/kg) densities, along with excellent cycling stability, retaining 91 % of the initial capacitance even after 20,000 cycles at 1 A/g. Besides, the QSS electrochemical performance remains unaffected under bending and rolling deformations at a low temperature, demonstrating excellent mechanical, thermal, and electrochemical stability of our system. This work provides an effective strategy for designing energy storage devices that are both foldable and reliable, making them suitable for use in extreme environments.

A Multi-Parameter-Coupled Mixed Lubrication Model for Rolling Interface Analysis: An Investigation on Interfacial Oil Pressure and Oil Film Thickness

Utilizing the average Reynolds equation, lubrication friction theory, metal rolling deformation theory, and temperature energy theory, a multi-parameter-coupling mixed lubrication model considering the influence of surface roughness with Gaussian distribution characteristics under rolling conditions was established. The results show that the stress distribution of the lubricating oil at the rolling interface conforms to the typical characteristics of line contact stress distribution. The oil film pressure does not increase significantly with the increase in the reduction ratio. A second peak pressure appears before the outlet. The second peak pressure reaches its maximum when ε = 0.2. The rolling speed has little effect on oil film pressure, but greatly affects oil film thickness. The influence of rolling speed mainly occurs in the outlet zone and at the second peak pressure location. The oil film thickness increases with rolling speed. During rolling, the temperature rise in the rolls exhibits two peak values. The first peak appears near the neutral point, and the second peak appears near the outlet, which is also where the second peak pressure is located. The influence of temperature will reduce the peak stress on the rolls. The overall stress on the rolls will also decrease.

Microstructure evolution and enhanced mechanical properties of as-rolled TiB/(TA15-Si) composite via heat treatment

To improve the mechanical properties of the as-rolled composite under large rolling deformation, the effect of solid solution and aging on the microstructural characteristics and mechanical properties of the as-rolled TiB/(TA15-Si) composite was detailedly investigated. The solid solution temperatures of 1050 °C in the β-phase field and different aging temperatures of 550–750 °C were chosen to regulate the evolution of matrix and silicides. After solid solution treatment, the matrix transformed from elongated and kinkled lamella into acicular martensite microstructure. And the silicides completely redissolved into matrix and a uniform diffusion of Si atom was presented. Meanwhile, the aging temperature can obviously affect the evolution of martensite and silicides. As aging temperature increased, the martensite gradually decomposed into acicular α+β lamella (at 650–700 °C) and abnormal growth of α phase appeared (at 750 °C), which dominated the decreasing trend of microhardness and high-temperature strength. Besides, the silicides gradually precipitated along the prior β phase and TiB whiskers (at 600 °C) as well as α/β phase boundaries (at 650 °C). Eventually, 600 °C and 700 °C strengths of the as-rolled composite can be obviously improved by 39.7 % and 84.6 % after solid solution and aging processes. And the composite aged at 600 °C can obtain the highest 600 °C strength of 992 MPa, which is mainly attributed to martensite, precipitation of silicides and weak α2 phase.

Analysis of the Varying Thickness Rolling Process Based on the Principle of Pre-Displacement

This paper conducts a comprehensive analysis of the varying thickness rolling process, grounded in the principle of pre-displacement. Within the rolling deformation zone, the subject is divided into three distinct areas: the backward slip zone, sticking zone, and forward slip zone. We propose a model that delineates the sticking-sliding motion between the rolled piece and the roller, all within the context of the rolling deformation zone, and derive a calculation method for determining the longitudinal lengths of both the sliding and sticking zones within this area. Unlike existing full sliding and full sticking models, our sticking-sliding model offers a novel perspective, overcoming inherent limitations when analyzing the rolling process. Furthermore, we establish models to describe the neutral angle and forward slip value and to predict the longitudinal length of the rolled piece during the varying thickness rolling process. A comparison of our calculated results with experimental data demonstrates the feasibility and effectiveness of the method, thereby laying a robust theoretical foundation for the varying thickness rolling process.

Effect of Defects and Oxidation on CNT-Copper Interface: First-Principles Calculation and Experiment.

In this paper, the effects of carbon nanotube defects and a copper surface oxide layer on a carbon nanotube-copper interface were studied via first-principles. A defect-free CNT-Cu interface, Stone-Wales defect CNT-Cu interface, single-hole and double-hole defect CNT-Cu interface, and Cu2O-Cu interface were simulated and calculated. By simulating the differential charge density, atomic population, bond population and density of states of the interface model, the effects of various defects on the interface bonding and electrical conductivity of the composites during the preparation of the CNT-reinforced copper matrix composites were analyzed, which provided theoretical guidance for the preparation of CNT/Cu composites. After that, copper matrix composites with different CNT defect contents were prepared via different rolling deformation processes. Their hardness and electrical conductivity were tested, and the results were consistent with the results obtained via the first-principles calculations.

