• <tr id="yyy80"></tr>
  • <sup id="yyy80"></sup>
  • <tfoot id="yyy80"><noscript id="yyy80"></noscript></tfoot>
  • 99热精品在线国产_美女午夜性视频免费_国产精品国产高清国产av_av欧美777_自拍偷自拍亚洲精品老妇_亚洲熟女精品中文字幕_www日本黄色视频网_国产精品野战在线观看 ?

    Effect of tool rotational speed on the particle distribution in friction stir welding of AA6092/17.5 SiCp-T6 composite plates and its consequences on the mechanical property of the joint

    2020-05-23 07:09:18UttamAcharyaBarnikSahaRoySubhashChandraSaha
    Defence Technology 2020年2期

    Uttam Acharya, Barnik Saha Roy, Subhash Chandra Saha

    Department of Mechanical Engineering, National Institute of Technology Agartala, Barjala, Jirania, West Tripura, 799046, India

    Keywords:Friction stir welding Aluminium matrix composite Tool rotational speed Particle distribution Mechanical property

    ABSTRACT This study investigates the effect of tool rotational speed (TRS) on particle distribution in nugget zone(NZ) through quantitative approach and its consequences on the mechanical property of friction stir welded joints of AA6092/17.5 SiCp-T6 composite. 6 mm thick plates are welded at a constant tool tilt angle of 2° and tool traverse speed of 1 mm/s by varying the TRS at 1000 rpm,1500 rpm and 2000 rpm with a taper pin profiled tool.Microstructure analysis shows large quantity of uniformly shaped smaller size SiC particle with lower average particle area which are homogeneously distributed in the NZ. The fragmentation of bigger size particles has been observed because of abrading action of the hard tool and resulting shearing effect and severe stress generation due to the rotation of tool. The particles occupy maximum area in the matrix compared to that of the base material (BM) due to the redistribution of broken particles as an effect of TRS.The migration of particles towards the TMAZ-NZ transition zone has been also encountered at higher TRS(2000 rpm).The microhardness analysis depicts variation in average hardness from top to bottom of the NZ,minimum for 1500 rpm and maximum for 2000 rpm.The impact strength at 1000 rpm and 1500 rpm remains close to that of BM (21.6 J) while 2000 rpm shows the accountable reduction. The maximum joint efficiency has been achieved at 1500 rpm (84%) and minimum at 1000 rpm (68%) under tensile loading. Fractographic analysis shows mixed mode of failure for BM,1000 rpm and 1500 rpm, whereas 2000 rpm shows the brittle mode of failure.

    1. Introduction

    Aluminium matrix composites(AMC)due to their extraordinary feature and properties like higher strength and stiffness, reduced density and lightweight nature, better thermal and mechanical properties,improved abrasion and wear resistance,better damping capability, etc. [1,2] over conventional materials. AMCs are extensively using in advanced areas like aerospace,military,automobile,marine, transportation, astronautics and electronic instruments in recent days [3,4]. However, the joining of these materials by conventional fusion welding is not an easy task because of the formation of unwanted defects like porosity, solidification cracking,distortion, reinforcement dissolution, reaction between reinforcement and matrix,etc.in the welding zone[5].Friction stir welding(FSW), established in the year 1991 by TWI, UK [6], joins the material in solid state condition and thus eliminates the defects associated with fusion welding and hence acts as a promising route to join this type of material.It is a green manufacturing and energy efficient process to particularly join nonferrous metals and alloys,MMCs,polymer,etc.[7].The formation and quality of weld joint in FSW largely depends on various aspects like machine parameters(traverse speed (TTS), tool rotational speed (TRS), tool tilt angle(TTA), process forces and torque, plunge rate and depth, tool material and design and types of materials (joint configuration, material property and dimensions) to be joint. Out of several parameters, TRS plays a vital role to impart required heat to plasticize the material in the weld zone so that it can be easily deformed by the tool[8]to achieve a sound joint.TRS is primarily responsible for the stirring and mixing of plasticized material. Frictional heat generated by the rubbing action of shoulder and workpiece surface application can find out elsewhere in the studies[15,19-22]carried out earlier by the different researcher on this material.provides smooth material flow in the weld zone and pushes it from leading edge to the trailing edge via retreating side (RS) while traversing [9] and also facilitate the downward and upward movement of the material. As TRS increases, the heat input also increases and the material experiences more intense stirring and mixing in NZ up to a certain limit of TRS and later decreases.So,it becomes very clear from the above discussion that the formation morphology of the NZ largely depends on TRS.

    Table 1 Chemical composition of the base material.

    On the other hand,Composite materials are composed of matrix and reinforcement phase, where the type, percentage, size and distribution of reinforcement in matrix characterize its property.The AMCs with a discontinuously reinforced particle in the matrix have their own effect in characterization and determining the properties over the other type of AMCs in its domain[10].Haghighi[11] has investigated the effect of equal channel angular pressing(ECAP) and conventional extrusion on particle distribution in Alnano-Al2O3composite. The result shows that four passes of ECAP samples have a better distribution of particles. Boselli et al. [12]have proposed a methodology for quantitatively analyzing the effects of reinforcement spatial distribution and morphology on short crack growth of Al/18.7 vol%SiCp composite.The above-mentioned literature implies the importance of particle distribution in AMCs.When this type of material is being joined by FSW the particles redistribute themselves in the NZ because of TRS. Thus, the distribution of particles in NZ differs from that of the base material(BM),which can largely affect the mechanical property of the joint.Marzoli et al. [13] have found that tool rotation in FSW greatly influence the particle shape and distribution while welding AA6061/Al2O3/20pcomposite plates. Earlier researchers have investigated the particle distribution in terms of particle size to characterize the property of the weld joint.Kim et al.[14]have found that the size of the Si particle reduces as welding speed increases while ADC12 die casting alloy is being FSWed. Acharya et al. [15] have investigated torque and force perspectives on the particle size in the weld zone and its effects of FSW of AMC.The study shows that the mechanical property of the joint increases as the particle size reduces. Few qualitative studies on particle distribution have been also reported.Liu et al.[16]has found improved particle distribution with smooth columnar pin tool than threaded one in FSW of AC4A+30 vol%SiC PRAMCs composites.Rathee et al.[17]suggest that,at an optimum plunge depth, the distribution of SiC particle is good in the Al matrix. In a different work [18], they also found that the groove technique exhibits better homogeneity in the distribution of SiC particle in AA 6063-T6 matrix over several other strategies implemented in that study of FSP.

