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Rice husk ash (RHA) is an economical and potential reinforcement for producing aluminum matrix composites (AMCs). The present work reports the production and characterization of AA6061/18 vol% RHA AMC using the novel method friction stir processing (FSP). The microstructure was studied using optical microscopy (OM), scanning electron microscopy (SEM) and electron back scattered diagram (EBSD). A homogenous dispersion of RHA particles was obtained in the composite. No agglomeration or segregation was observed. The produced composite exhibited a fine and equiaxed grain structure. RHA particles fragmented during FSP. An improvement in the tensile strength was observed subsequent to reinforcement of RHA particles. The fracture surface was dispersed with fractured RHA particles confirming excellent interfacial bonding with the aluminum matrix.

Friction stir processing (FSP) has been established as a novel solid state technique to produce bulk and surface metal matrix composites. The present work aim to produce copper matrix composites (CMCs) using FSP and analyze the effect of ceramic reinforcement type (SiC, Al 2 O 3 , B 4 C and TiC) on the evolving microstructure, microhardness and wear resistance behavior. A groove was made on 6 mm thick copper plates and packed with various ceramic particles. A single pass FSP was carried out using a tool rotational speed of 1000 rpm, travel speed of 40 mm/min and an axial force of 10 kN. The microstructure and distribution of the ceramic particles were studied using optical and field emission scanning electron microscopy. The sliding wear behavior was evaluated using a pin-on-disk apparatus. The results indicate that the variation in the stir zone, distribution, grain size, hardness and wear resistance of CMCs were within a short range. Nevertheless, Cu/B 4 C CMC exhibited superior hardness and wear resistance compared to other CMCs produced in this work under the same set of experimental conditions.

In the present research, the influence of friction stir welding (FSW) tool material on the mechanical and microstructural properties of friction stir (FS) welded 316L stainless steel butt joints is investigated. FS welds were produced using two different tungsten based FSW tools having identical tool shoulder and pin profiles. In both the cases, the FSW experimental runs were carried out using tool rotational speed of 600 rpm, welding speed of 45 mm/min, axial force of 11 kN and tool tilt angle of 1.5°. The results of the study show that the joints produced using the tungsten lanthanum oxide tool are having superior mechanical and microstructural properties when compared to the joints produced using tungsten heavy alloy tool. Furthermore, the tool degradation study by mass loss and photographic techniques suggests that the tungsten lanthanum oxide tool is more prone to degradation by plastic deformation, whereas the tungsten heavy alloy tool is more prone to degradation by wear.

In the present work, the effect of tool axis offset from the joint interface and geometry of the FSW tool pin on the mechanical and metallographic characteristics of dissimilar friction stir butt welded aluminum (Al) alloy, AA5052 H32 and HSLA steel, IRSM42-93 were investigated. FSW tools having fixed shoulder diameter, pin tip diameter and pin length with three different tapered cylindrical (TC) and one straight cylindrical (SC) tool pin profiles were experimented. The constant FSW parameters used were: tool rotational speed of 500 rpm, welding speed of 45 mm/min, axial load of 7 kN and tool tilt angle of 1.5°. The effect of tool axis offset was investigated by continuously changing the tool axis offset by keeping the tool traverse direction at an angle to the joint interface. The ultimate tensile strength (UTS) of the joint is considered as the main criterion of the joint performance. The results show that the TC pin profile is beneficial and for a given FSW tool geometry and parameters, the taper angle of the tool pin and volume of tool pin penetration into steel side have significant influence on the thickness and composition of the intermetallic compound (IMC) layer formed and hence the joint performance. FSW tool having TC pin with 10° taper angle has produced the best joint at a tool axis offset of 2 mm towards the Al alloy. For the experimented tool pin geometries, the IMC layer formed at the joint interface is consistent with FeAl, Fe2Al5 and FeAl3.