Numerical Simulation and Temperature Modeling of Magnesium Alloy Strip Rolled by Heated Roll

A prediction model for the outlet temperature of magnesium alloy strips in the process of heated-roll rolling was established by using linear fitting and nonlinear regression methods. By inputting the rolling parameters into the model, the outlet temperature of the strip can be accurately predicted, which will then optimize and regulate the properties and microstructures of the magnesium alloys in the rolled form. To verify the reliability of the model, heat transfer experiments of the magnesium alloy rolled by heated rolls were carried out. The results show that under the same conditions, the actual outlet temperature measured experimentally matches well with the outlet temperature predicted by the model, and the relative error is kept within 10%. In the modeling process, Deform V11.0 software was used to simulate the thermal–mechanical behavior of the magnesium alloy rolled by the heated roll. In the process of analyzing the simulated heat transfer, it was found that the temperature rise of the surface and the core is divided into three identical stages: the slow rise, the fast rise, and the thermal equilibrium stages. In addition, the mechanical behavior of the rolling deformation zone was also analyzed, and the strip was subjected to direct heat transfer from the heated rolls during the hot rolling process so that the softening played a major role and the stress value gradually decreased from the middle of the deformation zone to the inlet end and the outlet end. This is so that it can be known that the process of being rolled by the heated rolls not only improves the rolling efficiency, but also ensures the deformation temperature and obtains fine grains.

Microstructure Evolution and Deformation Mechanism of Ti‐55531 Alloy During Hot‐Rolling Process

Ti‐55531 alloy is a novel near‐β‐Ti alloy, which has promising application potential as critical aircraft components due to its outstanding mechanical properties. In this work, it is aimed to tailor the microstructure and mechanical properties of Ti‐55531 alloy by hot‐rolling in α + β‐phase field. In experimental results, it is indicated that an increasing number of α lamellae becomes globular or ellipsoidal shape with the increase of rolling reduction. As a result, the strength and elongation of the rolled samples continually increase. Lath‐like substructures are observed inside some residual lamellar α after 20% rolling reduction. Nearly all lath‐like substructures have their habit plane corresponding to (100)α and exhibit the orientation relationship (OR) of [0001]HCP //[001]FCC, [20]HCP //[]FCC, and (100)HCP //(FCC with α phase. At high rolling reductions, the face‐centered cubic (FCC) substructures disappeared. Instead, {101} twin structures are frequently observed in lamellar α grains, indicating that both {101} twinning and martensitic transformation can be activated in Ti‐55531 alloy to accommodate the applied rolling deformation. To the authors’ knowledge, such stress‐induced martensitic transformation has not been reported before in Ti‐55531 alloy. Therefore, the findings in this work should advance the understandings on the deformation behavior and mechanism in this alloy.

Effect of in-situ rolling and heat treatment on microstructure, mechanical and corrosion properties of wire-arc additively manufactured 316L stainless steel

Post-heat treatment and in-situ rolling, both can be used to improve the coarse grains and anisotropy that are prevalent in metallic materials, fabricated by wire and arc additive manufacturing (WAAM). In this study, the effect of in-situ rolling and heat treatment on the microstructure, mechanical and corrosion behaviors of WAAM 316L was investigated. The results showed that the microstructure of WAAM 316L changed considerably due to the introduction of rolling deformation, as it was observed that the ferrite was distributed in a reticulated or equiaxed morphology instead of dendritic distribution, columnar grains were found to be engulfed, while a large number of low angle grain boundaries (LAGBs) with high dislocation density were introduced. After heat treatment at 650 °C, there was no significant change in grain morphology, ferrite gradually transformed into σ phase, the tensile strength increased, yield strength and elongation decreased. After heat treatment above 1000 °C, the strength and ductility of the rolled WAAM 316L were higher than those of the unrolled WAAM 316L. As the heat treatment temperature increased, the corrosion resistance first decreased and then increased. In-situ rolling resulted in a decrease in the corrosion current density of the steel and also reduced the stability of the passive film.

