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.

Carbon Fiber Breakage Mechanism in Aluminum(Al)/Carbon Fibers(CFs) Composite Sheet during Accumulative Roll Bonding(ARB) Process

We put forward a method of fabricating Aluminum(Al)/carbon fibers(CFs) composite sheets by the accumulative roll bonding(ARB) method. The finished Al/CFs composite sheet has CFs and pure Al sheets as sandwich and surface layers. After cross-section observation of the Al/CFs composite sheet, we found that the CFs discretely distributed within the sandwich layer. Besides, the tensile test showed that the contribution of the sandwich CFs layer to tensile strength was less than 11% compared with annealed pure Al sheet. With ex-situ observation of the CFs breakage evolution with-16%,-32%, and-45% rolling reduction during the ARB process, the plastic instability of the Al layer was found to bring shear damages to the CFs. At last, the bridging strengthening mechanism introduced by CFs was sacrificed. We provide new insight into and instruction on Al/CFs composite sheet preparation method and processing parameters.

Influence of rolling temperature on the interfaces and mechanical performance of graphene-reinforced aluminum-matrix composites

To study the influence of rolling on the interfaces and mechanical performance of graphene-reinforced Al-matrix composites,a rolling method was used to process them.Using scanning electron microscopy(SEM),transmission electron microscopy(TEM),X-ray diffraction(XRD),Raman spectroscopy,and tensile testing,this study analyzed the micromorphology,interfaces,and mechanical performance of the composites before and after rolling.The experimental results demonstrates that the composites after hot rolling has uniform structures with strong interfacial bonding.With an increase in rolling temperature,the tensile strength and elastic modulus of the composites gradually increase.However,when the rolling temperature is higher than 500°C,granular and rod-like Al4C3 phases are observed at the interfaces and the mechanical performance of the composites is degraded.When the rolling temperature is 480°C,the composites show the optimal comprehensive mechanical performance,with a tensile strength and elastic modulus of 403.3 MPa and 77.6 GPa,respectively,which represent increases of 31.6%and 36.9%,respectively,compared with the corresponding values prior to rolling.

Effect of cold-rolling on tensile strength of SiCw/Al composite

SiC_w/Al composite was fabricated through a squeeze cast route and coldrolled to about 30 percent, 50 percent and 70 percent reduction In thickness, respectively. Thelength of whiskers in the composite before and after rolling was examined using SEM. Some of therolled composites were recrystallization annealed to remove the work hardening of matrix alloy. Thetensile strength of the rolled and annealed SiC_w/Al composites was examined and then associatedwith the change of the whisker length and the work hardening of matrix alloy. It was found that thetensile strength is a function of the degree of cold rolling. For the cold rolled composites, withthe increase in the degree of cold rolling, the tensile strength increases at first, and decreaseswhen the degree of cold rolling exceeds 50 percent. For the annealed ones, however; the tensilestrength decreases monotonously with the increase in rolling degree. The different changes intensile strength between the rolled and annealed composites could be attributed to the result of thecompetition between the work hardening of matrix resulting from the cold rolling and the worksoftening arising from the change of whisker length.

Effects of hot rolling on microstructure and properties of a 20 vol.% SiC_P/Al composite

A 20 vol. percent SiC_p/Al composite was fabricated by squeeze casting, ofwhich a new process for fabricating the preform was used by blending Al powder and SiC particulateswith average diameters of 10 and 3.5 mu m, respectively. The microstructure of the as-cast and thehot-rolled composite was investigated by using TEM, EDS, and SEM, and their tensile properties weremeasured at room temperature. The results show that the ultimate tensile strength and ultimateelongation of the hot-rolled composite are 80 percent and 140 percent higher than those of theas-cast one. The TEM observation result indicates that there are high density of dislocations anddislocation tangles in the hot-rolled composite. Al_2O_3 layers in the composite resulting from thesurface oxidation of the aluminum powders were damaged to spherical particles during hot rolling.All the results indicate that hot-rolling can improve the mechanical properties of the compositeand, therefore, engineering components of the 20 vol. percent SiC_p/Al composite can be produced bysqueeze casting followed by hot-rolling.

Finite element polycrystal model simulation of cold rolling textures in deformation processed two-phase Nb/Al metal-metal composites

The finite element polycrystal model (FEPM) was extended and applied to simulate the development of the cold rolling textures of matrix aluminum in deformation processed two-phase 10% and 20%Nb/Al(in volume fraction) metal-metal composites on the basis of slip deformation of individual grains. This simulation method can assure the continuity of stress and displacement at the boundary during heterogeneous deformation and take arbitrary boundary conditions into consideration. The starting hot-extruded textures, as initial input condition, were taken into account in the FEPM simulation. The simulation results show that the main texture components and their evolution after various cold rolling reductions in 10% and 20%Nb/Al metal-metal composites are well qualitatively in agreement with the experimental ones. The initially extruded textures are rather weak, so they have no much influence on the simulated final cold rolling textures of the matrix aluminum for Nb/Al composites.