An attempt was made to synthesize Cu/B4C surface composite using friction stir processing (FSP) and to analyze the influence of tool rotational speed on microstructure and sliding wear behavior of the composite. The tool rotational speed was varied from 800 to 1200 r/min in step of 200 r/min. The traverse speed, axial force, groove width and tool pin profile were kept constant. Optical microscopy and scanning electron microscopy were used to study the microstructure of the fabricated surface composites. The sliding wear behavior was evaluated using a pin-on-disc apparatus. The results indicate that the tool rotational speed significantly influences the area of the surface composite and the distribution of B4C particles. Higher rotational speed exhibits homogenous distribution of B4C particles, while lower rotational speed causes poor distribution of B4C particles in the surface composite. The effects of tool rotational speed on the grain size, microhardness, wear rate, worn surface and wear debris were reported.

Aluminum rich intermetallic particles are potential reinforcements for discontinuously reinforced aluminum matrix composites (DRAMCs). The objective of the present work is to produce AA6061/Al 3 Ti and AA6061/Al 3 Zr composites using in situ casting technique and applying friction stir processing (FSP) to enhance the distribution and morphology of Al 3 Ti and Al 3 Zr particles. AA6061/Al 3 Ti and AA6061/Al 3 Zr DRAMCs were produced by the in situ reaction of inorganic salts K 2 TiF 6 and K 2 ZrF 6 with molten aluminum. The microstructure was observed using optical and scanning electron microscopy. AA6061/Al 3 Ti DRAMC exhibited clusters of Al 3 Ti particles while the segregation of needle shape Al 3 Zr particles was observed in AA6061/Al 3 Zr DRAMC. The prepared composites were subjected to FSP. Significant changes in the distribution and morphology of Al 3 Ti and Al 3 Zr particles were observed after FSP. The changes in microhardness and sliding wear behavior of AA6061/Al 3 Ti and AA6061/Al 3 Zr DRAMCs before and after FSP is detailed in this paper.

The dry sliding wear behavior of AA6061 matrix composite reinforced with aluminium nitride particles (AlN) produced by stir casting process was investigated. A regression model was developed to predict the wear rate of the prepared composite. A four-factor, five-level central composite rotatable design matrix was used to minimize the number of experimental runs. The factors considered in this study were sliding velocity, sliding distance, normal load and mass fraction of AlN reinforcement in the matrix. The developed regression model was validated by statistical software SYSTAT 12 and statistical tools such as analysis of variance (ANOVA) and student's t test. It was found that the developed regression model could be effectively used to predict the wear rate at 95% confidence level. The influence of these factors on wear rate of AA6061/AlNp composite was analyzed using the developed regression model and predicted trends were discussed with the aid of worn surface morphologies. The regression model indicated that the wear rate of cast AA6061/AlNp composite decreased with an increase in the mass fraction of AlN and increased with an increase of the sliding velocity, sliding distance and normal load acting on the composite specimen.

Aluminium Matrix Composites (AMCs) reinforced with particulate form of reinforcement has replaced monolithic alloys in many engineering industries due to its superior mechanical properties and tailorable thermal and electrical properties. As aluminium nitride (AlN) has high specific strength, high thermal conductivity, high electrical resistivity, low dielectric constant, low coefficient of thermal expansion and good compatibility with aluminium alloy, Al/AlN composite is extensively used in electronic packaging industries. Joining of AMCs is unavoidable in many engineering applications. Friction Stir Welding (FSW) is one of the most suitable welding process to weld the AMCs reinforced with particulate form of ceramics without deteriorating its superior mechanical properties. An attempt has been made to develop regression models to predict the Ultimate Tensile Strength (UTS) and Percent Elongation (PE) of the friction stir welded AA6061 matrix composite reinforced with aluminium nitride particles (AlN p ) by correlating the significant parameters such as tool rotational speed, welding speed, axial force and percentage of AlN p reinforcement in the AA6061 matrix. Statistical software SYSTAT 12 and statistical tools such as analysis of variance (ANOVA) and student’s t test, have been used to validate the developed models. It was observed from the investigation that these factors independently influenced the UTS and PE of the friction stir welded composite joints. The developed regression models were optimized to maximize UTS of friction stir welded AA6061/AlN p composite joints.

