Cryorolling Research Articles

Microstructure-thermal transport property correlation after cold/cryo rolling deformation of alloy D9

ABSTRACT Plastic deformation alters the microstructure of a material due to the formation of twins, high density of dislocations and strain-induced phases and grain refinement. Such microstructural modifications can affect thermal transport properties of a material. In this work, variation in thermal diffusivity (TD) was investigated in cold worked (CW) and cryo rolled (CR) alloy D9 (ASTM designation A771/UNS S38660), using laser flash analyser after 20–80% thickness reduction. Deformed samples were characterised using XRD and microscopy techniques for structure and microstructure modifications besides correlating with the change in hardness. Temperature dependence of thermal diffusivity was measured from room temperature up to 1273 K. Microstructural features confirmed the formation of deformation-induced martensite in CR specimen. This was accompanied by up to 172% increase in hardness in 80% CR compared to annealed specimen. The dislocation density estimated from XRD structural profile showed an increase with the percentage of deformation. For all specimens, thermal diffusivity showed an increasing trend with temperature but decreased with deformation. The reduction in thermal diffusivity was non-negligible beyond 40% thickness reduction for all deformed specimen and was substantial specifically for CR alloy D9.

Microstructure, Mechanical, and Corrosion Performance of AA4343/AA3003/AA4343 Laminated Sheets Subjected to Cryorolling and Annealing

The effects of cryorolling (CR), hot rolling (HR), and different annealing temperatures on the microstructure, mechanical, and corrosion performance of AA4343/AA3003/AA4343 laminated sheets are studied. Compared with the HR samples, the microstructure of the CR samples presents a significant decrease in the size of elongated grains and significantly large second‐phase particles Al(Mn, Fe)Si in the AA3003 alloy. Grains in CR samples subjected annealing at 200–300 °C become finer. Increasing to 400–550 °C, the grains begin to grow, and the Si is diffused into the core layer. A comparison of HR and CR processing reveals a significant increase in the yield strength from 153 to 209 MPa and the ultimate tensile strength from 168 MPa to 217 MPa of the laminated sheet. Potentiodynamic polarization measurements and immersion tests are conducted to assess the corrosion morphology. After being immersed in a 3.5% NaCl solution for two weeks, the clad surface of the laminated sheet exhibits uniform corrosion products and pitting corrosion, which shows the pitting corrosion depth of the CR sample improved compared to the HR sample. The study suggests that both CR and annealing can be useful for enhancing the mechanical properties, and corrosion morphology of laminated sheets.

Microstructure evolution, mechanical response, and corrosion resistance for a 2195 Al-Li alloy under different rolling reductions during cryorolling

This study used cryorolling (CR) and room temperature rolling (RTR) with different rolling reductions to process the 2195 aluminum-lithium alloy (Al-Li alloy, AA2195) sheets. Subsequently, the AA2195 sheets were artificially aged to the peak aging stage. Their mechanical properties, corrosion resistance, and microstructural evolution sheets were investigated using methods such as hardness testing, tensile testing, intergranular corrosion (IGC) experiments, electrochemical experiments, transmission electron microscopy (TEM), and electron probe microanalysis (EPMA). Compared to the RTR samples, the CR samples exhibited higher hardness, ultimate tensile strength, and elongation under the same rolling reduction conditions due to the combined effect of dislocation strengthening, grain boundary strengthening, and precipitation strengthening. The corrosion resistance of the RTR samples showed a declining trend with the increased rolling reduction. However, the corrosion potential of the CR samples exhibited a non-monotonic trend, first increasing and then decreasing, with the increased rolling reduction. The CR and RTR samples had similar microstructural evolution trends, leading to predominantly IGC morphologies in the IGC tests. The RTR and CR samples exhibited partial pitting morphologies at 70% rolling reduction, and the CR samples had more pronounced pitting characteristics than the RTR samples.

Integrating Experimental and Computational Analyses for Mechanical Characterization of Titanium Carbide/Aluminum Metal Matrix Composites.