    Despite of a huge impetus that have developed in the recent years regarding study on FSW of AMCs,very limited work has been conducted till date showing the quantitative analysis of the particle distribution in the nugget zone (NZ), the underlying physics involved in particle distribution due to rotation of the tool and its subsequent effect on the microstructure and mechanical property.This acts as motivation for the current work and an attempt has been made to fill the gap in the field of FSW of AMCs. The current investigation has been carried out on 6 mm thick discontinuously reinforced AMC named AA6092/17.5 SiCp-T6 FSWed at different TRS. This material is very effectively used in industrial and advanced aerostructural applications due to its good physical,mechanical and thermal properties. The detail advantage and

    2. Experimental procedure

    The present investigation is carried out in a dedicated 3T FSW setup on AA6092/17.5 SiCp-T6 composite material plates having a dimension of (150×60×6) mm each. The plates are supplied by DWA ALUMINUM COMPOSITES USA and the chemical composition and mechanical properties of the material are enlisted in Table 1 and Table 2 [15]. The welding is performed at a fixed traverse speed (TS) of 1 mm/s and tool tilt angle (TTA) of 2°with three different tool rotational speeds (TRS) of 1000 rpm, 1500 rpm and 2000 rpm. The parameters are chosen based on the trial run. A plane taper tool pin of 6 mm bottom dia.,3 mm tip dia.and 5.7 mm pin length with 18 mm shoulder dia.made of H13 tool steel having hardness of 56 HRC has been used for welding. This specific configuration is chosen to ensure minimum tool wear and to maintain a homogeneous distribution of reinforcement in the weldment. All the welding is performed at a fixed dwell time of 5 mm/s and with a plunge depth of 0.1 mm. The surface of the plates are carefully cleaned by ethanol prior to a weld run of 100 mm,aimed to eliminate the presence of any foreign material in the plate.

    All the required samples (base material as well as welded samples) for the testing are taken from a region of welding where the torque and force are comparatively stable. The metallography samples were carefully polished and etched before macrostructural analysis in macroscope and microstructural analysis in Carl Zeiss EVO 50 (WSEM) machine. Later, the quantified values of particle distribution has been analysed at different spots from the SEM image of NZ and BM. The samples are then subjected to hardness testing at a load of 100 gf for 10 s in Matsuzawa MMT-X Series ASTM E-384 Vickers microhardness tester. Three samples for Charpy impact testing were prepared for each welding and were tested as per ASTM E-23 standard aimed to investigate the average impact energy at the nugget zone. Similarly, three set of ASTM E8 standard tensile samples were prepared along the transverse direction of each welding and were tested in INSTRON-1195 UTM at a strain rate of 0.5 mm/min. The ultimate tensile strength (UTS),percentage elongation and the joint efficiency were calculated.The tensile fractured samples are subjected to fractographic analysis.

    3. Results & discussion

    The aim of the study is mainly supported by three parts in the current section. In the first part, the formation of particular macrostructures is analysed on different TRS perspectives. Thereafter,the morphology of NZ at different TRS as well as the BM is analysed in terms of particle distribution. In the last part, the effects of change in particle distribution in NZ at different TRS are evaluated in terms of various mechanical property analyses.In this analysis itis assumed that the change in particle distribution in NZ is largely influenced due to TRS involve in the process and not by TS or heat input.

    Table 2 Mechanical properties of the base material.

    Fig.1. Macrostructure of the samples welded at different TRS.

    3.1. Macrostructural observation

    Fig. 1 shows the macrostructures of the samples welded at different TRS. The macrostructures at different TRS looks macroscopically sound. A clear distinction of NZ can be observed in AS than RS for all samples.However,morphological differences can be observed in the samples in terms of formation of the onion ring.The sample at TRS 1000 rpm shows a clear band like structure in the advancing side rather than the formation of conventional onion rings in the NZ.On the other hand,as the TRS increases,the onion ring becomes clearer in the samples.The reason may be related to the generation of required heat input responsible for the smooth and easy flow the plasticized material in NZ.At 1000 rpm,the heat input may not have reached to the optimum extent and as a result,the material in the NZ becomes highly viscous. Due to the higher viscosity of the material at NZ,the shear force acting there becomes more prominent and tries to pull the material from outside the pin area.This led to a less conspicuous distinction between TMAZ and NZ and results in larger NZ area with a band like structure.On the other hand,the micrograph at 1500 rpm and 2000 rpm shows more prominent onion rings and shifts to downward with an increase in TRS.As the TRS increases,the heat input also increases and material in NZ become softer.This facilitates easy flow of material in the pin influenced region and results in the formation of an onion ring. It can be also observed that the area of pin influenced region at 2000 rpm reduces.This may be due to the increased fluidity[15]of the material in NZ at higher heat input which reduces the viscosity of the material.As a result,the material adjacent to the tool pin area experiences less shear force and led to the reduction in pin influenced area. A similar type of happening is also observed by Krishnan [23] in their investigation.

    3.2. Microstructural evolution

    Fig. 2. Schematic representation of macrostructure showing different spots with its respective location where the microstructural and hardness analysis are concentrated.

    Fig. 2 shows a schematic representation of macrostructure where the microstructure and hardness analyses are carried out.The analyses are focused in three individual locations(1 mm below from two surfaces (1 & 3) and at the mid-width (2)) at the NZ.Further three different spots(spot a,spot b and spot c)are chosen in each location for a thorough analysis of the microstructure and related hardness. Such analysis has been framed aimed to get a clear picture of NZ in terms of its particle distribution and mechanical property. The spots are chosen exactly at weld centreline(spot b) and 1.5 mm away from the weld centreline in both sides(spot a & spot c). An assumption has been made in the study that the redistribution of particles in the matrix due to TRS is largely limited to NZ and it also influences the characteristics of the joint.

    3.2.1. Morphological study

    Fig.3 illustrates the microstructure of BM and the selected spot of NZ welded at various TRS. In BM three spots are randomly selected to inspect the consistency of particle distribution in terms of homogeneity, the number of particles distributed, average area of particles and total area occupied by particle over a fixed area in the SEM image with minimum error.All the images are occupied at fixed resolution and area of 9520 μm2for easy comparison of the images and for further analysis. The microstructure of BM shows nearly uniform distribution in the matrix barring agglomeration.However,a higher inter-particle distance can be observed in some region than usual which results in few particle free areas in BM.The bond between the particle and the matrix looks excellent.It can be observed that the maximum number of particle present in the matrix possesses similar size of non-uniform shape with sharp edges. The avg. particle size and area calculated for BM is 7.92 μm and 26.61 μm2. For welded samples, the images are taken at selected spots of different selected locations of NZ to fulfil similar aim at different TRS.As images of the different spot in a particular locations of NZ at varying TRS depicts almost similar morphology characteristics, so only one image (at spot b, excluding spot a and spot c) is considered for the morphology analysis in the current study. The microstructures of different spots of NZ at varying TRS also show homogeneous redistribution of particles in the matrix.The inter-particle distance between particles seems to be more uniform in the microstructures of NZs at 1000 rpm and 1500 rpm compares to that of BM and NZ at 2000 rpm. Compare to BM, a higher amount of smaller size particle can be observed. Additionally, the images of NZ give evidence that the sharp corners of the particles gets blunt and brings more uniformity in shape compared to that of BM.This certain changes in the microstructure of various spots in NZ are exclusively due to the TRS.