Friction stir processing (FSP) has evolved as a novel solid state method to prepare surface composites. In this work, FSP technique has been successfully applied to prepare copper surface composites reinforced with variety of ceramic particles such as SiC, TiC, B4C, WC and Al2O3. Empirical relationships are developed to predict the effect of FSP parameters on the properties of copper surface composites such as the area of the surface composite, microhardness and wear rate. A central composite rotatable design consisting of four factors and five levels is used to minimize the number of experiments. The factors considered are tool rotational speed, traverse speed, groove width and type of ceramic particle. The effect of those factors on the properties of copper surface composites is analyzed using the developed empirical relationships and explained in this paper taking into account the microstructural characterization of the prepared copper surface composites. B4C reinforced composites have higher microhardness and lower wear rate.

Development of welding procedures to join aluminum matrix composite (AMCs) holds the key to replace conventional aluminum alloys in many applications. In this research work, AA6061/B4C AMC was produced using stir casting route with the aid of K2TiF6 flux. Plates of 6 mm thickness were prepared from the castings and successfully butt joined using friction stir welding (FSW). The FSW was carried out using a tool rotational speed of 1000 rpm, welding speed of 80 mm/min and axial force of 10 kN. A tool made of high carbon high chromium steel with square pin profile was used. The microstructure of the welded joint was characterized using optical and scanning electron microscopy. The welded joint showed the presence of four zones typically observed in FSW of aluminum alloys. The weld zone showed fine grains and homogeneous distribution of B4C particles. A joint efficiency of 93.4% was realized under the experimental conditions. But, FSW reduced the ductility of the composite.

The microstructure and mechanical characterization of dissimilar friction stir welded AA5083-H111 and AA6351-T6 aluminum alloys were studied. Three different welding speeds (36, 63 and 90 mm/min) were used to weld the dissimilar alloys. The effect of welding speed on mechanical and metallurgical properties was analyzed. It is found that the welding speed of 63 mm/min produces better mechanical and metallurgical properties than other welding speeds. The weld zone is composed of three kinds of microstructures, namely unmixed region, mechanically mixed region and mixed flow region. The fracture mode was observed to be a ductile fibrous fracture.

Multi-criteria integrated production–distribution problems were solved by many researchers using different optimization techniques. A novel analytic hierarchy process (AHP) based heuristic discrete particle swarm optimization (DPSO) algorithm is proposed in this research for solving difficult production–distribution problems. A bearing manufacturing industry's case is considered in this paper and the mathematical model is formulated as mixed integer linear programming (MILP) problem considering multi-period, multi-product and multi-plant scenarios. The three major objectives considered are total cost reduction, minimization of change in labor levels and percentage under-utilization. The results of the AHP based heuristic DPSO algorithm are compared with the branch and bound algorithm results generated using LINGO software. The approach gives good near optimal solutions. In addition to the bearing manufacturing industry dataset, two other test datasets are also solved.

Over the last two decades, aluminium matrix composites (AMCs) reinforced with particulate form of ceramics have attracted much attention due to their superior mechanical properties. In recent years, friction stir welding (FSW) is largely employed to successfully join the AMCs reinforced with ceramic particulates. An attempt has been made to develop a regression model to predict the ultimate tensile strength (UTS) of the friction stir (FS) welded AA6061 matrix composite reinforced with aluminium nitride particles (AlNp) by incorporating significant parameters such as tool rotational speed, welding speed, axial force and percentage of AlNp reinforcement in the matrix. A four factor, five level central composite rotatable design has been used to minimize the number of experimental runs. The effects of those factors on UTS of the welded joints have been analyzed using the developed regression model. The developed regression model has been validated by statistical software SYSTAT 12 and statistical tools such as analysis of variance (ANOVA) and student’s t test. It was found that the model was accurate. The developed regression model can be effectively used to predict the UTS of FS welded joints at 95% confidence level. It was observed from the investigation that factors considered in this study independently influenced the UTS of the FS welded composite joints.