This study investigates the mechanical properties of titanium carbide/aluminum metal matrix composites (AMMCs) using both experimental and computational methods. Through accumulative roll bonding (ARB) and cryorolling (CR) processes, AA1050 alloy surfaces were reinforced with TiCp particles to create the Al-TiCp composite. The experimental analysis shows significant improvements in tensile strength, yield strength, elastic modulus, and hardness. The finite element analysis (FEA) simulations, particularly the microstructural modeling of RVE-1 (the experimental case model), align closely with the experimental results observed through scanning electron microscopy (SEM). This validation underscores the accuracy of the computational models in predicting the mechanical behavior under identical experimental conditions. The simulated elastic modulus deviates by 5.49% from the experimental value, while the tensile strength shows a 6.81% difference. Additionally, the simulated yield strength indicates a 2.85% deviation. The simulation data provide insights into the microstructural behavior, stress distribution, and particle-matrix interactions, facilitating the design optimization for enhanced performance. The study also explores the influence of particle shapes and sizes through Representative Volume Element (RVE) models, highlighting nuanced effects on stress-strain behavior. The microstructural evolution is examined via transmission electron microscopy (TEM), revealing insights regarding grain refinement. These findings demonstrate the potential of Al-TiCp composites for lightweight applications.

Microstructure evolution and mechanical properties of Al/Mg–Li/Al laminate metallic composites via hot roll bonding and subsequent cryorolling

Hot roll (HR) bonded Al/Mg–Li laminated metallic composites (LMCs) were subsequent processed using room-temperature rolling (RTR) and cryorolling (CR), respectively. Afterward, the mechanical properties and the microstructure evolution of these LMCs under different rolling temperatures and reductions were studied. The results revealed that the Al/Mg–Li LMCs in the HR + CR1 group (a total reduction of 67 %) exhibited the best comprehensive mechanical properties, with the ultimate tensile strength and elongation ratio of 176.8 MPa and 10 %, respectively. The SEM and EBSD results revealed that the intermediate Mg–Li layer underwent an intense strain-induced phase transformation from the β-Li phase to the α-Mg phase during the RTR, while the strain-induced phase transformation during CR was inhibited due to the gradual atomic diffusion and insufficient driving energy. Therefore, the fraction of the β-Li phases in the Mg–Li layer was higher in HR + CR LMCs compared to HR + RTR LMCs, with the α-Mg phases in the former being evenly distributed in its β-Li matrix. Both β-Li and α-Mg phases in the Mg–Li layer held the stress and strain to ensure the ductility of the Mg–Li layer, which could consequently co-deform with the Al layers, thereby increasing the tensile strength and the elongation simultaneously in HR + CR LMCs. The XRD results revealed that during CR, multiple prismatic <a> slip systems and pyramidal <c+a> slip systems were activated in α-Mg phases, and the slip systems {110}<111>, {123}<111>, and {112}<111> were activated in β-Li phases simultaneously. The activation of a greater number of slip systems in both β-Li and α-Mg phases improved the overall ductility of the LMCs.

Investigation on Various Ceramic Nanoparticles Reinforced Aluminum Matrix Composites via Accumulative Roll Bonding and Cryorolling

Accumulative roll bonding (ARB) and cryorolling (CR) processes are used to fabricate three kinds of composites of AA1050 reinforced with SiCp and TiCp, to become the Al‐SiCp, Al‐TiCp, and Al‐SiCp‐TiCp composites. The effects of reinforced particles and different passes of ARB and CR on mechanical properties, microstructure, and particle distribution are studied. The microstructure shows the uniform distribution of particulates, decreased porosity, and excellent bonding between particle and matrix as the rolling cycles increased. Mechanical properties of the ARBed and cryorolled sheets are examined, and samples are compared with matrix alloy and composites. The findings demonstrate that the Al‐SiCp, Al‐TiCp, and Al‐SiCp‐TiCp composites improve the elastic modulus, yield strength, and hardness. After comparing the results of composites, the best combination of hardness, yield strength, ultimate tensile strength, toughness, and young modulus base composite has been chosen. Al‐TiCp and Al‐SiCp composites demonstrate ductile fracture behavior, as observed through SEM testing, while Al‐SiCp‐TiCp composite sample exhibits a bimodal fracture. This composite should aid in the creation of lightweight composites for use in aeronautical applications.