    TRS plays multiple roles in the formation of sound weld in FSW.Firstly,it produces the required amount of heat for the softening of material to provide an ideal material flow for the formation of sound joints. Secondly, for joining of AMCs, maintaining the first point it breaks the bigger size particle by the abrasive action of the tool while rotating through highly viscous material and redistribute it the matrix phase[24].In addition to this the fragmentation of the particle is also supported by the shear effect and severe stress generated due to the rotation of tool through highly viscous medium [5,25]. This fragmentation results bigger size particle into smaller pieces and might have brought the variation of structure and shape of the particle in the NZ as observe from Fig.3.Also,the Fig. at various spots of NZ looks denser in terms of particle distribution in the matrix compared to BM due to the same reason.The images of three different spots of each particular location show similar observation. The quantitative analysis of particle distribution is explained in the following sub-section.

    Fig.4 shows the Energy Dispersive Spectroscopy(EDS)analysis of matrix and reinforcement particle of the BM in the spots indicating in Fig.3.This analysis acts as an evidence for using the said material used in this current investigation. Table 3 shows the elemental composition of constituent of BM in wt.%. Spot EDS analysis has been conducted in BM as shown in spot 1 and 2 of BM in Fig. 2. The analysis confirms the presence of the probable elemental composition of matrix and reinforcement phase.

    Fig. 4. Energy Dispersive Spectroscopy (EDS) analysis of matrix and reinforcement in BM at spectrum 1 and spectrum 2 in marked in Fig. 3.

    Table 3 EDS analysis confirming the composition of matrix and reinforcement in BM in wt.%.

    3.2.2. Particle distribution analysis

    A quantitative analysis of particle distribution has been carried out in this study to thoroughly investigate the effect of TRS in morphological changes in NZ at different TRS.The investigation has been carried out minutely starting from different spot to its respective location(shown in Fig.2)and ultimately to the whole NZ at particular TRS. In the end, the particle distribution of NZ at different TRS is compared with one another and with that of BM.Quantification has been made stepwise.Firstly,the total number of particle has been manually calculated in a definite area for each spot. In the second step, the average particle area has been calculated by the manual method in Image-J software in each spot.In the third step,the total area occupied by the particle in a definite area of the image has been revealed for each spot by using first and second step. Then the quantified values of different spots later converge to its respective locations (e.g. location 1 = spot a+ spot b + spot c) of the particular NZ. Lastly, the results from different steps of three locations are converged for a particular NZ,aimed to attain a clear picture of particle distribution of NZ at different TRS so that a fruitful comparison can be made between NZ at different TRS with BM.

    Table 4 exhaustively represents the data of different step for all the spots in BM and NZ at different TRS.The table indicates that the morphology of BM at different spot possesses a nearly equal quantity of particles,unique average particle area and the particles have occupied an equal amount of area in the matrix phase.These indicate the uniformity in particle distribution and therefore confirming a firm microstructure of BM.The particle distribution in NZ(spots)shows the higher amount of particle compare to BM whichcan act as quantitative evidence for the morphological study. In FSW of AMCs,the particle breaks at the shoulder influenced region due to the abrading action of the hard tool with high frictional force at the interface due to tool rotation.This led to a higher quantity of particle at the spots in NZ than BM within the equal area.Variation can be observed in the quantity of particles present and total area occupied by particles in three different spots of each location,while the average particle area remains the same.However,this variation of number of particle present in between each spot for a particular location is negligible compared to the number of particle present in the spots that lies in a particular vertical line for different locations.In FSW, the flow of material is more prominent in the vertical direction rather in horizontal direction and the migration of the particles also depends on this flow. To justify the study, vertically three different locations(1,2,3)along the NZ have been chosen as shown in Fig. 2 to see the variation of overall particle distribution.Further to make the study more accurate and of minimum error three spots on a particular location have been chosen(a,b,c).From Table 4 it can be clearly seen that considering any rpm(say 1000),the variation of particles at the same axis along vertical direction(say 1b,2b and 3b)is much more(191,162 and 143)in comparison to flow in the horizontal direction(say 2a,2b and 2c).This indicates that material flow is much more prominent along vertical direction rather than horizontal direction. As the migration of particle also depends on this flow, so the variation in particle distribution horizontally in a particular zone is limited thereby showing minimum difference in the particle counts of different spot in a particular location. In addition to this, another interesting phenomenon prevails within the three spots of each location. The spot at the weld centreline(spot b)shows a minimum amount of particle while the spot in AS (spot a) have the maximum amount of particle and the spot at RS(spot c)shows the intermediate values.The reason can be related to the mechanics of the material flow of NZ in FSW. FSW involve a high rate of shear stress for the plastic deformation of the material.As a result,the material from the centre of the weld zone may tend to move towards NZ boundary.Due to this phenomenon,the particle from the weld centreline may have tried to push themselves towards the boundary and stretched along the shear stress direction due to high plastic strain and migrates.This causes a continuous deficiency of particle from boundary to the weld centreline. The similar observation has been investigated by Amirizad et al. [26] in their study. It has been observed from the past literature [27] that the material from leading edge travels towards trailing edge and AS via RS.This may be the particular reason that spot at AS (spot a) shows a higher quantity of particles compared to that of the RS (spot c).

    Table 4 Table showing the distribution of the total number of particle, avg. particle area& total particle area in different spots of BM and NZ at different TRS.

    Fig.5 show the analysis of particle distribution at three different locations for each NZ. Fig. 5(a) shows the comparison in terms of variation in the quantity of particle distributed in different locations. The Fig. clearly shows variation in particle distributed in different locations in terms of quantity of particle present for each NZ.Reduction in the quantity of particle from top to bottom of the NZ at 1000 rpm can be observed,while NZ at 2000 rpm shows the opposite trend. Previous literature [28] reported that friction between the shoulder and the workpiece is the main reason for the availability of heat in FSW.Thus the material flows from top to the bottom by achieving the ideal heating condition [29]. Further, the deformed material experiences an outward spinning movement from the pin surface and thus the material reach at the top from bottom and the vice-versa happens when the shoulder pushes back the plasticize material at the bottom. Thus ideal material flow is driven at an ideal heating condition which further depends on TRS and provides a critical viscosity to the material and gets fluidized enough to favour such flow.In this condition,the particle in the NZ migrates with the material flow from top to bottom and vice-versa.The NZ At 1500 rpm might have achieved this ideal condition and results in minimum variation of the particle at the various location from top to bottom. Contrariwise, the heat input at 1000 rpm compared to 1500 rpm is low; as a result, the material at NZ possesses higher viscosity and facilitates higher abrading action to the particle at the interface. This restricts the smooth flow of the material from top to bottom and vice-versa and results in a higher amount of particle at the top and decreases toward the bottom.On the other hand, the higher heat input at 2000 rpm results in more fluidized material leading to lower viscosity. At this condition, the abrading action on the particle reduces due to the lower viscosity and results in a lower density of particle at various locations compare to that of at 1000 rpm and 1500 rpm. The increase in particle density from top to bottom at TRS of 2000 rpm may be due to the better downward flow of material. Fig. 5(b) shows the variation of average particle area with standard deviation at three different locations of all the NZ.Here also the minimum variation is observed at 1500 rpm, whereas, at TRS 2000 rpm the average particle area decreases from top to the bottom of the NZ and 1000 rpm shows the opposite trend.This observation may be due to the same reason as explained before.It can be noticed from the analysis that,the average particle area in the NZ is inversely proportional to the amount of particle present in NZ.The observation implies that the average particle area of NZ depends on TRS at ideal FSW condition with an optimum amount of heat at the NZ. Fig. 5(c) shows the comparison of variation in total area occupied by the particles in the matrix phase over a fixed amount of total area (28560 μm2) of the images at three different locations of a particular NZ. It is a mathematical quantification and is a product of the average particle area and the total amount of particle present in the 2D images of a particular location.This analysis may not lead to an accurate result experimentally,as this analysis is shaped from 2D images and also the shape of the particles in the composite is not similar. Yet the analysis is incorporated in the study,as theoretically the trend will remain the same with a change in particle distribution and will act as a platform for predicting the properties in the NZ. The analysis shows a reduction from top to bottom of the NZ with minimum variation for 1000 TRS and 1500 TRS,while 2000 rpm results in the opposite type.