Microstructures and properties of 1.0%Al_2O_3/Cu composite treated by rolling

The 1.0%Al2O3/Cu(mass fraction) composite was prepared by hot pressing(HP),then treated by rolling to get a full density. The microstructures and the micro area element distribution of the composite were analyzed by SEM. The density,electric conductivity and tensile strength were also investigated. The experimental results show that the alumina particles are more dispersed and become smaller through a single-pass rolling. The pore existing in the composite is eliminated or closed under the rolling force. The relative density increases from 98.4% to 99.2%. The electric conductivity increases from 88.9%IACS to 91.2%IACS. The tensile strength is increased by 47% from 300 MPa to 440 MPa.

Bending stress of rolling element in elastic composite cylindrical roller bearing

A new structure design method of elastic composite cylindrical roller bearing is proposed, in which PTFE is embedded into a hollow cylindrical rolling element, according to the principle of creative combinations and through innovation research on cylindrical roller bearing structure. In order to systematically investigate the inner wall bending stress of the rolling element in elastic composite cylindrical roller bearing, finite element analysis on different elastic composite cylindrical rolling elements was conducted. The results show that, the bending stress of the elastic composite cylindrical rolling increases along with the increase of hollowness with the same filling material. The bending stress of the elastic composite cylindrical rolling element decreases along with the increase of the elasticity modulus of the material under the same physical dimension. Under the same load, on hollow cylindrical rolling element, the maximum bending tensile stress values of the elastic composite cylindrical rolling element after material filling at 0° and 180° are 8.2% and 9.5%, respectively, lower than those of the deep cavity hollow cylindrical rolling element. In addition, the maximum bending-compressive stress value at 90° is decreased by 6.1%.

Mathematical modeling and simulation of the interface region of a tri-layer composite material,brass-steel-brass,produced by cold rolling

The object of this study was to find the optimum conditions for the production of a sandwich composite from the sheets of brass-steel-brass. The experimental data obtained during the production process were used to validate the simulation program, which was written to establish the relation between the interface morphology and the thickness reduction amount of the composite. For this purpose, two surfaces of a steel sheet were first prepared by scratching brushing before inserting it between two brass sheets with smooth surfaces. Three sheets were then subjected to a cold rolling process for producing a tri-layer composite with various thick- nesses. The sheet interface after rolling was studied by different techniques, and the bonding strength for each rolling condition was determined by peeling test. Moreover, a relation between interfacial bonding strength and thickness reduction was found. The simulation results were compared with the experimental data and the available theoretical models to modify the original simulation program with high application efficiency used for predicting the behavior of the interface under different pressures.

THE OPERATIONAL PROPERTY ANALYSES OF THE COMPOSITE ROLLING BEARING

This paper deals with the test research on noise and fatigue life of the composite rolling bearings which have been developed recently. The test results show that the-composite rolling bearings have remarkable advantages of low noise and great load-bearing capacity over plastic ones.

Effect of Cold-rolling on Hardness of SiC_w/Al Composite

A SiC w/Al composite was fabricated through a squeeze cast route and cold rolled to about 30%, 50% and 70% reduction in thickness, respectively. The length of whiskers in the composite before and after rolling was examined using SEM. Some of the rolled composites were annealed by recrystallizing to remove the work hardening of the matrix alloy. The hardness of the rolled and annealed SiC w/Al composites was examined and then associated with the change of the whisker length and the work hardening of the matrix alloy. It was found that the hardness was a function of the degree of cold rolling. For the cold rolled composites, with the increase in the degree of cold rolling, the hardness increases at first, and decreases when the degree of cold rolling exceeds 50%. For the annealed ones, however, the hardness decreases monotonously with the increase in rolling degree. The different changes in hardness between the rolled and annealed composites could be attributed to a result of the competition between the work hardening of the matrix resulting from the cold rolling and the work softening arising from the change of whisker length.

