Pulsed current-assisted twelve-roll precision rolling deformation of SUS304 ultra-thin strips with exceptional mechanical properties

Innovative pulsed current-assisted multi-pass rolling tests were conducted on a 12-roll mill during the rolling deformation processing of SUS304 ultra-thin strips.The results show that in the first rolling pass,the rolling reduction rate of a conventionally rolled sample(at room temperature)is 33.8%,which can be increased to 41.5%by pulsed current-assisted rolling,enabling the formation of an ultra-thin strip with a size of 67.3μm in only one rolling pass.After three passes of pulsed current-assisted rolling,the thickness of the ultra-thin strip can be further reduced to 51.7μm.To clearly compare the effects of a pulsed current on the microstructure and mechanical response of the ultra-thin strip,ultra-thin strips with nearly the same thickness reduction were analyzed.It was found that pulsed current can reduce the degree of work-hardening of the rolled samples by promoting dislocation detachment,reducing the density of stacking faults,inhibiting martensitic phase transformation,and shortening the total length of grain boundaries.As a result,the ductility of ultra-thin strips can be effectively restored to approximately 16.3%while maintaining a high tensile strength of 1118 MPa.Therefore,pulsed current-assisted rolling deformation shows great potential for the formation of ultra-thin strips with a combination of high strength and ductility.

Microstructure evolution and strengthening mechanism of high -performance powder metallurgy TA15 titanium alloy by hot rolling

Hot deformation of sintered billets by powder metallurgy(PM)is an effective preparation technique for titanium alloys,which is more significant for high-alloying alloys.In this study,Ti–6.5Al–2Zr–Mo–V(TA15)titanium alloy plates were prepared by cold press-ing sintering combined with high-temperature hot rolling.The microstructure and mechanical properties under different process paramet-ers were investigated.Optical microscope,electron backscatter diffraction,and others were applied to characterize the microstructure evolution and mechanical properties strengthening mechanism.The results showed that the chemical compositions were uniformly dif-fused without segregation during sintering,and the closing of the matrix craters was accelerated by increasing the sintering temperature.The block was hot rolled at 1200℃ with an 80%reduction under only two passes without annealing.The strength and elongation of the plate at 20–25℃ after solution and aging were 1247 MPa and 14.0%,respectively,which were increased by 24.5%and 40.0%,respect-ively,compared with the as-sintered alloy at 1300℃.The microstructure was significantly refined by continuous dynamic recrystalliza-tion,which was completed by the rotation and dislocation absorption of the substructure surrounded by low-angle grain boundaries.After hot rolling combined with heat treatment,the strength and plasticity of PM-TA15 were significantly improved,which resulted from the dense,uniform,and fine recrystallization structure and the synergistic effect of multiple slip systems.

Tailoring the texture and mechanical properties of 3%Y_(2)O_(3)p/ZGK200 composites fabricated by unidirectional and cross rolling followed by annealing

3%Y_(2)O_(3)p/ZGK200 composites were subjected to unidirectional rolling(UR)and cross rolling(CR)at 400℃and 350℃followed by annealing at 300℃for 1 h.The microstructure,texture and mechanical properties of rolled and annealed composites were systematically studied.The rolled composites exhibited a heterogeneous microstructure,consisting of deformed grains elongated along rolling direction(RD)and Y_(2)O_(3)particles bands distributed along RD.After annealing,static recrystallization(SRX)occurred and most deformed grains transformed into equiaxed grains.A non-basal texture with two strong T-texture components was obtained after UR while a non-basal elliptical/circle texture with circle multi-peaks was obtained after CR,indicating that rolling path had great influences on texture of the composites.After annealing process,R-texture component disappeared or weakened,as results,a non-basal texture with double peaks tilting from normal direction(ND)to transverse direction(TD)and a more random non-basal texture with circle multi-peaks were obtained for UR and CR composites,respectively.The yield strength of rolled composites after UR showed obvious anisotropy along RD and TD while a low anisotropic yield strength was obtained after CR.Some Y_(2)O_(3)particles broke during rolling.The fracture of the composites was attributed to the existence of Y_(2)O_(3)clusters and interfacial debonding between particles and matrix during tension,as a result,the ductility was not as superior as matrix alloy.