    Fig. 5. Analysis of particle distribution at three different locations of each NZ (a) variation in quantity of particle (b) variation in average particle area, (c) variation in total area occupied by particles.

    Fig. 6 shows the comparison on different aspects of particle distribution of NZ at different TRS with that of BM. In this part, all the aspects are converged from a different location to the whole NZ at particular TRS aimed to uncover a gross outline for NZ so that a fruitful comparison can be made with BM. Here the observation and findings remains the same due to the similar reason as discussed above.However,it can be observed form the Fig.that,after summing up all the particle areas of each sample,the total particle area of BM,1000 rpm and 1500 rpm samples are quite close. This observation confirms that all the local changes in particle size and quantity happens due to the separation of the particle. However,the Fig. also suggests that the total particle quantity and total particle area in the 2000 rpm sample has decreased noticeably.This may be due to the fact that at higher TRS as the material attains higher plastic state and also becomes less viscous in the NZ, the particle may have moved towards the TMAZ-NZ transition zone.Fig. 7 shows that the TMAZ-NZ transition zone in both the AS and RS for the sample 2000 rpm possesses higher density of bigger size particle which may support the above statement more clearly. A similar type of observation has been also reported by Pol et al.[30]in their study. The effects of TRS on particle distribution are investigated in terms of mechanical property and are explained in the subsequent section.

    Fig. 6. Comparison of the number of particles, average particle area and total area occupied by particles in NZ at different TRS with BM.

    Fig. 7. Accumulation of bigger size particle in the TMAZ-NZ transition zone at higher TRS (2000 rpm).

    3.3. Mechanical property analysis

    This section supports the effect of different TRS in variation of particle distribution in the NZ in terms of mechanical property of the joint. The hardness analysis will support the variation of particle distribution at different location of each NZ.Impact testing will support the effect of variation in particle distribution at NZ at different TRS in terms of total impact energy absorbed by the nugget.The tensile testing supports the overall effect of TRS in the weld zone in terms of its mechanical strength. The fractographic analysis will reveal the effect of TRS in terms of fracture mode of the sample.

    3.3.1. Hardness analysis

    Fig. 8. Comparison of the hardness at different locations of NZ at different TRS.

    Fig.8 shows the Vickers microhardness plot at three locations of each NZ.This analysis has been carried out exactly at the locations where the microstructural and particle distribution analysis has been conducted.The analysis aimed to investigate the effect of TRS perspective on particle distribution and its effect on the variation of hardness at different locations of each NZ. Hardness has been checked by considering random multiple indentations at each location. But the results are inconsistent which leads to the evaluation of an average value of the hardness with standard deviation for best reflection of the result.The hardness of the BM is measured and shown a value of 159 Hv.While graph shows a reduction in the hardness of each NZ compare to BM. The reduction in hardness values can be related to the particle distribution in terms of the amount of particle present in the zone, its shape and total area occupied by it in the matrix phase. It has been observed in the particle distribution analysis section that though the amount of particle increases, the total area occupied by the particle in the matrix reduces.This can be the probable reason as this may disturb the inter particular distance and lead to such reduction in hardness at the particular zone. Additionally, it has been observed that the hardness at different locations of 1000 TRS and 1500 TRS shows lower variation compare to that of 2000 rpm. The variation of hardness in NZ at 2000 rpm varies from 148 Hv to 172 Hv. This variation is resembled with variation in particle distribution in the different location of NZ at 2000 rpm as shown in Fig. 5(a) and (c)which is enough to reveal the reason for such variation in hardness.The average hardness of the total NZ area at TRS of 1000 rpm,1500 rpm and 2000 rpm are 152 Hv, 137 Hv and 159 Hv respectively. So, this observation reveals that the hardness in NZ maybe decrease or increase compared to that of BM. The increase or decrease in hardness of NZ completely depends on the particle distribution along with the type of material flow at the particular heat input.

    Fig. 9. Comparison of impact strength of the nugget zone at different TRS and base material.

    3.3.2. Impact strength analysis

    The Charpy impact testing is carried out on three sub-size specimens of each category to trace the average values. It is aimed to evaluate the impact energy of NZ at different TRS and to compare it with BM as shown in Fig. 9. This type of analysis seeks importance to understand the amount energy absorbed by the welded material before failure, though very few work has been reported till date on FSW of this type of material. However the result of the impact strength of the current material on this study is in conformity with the values cited in literature[31]on same type of material for a preliminary understanding. The current material possesses 17.5 vol% of SiCpreinforced particles of average size of 7.92 μm embedded in AA6092 matrix phase. The presence of particles increases the hardness and UTS while compromising the ductility of the composite material compare to its base matrix material. The effect of reinforcement on the reduction in ductility has been clearly reflected during testing when all the samples failed in two separate parts. In this study, the BM shows higher impact energy among all the samples.The lower values in absorbed impact energies for the welded samples may be due to the reduction in effective area at the weld zone which plays a vital role in the calculation. It is due to the fact that the tool shoulder plunges 0.1 mm in the workpiece during welding so that maximum area of tool shoulder can take part in the welding at TTA of 2°.It facilitates maximum heat input at particular TRS for the necessary material flow in the NZ. However, the graph also shows that the absorbed impact energy decreases as the TRS increases from 1000 rpm to 2000 rpm.The continuous decrease in the absorbed impact energy values can be attributed to the microstructural changes in the NZ due to the induced heat and rotational motion of hard tool in terms of roundness, refinement, quantity and type of distribution of reinforcement and the increase or decrease in matrix grain size[32]. The optimum quantity, uniform shape and distribution of particle in matrix with comparatively smaller grain size increase the property of AMCs. The discussions on microstructure and particle analysis part supports that this deal situation is more prominently prevail in 1000 rpm and 1500 rpm sample compare to 2000 rpm sample.This may be reason that the samples of 1000 rpm and 1500 rpm shows more or less similar absorb impact energy values while 2000 rpm shows comparatively lower value.