Rolling of Al-SiC_p Composites

Aluminum based metal matrix composites are offering o utstanding properties in a number of automotive and aircraft components and body structures. The major advantages of these composite materials are their high st rength to weight ratio, high stiffness, high hardness, wear resistance, low coef ficient of thermal expansion, superior dimensional stability and versatility to designer. In addition to these their isotropic properties, good forming characte ristics, easy availability of cheaper reinforcements along with the availability of comparatively low cost, high volume production methods have made them a prom ising material for future growth. Weight reduction is a major goal of automotive innovations. Lighter vehicles/ ai rcraft means less fuel consumption, reduced emissions, and improved performance. Components made from highly loaded aluminium matrix composites are attractive r elative to iron based materials because of their low density, high stiffness (eq uivalent to nodular iron) and better heat transfer characteristics. The basic co st of materials is higher with these advanced composites; however, manufacturing the part to near net shape may offset basic material costs. A good aluminium based material design can improves safety. The aluminium-based composites can give cars better acceleration and braking, improved handling, ex cellent durability, and ease of repair. Tha aluminum-based composite performs a s well or better in crash than conventional steel-structured cars because of th eir larger volume, which can absorb more crash energy. Another excellent advanta ge of Al-SiC p composite in auto design is better stability and response, and reduced noise, vibration/harshness (NHV). These advantages stem from reduced veh icle weight combined with high structural stiffness and also lead to improved st ability and turning response. In the present work Al-SiC p composite plates of 10 to 12 mm thickness w ere cast using sand casting as well as die casting process. The plates were furt her machined to 3 to 4 mm thicknesses. The machined plates were subjected to col d as well hot rolling. The cold rolling of Al-3 wt.% SiC composite plates was done on 2 high experimental cold rolling mill at Indian Oil Corporation Ltd., R esearch and Development centre, Faridabad. For hot rolling, the Al-5 weight % SiC p composite plates were heat treated at 500 ℃ temperature and Al-15 weight % SiC p composite plates were heat treate d at 550 ℃ temperature for 20 minutes. The plates were hot rolled on 2 high ro lling mill of one ton capacity at IIT Delhi. The maximum percentage reduction ob tained after hot rolling of Al-5 weight % SiC p composite and Al- 15 weight % SiC p composite plates for 10 passes was 11 % and 6 % respectively. During col d rolling of Al-SiC p composites cracks (particle fracture) were observed due to the low ductility of Al-SiC p composties at room temperature. The various m echanical properties such as tensile strength, hardness and wear resistance were measured for the rolled and un-rolled Al-SiC p composite plates. The tensile strength of un-rolled and rolled Al-5wt.% SiC p composites are shown in Tab. 1. Table shows that the tensile strength decreases after rolling. This may be du e to the damage of the bonding between aluminum and silicon carbide particulates . The Rockwell hardness values of Al-5 wt.% SiC p composites measured before a nd after hot rolling are shown in Tab.2. The hardness was found to decrease afte r hot rolling, which may be due to the annealing of composites during heating. T he Rockwell hardness values of Al-3 wt.% SiC p composites before and after cold rolling are shown in Tab.3. The Table shows that the Rockwell hardness of Al-SiC p compostes increases after cold rolling due to the workhardening effec t. The wear resistance of rolled and un-rolled Al-SiC p composites were teste d on reciprocating ball on flat wear testing machine. The wear resistance of Al -SiC p composites decreases after hot rolling due to decrease in hardness

Effect of Hot-Plate Rolling on the Microstructure Evolution and Mechanical Properties of In-Situ Nano-TiC_(P)/Al-Mg-Si Composites

The hot-plate rolling(HPR)process is adopted to achieve the optimal strength-ductility for the in-situ nano-TiC_(P)/Al-Mg-Si composites.There was no crack in the sheet by single pass of hot-plate rolling with a thickness reduction of 80%,while there were numerous cracks in the sheet by two passes of conventional hot rolling to achieve a total reduction of 50%.The microstructure and mechanical properties of the composites subjected to 80%thickness reduction of hot rolling at 540℃were investigated by tensile tests,scanning electron microscopy,and electron backscatter diffraction.The yield strength and ultimate tensile strength of in-situ nano-TiC_(P)/Al-Mg-Si composites after the hot-plate rolling process and T6 heat treatment increased significantly due to the dislocation strengthening and precipitation strengthening.

The finite element analysis of articular cartilage fiber-reinforced composite model under rolling load

Articular cartilage is a layer of low-friction,load-bearing soft hydrated tissue covering bone-ends in diarthrosis,which plays an important role in spreading the load,reducing the joint contact stress,joint friction and wear during exercise.The vital mechanical function

Effects of intermediate Ni layer on mechanical properties of Al–Cu layered composites fabricated through cold roll bonding

Layered composites have attracted considerable interest in the recent literature on metal composites. Their mechanical properties depend on the quality of the bonding provided by the intermediate layers. In this study, we analyzed the mechanical properties and bond strengths provided by the nickel layer with respect to its thickness and nature(either powder or coating). The results suggest that bond strength decreases with an increase in the content of nickel powder. At 0.3 vol% of nickel coating, we found the nature of nickel to be less efficient in terms of bond strength. A different picture arose when the content of nickel was increased and the bond strength increased in nickel coated samples. In addition, the results demonstrate that mechanical properties such as bend strength are strongly dependent on bond strength.