Sandwich structures with tapered tubes as core:A quasi-static investigation

In this article,the experimental and finite element analysis is utilized to investigate the quasi-static compression features of sandwich constructions built with tapered tubes.3D printing technology was utilized to create the hollow centers of the tapering tubes,with and without corrugations.The results demonstrate that the energy absorption(EA)and specific energy absorption(SEA)of the single corrugated tapered tube sandwich are 51.6% and 19.8% higher,respectively,than those of the conical tube sandwich.Furthermore,the results demonstrate that energy absorbers can benefit from corrugation in order to increase their efficiency.Additionally,the tapered corrugated tubes'resistance to oblique impacts was studied.Compared to a straight tube,the tapered tube is more resistant to oblique loads and has a lower initial peak crushing force(PCF),according to numerical simulations.After conducting a parametric study,it was discovered that the energy absorption performance of the sandwich construction is significantly affected by the amplitude,number of corrugations,and wall thickness.EA and SEA of DTS with corrugation number of 8 increased by 17.4%and 29.6%,respectively,while PCF decreased by 9.2% compared to DTS with corrugation number of 10.

Quasi-static and dynamic compressive behaviour of additively manufactured Menger fractal cube structures

This paper presents the first-ever investigation of Menger fractal cubes'quasi-static compression and impact behaviour.Menger cubes with different void ratios were 3D printed using polylactic acid(PLA)with dimensions of 40 mm×40 mm×40 mm.Three different orders of Menger cubes with different void ratios were considered,namely M1 with a void ratio of 0.26,M2 with a void ratio of 0.45,and M3with a void ratio of 0.60.Quasi-static Compression tests were conducted using a universal testing machine,while the drop hammer was used to observe the behaviour under impact loading.The fracture mechanism,energy efficiency and force-time histories were studied.With the structured nature of the void formation and predictability of the failure modes,the Menger geometry showed some promise compared to other alternatives,such as foams and honeycombs.With the increasing void ratio,the Menger geometries show force-displacement behaviour similar to hyper-elastic materials such as rubber and polymers.The third-order Menger cubes showed the highest energy absorption efficiency compared to the other two geometries in this study.The findings of the present work reveal the possibility of using additively manufactured Menger geometries as an energy-efficient system capable of reducing the transmitting force in applications such as crash barriers.

Experimental crushing behavior and energy absorption of angular gradient honeycomb structures under quasi-static and dynamic compression

The high variability of shock in terrorist attacks poses a threat to people's lives and properties,necessitating the development of more effective protective structures.This study focuses on the angle gradient and proposes four different configurations of concave hexagonal honeycomb structures.The structures'macroscopic deformation behavior,stress-strain relationship,and energy dissipation characteristics are evaluated through quasi-static compression and Hopkinson pressure bar impact experiments.The study reveals that,under varying strain rates,the structures deform starting from the weak layer and exhibit significant interlayer separation.Additionally,interlayer shear slip becomes more pronounced with increasing strain rate.In terms of quasi-static compression,symmetric gradient structures demonstrate superior energy absorption,particularly the symmetric negative gradient structure(SNG-SMS)with a specific energy absorption of 13.77 J/cm~3.For dynamic impact,unidirectional gradient structures exhibit exceptional energy absorption,particularly the unidirectional positive gradient honeycomb structure(UPG-SML)with outstanding mechanical properties.The angle gradient design plays a crucial role in determining the structure's stability and deformation mode during impact.Fewer interlayer separations result in a more pronounced negative Poisson's ratio effect and enhance the structure's energy absorption capacity.These findings provide a foundation for the rational design and selection of seismic protection structures in different strain rate impact environments.

Unveiling the rolling texture variations ofα-Mg phases in a dual-phase Mg-Li alloy

LZ91 Mg-Li alloy plates with three types of initial texture were rolled by 70%reduction at both room temperature and 200℃to explore the rolling texture formation ofα-Mg phase.The results showed that the rolling texture is largely affected by the initial texture.All the samples exhibited two main texture components as RD-split double peaks texture and TD-split double peaks texture after large strain rolling.The intensity of the two texture components was strongly influenced by the initial orientation and rolling temperature.Extension twinning altered the large-split non-basal orientation to a near basal one at low rolling strain.The basal orientation induced by twinning is unstable,which finally transmitted to the RD-split texture.The strong TD-split texture formed due to slip-induced orientation transition from its initial orientation.The competition between prismatic and basal slip determined the intensity and tilt angle of the TD-split texture.By increasing the rolling temperature,the TD-split texture component was enhanced in all three samples.Limitation of extension twinning behavior and the promotion of prismatic slip at elevated temperature are the main reasons for the difference in hot and cold rolling texture.