    3.3.3. Tensile strength analysis

    Fig.10. Tensile strength comparison (a) Graph showing the comparison of experimental tensile plots, (b) % elongation, joint efficiency and ultimate tensile strength of joints at different tool rotational speed and base material.

    Fig.11. Figure showing different views of tensile fracture samples at different TRS with respective SEM fractography and base material.

    Tensile strength analysis is performed aimed to investigate the overall effect of TRS on the weld zone.This testing is very important for the welded structure to evaluate its quality in the practical application in terms of its mechanical strength. Fig.10 showing a comparison of the tensile strength of the samples welded at different TRS with BM. Fig.10(a) shows the comparison of experimental tensile plots whereas Fig. 10(b) shows the comparison of ultimate tensile strength (UTS), elongation (%) and joint efficiency(%) the samples welded at different TRS to that of BM. Three samples from each type of ASTM-E8 standard are tested at a strain rate of 0.5 mm/min and the average value are considered in the study.Both the plot shows a clear reduction of UTS,joint efficiency and%elongation (except 1500 rpm) with compare to that of BM. The reason may be similar as described for impact strength analysis part.The other probable reason may be supported by the study by Moshwan et al. [33] The joint prepared at TRS of 1000 rpm,1500 rpm and 2000 rpm shows a UTS of 341 MPa, 354 MPa and 282 MPa respectively with a joint efficiency of 82%, 84% and 68%having % elongation of 7.05, 7.8 and 6.95. So. This implies that, as the TRS increases from 1000 rpm to 1500 rpm keeping TS and TTA fixed the property increases and reduces thereafter. This may be due to the better homogeneous structure of the weld zone up toTRS of 1500 rpm at the ideal condition.The ideal condition is in terms of smooth material flow which leads to better particle distribution at the weld zone.The combination of fixed TS and TTA with TRS from 1000 rpm to 1500 rpm may have facilitated the optimum heat input in the weld zone to plasticize the material to a certain level for easy and smooth flow of the material. On the other hand, this ideal condition may not be in the picture for higher heat input at TRS of 2000 rpm and results in reduction of the values.Moreover,there is high chances of oxidation in the weld surface at high heat input which can make the surface brittle and crack may initiates easily from the weld surface at the time of testing and the samples break early. The analysis can be more fruitfully supported by previous literature showing the influences of TRS on tensile strength [29].The higher elongation at TRS of 1500 rpm compared to BM may be due to the presence of more abraded particle. This brings more ductility to the weld zone bt reducing the stress intensity in the structure. It is also a well-established fact that the presence of smaller size particle enhances the mechanical property in AMCs[34].

    3.3.4. Tensile fracture analysis

    The fractographic images of the tensile fracture samples along with their different representative views are shown in Fig.11.Two different views (top & side view) of each fractured samples along with the close view of fracture surface of AS are shown for the better understanding of the fracture mode. All the samples of a particular welding break almost at a similar site in the weld zone.It can be observed from the top and side view of tensile fractured sample that the all the welded sample breaks almost at a fixed distance in the either side of weld centreline and near to the TMAZNZ transition zone.Where,the sample welded at 1000 rpm breaks near the AS and the samples welded at 1500 rpm and 2000 rpm breaks near to the RS.This may be due to the fact that during FSW some amount of bigger size particle shifts towards the TMAZ-NZ transition zone. The accumulation of bigger size particle in this region makes it a weaker site compare to the NZ and the sample breaks in this site under tensile loading.The close view of fracture surface shows that the crack initiates at the weld bead surface and propagate through the NZ-TMAZ interface and ends at the untouched area at the bottom of the plate. The fractograph of BM shows dimple like structure having some particles resides inside the void. This indicates that the BM samples have been failed in mixed mode under tensile loading due to the presence of high amount of particles uniformly distributed in the matrix phase.The fractograph of 1000 rpm and 1500 rpm also shows very similar observation and thereby confirming the more or less similar mode of failure of the samples. This can also be supported by the stressstrain plots shown in Fig.10. On the other hand, the fractographic image of the sample at 2000 rpm shows flat surfaces.This indicates that the sample fractured in a fully brittle manner.This may be due to the improper material flow and variation in particle distribution which led to the disorientation of grains and increases the dislocation density which results in transgranular fracture of the sample under tension.

    4. Conclusion

    In the current research work, an effort has been made to investigate the role of varying TRS in the characterization of NZ in terms of microstructure and particle distribution and its consequences on the mechanical property evolution. A detailed quantitative analysis of particle distribution in the NZ has been studied in terms of total amount of particle present,average particle area and total area occupied by the particle in the matrix. Thereafter, the effect of variation in particle distribution in terms of mechanical property change at different TRS has been studied extensively.The major findings of the study are concluded below:

    a) The macrostructural analysis reveals defect free welding at different TRS. The microstructural analysis shows uniform distribution of particle in BM as well as in different spots on NZ at varying TRS.More uniform shape of the particle can be observed at NZ (1000 rpm and 1500 rpm) compared to BM owing to the breaking of particles.

    b) The distribution of particle is more prominent along the vertical direction compared to the horizontal direction of the nugget for all TRS. The migration of particles towards the TMAZ-NZ transition zone has been also encountered at TRS of 2000 rpm.

    c) Study shows that the hardness of NZ varies from top to bottom of the NZ for all TRS.The impact strength of 1000 rpm and 1500 rpm remains close to that of BM while at 2000 rpm shows deduction. The samples at 1000 rpm and 1500 rpm shows higher joint efficiency compare to 2000 rpm. While,the elongation at 1500 rpm is higher compare to that of BM.The fractographic analysis evident mixed mode of failure for BM, 1000 rpm and 1500 rpm, where samples of 2000 rpm fails in brittle mode.

    d) Overall, the study reveals that the sample welded at TRS of 1500 rpm keeping the TS and TTA fixed at 1 mm/s and 2°shows better result followed by the samples welded at 1000 rpm for all the analysis compare to 2000 rpm.

    Acknowledgment

    The authors would like to acknowledge Ministry of Human Resource, Government of India for providing necessary funding through scholarship to carry out the research activities.The authors would also like to acknowledge DWA ALUMINUM COMPOSITES USA and MSE and ACMS Department, IIT Kanpur for providing plates for the experiment and necessary facilities to conduct the tests respectively.