Friction stir processing has evolved as a novel solid state technique to fabricate surface composites. The objective of this work is to apply the friction stir processing technique to fabricate boron carbide particulate reinforced copper surface composites and investigate the effect of B4C particles and its volume fraction on microstructure and sliding wear behavior of the same. A groove was prepared on 6 mm thick copper plates and packed with B4C particles. The dimensions of the groove was varied to result in five different volume fractions of B4C particles (0, 6, 12, 18 and 24 vol.%). A single pass friction stir processing was done using a tool rotational speed of 1000 rpm, travel speed of 40 mm/min and an axial force of 10 kN. Metallurgical characterization of the Cu/B4C surface composites was carried out using optical microscope and scanning electron microscope. The sliding wear behavior was evaluated using a pin-on-disk apparatus. Results indicated that the B4C particles significantly influenced the area, dispersion, grain size, microhardness and sliding wear behavior of the Cu/B4C surface composites. When the volume fraction of B4C was increased, the wear mode changed from microcutting to abrasive wear and wear debris was found to be finer.

Pitting is a form of extremely localized attack that results in holes in the metal. It is one of the most destructive and insidious forms of corrosion. It causes equipment to fail because of perforation with only a small percent weight loss of the entire structure. In this study, effects of plasma transferred arc welding parameters on the pitting corrosion resistance of Colmonoy 5 overlays deposited on austenitic stainless steel plates is investigated. Overlays were deposited as per designed experiments using response surface methodology. Potentiodynamic polarization technique was used for conducting the corrosion tests. A mathematical model for the pitting potential measured during the corrosion tests was developed using the multiple regression technique and it was used to correlate the effect of process parameters on the pitting potential of the overlays.

The relatively new welding process friction stir welding (FSW) was applied in this research work to join 6 mm thick dissimilar aluminum alloys AA5083-H111 and AA6351-T6. The effect of tool rotational speed and pin profile on the microstructure and tensile strength of the joints were studied. Dissimilar joints were made using three different tool rotational speeds of 600 rpm, 950 rpm and 1300 rpm and five different tool pin profiles of straight square (SS), straight hexagon (SH), straight octagon (SO), tapered square (TS), and tapered octagon (TO). Three different regions namely unmixed region, mechanically mixed region and mixed flow region were observed in the weld zone. The tool rotational speed and pin profile considerably influenced the microstructure and tensile strength of the joints. The joint which was fabricated using tool rotational speed of 950 rpm and straight square pin profile yielded highest tensile strength of 273 MPa. The two process parameters affected the joint strength due to variations in material flow behavior, loss of cold work in the HAZ of AA5083 side, dissolution and over aging of precipitates of AA6351 side and formation of macroscopic defects in the weld zone.

Deciding the strategy for production and distribution in a stochastic demand scenario is important for the manufacturing industries. An integrated production-distribution plan considering regular, overtime and outsourced production costs along with inventory holding, backorder, hiring/laying-off and trip-wise distribution costs is developed for a renowned bearing manufacturing industry producing three types of products at three locations. Demand is assumed to vary uniformly and a novel simulation based heuristic discrete particle swarm optimization (DPSO) algorithm is used for obtaining the best production-distribution plan that serves as a trade-off between holding inventory and backordering products. The algorithm also uses an innovative regeneration type constraint handling method which does not require a penalty operator. In addition to the bearing manufacturing industry data set, two other test data sets are also solved. The simulation based optimization approach gives good approximate solutions for the stochastic demand problems.