Deformation mechanism and mechanical properties of a CoCrFeNi high-entropy alloy via room-temperature rolling, cryorolling, and asymmetric cryorolling

The deformation mechanism and mechanical properties of CoCrFeNi high-entropy alloys (HEA) processed by room-temperature rolling (RTR), cryorolling (CR) and asymmetric cryorolling (ACR) were studied. As the rolling reduction increased from 20 % to 80 %, a transition in the dislocation and twinning deformation mechanisms occurred. The cryogenic environment in rolling process can promote the activation of the twins in the HEA at a lower strain, improving the deformation efficiency. The introduction of differential speed ratio led to the finer micro-shear bands with a more uniform distribution, so that the grains were refined to a greater extent. In the ACR HEA after large deformation, the stacking faults accumulated inside the deformation twins further refined the twins along the direction of long axis. This increased the strength of ACR HEA together with Lomer-Cottrell locks and FCC/HCP boundaries, reaching the maximum value compared with CR and RTR. The ultimate tensile strength exceeded 1450 MPa, and the yield strength of ACR HEA increased by nearly 1200 MPa compared to the initial material, while it still maintained the same elongation as RTR and CR. ACR showed the best strength-ductility combination during the whole rolling deformation process. The microstructure evolution and the strengthening contribution mechanism of different rolling were discussed and calculated, and the specific mechanism of how the introduced differential speed ratio further improves the strength-ductility synergistic strengthening in CR was clarified.

A novel way to fabricate high elastic modulus and high strength of TiC reinforced aluminum matrix composite

ABSTRACT This study presents an experimental investigation on Al matrix composites (AMCs) reinforced titanium carbide (TiC) nano-particles produced by five accumulative roll bonding cycles and three cryorolling (CR) cycles. The microstructures and mechanical properties of composites were studied. The results exhibited consequentially improved mechanical properties for processed Al/TiC AMCs as the number of rolling cycles increased. The presence of TiC in Al matrix showed the combination of elastic modulus, hardness, yield, and ultimate tensile stress of 84 ± 2GPa, 86 ± 3HV, 240 ± 12MPa, and 308 ± 15MPa, respectively. The dispersion of TiC particles was improved with increasing in the number of rolling cycles, resulting in a decrease in porosity between the matrix and reinforcement. This phenomenon was attributed to the breakup of particle clusters and their subsequent uniform dispersion within the Al matrix under CR. The composite microstructure shows uniform TiC particle distribution and grain refinement in the Al matrix, which all contribute to the enhanced mechanical properties.

A comprehensive study on size-effect, plastic anisotropy and microformability of aluminum with varied alloy chemistry, crystallographic texture, and microstructure

Fabrication of microparts with large aspect-ratio and complex shapes remains a huge challenge for industries and microforming is a potential solution to manufacture such microparts. However, similarity in specimen-deformation and microstructural length scales during microforming results in size effect, leading to unpredictable plastic behavior and increased process scatter. One approach to counter size effect is by engineering suitable microstructure in the material. In the present work, three grades of Al (AA1070, AA5083, AA2014) with unique alloy chemistry and microstructural profile are processed by cryorolling (CR) to 95% thickness reduction. By imparting controlled postprocess annealing on the CR materials, three distinctive microstructures – (i) ultrafine grained (UFG) with average grain size around 1 μm, (ii) fine grained (FG) with average grain size near to 5 μm, and (iii) coarse grained (CG) with approximate average grain size of 20 μm are engineered. The influence of alloy chemistry, grain boundary engineering and crystallographic texture on microformability are studied. For pure Al (AA1070), the UFG and FG microstructures show superior microformability than the CG counterparts. The equiaxed UFG grains present in these microstructures mitigate the size effect abnormalities by increasing the number of grains in the deformation volume and uniformly distributing the complex microforming strain via grain boundary mediated plasticity. Their corresponding texture containing strong Copper mixed with scattered Cube elements promotes in-plane strain condition and high resistance to localized thinning. Also, the material shows near-zero planar anisotropy that leads to a homogenous in-plane strain distribution. Unlike pure Al, the UFG and FG Al alloys suffer from increased strain localization due to presence of solute clouds and nanoprecipitates. They influence strain-aging (Portevin–Le Chatelier effect), strain gradient hardening phenomenon, and shear propensity during failure of the Al alloys. A composite texture consisting of a combination of Brass, Dillamore, S, and β-fiber elements in the Al alloys is found to be detrimental to their microformability. The Dillamore texture is contributed by formation of adiabatic shear bands during deformation of Al alloys.

