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Prior to manufacturing, designing plays a vital role in the selection of materials and other design parameters. Therefore, during the deposition of materials, substrate materials provide support and affect the microstructure of the deposits, which may not be desirable in the manufactured product. Hence, the main purpose of the study is to analyse the behaviour of the microstructure at the interface of deposited material and substrate.

In this study, two blocks of Inconel 625 (IN625) and Stainless steel 304L (SS304L) metal powders were deposited on an SS304L substrate using laser directed energy deposition (DED) technique. Deposited blocks comprised 50% IN625 + 50% SS304L or 100% IN625. After deposition, microstructural behaviour at the interface of the deposits and substrates was analysed using different tests such as optical microscopy (OM), microhardness testing, X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). An improvement in microstructure was proposed by performing heat treatment of the deposited sample.

Formation of martensite and precipitates at the interface of the deposit and substrate was observed. Formation of martensite and precipitates such as α, carbide and δ phases were observed in OM and SEM images. Due to the formation of these phases, interface regions showed a peak in the hardness graphs. Post-heat treatment of the samples was one of the solutions to resolve these issues.

This paper suggests the formation of a heat-affected zone (HAZ) at the interface of the deposit and substrate, which may negatively affect the overall utility of the deposited part. The properties of the HAZ were investigated. To suppress these detrimental effects, post-heat treatment of the deposited sample was performed, and the samples were further analysed. The post-heat-treated samples exhibited as reduction in HAZ thickness and had more uniform hardness throughout the cross-section compared with the untreated samples.

In friction welding of dissimilar joint method, few material compositions are not possible to weld effectively. For better dissimilar metal joining in friction welding, the interlayer techniques are used by the third metal to increase the diffusion for suitable metal bonding. The interlayer metals are popularly held by coating, foils, sheet and solid rod form. The coating method needs more care for surface preparation with special coating equipment with high workmanship. In case of foil as intermediate metal, more care is neededfor holding between the metal; most of the time this technique has the possibility of failure by peeling off from the contact surface during high speed rotation with pressure during friction generation.

In this investigation, a copper coin was machined to a suitable size (transition fit) to suit the recess inside the SS rod. The mating surfaces of Cu coin, SS rod and Ti alloy were machined, polished to mirror finish and handled in friction welding machine. The purpose of the transition fit between the coin and SS rod is for holding the same intact before the beginning of the process.

Successful joint was achieved with good joint strength at less time. Empirical models were established to fin out the joint strength at any given parameter within the range of investigation

The models developed can be used only within the range of investigation considered for experimentation.

The paper includes implications for the development of a method of joining any dissimilar joints

In this investigation, a copper coin was machined to a suitable size (transition fit) to suit the recess inside the SS rod. The mating surfaces of Cu coin, SS rod and Ti alloy were machined, polished to mirror finish and handled in friction welding machine. The purpose of the transition fit between the coin and SS rod is for holding the same intact before the beginning of the process.

This study presents a numerical modeling by the finite element method of galvanic corrosion between the bolt (cathode) and the end plate (anode). The bolt is made of three types of stainless steel: austenitic (SS304L, SS316L), martensitic (SS410, SS420) and duplex (32,101), and the end plate is made of carbon steel (S235JR).

Finite element modeling.

The results obtained show, on the one hand, that this corrosion rate increases as the conductivity increases, on the other hand, the stainless steels having the highest corrosion resistance causes a considerable loss of mass of the end plate and subsequently a decrease in the lifetime of the bolted joint.

The galvanic corrosion of beam to column bolted joint with end plate, used in steel structures, was studied in order to determine the corrosion rate of the end plate and subsequently to predict the total lifetime of the bolted joint.

Validate the resistance of bolted connections in terms of stresses, resistant moment and contact pressure.

Finite element modeling of corroded bolted joint.

The three types of corroded assemblies are resistant to the applied loads.

The research is original, it studies the stress corrosion cracking of a bolted assembly's end plate by the finite element method.

