Laser metal deposition (LMD) is an advanced manufacturing technology combining rapid prototyping and laser cladding technology, which has been applied to manufacture high performance parts with complex structure. In this study, Inconel-steel functionally graded materials (FGMs) with composition transitioning from 100% 316 L incrementally graded to 100% Inconel718 by different composition gradients

In contrast to other welding processes of aluminum alloys, variable polarity plasma arc (VPPA) nonvertical-up welding produces pores in specific positions (on the upper side of the welded joint) rather than throughout the whole welded joint due to the effect of gravity. In horizontal welding, the porosity area percentage on the upper side of the welded joint reached about ∼20%. Asymmetric metal flow

In this study, the modified Mohr-Coulomb (MMC) ductile fracture criterion was employed to investigate the ductile fracture during the roll forming process of the AA6061-T6 aluminum alloy. To this aim, the MMC fracture criterion was calibrated based on the tension tests and was integrated into the commercial finite element (FE) Abaqus/Explicit using an appropriate user subroutine. The experimental procedures

Abrasive flow machining (AFM) is a surface finishing process for internal channels and freeform surfaces that is based on the extrusion of an abrasive-laden viscoelastic media. AFM can be applied to additively manufactured (AM) components with high initial surface roughness, but the final geometry after AFM may not meet the required dimensional accuracy due to highly inhomogeneous material removal

Metallic narrow grooves with high aspect ratio, referred to here as deep narrow grooves (DNGs), are used widely in precision instruments, medical devices and other industries. However, because DNGs are usually less than 4 mm in width with depth-width ratio (aspect ratio) more than 2, it remains extremely challenging to machine them with high precision and efficiency, especially for blind (i.e., closed-end)

This study presents an approach to extra-hard material removal using "medium-frequency vibration-assisted grinding with self-sensing grinding force" for producing a microgroove array on monocrystalline diamond (MCD). Vibration mode at nano-amplitude is employed to vibrate the MCD workpiece against the polycrystalline composite diamond (PCD) wheel-tool during grinding. This approach is used to break

Friction stir incremental forming (FSIF) process was applied to join a commercial open-cell type nickel foam with a polymethyl methacrylate (PMMA) sheet for fabrication of porous metal–nonporous resin composite. In this process, a rotating rod-shaped tool was vertically pushed and horizontally fed against the sheet on the foam. The sheet was frictionally heated and incrementally deformed by the rotating

At present, a tokamak divertor1 is being developed with a reservoir for feeding the receiving surface with liquid metal, and real designs with high reliability and a long service life are being created. There is therefore a need to develop methods for combining dissimilar materials. The aim is for the unit of the adapter to use a brazed joint between the molybdenum tube and the steel (12Cr18Ni10Ti)

The manufacturing of components from the titanium alloy Ti-6Al-4 V is of great significance for many industrial sectors. The production of high-performance Ti-6Al-4 V components typically requires multiple hot forging steps and leads to parts with tolerances that need extensive machining to create the final shape. For many applications, net-shape technologies such as additive manufacturing (AM) could

In order to reveal the evolution mechanism of failure-to-fracture through thickness direction, quantify failure distribution of micro-crack, predict fracture forming limit (FFL) for single point incremental forming (SPIF) with high-speed tool and compare with conventional SPIF, the flow stress model and thermal ductile fracture criterion are calibrated and integrated with the numerical simulation of

The bobbin tool friction stir welding (BTFSW) technique was applied to a Mg-Zn-Zr alloy, ZK60-T5. The effects of shoulder diameter and stir pin geometry on the macrostructure, microstructure and mechanical properties of the BTFSW joints were studied. Weld quality was sensitive to the interaction of bobbin tool geometries and processing parameters. The reduction in the shoulder diameter led to less

Hybrid Metal Extrusion and Bonding Additive Manufacturing (HYB-AM) is a new solid-state process for the production of 3D metal structures. In HYB-AM, the wire feedstock is continuously processed through an extruder and deposited in a stringer-by-stringer manner to form layers and eventually a near net-shape component. In this work, the layer bonding of AA6082 samples produced by this process has been

In the present investigation, effects of length and geometry of die land/bearing on curved profiles/sections produced by a novel process, differential velocity sideways extrusion (DVSE), were studied through physical experiments using plasticine as a model material and finite element modelling. Profile curvature decreases as die land length increases due to its negative influence on exit velocity gradient

Herein, a method is described to weld polytetrafluoroethylene (PTFE), a non-melt processable thermoplast, using a thulium laser. Different settings for laser power and speed were used. The resulting mean lap shear strength per setting ranged from 0.081 N/mm² to 0.297 N/mm². The optimal setting was found to be 12 W irrespective of the welding speed applied. Micro-computed tomography (µ-CT) and optical

Quantitative analysis is required to explore the mechanism of crack generation in ultrafast laser drilling of thermal barrier coated nickel superalloy. In this study, a simple thermo-mechanical coupled model is established to obtain temperature history, phase transformation stress and thermal stress during drilling process, in which laser beam scanning, laser intensity attenuation, the nonlinear relationship

Hot gas atomization in spray forming has been used for the first time to improve the quality of spray-formed tubular deposits. This technique reduces gas consumption and produces smaller droplets than cold gas atomization. The flight velocity and cooling rate of the atomized droplets increase with higher gas temperature. These features can further influence the quality of the spray-formed deposits