    午夜福利在线观看免费完整高清在 | 变态另类成人亚洲欧美熟女| x7x7x7水蜜桃| 黄片大片在线免费观看| 精品人妻1区二区| 午夜久久久久精精品| 精品熟女少妇八av免费久了| 欧美性猛交黑人性爽| 99久久久亚洲精品蜜臀av| 国产欧美日韩精品一区二区| 日本三级黄在线观看| 很黄的视频免费| 国模一区二区三区四区视频| 日韩欧美免费精品| 精品欧美国产一区二区三| 男人舔奶头视频| 日本黄色片子视频| 欧美性猛交黑人性爽| 黄色女人牲交| 欧美区成人在线视频| 狂野欧美激情性xxxx| 黄色视频,在线免费观看| 少妇人妻一区二区三区视频| 成年女人看的毛片在线观看| 久久久久国产精品人妻aⅴ院| 脱女人内裤的视频| 国产av一区在线观看免费| 一级黄片播放器| 欧美色视频一区免费| 亚洲av日韩精品久久久久久密| 每晚都被弄得嗷嗷叫到高潮| 操出白浆在线播放| 国产老妇女一区| 欧美中文日本在线观看视频| 淫秽高清视频在线观看| 亚洲成人免费电影在线观看| 亚洲精品456在线播放app | 国产在视频线在精品| 一边摸一边抽搐一进一小说| 亚洲成人中文字幕在线播放| 91九色精品人成在线观看| 欧美乱妇无乱码| 日韩欧美三级三区| 久久精品人妻少妇| 特级一级黄色大片| 国内久久婷婷六月综合欲色啪| 日韩欧美免费精品| 国内精品美女久久久久久| 亚洲男人的天堂狠狠| 中亚洲国语对白在线视频| 久久精品国产亚洲av香蕉五月| 国产探花在线观看一区二区| 亚洲人成伊人成综合网2020| 欧美黑人巨大hd| АⅤ资源中文在线天堂| 亚洲自拍偷在线| 精品不卡国产一区二区三区| 欧美最黄视频在线播放免费| 麻豆国产av国片精品| 九色成人免费人妻av| 欧美乱码精品一区二区三区| 欧美成人一区二区免费高清观看| 全区人妻精品视频| 精品午夜福利视频在线观看一区| 18禁在线播放成人免费| 日韩成人在线观看一区二区三区| 国产毛片a区久久久久| xxx96com| 国产真实乱freesex| 一本久久中文字幕| 色吧在线观看| 亚洲国产精品合色在线| 国产亚洲精品久久久com| eeuss影院久久| 国产黄片美女视频| av黄色大香蕉| 国模一区二区三区四区视频| 男女床上黄色一级片免费看| 亚洲一区二区三区色噜噜| 亚洲无线观看免费| 欧美3d第一页| 欧美成狂野欧美在线观看| 乱人视频在线观看| 欧美日本亚洲视频在线播放| 在线观看舔阴道视频| 亚洲欧美精品综合久久99| 欧美日韩一级在线毛片| 欧美zozozo另类| 国产欧美日韩一区二区三| 天天一区二区日本电影三级| 精品日产1卡2卡| 日本一二三区视频观看| 欧美黄色片欧美黄色片| 欧美+亚洲+日韩+国产| 久久精品综合一区二区三区| 国产精品香港三级国产av潘金莲| 麻豆成人av在线观看| 啦啦啦观看免费观看视频高清| 99久久精品国产亚洲精品| 日韩欧美精品免费久久 | 中出人妻视频一区二区| 亚洲精品美女久久久久99蜜臀| 久久久久国产精品人妻aⅴ院| 老司机午夜十八禁免费视频| 琪琪午夜伦伦电影理论片6080| 国产野战对白在线观看| 婷婷亚洲欧美| 国产激情偷乱视频一区二区| 性欧美人与动物交配| 1024手机看黄色片| 国内毛片毛片毛片毛片毛片| 一区福利在线观看| 亚洲欧美日韩高清在线视频| a在线观看视频网站| 女人高潮潮喷娇喘18禁视频| 九色国产91popny在线| 可以在线观看的亚洲视频| 两个人视频免费观看高清| 国内揄拍国产精品人妻在线| 久久精品国产综合久久久| 尤物成人国产欧美一区二区三区| 级片在线观看| 欧美另类亚洲清纯唯美| 亚洲五月天丁香| 国产精品精品国产色婷婷| 97超视频在线观看视频| 嫩草影视91久久| 亚洲专区国产一区二区| 日韩大尺度精品在线看网址| 一卡2卡三卡四卡精品乱码亚洲| 91久久精品国产一区二区成人 | 国产亚洲精品久久久久久毛片| 国产毛片a区久久久久| 精品福利观看| 欧美绝顶高潮抽搐喷水| 亚洲国产色片| 中文字幕熟女人妻在线| 亚洲美女黄片视频| 亚洲中文字幕一区二区三区有码在线看| 人人妻人人看人人澡| 狂野欧美激情性xxxx| 久9热在线精品视频| 成年女人永久免费观看视频| 每晚都被弄得嗷嗷叫到高潮| 国产黄片美女视频| www日本在线高清视频| 久久久久久久久中文| 国产亚洲精品久久久com| 亚洲熟妇中文字幕五十中出| 好男人电影高清在线观看| 可以在线观看毛片的网站| 毛片女人毛片| 欧美一区二区国产精品久久精品| 在线视频色国产色| 日韩人妻高清精品专区| 又紧又爽又黄一区二区| 成人永久免费在线观看视频| 久久久精品大字幕| 国产精品永久免费网站| 18禁黄网站禁片午夜丰满| 国产91精品成人一区二区三区| 久久久久免费精品人妻一区二区| 亚洲av不卡在线观看| 一边摸一边抽搐一进一小说| 噜噜噜噜噜久久久久久91| 一a级毛片在线观看| 久久久久久人人人人人| 国产精品1区2区在线观看.| 午夜日韩欧美国产| 日韩欧美在线二视频| xxxwww97欧美| 欧美成狂野欧美在线观看| 欧美黑人巨大hd| 夜夜爽天天搞| 亚洲av熟女| 美女高潮喷水抽搐中文字幕| 国产精品影院久久| 亚洲精品在线美女| 亚洲成人免费电影在线观看| 一级黄色大片毛片| 一级毛片女人18水好多| 丰满人妻熟妇乱又伦精品不卡| svipshipincom国产片| 色吧在线观看| 日韩欧美精品v在线| 欧美+亚洲+日韩+国产| 色综合婷婷激情| 特大巨黑吊av在线直播| 午夜精品在线福利| 日本a在线网址| 五月伊人婷婷丁香| 国产一区二区三区视频了| 内射极品少妇av片p| 国产亚洲精品一区二区www| 搞女人的毛片| 看免费av毛片| 99国产综合亚洲精品| 国产99白浆流出| 亚洲va日本ⅴa欧美va伊人久久| 可以在线观看毛片的网站| 成人18禁在线播放| 老司机午夜福利在线观看视频| 亚洲人成伊人成综合网2020| 夜夜夜夜夜久久久久| 性欧美人与动物交配| 精品无人区乱码1区二区| 黄色丝袜av网址大全| 