An attempt has been made to manufacture aluminium (6061-T6) matrix composites reinforced with aluminium nitride particles (AlNp) of size 3–4 μ using indigenously developed modified stir casting method with bottom pouring arrangement in controlled argon environment. To improve the wettability of AlNp with molten Al matrix, 2% Mg has been added. AA6061–AlNp composites have been successfully produced at different weight percentages (viz 0, 5, 10, 15 and 20) of AlNp and their metallurgical and mechanical properties have been analysed. Macrohardness, microhardness, Yield strength and ultimate tensile strength of the composite have improved with the addition of AlNp in the Al matrix. Optical and SEM micrographs reveal the homogeneous distribution of reinforcement particles in the matrix and X-ray diffraction patterns ensure the dispersion of AlNp reinforcement in AA6061 matrix.

Friction stir processing (FSP) has evolved as a viable technology to fabricate surface composite layers. Hybrid composites have attracted the attention of researchers to minimize the wear of counterface materials. In this work, AA6360/(TiC + B4C) hybrid surface composite layers (SCLs) with various volume ratios of TiC and B4C were synthesized by FSP. The particles were compacted into a groove of width 0.5 mm, depth 5.5 mm and length 100 mm cut on the surface of the aluminum plate. The FSP was carried out at a tool rotational speed of 1600 rpm, traverse speed of 60 mm/min and axial force of 8 kN. Two passes were applied in opposite directions. The microstructure and sliding wear behavior of the fabricated SCLs were evaluated. TiC and B4C particles were distributed homogeneously in the SCLs. Both the particles behaved as one type of reinforcement particle during FSP. There was little or no comminution of ceramic particles. Addition of TiC and B4C particles enhanced the wear resistance of AA6360. 50%TiC + 50% B4C hybrid SCL exhibited lowest wear rate due to the formation of a thin tribo film. Detailed characterization of the worn surfaces and the wear debris was also reported.

Inadequate development of fabrication methods restricts the applications of new families of aluminum matrix composites (AMCs). Friction stir welding (FSW) is a potential candidate to join AMCs without any defects associated with conventional fusion welding processes. The primary objective of the present work is to apply FSW process to join AA6061/(0, 5 and 10 wt.%) ZrB 2 in situ cast composites and evaluate the joint properties. The composites were prepared by reacting inorganic salts K 2 ZrF 6 and KBF 4 with molten aluminum and joined using a FSW machine at a tool rotational speed of 1150 rpm, welding speed of 50 mm/min and axial force of 6 kN. The joints showed the presence of various zones such as weld zone (WZ), thermomechanically affected zone (TMAZ) and heat affected zone (HAZ). The weld zone was characterized with a homogenous distribution of ZrB 2 particles. The stirring action of the tool resulted in fragmentation of several clusters present in the parent composite. The weld zone exhibited higher hardness than that of the parent composite. The tensile strength of welded joints was comparable to that of parent composites. The wear resistance of the composites improved subsequent to FSW.

The dry sliding wear behavior of AA6061/ZrB2 in-situ composite prepared by the reaction of inorganic salts K2ZrF6 and KBF4 with molten aluminum was investigated. An attempt was made to develop a mathematical model to predict the wear rate of AA6061/(0–10%) ZrB2 in-situ composites. Four-factor, five-level central composite rotatable design was used to minimize the number of experiments. The factors considered are sliding velocity, sliding distance, normal load and mass fraction of ZrB2 particles. The effect of these factors on the wear rate of the fabricated composite was analyzed and the predicted trends were discussed by observing the wear surface morphologies. The in-situ formed ZrB2 particles enhance the wear performance of the composite. The wear rate of the composite bears a proportional relationship with the sliding velocity, sliding distance and normal load.

Metal matrix composite (MMC) focuses primarily on improved specific strength, high temperature and wear resistance application. Aluminium matrix reinforced with titanium carbide (Al–TiC p ) has good potential. The main challenge is to produce this composite in a cost effective way to meet the above requirements. In this study Al–TiC p castings with different volume fraction of TiC were produced in an argon atmosphere by an enhanced stir casting method. Specific strength of the composite has increased with higher % of TiC addition. Dry sliding wear behaviour of AMC was analysed with the help of a pin on disc wear and friction monitor. The present analyses reveal the improved specific strength as well as wear resistance.