Mechanical anisotropy and fracture behaviour of bulk ultra-fine grained AA2099 alloy

ABSTRACT In this work, the effect of cryo-deformation and post-deformation annealing process on tensile, anisotropic and fracture behaviour of AA2099 has been investigated. The development of ultrafine-grained (UFG) microstructure is achieved initially by cryorolling (CR) process on the solution-treated (ST) alloy by subjecting it to a true strain value of 2.3. Cryorolled samples are then followed by annealing process at temperatures of 150°C (CR + 150°C) and 200°C (CR + 200°C). A notable improvement in yield strength (~342 MPa), ultimate tensile strength (~472 MPa), hardness (~138 HV) and fracture toughness parameters (K Q (31.8 MPa √ m ), K ee (31 MPa √ m ) and J integral (57.67 kJ/m2)) is recorded, whereas anisotropy increases in the rolling direction and ductility show a significant drop at CR sample condition in comparison with coarse grains at ST condition. When annealing was executed at 150°C and 200°C, notable improvements in tensile, anisotropic and fracture behaviour of UFG AA2099 were observed. There has been a significant enhancement in tensile strength, anisotropy and fracture toughness until temperature reaches 150°C being the highest (~506 MPa), whereas after 150°C, these properties have been shown to decrease notably.

Microstructure Evolution and Fracture Toughness Behaviour of Cryorolled LM6 Al Alloy

In the present work, the effect of cryo-rolling on the processed LM6 alloy samples has been studied. The solution treated (ST) sample of LM6 alloy has been processed through cryo-rolling with reduction of its thickness with values such as 30%, 40%, and 75%. One of the key material properties i.e., fracture toughness has been studied and equivalent energy fracture toughness ( ) is being evaluated according to the ASTM E 992 standard. The microstructure evolution after processing through cryorolling (CR) has been carried out with the help of optical microscopy and Scanning Electron Microscopy (SEM). Then, the calculated values of fracture toughness parameter i.e., equivalent energy fracture toughness ( is being correlated with the microstructure evolution after processing of LM6 alloy. It was found out that there is an improvement in equivalent energy fracture toughness ( ) as the reduction values increases. The 75% CR sample showed great increment of 67% as compared to ST alloy sample. The microstructure evolution also signifies the mix-mode fracture visualized through Scanning Electron Microscopy (SEM) and as the reduction values increase, the ductile fracture zone dominance increases on brittle fracture zone indicating there is improvement in fracture toughness of the ultra-fined grain LM6 alloy due to the grain refinement, dislocation strengthening and grain boundary strengthening.

Hydrogen Generation from Mg Wastes by Cold Rolling and Ball Milling by Hydrolysis Reaction: Elektron 21 (UNS-M12310) in Simulated Seawater

Hydrolysis is an efficient way of producing hydrogen by using Mg-based waste. In this study, H2 production is realized in simulated seawater (i.e., 3.5 wt.% NaCl) using the Elektron21 (EL21) alloy as a reagent. This alloy is a magnesium-based alloy composed of 96 wt.% Mg and 4 wt.% rare earth (approx. 3 wt.% Nd and 1 wt.% Gd). EL21 is known for its excellent corrosion resistance and high tensile strength. The impact of different mechanical treatments (ball milling, cold rolling, cryo rolling, and cryo ball milling) on the hydrolysis yield of the material was discussed. A pretreatment with cryo rolling before ball-milling treatment shows the best hydrolysis performance, with a yield of 90.5% achieved in 10 min in salted water. The ductile-to-brittle transition induced a modification of the microstructure, which explains the good hydrolysis performances.