Design,preparation,microstructure and mechanical property of the lightweight radiation-shielding Mg-Ta-Al composites basing differential temperature hot rolling

A novel lightweight,radiation-shielding Mg-Ta-Al layered metal-matrix composite(LMC)was successful designed by doping the extremely refractory metal(Ta)into Mg sheets.These Mg-based LMCs sheets shows excellent radiation-dose shield effect,about 145 krad·a^(−1),which is about 17 times of traditional Mg alloy,while its surface density is only about 0.9 g·cm^(−2),reducing by 60%than that of pure Ta.The quantitate relationship between radiation-dose and the materials’thickness was also confirmed to the logistic function when the surface density is in the range of 0.6-1.5 g·cm^(−2).Meantime,the rolling parameters,interface microstructure and mechanical properties in both as-rolled and annealing treated samples were evaluated.The sheets possess a special dissimilar atoms diffusion transitional zone containing an obvious inter-diffusion Mg-Al interface and the unique micro-corrugated Ta-Al interface,as well as a thin Al film with a thickness of about 10μm.The special zone could reduce the stress concentration and enhance the strength of Mg-Ta-Al LMCs.The interface bonding strength reaches up to 54-76 MPa.The ultimate tensile strength(UTS)and yield strength(TYS)of the Mg-Ta-Al sheet were high to 413 MPa and 263 MPa,respectively,along with an elongation of 5.8%.The molecular dynamics(MD)analysis results show that the two interfaces exhibit different formation mechanism,the Mg-Al interface primarily depended on Mg/Al atoms diffusion basing point defects movement,while the Ta-Al interface with a micro-interlock pining shape formed by close-packed planes slipping during high temperature strain-induced deformation process.

Effects of cold rolling path on recrystallization behavior and mechanical properties of pure copper during annealing

The recrystallization behavior,grain boundary characteristic distribution,and mechanical properties of pure Cu sheets that were subjected to different cold rolling paths,and then annealed at 400°C for 10,30,60,and 420 min,were investigated.Different rolling paths changed the grain boundary orientations of cold-rolled copper,causing recrystallized grains to nucleate and grow in an oriented manner.However,the evolution of the texture indicated that cold-rolled copper with different rolling paths did not show an obvious preferred orientation after annealing.The RD-60 specimen exhibited the smallest grain size(6.6μm).The results indicated that the grain size and low-ΣCSL grain boundaries worked together to provide RD-60 samples with appropriate mechanical properties and high plasticity.The yield strength,ultimate tensile strength,and elongation of RD-60 sample were 81 MPa,230 MPa,and 49%,respectively.These results could provide guidance for tuning the microstructures and properties of pure Cu foils,as well as designing fabrication routes for pure Cu foils through processes such as rolling and drawing.

Effect of annealing temperature on microstructure and mechanical properties of Mg-Zn-Zr-Nd alloy with large final rolling deformation

In this study,the Mg-3Zn-0.5Zr-χNd(χ=0,0.6)alloys were subjected to final rolling treatment with large deformation of 50%.The impact of annealing temperatures on the microstructure and mechanical properties was investigated.The rolled Mg-3Zn-0.5Zr-0.6Nd alloy exhibited an ultimate tensile strength of 386 MPa,a yield strength of 361 MPa,and an elongation of 7.1%.Annealing at different temperatures resulted in reduced strength and obviously increased elongation for both alloys.Optimal mechanical properties for the Mg-3Zn-0.5Zr-0.6Nd alloy were achieved after annealing at 200℃,with an ultimate tensile strength of 287 MPa,a yield strength of 235 MPa,and an elongation of 26.1%.The numerous deformed microstructures,twins,and precipitated phases in the rolled alloy could impede the deformation at room temperature and increase the work hardening rate.After annealing,a decrease in the work hardening effect and an increase in the dynamic recovery effect were obtained due to the formation of fine equiaxed grains,and the increased volume fraction of precipitated phases,which significantly improved the elongation of the alloy.Additionally,the addition of Nd element could enhance the annealing recrystallization rate,reduce the Schmid factor difference between basal and prismatic slip systems,facilitate multi-system slip initiation and improve the alloy plasticity.

