Stephen A. Akinlabi

Effect of heat input on the electrical resistivity of dissimilar friction stir welded joints of aluminium and copper

This paper reports the effect of heat input on the resulting electrical resistivities of joints between aluminium and copper produced with the friction stir welding process. Welds were produced using three different shoulder diameter tools, viz: 15, 18 and 25 mm by varying the rotational speed between 600 and 1200 rpm and the traverse speed between 50 and 300 mm/min in order to vary the heat input to the welds. The microstructures of the joint interfaces were characterized, and the electrical resistivities measured. The resulting microstructural characterization revealed that metallurgical bonding was achieved at the joint interfaces of the welds produced. It was also observed that the electrical resistivity of the joint increased as the heat input to the welds increases.

Finite Element Modelling of Electrokinetic Deposition of Zinc on Mild Steel with ZnO-Citrus sinensis as Nano-Additive

The electrokinetic deposition of zinc on mild steel substrate under the influence of ZnO-Citrus sinensis nano-additive was investigated numerically using a Finite Element (FE) solver. The conductivity of the Acid chloride plus ZnO-Citrus sinensis nano-additive electrolyte and the properties of Zinc and mild steel electrodes were used as the input codes for the model. The model was designed on a 3-dimensional scale. The boundary conditions were set and the model was meshed using the finer mesh capability in the FE solver. The model was processed and readings of the modelled zinc deposited mild steel were taken, validated and analysed so as to get the optimum parameters from the deposition process. Based on the results, the deposition mass and thickness increased with deposition time with ZnO-Citrus sinensis nano-additive, it is thus recommended that relatively high deposition time should be used in order to achieve optimum deposition.

Effect of Scan Velocity on Resulting Curvatures during Laser Beam Bending of AISI 1008 Steel Plates

Forming is a flexible process, by which a variety of different shapes can be produced through mechanical, thermo-mechanical, or thermal [Laser Beam Forming] process. Laser beam forming [LBF] process has been successfully applied to a variety of sheet metal components thereby plastically deforming it. This paper investigates the producing effect of scan velocity on the resulting curvatures and resulting properties of the bent components. The results show that three different curvatures (120, 180 and 240 mm) of 4 mm AISI 1008 low carbon steel plate was successfully produced under an optimized set of process parameters and a direct relationship was observed between the scan velocity and the resulting curvatures. Furthermore, microstructural characterization revealed that the grain structures of the irradiated surfaces are refined with cooling than the bottom due to the nucleation rate of new grains formed at the irradiated surface.

Experimental Investigation of the Effect of ZnO-Citrus sinensis Nano-additive on the Electrokinetic Deposition of Zinc on Mild Steel in Acid Chloride

This work investigated the effect of ZnO-Citrus sinensis nano-additive on the electrokinetic deposition of Zinc on mild steel in acid chloride. Fifty-four plates of (100 × 10 × 3) mm3 mild steel samples were cut, cleaned with dilute H2SO4 solution, rinsed in water and dried. The nano-additive was produced by infusing 30 ml Orange Juice extract in Zinc Oxide solution. The acid chloride electrolyte consisting of 71 g ZnCl, 207 g KCl and 35 g H3BO3 in 1 l of distilled water was divided into six portions. The nano-additive with different molar concentrations 0(0.2)1.0 was added to each portion of the acid chloride. Nine plates of mild steel samples were electroplated with zinc as the anode in each of the six prepared electrolyte solution and plated at different times (three plates each at 10, 15 and 20 min). The effects of electroplating on the average weights were measured and the results from the experiment showed the optimal nano-additive concentration and electroplating time.

The Effects of Sn Addition on the Microstructure and Surface Properties of Laser Deposited Al-Si-Sn Coatings on ASTM A29 Steel

Aluminium and its alloys have been successful metal materials used for many applications like commodity roles, automotive and vital structural components in aircrafts. A substantial portion of Al-Fe-Si alloy is also used for manufacturing the packaging foils and sheets for common heat exchanger applications. The present research was aimed at studying the morphology and surface analyses of laser deposited Al-Sn-Si coatings on ASTM A29 steel. These Fe-intermetallic compounds influence the material properties during rapid cooling by laser alloying technique and play a crucial role for the material quality. Thus, it is of considerable technological interest to control the morphology and distribution of these phases in order to eliminate the negative effects on microstructure. A 3 kW continuous wave ytterbium laser system (YLS) attached to a KUKA robot which controls the movement of the alloying process was utilized for the fabrication of the coatings at optimum laser parameters. The fabricated coatings were investigated for its hardness and wear resistance performance. The field emission scanning electron microscope equipped with energy dispersive spectroscopy (SEM/EDS) was used to study the morphology of the fabricated coatings and X-ray diffractometer (XRD) for the identification of the phases present in the coatings. The coatings were free of cracks and pores with homogeneous and refined microstructures. The enhanced hardness and wear resistance performance were attributed to metastable intermetallic compounds formed.