A low-cost strategy to enhance strength-ductility balance in AISI1045 steel

In the current research, the impact of cold single-roll drive rolling as a low-cost technique on the microstructural evolution and mechanical properties of the AISI1045 sheet was studied. The microstructure of the as-received sample was a lamellar structure consisting of soft domains (proeutectoid ferrite) and hard domains (pearlite). The average grain size of proeutectoid α decreased from 24.5 μm (for the initial steel) to 7.1 μm (for the 60 % rolled steel) due to the occurrence of continuous dynamic recrystallization (CDRX). With an increase in the rolling deformation, the homogeneity of the ferrite and pearlite distribution in the microstructure was improved. Fragmentation and bending of the θ lamellae and several shear bands were seen in the 60 % deformed steel. By increasing the strain, the rotation of ferrite grains towards the θ fiber (as shear texture) increased due to the introduction of severe shear plastic deformation caused by the single-roll drive rolling. By increasing the intensity of ⟨100⟩‖ND (caused by the rolling deformation increasing), the amount of hardness enhanced less in the RD-TD section compared to the RD-ND section. As the rolling reduction increased to 60 %, the yield and tensile strength significantly enhanced and reached a maximum of 993.1 MPa and 1017.8 MPa, respectively. This was due to work hardening, grain refinement strengthening of α, and fragmentation of θ. The decreasing trend of the work hardening of the 60 % rolled steel was not similar to the strain hardening behavior of homogeneous materials, indicating that the number of geometrically necessary dislocations accumulated at the hard domain/soft domain interfaces was large, which was beneficial to the increment of work hardening in the second stage. After the rolling reduction increased, the proportion of dimples reduced, the depth and number of dimples decreased, and the plasticity reduced, which had a large effect on the secondary cracks.

A well-balanced strength and electrical conductivity in rolled composite prepared by in-situ TiB2p/Cu composite powder

The TiB2p/Cu composites were prepared by current-assisted vacuum hot pressing (CAVHP) combined with rolling using in-situ spherical TiB2p/Cu composite powder as raw material. The effects of rolling deformation on the microstructure and properties of the sintered TiB2p/Cu composite were investigated. The results show that CAVHP leads to a rapid densification of the composite powder compact, and the subsequent rolling deformation is able to eliminate the unclosed pores and achieve a uniform distribution of TiB2p. The dynamic recrystallization during cold rolling refines the Cu matrix grains to ultrafine grains with an average grain size of 0.47 μm. The cold rolled TiB2p/Cu composite obtains a remarkable comprehensive performance with ultimate tensile strength, yield strength and electrical conductivity of 621 MPa, 567 MPa and 86.3% IACS, respectively. In addition, the strengthening and fracture mechanism of the cold rolled TiB2p/Cu composite are analyzed. This work will explore a new technological solution for the preparation of high-performance Cu matrix composites.

Modeling the Influence of Okara Flour Supplementation from Time-Temperature Drying Treatment on the Quality of Gluten-Free Roll Produced from Rice Flour.

Okara, an unassuming residue, is emerging as a notable reservoir of essential nutrients, encompassing an abundant supply of protein, dietary fiber, and potent antioxidant components. Hence, the incorporation of okara as an ingredient in the production of rice flour-based rolls held a considerable interest in nutritional and functional aspects. Okara flour supplement was prepared by drying at 100 °C for 2 h and selected based on the highest antioxidant level. Gluten-free rolls were prepared containing 0, 5, and 10% okara flour dried at 100 °C for 2 h, and their physicochemical properties were analyzed. Okara flour addition reduced the deformation of gluten-free batter roll by improving solid and liquid-like behavior, as evaluated with rheological measurements. Rolls containing okara flour processed at 100 °C for 2 h had increased firmness and decreased specific volume compared to the control. However, there were no significant differences in the sensory evaluation scores, suggesting that the consumers' acceptance of the control and the Okara rolls was similar. Okara flour supplement at 10% addition led to the nutritional improvement of the gluten-free rolls (increase of 2.4% protein and 1.32 times dietary fiber, dry basis). In contrast, there were no significant differences in the antioxidant level compared to the control. Okara flour is a functional ingredient with potential use in gluten-free products and a variety of novel products where enrichment is desirable.

Achieving ultra-fine grains and high corrosion resistance of Al–Zn–Mg–Cu alloy by ECAP and post cold rolling

The ultra-fine grain structure of Al–Zn–Mg–Cu alloy was prepared by equal channel angular pressing (ECAP) and post cold rolling (CR) combined deformation process. The effect of different rolling deformation on the microstructure, microhardness and corrosion behavior of the ECAP alloy were studied. The results show that with the increase of rolling deformation, the dislocation density increased, the grain and second phases of the deformed alloy were obviously refined. Grain refinement was mainly due to the gradual transformation of some subgrain boundaries and low angle grain boundaries (LAGBs) of deformed alloys into high angle grain boundaries (HAGBs), which eventually form fine grains. The microhardness improvement was attributed to dislocation strengthening, fine grain strengthening and second phase strengthening. Simultaneously, the corrosion behavior of the alloy was tested by immersion corrosion and intergranular corrosion, which revealed that high-density lattice defects, refined grain and second-phase particles can improve the corrosion resistance of the deformed alloys.