Now a days Friction stir Welding (FSW) has become very popular for joining of aluminium alloys and aluminium based composites. FSW produced the effective joints on the Metal matrix composites (MMCs) without defects like porosity, interfacial chemical reactions, reinforcement segregation etc., The desired mechanical properties of the weld can be achieved, depends on the FSW parameters such as rotational speed (N), welding speed (S), axial force (F) and the reinforcement content (%R) in the MMCs. In this study, a mathematical model was developed to predict the tensile strength friction stir welded Al/B4C joints using SYSTAT software. The central composite design of four factors and five levels has been used to conduct the experiments. The optimal process parameters were estimated from the developed regression equation using Generalized Reduced Gradient (GRG) method.

The process of metal joining for cladding is largely used in many process industries. Plasma transferred arc welding (PTAW) is accurate, and is easily available, with very low dilution and high volume of production. Computation of process equations by PTAW to predict the weld bead geometry is largely used in automatic PTAW. A five factor, five level technique used for the development of mathematical equations for the predicting the weld bead geometry for cladding SS410L (Cr-Si-Ni) onto carbon seat valve rings (ASTM A105) and is presented. The sufficiency and significance of the developed models by F test and t test have been checked respectively. To achieve the desired quality of overlay, the main and interaction effects of the control factors on dilution and bead geometry is presented. The mathematical model and the results obtained were optimized with conformity test. The artificial neural network model was developed to optimize the amount of metal deposited with regards to dilution.

The objective of this research work is to identify a set of friction stir welding parameters to join aluminum matrix composites which will give higher tensile strength, ductility and wear resistance. AA6061/ZrB2 composites were produced by the in situ reaction of K2ZrF6 and KBF4 with molten aluminum. Plates of 6 mm thickness were prepared from castings and joined using friction stir welding. Four factors, five levels central composite rotatable design was used to minimize the number of experiments. The factors considered were tool rotational speed, welding speed, axial force and weight percentage of ZrB2. Mathematical models were developed to predict tensile strength, elongation and wear rate. The developed mathematical models were optimized using generalized reduced gradient method to obtain higher tensile strength, ductility and wear resistance. The optimized parameters can be fed into the friction stir welding machine to automate the process to achieve desirable joint properties.

Aluminum alloys generally present low weldability by traditional fusion welding process. Development of Friction Stir Welding (FSW) has provided an alternative improved way of producing aluminum joints, in a faster and reliable manner. The quality of a weld joint is stalwartly influenced by process parameters used during welding. In this paper an attempt has been made to develop an empirical relationship between FSW process parameters to predict wear resistance of friction stir welded dissimilar aluminum alloys. Four factors, five levels central composite rotatable design has been used to minimize the number of experiments. The FSW parameter considered for experiments are tool pin profile, tool rotational speed, welding speed and axial force. Analysis of variance (ANOVA) technique has been used to check the adequacy of the developed model. The effect of these FSW parameters on wear resistance of the welded joints has been analyzed and the predicted trends are discussed. The FSW process parameters are optimized using Response Surface Methodology (RSM) to maximize the wear resistance. The optimum FSW welding parameters have been identified to maximize the wear resistance.

This work focuses on the fabrication of aluminum (6061-T6) matrix composites (AMCs) reinforced with various weight percentage of B 4 C particulates by modified stir casting route. The wettability of B 4 C particles in the matrix has been improved by adding K 2 TiF 6 flux into the melt. The microstructure and mechanical properties of the fabricated AMCs are analyzed. The optical microstructure and scanning electron microscope (SEM) images reveal the homogeneous dispersion of B 4 C particles in the matrix. The reinforcement dispersion has also been identified with X-ray diffraction (XRD). The mechanical properties like hardness and tensile strength have improved with the increase in weight percentage of B 4 C particulates in the aluminum matrix.