Reshaping force for deformed casing repairing with hydraulic rolling reshaper and its influencing factors

Hydraulic rolling reshaper is an advanced reshaping tool to solve the problem of casing deformation,which has been widely used in recent years.When it is used for well repair operation,the reshaping force provided by ground devices is generally determined by experience.However,too large reshaping force may destroy the deformed casing,and too small reshaping force may also prolong the construction period and affect the repairing effect.In this paper,based on Hertz contact theory and elastic-plastic theory,combined with the process parameters of shaping,and considering the structural characteristics of the deformed casing and reshaper,we propose a mathematical model for calculating the reshaping force required for repairing deformed casing by hydraulic rolling reshaper.Meanwhile,the finite element model and numerical method of hydraulic rolling reshaper repairing deformed casing are established by using the finite element method,and the reliability of the mathematical model is verified by several examples.On this basis,the control variable method is used to investigate the influence of each parameter on the reshaping force,and the influence degree of each parameter is explored by orthogonal simulation test and Pearson correlation analysis.The research results not only provide an important theoretical basis for the prediction of reshaping force in on-site construction,but also provide a reference for the subsequent improvement of the shaping process.

Online task planning method of anti-ship missile based on rolling optimization

Based on the wave attack task planning method in static complex environment and the rolling optimization framework, an online task planning method in dynamic complex environment based on rolling optimization is proposed. In the process of online task planning in dynamic complex environment,online task planning is based on event triggering including target information update event, new target addition event, target failure event, weapon failure event, etc., and the methods include defense area reanalysis, parameter space update, and mission re-planning. Simulation is conducted for different events and the result shows that the index value of the attack scenario after re-planning is better than that before re-planning and according to the probability distribution of statistical simulation method, the index value distribution after re-planning is obviously in the region of high index value, and the index value gap before and after re-planning is related to the degree of posture change.

Design,Development and Testing of the JTech Bolt for Use in Static,Quasi-Static and Dynamic Domains

Designing a rock reinforcement element requires knowledge of:geomechanical behaviour,interaction of the reinforcement element with rock mass and the element’s mechanistic response in static and dynamic environments.Using this knowledge the JTech bolt was developed and subjected to a thorough program to test,gather data and validate the bolt performance in varying domains.By conducting FE(finite element)modeling,the simulation reviews the JTech bolt design evaluating the effects of threadbar geometric variation,threadbar and nut engagement results under high stress,coating friction response and effects of thread tolerance extremes on the failure mode.These results determine safety factors,tolerances and quality management criteria.Once manufactured,in-situ system testing,laboratory and underground short encapsulation testing,resin mixing testing,double shear testing and dynamic testing at varying velocity and mass,determine the system’s capacity and effectiveness in static,quasi-static and dynamic mining environments.In this paper,the process and results are described.

Intelligent Fault Diagnosis Method of Rolling Bearings Based on Transfer Residual Swin Transformer with Shifted Windows

Due to their robust learning and expression ability for complex features,the deep learning(DL)model plays a vital role in bearing fault diagnosis.However,since there are fewer labeled samples in fault diagnosis,the depth of DL models in fault diagnosis is generally shallower than that of DL models in other fields,which limits the diagnostic performance.To solve this problem,a novel transfer residual Swin Transformer(RST)is proposed for rolling bearings in this paper.RST has 24 residual self-attention layers,which use the hierarchical design and the shifted window-based residual self-attention.Combined with transfer learning techniques,the transfer RST model uses pre-trained parameters from ImageNet.A new end-to-end method for fault diagnosis based on deep transfer RST is proposed.Firstly,wavelet transform transforms the vibration signal into a wavelet time-frequency diagram.The signal’s time-frequency domain representation can be represented simultaneously.Secondly,the wavelet time-frequency diagram is the input of the RST model to obtain the fault type.Finally,our method is verified on public and self-built datasets.Experimental results show the superior performance of our method by comparing it with a shallow neural network.