Effects of cryorolling, room temperature rolling and aging treatment on mechanical and corrosion properties of 7050 aluminum alloy

In this study, effects of cryorolling (CR), room temperature rolling (RTR) and subsequent aging treatment on mechanical and corrosion properties of 7050 aluminum alloy (AA7050) were investigated. After the severe rolling deformation, the ultrafine-grained structure and high-density dislocations are produced in CR and RTR AA7050 alloys. CR AA7050 exhibits higher volume fraction of UFGs and dislocation density compared to RTR AA7050. Both CR and RTR AA7050 alloys follow the precipitation procedure of nucleation, growth and coarsening, while the DSC test shows that CR AA7050 has stronger response to aging treatment and age-hardening effect. CR AA7050 presents higher micro-hardness (253 HV), yield strength (650 MPa) and ultimate tensile strength (685 MPa), while the elongation (2.2%) is less than RTR AA7050 (245 HV, 573 MPa, 613 MPa, 3.5%). The aging treatment can improve the elongation of rolled samples, while the other mechanical properties are gradually decreased with the increasing in aging time. CR and RTR AA7050 sheets show a low corrosion resistance, while CR are beneficial to improving the corrosion resistance of the aged samples.

Microstructure evolution and strengthening mechanisms of MP159 superalloy during room temperature rolling and cryorolling

Microstructure evolution and strengthening mechanisms of MP159 superalloy during room temperature rolling (RTR) and cryorolling (CR) were studied by using the XRD, EBSD and HRTEM methods. The results suggest that the grains size is finer and the density of dislocations is higher in the CR specimens with the same rolling reduction compared with the RTR specimens. Moreover, the deformation nano-twins and L-C locks can form in the RTR and CR specimens. The strengthening mechanism of the MP159 superalloy during RTR and CR processing is mainly ascribed to the dislocation strengthening, grain refinement strengthening and deformation nano-twins strengthening. After rolling deformation, a higher yield strength (YS) and ultimate tensile strength (UTS) were obtained in the CR specimens. Especially, at the rolling reduction of 48%, the YS and UTS of the CR specimens are 342 MPa and 314 MPa higher than that of the RTR specimens, respectively.

Influence of processing and microstructure on the corrosion behavior of ultrafine grained Al 5083 alloy

Ultrafine grained (UFG) material has received significant research interest due to its combination of strength and toughness when compared with its coarse-grained counterpart. In the present investigation, a distinct UFG microstructure of Al 5083 alloy fabricated through cryorolling (CR), CR followed by warm rolling (WR), and CR followed by short annealing (SA) have been subjected to salt immersion, polarization, and intergranular corrosion tests in 3.5% NaCl solution. A salt immersion test revealed that UFG structures have resistance to pitting corrosion for all conditions when compared to their coarse-grained counterpart. The presence of coarse intermetallic second phase particles leads to the formation of micro galvanic cells with matrix resulting in highly localized pitting corrosion in the solution treated (ST) material, whereas crystallographic pits along the lateral direction have been observed in deformed material. The lower values of corrosion current density ( icorr = 3.640 and 3.910 μA/cm2) were observed for CR and WR conditions, respectively, than ST samples ( icorr = 8.140 μA/cm2) were attributed to the presence of a higher volume fraction of low angle grain boundaries along with a high density of dislocations. SA after CR has slightly increased the corrosion current ( icorr = 3.8 μA/cm2) values thereby shifting the corrosion potentials to a noble direction.

Mechanical properties and microstructure evolution of an Al–Cu–Li alloy via cross cryorolling

The anisotropy of mechanical properties limits the applications of Al–Cu–Li alloys. In this study, microstructure evolution and mechanical properties of an Al–Cu–Li alloy via room-temperature rolling (RTR), room-temperature cross rolling (RCR), cryorolling (CR) and cross cryorolling (CCR) were investigated. The processing of Al–Cu–Li alloy by CCR gave the highest ultimate tensile strength of 471 MPa and an elongation of 8.4% along rolling direction (RD). The elongation of the CCR alloy along the diagonal direction (DD) was higher than those processed by CR, RCR, and RTR. The in-plane anisotropy (IPA) factor of the ultimate tensile strength (3.26%) of the CCR alloy indicated its relatively low anisotropy of the strength. Kernel average mapping (KAM) showed that the deformation was relatively uniform for the CCR alloy. A prominent local low KAM zone appeared in the alloy processed by RCR and RTR. The alloy in the CCR condition exhibits the highest strain hardening rate, progressively decreasing in a sequence of CR, RCR, and RTR. The refined grains and the texture, including mainly copper texture, little Cube texture, little Goss texture and little S texture, are the main reasons for the excellent mechanical properties and balanced strength-ductility of the CCR alloys.