During the powder bed fusion process, thermal distortion is one big problem owing to the thermal stress caused by the high cooling rate and temperature gradient. For the purpose of avoiding distortion caused by internal residual stresses, support structures are used in most selective laser melting (SLM) process especially for cantilever beams because they can assist the heat dissipation. Support structures can also help to hold the work piece in its place and reduce volume of the printing materials. The mitigation of high thermal gradients during the manufacturing process helps to reduce thermal distortion and thus alleviate cracking, curling, delamination and shrinkage. Therefore, this paper aims to study the displacement and residual stress evolution of SLMed parts.

The objective of this study was to examine and compare the distortion and residual stress properties of two cantilever structures, using both numerical and experimental methods. The part-scale finite element analysis modeling technique was applied to numerically analyze the overhang distortions, using the layer-by-layer model for predicting a part scale model. The validation experiments of these two samples were built in a SLM platform. Then average displacement of the four tip corners and residual stress on top surface of cantilever beams were tested to validate the model.

The validation experiments results of average displacement of the four tip corners and residual stress on top surface of cantilever beams were tested to validate the model. It was found that they matched well with each other. From displacement and residual stress standpoint, by introducing two different support structure, two samples with the same cantilever beam can be successfully printed. In terms of reducing wasted support materials, print time and high surface quality, sample with less support will need less post-processing and waste energy.

Numerical modeling in this work can be a very useful tool to parametrically study the feasibility of support structures of SLM parts in terms of residual stresses and deformations. It has the capability for fast prediction in the SLMed parts.

This paper aims to present the fabrication of 6061 aluminum alloy (AA6061) using a promising laser additive manufacturing process, called the laser-foil-printing (LFP) process. The process window of AA6061 in LFP was established to optimize process parameters for the fabrication of high strength, dense and crack-free parts even though AA6061 is challenging for laser additive manufacturing processes due to hot-cracking issues.

The multilayers AA6061 parts were fabricated by LFP to characterize for cracks and porosity. Mechanical properties of the LFP-fabricated AA6061 parts were tested using Vicker’s microhardness and tensile testes. The electron backscattered diffraction (EBSD) technique was used to reveal the grain structure and preferred orientation of AA6061 parts.

The crack-free AA6061 parts with a high relative density of 99.8% were successfully fabricated using the optimal process parameters in LFP. The LFP-fabricated parts exhibited exceptional tensile strength and comparable ductility compared to AA6061 samples fabricated by conventional laser powder bed fusion (LPBF) processes. The EBSD result shows the formation of cracks was correlated with the cooling rate of the melt pool as cracks tended to develop within finer grain structures, which were formed in a shorter solidification time and higher cooling rate.

This study presents the pioneering achievement of fabricating crack-free AA6061 parts using LFP without the necessity of preheating the substrate or mixing nanoparticles into the melt pool during the laser melting. The study includes a comprehensive examination of both the mechanical properties and grain structures, with comparisons made to parts produced through the traditional LPBF method.

The purpose of this paper is to optimize the process parameters to obtain the best dimensional accuracy, surface finish and hardness of the castings produced by using fused deposition modeling (FDM)-based patterns in investment casting (IC).

In this paper, hip implants have been prepared by using plastic patterns in IC process. Taguchi design of experiments has been used to study the effect of six different input process parameters on the dimensional deviation, surface roughness and hardness of the implants. Analysis of variance has been used to find the effect of each input factor on the output. Multi-objective optimization has been done to find the combined best values of output.

The results proved that the FDM patterns can be used successfully in IC. A wax coating on the FDM patterns improves the surface finish and dimensional accuracy. The improved dimensional accuracy, surface finish and hardness have been achieved simultaneously through multi-objective optimization.

A thin layer of wax is used on the plastic patterns. The effect of thickness of the layer has not been considered. Further research is needed to study the effect of the thickness of the wax layer.

The results obtained by the study would be helpful in making decisions regarding machining and/or coating on the parts produced by this process.

In this paper, multi-objective optimization of dimensional accuracy, surface roughness and hardness of hybrid investment cast components has been performed.