Microstructure and mechanical properties of SiC-particle-strengthening tri-metal Al/Cu/Ni composite produced by accumulative roll bonding process

In this study, a multilayer Al/Ni/Cu composite reinforced with Si C particles was produced using an accumulative roll bonding(ARB) process with different cycles. The microstructure and mechanical properties of this composite were investigated using optical and scanning microscopy and hardness and tensile testing. The results show that by increasing the applied strain, the Al/Ni/Cu multilayer composite converted from layer features to near a particle-strengthening characteristic. After the fifth ARB cycle, a composite with a uniform distribution of reinforcements(Cu, Ni, and SiC) was fabricated. The tensile strength of the composite increased from the initial sandwich structure to the first ARB cycle and then decreased from the first to the third ARB cycle. Upon reaching five ARB cycles, the tensile strength of the composite increased again. The variation in the elongation of the composite exhibited a tendency similar to that of its tensile strength. It is observed that with increasing strain, the microhardness values of the Al, Cu, and Ni layers increased, and that the dominant fracture mechanisms of Al and Cu were dimple formation and ductile fracture. In contrast, brittle fracture in specific plains was the main characteristic of Ni fractures.

Processing of nanostructured metallic matrix composites by a modified accumulative roll bonding method with structural and mechanical considerations

Particulate reinforced metallic matrix composites have attracted considerable attention due to their lightweight, high strength, high specific modulus, and good wear resistance. A1/B4C composite strips were produced in this work by a modified accumulative roll bonding process where the strips were rotated 90° around the normal direction between successive passes. Transmission electron microscopy and X-ray diffraction analyses reveal the development of nanostructures in the Al matrix after seven passes. It is found that the B4C reinforcement distribution in the matrix is improved by progression of the process. Additionally, the tensile yield strength and elongation of the processed materials are increased with the increase of passes.

Texture evaluation in AZ31/AZ31 multilayer and AZ31/AA5068 laminar composite during accumulative roll bonding

This article presents the texture development of magnesium AZ31 alloy in the accumulative roll bonded(ARB) AZ31/AZ31 multilayer and AZ31/AA5086 laminate composite.The comparative study demonstrates that the texture evolution in AZ31 in a multilayer system is strongly influenced by the interfaces.A typical basal texture of AZ31 has been observed in AZ31/AZ31 multilayer with texture intensity increased with the rolling deformation.Presence of AZ31/AA5086 interface in the laminate composite leads to a tilted basal texture along the rolling direction(RD) in AZ31 alloy.The texture intensity of composite increased initially with rolling reduction and weakened at the higher rolling strain.Weakening of texture in AZ31 during the laminate processing at higher strain has been attributed to the development of wavy interfaces in AZ31/AA5086 laminate.

Modeling of the Shape Forming of Composite Roll

A shape modeling of spray formed composite roll, which is utilized to predict the shape and dimension of roll during spray forming process, is developed in this paper. The influences of the principal spray forming parameters, such as the spatial distribution of melt mass flux, spray distance, rotating and translating speeds of substrate bar etc. , on the geometry and dimension of spray formed product were investigated.

Experimental research on electromagnetic continuous casting high-speed steel composite roll

A high speed steel composite roll billet was fabricated, which is regular in shape, smooth in surface, slight in trace, compact in internal structure, free of slag inclusion, shrinkage cavity, cracks and other flaws, and good in macro quality of junction surface using a vertical continuous casting machine. The interface zone microstructure of bimetallic in billet of high speed steel composite roll was analyzed by metallurgical microscope(OM), X-ray diffractmeter(XRD), scanning electron microscopy(SEM) and energy-dispersive X-ray analysis(EDS). The results indicate that the microstructure of roll billet is composed of chilled solidified layer, dendrite zone, interfacial zone of bimetal and core material zone. The microstructure of outer shell material is composed of martensite + bainite + residual austenite + some small labyrinth-shape, small-short lath-shape, or dollop-shape eutectic carbides. The microstructure of core material is slice-shape pearlite and a little ferrite along boundary of cells. The interface region microstructure of bimetallic composite roll consists of diffusion region, chilled solidified layer and columnar grain region.