国产久久久一区二区三区| 国产又黄又爽又无遮挡在线| 日韩大尺度精品在线看网址| 久久人妻av系列| 性欧美人与动物交配| 亚洲aⅴ乱码一区二区在线播放| 午夜福利免费观看在线| 女人高潮潮喷娇喘18禁视频| 亚洲中文字幕一区二区三区有码在线看| 国产色婷婷99| 国产精品 欧美亚洲| 51国产日韩欧美| 久9热在线精品视频| 国产麻豆成人av免费视频| 18禁黄网站禁片午夜丰满| 97超级碰碰碰精品色视频在线观看| xxxwww97欧美| 麻豆国产av国片精品| 无人区码免费观看不卡| 90打野战视频偷拍视频| 3wmmmm亚洲av在线观看| 在线观看免费视频日本深夜| 亚洲专区国产一区二区| 香蕉久久夜色| 色综合婷婷激情| 国产精品电影一区二区三区| 亚洲av成人精品一区久久| 国产aⅴ精品一区二区三区波| 久久国产精品人妻蜜桃| 黑人欧美特级aaaaaa片| 成人欧美大片| 久久久久免费精品人妻一区二区| 国产亚洲精品一区二区www| 国产精品99久久久久久久久| 欧美不卡视频在线免费观看| 免费在线观看日本一区| 国产又黄又爽又无遮挡在线| 天堂影院成人在线观看| xxx96com| 成年免费大片在线观看| 天天躁日日操中文字幕| 十八禁人妻一区二区| 中亚洲国语对白在线视频| 国产国拍精品亚洲av在线观看 | 国产黄片美女视频| 真实男女啪啪啪动态图| 乱人视频在线观看| 亚洲精品色激情综合| 久久国产乱子伦精品免费另类| 三级国产精品欧美在线观看| 亚洲 欧美 日韩 在线 免费| 欧美三级亚洲精品| 夜夜看夜夜爽夜夜摸| 欧美三级亚洲精品| 欧美日本亚洲视频在线播放| 国产精品99久久99久久久不卡| 中文资源天堂在线| 国产毛片a区久久久久| 久久精品91蜜桃| 午夜福利高清视频| 中文字幕av成人在线电影| 18禁黄网站禁片免费观看直播| 性色av乱码一区二区三区2| 国内毛片毛片毛片毛片毛片| 最近视频中文字幕2019在线8| 偷拍熟女少妇极品色| 老鸭窝网址在线观看| 麻豆成人午夜福利视频| 少妇的丰满在线观看| www.www免费av| 可以在线观看的亚洲视频| 69人妻影院| 51午夜福利影视在线观看| 一个人免费在线观看的高清视频| 国产午夜精品久久久久久一区二区三区 | tocl精华| 亚洲国产色片| 两人在一起打扑克的视频| 尤物成人国产欧美一区二区三区| 丁香六月欧美| 成人欧美大片| 国产探花在线观看一区二区| 精品国内亚洲2022精品成人| 国产97色在线日韩免费| 毛片女人毛片| 国产成人影院久久av| 高清毛片免费观看视频网站| 毛片女人毛片| 三级毛片av免费| 欧美日韩福利视频一区二区| 美女高潮的动态| 亚洲av不卡在线观看| 国产高清videossex| 两性午夜刺激爽爽歪歪视频在线观看| 国产亚洲精品av在线| 老司机在亚洲福利影院| 小说图片视频综合网站| 日韩中文字幕欧美一区二区| 日本五十路高清| 久久精品国产亚洲av香蕉五月| 国产真人三级小视频在线观看| 少妇丰满av| 色吧在线观看| 亚洲av电影在线进入| 18禁裸乳无遮挡免费网站照片| 亚洲av不卡在线观看| 美女被艹到高潮喷水动态| 老司机在亚洲福利影院| 日韩精品青青久久久久久| 搡老岳熟女国产| 国产主播在线观看一区二区| 亚洲,欧美精品.| 免费大片18禁| 嫩草影院入口| 欧美日韩一级在线毛片| av黄色大香蕉| 亚洲无线观看免费| 亚洲成人免费电影在线观看| 亚洲国产精品999在线| 国产成年人精品一区二区| 男女之事视频高清在线观看| 一本一本综合久久| 亚洲av不卡在线观看| 久久久久久久亚洲中文字幕 | 亚洲,欧美精品.| 色吧在线观看| 亚洲精品美女久久久久99蜜臀| 国产黄色小视频在线观看| 观看美女的网站| 搡老妇女老女人老熟妇| 国产精品嫩草影院av在线观看 | 欧美日韩黄片免| av国产免费在线观看| 国产精品一区二区三区四区久久| 一夜夜www| 女生性感内裤真人,穿戴方法视频| 亚洲五月天丁香| 免费在线观看成人毛片| 观看免费一级毛片| 午夜精品一区二区三区免费看| 亚洲在线自拍视频| 午夜视频国产福利| 激情在线观看视频在线高清| 色哟哟哟哟哟哟| 美女免费视频网站| 变态另类丝袜制服| 男女之事视频高清在线观看| 国产亚洲av嫩草精品影院| 美女 人体艺术 gogo| 一本精品99久久精品77| 欧美乱色亚洲激情| 国产精品99久久99久久久不卡| av欧美777| 18禁美女被吸乳视频| 在线观看日韩欧美| 国产久久久一区二区三区| 久久精品亚洲精品国产色婷小说| 国产99白浆流出| 长腿黑丝高跟| 日日干狠狠操夜夜爽| 三级毛片av免费| 久久国产精品人妻蜜桃| 我要搜黄色片| 色播亚洲综合网| 18禁黄网站禁片午夜丰满| 亚洲天堂国产精品一区在线| 欧美不卡视频在线免费观看| 亚洲乱码一区二区免费版| 久久婷婷人人爽人人干人人爱| 中文字幕人妻丝袜一区二区| 精品久久久久久久末码| 亚洲精品456在线播放app | 婷婷丁香在线五月| 中文字幕人妻熟人妻熟丝袜美 | www日本在线高清视频| av福利片在线观看| 美女黄网站色视频| 亚洲狠狠婷婷综合久久图片| 麻豆成人午夜福利视频| 99热这里只有是精品50| 国产精品99久久99久久久不卡| 日本黄色视频三级网站网址| 男女午夜视频在线观看| 黄色女人牲交| 精品免费久久久久久久清纯| 亚洲人与动物交配视频| 欧美高清成人免费视频www| 免费av不卡在线播放| 亚洲精品一区av在线观看| 国产成年人精品一区二区| 亚洲国产色片| 国产综合懂色| 国产精品99久久99久久久不卡| 国产av在哪里看| 丰满乱子伦码专区| 久久久久九九精品影院| 亚洲欧美日韩高清在线视频| 精品不卡国产一区二区三区| 我的老师免费观看完整版| 色噜噜av男人的天堂激情| 我要搜黄色片| 老司机午夜十八禁免费视频| 一卡2卡三卡四卡精品乱码亚洲| 黑人欧美特级aaaaaa片| 国产午夜精品论理片| 在线天堂最新版资源| 欧美又色又爽又黄视频| 