Effects of forces on the welding tool during the dissimilar joining of aluminium and copper

In 1991, a game changing technique was introduced into the metal joining community. Patented in 1991 by The Welding Institute, the Friction Stir Welding (FSW) process has since transformed the way metal joining is being done. Since then, many industries have come to embrace the new joining technology due to its ease of operation and other numerous advantages it offers. Aside from the ease with which it is employed to join similar metals, FSW provides a way of joining dissimilar metals at the microstructural level without some of the problems that traditional metal joining technologies (especially fusion welding) encounter.

The influence of scanning speed and number of scans on the properties of laser formed steel

Laser Beam Forming (LBF) process is an emerging and new forming method that generally requires brute force to forge the steel into the desired shape instead of using conventional methods. This study investigates the changes that occur in low carbon steel through the laser beam forming process. The parameters under investigation include variable scanning speed and number of scans at fixed laser intensity. The effect of these laser parameters on the chemical composition and properties of low carbon steel is assessed through characterisation of both the as received and LBF formed specimens. Characterizations of the laser formed steels were studied using microstructural analysis and micro hardness profiling. The results show that there is a significant increase in the mechanical properties of the LBF formed materials. Scanning power and the number of scans have a noticeable effect on the curvature achieved in the formed samples. The results obtained will contribute towards the further optimization of laser forming methods for steel for the optimization of the properties of steel using Laser Beam Forming process.

Effect of friction stir processing on the electrical resistivity of AA 6082

The effect of friction stir processing on the electrical resistivity of aluminium alloy (AA6082) is characterised and reported in this paper. The AA 6082 aluminium alloy was friction stir processed at three rotational speeds of 1500, 2500 and 3500 rpm and three different traverse speeds of 50, 150 and 250 mm/min. The processed samples were characterised by optical microscopy and electrical resistivity measurements. Optical microscopy showed a decrease in the grain size of the processed metal compared to the base metal. The electrical resistivity measurements showed that the resistivity of the processed samples is higher compared to the base material.

Statistical Analysis of Friction Stir Weld Data

This chapter discusses the results of statistical analysis conducted on the weld data obtained from friction stir welding of aluminium and copper. The welds were produced by varying the process parameters; the rotational speed was varied between 600 and 1200 rpm and the welding speed varied between 50 and 300 mm/min. The Statistica (version 9.0) statistical analysis software package was used to generate the scatter and surface plots relative to the experimental results obtained from the tensile testing and the FSW data. Regression analysis was also done on the weld data. It was found that the downward vertical force during the welding process has a significant effect on the Ultimate Tensile Strength of the weld and that strong relationships exist between the heat input into the welds and the measured electrical resistivities of the welds.

Laser beam forming: Experimental investigation and statistical analysis of the effects of parameters on bending angle

Laser Beam Forming (LBF), a non-contact manufacturing process has become a viable manufacturing process for shaping of metallic components. The capability of LBF and bending demands more on experimental studies to identify optimized parameter settings and also establish the probable influence of process parameters on the response i.e. the resulting bending angles in the present work. The experiments on laser forming process of 3 mm steel plate were conducted using a 4.4 kW Nd: YAG laser (Rofin DY 044), at the Council for Science and Industrial Research - National Laser Centre (CSIR-NLC), Pretoria, South Africa. This paper investigates the effects of five important process parameters such as namely laser power, beam diameter, number of scan tracks, scan velocity and cooling effect on the resulting formed sample curvature. Statistical tools combined with the Taguchi robust Design of Experiment, based on the L-27 Taguchi Orthogonal array (TOA) have been used. The samples were successfully formed to different curvatures following the experimental design. Both the Taguchi analysis and Analysis of Variance (ANOVA) established that the number of scan irradiation had the maximum effect while cooling effect coolant flow had the least contribution on the bending angle of formed components. Regression analysis was also conducted on the experimental data and a linear model relating all the influencing parameters was developed with an R-square value of around 98% showing the goodness of fit of the model. The regression model confirms that the experimentally measured bending angles were in good agreement with the model predicted values. This model can ultimately be used to estimate the bending angle in LBF of 3 mm steel plate within the study range of parameters.© 2013 ASME