Mechanical performance and characteristics evaluation of material through Cryo rolling process: A review

The demands for lightweight automotive parts are increasing tremendously in the industry. Most of these parts are produced using metal forming processes in order to gain parts that has lightweight, good strength and rigidity. Most of the rolling processes are used to improve ductility and the strength of the material the rolling surface is modified through introduction of an additional step of cross-rolling during the deformation. The mechanical and the microstructure characteristics have been review in this article. The article imposing on the present scenario, last developments and upcoming future directions on topics. This article has been made an attempt to equate the performance of different rolling processes (i.e. Room Temperature Rolling, Cryo rolling, Cryo cross Rolling, Asymmetric Cryorolling) on the material, in the literature.

Mechanical property enhancement and microstructure evolution of an Al-Cu-Li alloy via rolling at different temperatures

An Al-Cu-Li alloy was selected as the model material to get insight into the mechanism of deformation strengthening at cryogenic temperatures. The mechanical properties and microstructure evolution of the alloy fabricated by symmetric rolling and asymmetric rolling (the rolling ratio was 1.3) at different temperatures (25 °C, − 100 °C, − 190 °C) were investigated. Smaller grains and denser dislocations were observed in the cryorolled samples, leading to strength enhancement compared to the samples processed at room temperature. The heterogeneous grain structure was made of coarse and fine grains in the samples processed by cryorolling (CR) at − 100 °C, which resulted in higher strength and better ductility than those processed by CR at − 190 °C and room temperature rolling. Finally, a new back stress model was employed to calculate the yield strength of the heterogeneous structure, which could explain the highest strength of samples processed by CR at − 100 °C.

Effect of cryorolling and ageing on the microstructure and mechanical properties of Al 7085 alloy

Cryorolling (CR) can effectively avoid room temperature rolling cracking of high-strength aluminum alloy. In this work, solution-treated bulk Al 7085 alloy samples were subjected to CR and room temperature rolling (RTR), respectively. When the deformation was 70%, the RTR sample was broken, while the CR one still had no cracks when the deformation was up to 90%. Consequently, the microstructure and mechanical properties of the CR samples before and after ageing treatment were investigated. The results show that after the solution-treated bulk Al 7085 alloy samples were cryorolled, the yield strength (YS) and the ultimate tensile strength (UTS) were increased by 74% and 31%, respectively. However, the elongation to failure (EtF) was decreased. After the subsequent 100 °C/20 h peak ageing (PA) treatment, the YS and UTS can be further increased by 14% and 10%, respectively, and the EtF was increased by 39% compared with that of the CR samples. After PA treatment, nanosized GP zones and η′ precipitates were precipitated. Precipitation strengthening is the main contributor to the strength enhancement of CR samples after PA treatment, which can not only compensate for the reduction caused by the decrease in dislocation density but also improve the strength of the material.

XFEM Simulation of Tensile and Fracture Behavior of Ultrafine-Grained Al 6061 Alloy

In the present work, the tensile and fracture behavior of ultra-fine grained (UFG) Al 6061 alloy was simulated using extended finite element method (XFEM). UFG Al 6061 alloy processed by cryorolling (CR) and accumulative roll bonding (ARB) was investigated in this work. Numerical simulations of two-dimensional and three-dimensional models were performed in “Abaqus 6.14” software using an elastic-plastic approach, and the results obtained were validated with the experimental results. The specimens corresponding to the three-point bend test, compact tension test with center crack, and double edge cracks were analyzed using XFEM (eXtended Finite Element Method) approach. In XFEM, the partition of unity (PU) was used to model a crack in the standard finite element mesh. The tensile and fracture properties obtained from the simulation were in tandem with the experimental data. UFG Al alloy showed higher tensile strength and fracture toughness compared to their bulk solution treated counterparts. Fracture toughness was measured in terms of stress intensity factor and J integral. In CR Al alloys, with increasing thickness reduction, an increase in stress intensity factor and a decrease in the J integral was observed. This behavior is attributed to the increase in strength and decrease in ductility of CR samples with increasing thickness reduction. In ARB Al alloys, the strength and ductility have increased with an increase in number of cycles. It also revealed an increase in both the stress intensity factor and J integral in ARB processed Al alloys with increase in number of cycles, as evident from XFEM simulation results.