Multi-dimension and multi-modal rolling mill vibration prediction model based on multi-level network fusion

Mill vibration is a common problem in rolling production,which directly affects the thickness accuracy of the strip and may even lead to strip fracture accidents in serious cases.The existing vibration prediction models do not consider the features contained in the data,resulting in limited improvement of model accuracy.To address these challenges,this paper proposes a multi-dimensional multi-modal cold rolling vibration time series prediction model(MDMMVPM)based on the deep fusion of multi-level networks.In the model,the long-term and short-term modal features of multi-dimensional data are considered,and the appropriate prediction algorithms are selected for different data features.Based on the established prediction model,the effects of tension and rolling force on mill vibration are analyzed.Taking the 5th stand of a cold mill in a steel mill as the research object,the innovative model is applied to predict the mill vibration for the first time.The experimental results show that the correlation coefficient(R^(2))of the model proposed in this paper is 92.5%,and the root-mean-square error(RMSE)is 0.0011,which significantly improves the modeling accuracy compared with the existing models.The proposed model is also suitable for the hot rolling process,which provides a new method for the prediction of strip rolling vibration.

Bonding enhancement of cold rolling TA1 P-Ti/AA6061 composite plates via surface oxidation treatment

TA1 P-Ti/AA6061 composite plate was produced by oxidizing the surface of the titanium plate and adopting a cold roll bonding process.The results revealed that the oxide film(Ti6O)prepared on the surface of TA1 pure titanium was easy to crack during the cold roll bonding,thereby promoting the formation of an effective mechanical interlock at the interface,which can effectively reduce the minimum reduction rate of the composite plates produced by cold rolling of titanium and aluminium plates.Moreover,the composite plate subjected to oxidation treatment exhibited high shear strength,particularly at a 43%reduction rate,achieving a commendable value of 117 MPa.Based on oxidation treatment and different reduction rates,the annealed composite plates at temperatures of 400,450,and 500°C displayed favorable resistance to interface delamination,highlighting their remarkable strength-plasticity compatibility as evidenced by a maximum elongation of 31.845%.

Study of the Characteristics of Large-Diameter Iron Bars Obtained by Rolling at the ODHAV Foundry in the Republic of Guinea

This work consists of evaluating the quality of the mechanical parameters of large-diameter steels, i.e. 20, 25, 28 and 32, through a process of recycling scrap metal that fills garages, rubbish dumps, gutters and other abandoned sites, as well as imported concrete reinforcing steel sold in the Republic of Guinea. To carry out this important work, a number of mechanical tensile and bending tests and a microscopic analysis combining two devices, an electron microscope and a photographic camera, were carried out. The samples were taken from sampling areas in the major communes of Conakry, namely: Casse Sonfonia, Matoto and Kagbélen. The tensile strength values of the large dimensions 20, 25, 28 and 32 are given in the tables.

Improvement of Temperature Drop Model Parameters for 4200mm/3500mm Rolling of Baosteel Medium and Thick Plate

Based on the temperature situation during the rolling process of 4200 mm/3500 mm medium and thick plates at Baosteel,this article analyzes the influencing factors of temperature changes during the rolling process from the perspective of heat transfer theory and the temperature change law during the rolling process.The temperature loss during the four rolling processes is tracked on site,and the temperature drop model parameters during the rolling process of 4200mm/3500mm medium and thick plates at Baosteel are quantitatively provided.It is applied to actual rolling production and has achieved good results.

Influence of Production Sequence of Aluminum Alloy Hot Rolling on Strip Surface Quality

With the intensification of market competition in the aluminum alloy strip processing industry,it is dif-ficult to control the mass production of the same specifications,which is bound to affect the hot rolling production.This paper studied the effect of the hot rolling order of aluminum alloy on the surface quality of strip,such as roll printing,color difference,anodic oxidation,etc.,reasonable discharge sequence and corresponding optimization measures were formulated.

Research on new software compensation method of static and quasi-static errors for precision motion controller

To reduce mechanical vibrations induced by big errors compensation, a new software compensation method based on an improved digital differential analyzer (DDA) interpolator for static and quasi-static errors of machine tools is proposed. Based on principle of traditional DDA interpolator, a DDA interpolator is divided into command generator and command analyzer. There are three types of errors, considering the difference of positions between compensation points and interpolation segments. According to the classification, errors are distributed evenly in data processing and compensated to certain interpolation segments in machining. On-line implementation results show that the proposed approach greatly improves positioning accuracy of computer numerical control (CNC) machine tools.