国产一区二区在线观看日韩 | 久久国产乱子伦精品免费另类| 国产高清视频在线观看网站| 中国美女看黄片| 蜜桃久久精品国产亚洲av| 亚洲国产精品合色在线| 欧美又色又爽又黄视频| av视频在线观看入口| 国产单亲对白刺激| 欧美绝顶高潮抽搐喷水| 亚洲真实伦在线观看| 久久精品影院6| or卡值多少钱| 国产亚洲精品久久久com| 国产精品亚洲av一区麻豆| 国产熟女xx| av天堂在线播放| 亚洲内射少妇av| 最后的刺客免费高清国语| 亚洲国产中文字幕在线视频| 国产成+人综合+亚洲专区| 午夜福利在线在线| 国产精品日韩av在线免费观看| 欧美乱妇无乱码| 高清在线国产一区| 成人永久免费在线观看视频| 国产精品av视频在线免费观看| 精品免费久久久久久久清纯| e午夜精品久久久久久久| 国产激情欧美一区二区| 国产免费一级a男人的天堂| 他把我摸到了高潮在线观看| 真人一进一出gif抽搐免费| 国产高清三级在线| 亚洲av二区三区四区| 美女免费视频网站| 欧美激情在线99| 国产久久久一区二区三区| 在线免费观看不下载黄p国产 | 99久久无色码亚洲精品果冻| 亚洲精品456在线播放app | 日本免费一区二区三区高清不卡| 日韩欧美一区二区三区在线观看| 99久久无色码亚洲精品果冻| 中国美女看黄片| 国产 一区 欧美 日韩| 少妇熟女aⅴ在线视频| 欧美bdsm另类| 中文字幕熟女人妻在线| 非洲黑人性xxxx精品又粗又长| 午夜精品一区二区三区免费看| 成人av一区二区三区在线看| 天堂√8在线中文| 操出白浆在线播放| 手机成人av网站| 久久精品国产亚洲av香蕉五月| 国产色婷婷99| 亚洲中文字幕一区二区三区有码在线看| 九九热线精品视视频播放| 久久久国产成人精品二区| 天天一区二区日本电影三级| 亚洲国产精品sss在线观看| 给我免费播放毛片高清在线观看| 看黄色毛片网站| 九九久久精品国产亚洲av麻豆| 亚洲精品久久国产高清桃花| 亚洲在线观看片| 国产精品亚洲一级av第二区| 色综合婷婷激情| 中文字幕高清在线视频| 亚洲 国产 在线| 色综合站精品国产| 中文字幕精品亚洲无线码一区| 国产欧美日韩精品一区二区| 3wmmmm亚洲av在线观看| 母亲3免费完整高清在线观看| svipshipincom国产片| 亚洲人成网站在线播放欧美日韩| 十八禁网站免费在线| 夜夜夜夜夜久久久久| 国产高潮美女av| 日韩av在线大香蕉| 99久久99久久久精品蜜桃| 在线免费观看的www视频| 亚洲精品456在线播放app | 99热只有精品国产| 老司机午夜十八禁免费视频| 动漫黄色视频在线观看| 亚洲av第一区精品v没综合| 免费一级毛片在线播放高清视频| 精品国产美女av久久久久小说| 又爽又黄无遮挡网站| 嫩草影视91久久| 欧美乱妇无乱码| 婷婷精品国产亚洲av| 免费观看人在逋| 丁香六月欧美| 亚洲av免费在线观看| 国产精品亚洲av一区麻豆| 亚洲专区国产一区二区| 18禁国产床啪视频网站| 亚洲欧美日韩高清专用| 啦啦啦韩国在线观看视频| 丁香欧美五月| 日韩欧美三级三区| 国产精品久久久久久人妻精品电影| 人妻丰满熟妇av一区二区三区| 99久久九九国产精品国产免费| 欧美黄色片欧美黄色片| 狂野欧美白嫩少妇大欣赏| 欧美+日韩+精品| 日韩中文字幕欧美一区二区| 香蕉av资源在线| 午夜福利成人在线免费观看| 亚洲成人免费电影在线观看| 亚洲熟妇熟女久久| 少妇的丰满在线观看| 婷婷精品国产亚洲av| 老汉色av国产亚洲站长工具| 无人区码免费观看不卡| 国产极品精品免费视频能看的| 午夜福利免费观看在线| 精品久久久久久成人av| 99久久九九国产精品国产免费| 国产免费av片在线观看野外av| 99精品久久久久人妻精品| 午夜视频国产福利| 国产野战对白在线观看| 欧美成人性av电影在线观看| 精品久久久久久成人av| 亚洲专区国产一区二区| 久久精品国产亚洲av香蕉五月| 欧美xxxx黑人xx丫x性爽| 一本精品99久久精品77| 国产精品综合久久久久久久免费| 欧美性感艳星| 一本精品99久久精品77| 久久欧美精品欧美久久欧美| 久久久久久久精品吃奶| 啦啦啦观看免费观看视频高清| 日本五十路高清| 亚洲av第一区精品v没综合| av黄色大香蕉| 精品人妻1区二区| 国产成人影院久久av| 午夜视频国产福利| av天堂在线播放| 日本a在线网址| 午夜久久久久精精品| 男女午夜视频在线观看| 亚洲av一区综合| 亚洲精品456在线播放app | 看免费av毛片| 国产精品影院久久| 可以在线观看的亚洲视频| 手机成人av网站| 国产三级黄色录像| 熟女少妇亚洲综合色aaa.| 午夜福利高清视频| 亚洲黑人精品在线| 午夜精品一区二区三区免费看| 久久精品国产清高在天天线| 精品无人区乱码1区二区| 国产精品久久久久久久电影 | 久久久国产成人精品二区| 麻豆成人av在线观看| a级毛片a级免费在线| 精品久久久久久成人av| 国产真人三级小视频在线观看| 成人av在线播放网站| 国产毛片a区久久久久| 丰满乱子伦码专区| 日本在线视频免费播放| 成人av一区二区三区在线看| 男女之事视频高清在线观看| 国产伦一二天堂av在线观看| 老汉色av国产亚洲站长工具| 99久国产av精品| 老汉色∧v一级毛片| 亚洲欧美一区二区三区黑人| 国产探花在线观看一区二区| 中文字幕人成人乱码亚洲影| 日韩有码中文字幕| 99精品在免费线老司机午夜| 一二三四社区在线视频社区8| 一卡2卡三卡四卡精品乱码亚洲| 国产免费一级a男人的天堂| 亚洲欧美日韩卡通动漫| 国产激情偷乱视频一区二区| 亚洲熟妇中文字幕五十中出| 99热这里只有精品一区| 中文字幕av成人在线电影| 黄片大片在线免费观看| 一本综合久久免费| 久久精品影院6| a级一级毛片免费在线观看| 丰满人妻一区二区三区视频av | 欧美午夜高清在线| 精品乱码久久久久久99久播| 日韩欧美在线二视频| 人人妻人人澡欧美一区二区|