In order to join metal-plastic hybrid parts so as to achieve lightweight constructions, innovative joining technologies are essential. For this, thermal joining is a promising approach due to the absence of any joining agent. The joint strength can be increased by surface pre-treatment of the metal with continuous wave laser radiation. Large joining areas, however, are challenging in terms of productivity

In-situ X-ray observation was used to investigate the effect of process conditions on keyhole behavior in laser melting with austenitic stainless steel. It was confirmed that the keyhole depth and width increased, and the fluctuation in the keyhole depth decreased as laser power increased. With no shielding gas, there was a large fluctuation in keyhole depth. This is presumed due to the attenuation

Printed circuit heat exchangers (PCHEs) have attracted wide attention in the nuclear energy field owing to their high compactness, strong pressure endurance, and high heat transfer capacity. In situations where corrosion resistance or light weight is required, PCHEs made of titanium exhibit obvious advantages. However, the corrosion resistance of titanium is so high that it is hard to machining titanium

Producing nearer to net-shape hot rolled rings whilst meeting demanding product property requirements is a major industrial challenge, especially in high value materials such as Nickel-based superalloys. Recent process innovations propose additional tooling to improve control over the geometric accuracy, but it is not known what influence this will have on the temperature distribution and product properties

This work concerns the novel Metal Continuous Screw Extrusion process (MCSE). The process gives new opportunities for processing metal alloys, composites and novel multi-materials. By principle, one feeds granulated material into the screw extruder which compacts and extrudes the material in a continuous manner. The inherent deformation is very complex and based on empirical knowledge, a comprehensive

Multi-material design offers cost-efficient lightweight solutions for automotive body-in-white production. It can be realized by joining ultra-high strength steels with aluminum alloys, using adhesive bonding, combined with another commonly used joining process. For these applications, processes like riveting, clinching, resistance spot welding have been pushed to their technological limits and a further

Al/Ti dissimilar welds were fabricated by ultrasonic vibrations assisted friction stir welding, which eliminated the tool wear and enhanced the material flow. The peak temperature was lowered, and a pre-heating period was introduced into welding by ultrasonic vibrations. Wider interface and smaller grain structures were observed in the welds due to the reinforced material flows. Ti fragments were spun

The joining of fiber-reinforced plastics (FRP) currently poses particular process engineering challenges. Adhesive bonding or mechanical joining is normally used for such joints. However, bonding processes require complex measures for surface pre-treatment, fixing concepts and usually requires long curing times. On the other hand, mechanical joining processes such as screws or semi-hollow punch rivets

Subsurface damage (SSD) and surface roughness (SR) induced by the finishing process significantly influence the industrial and technological application of optical components. In this paper, a novel non-resonant vibration-assisted roll-type polishing (NVRP) was presented to process the silicon carbide (SiC) ceramic workpiece. The feasibility of the two-dimensional vibration-assisted processing device

Drilling of composite materials is a challenge in aviation and aerospace field. Delamination often occurs at the hole exit which can reduce the strength of the structure. In this study, to reduce delamination, an analytical model with thermal effect is proposed to predict critical delamination condition of composite. Anisotropy of the composite, thermos-mechanical deformation and load cases of the

Electron beam melting (EBM) is one of the promising technologies with the capability of producing complex near-net shapes from difficult to process materials such as titanium alloys. However, the parts produced from the EBM process suffer from the poor surface quality and machining is required to finish the EBM parts to achieve the necessary surface quality. Unlike the reported studies in the literature

A novel cutting method that combines shearing and torsion was investigated. Shearing is a fast process that has high precision in term of cut length. However shape defects such as droop and burr occur. Droop and burr do not occur in a rod cut using torsion, but, controlling the location of the cut is difficult. As each of these processes can compensate for the other’s shortcomings, by combining them

Knowledge of the deformation mechanics in single point incremental forming of tubes is of great importance to understand the physics behind failure and the workability limits in thin-walled tube expansion. Which are the states of stress and strain in the small localized plastic deformation region between the tube and the single point forming tool, and how damage accumulates until fracture are important

In earlier contributions, we discussed continuous-bending-under-tension (CBT) experiments on AA6022-T4. We found that CBT significantly enhanced the elongation-to-fracture and strength over uniaxial tension. In the present paper, our understanding of CBT is expanded beyond these experimental observations, with the aid of material modeling and numerical simulations of the process. Cyclic tension-compression

Free bending technology is a new bending process for manufacturing freeform tube products. When manufacturing a complex spatial product, the variation of bending curvatures and torsions will accompany with a frequent changing of forming parameters, which will increase the manufacturing difficulties greatly. Until now, there is no effective way for determining the forming parameters of a complex spatial

The self-excited water jet technology is widely used in submerged conditions, while its performance is restricted under high confining pressure. To improve its erosive capability, the cavitation intensity and the erosion pattern of a self-excited cavitating jet (SECJ) were investigated through mass loss and the microscopic images of the eroded specimens. The experiment was carried out in a certain

There are huge disparities in the physical and mechanical properties between the two-phase materials of particle reinforced metal matrix composites (PRMMCs). Therefore, the heat generated by reinforced particles and metal matrix is different under the action of cutting and rubbing of the cutting tool. However, limited studies have been done using analytical method to predict the cutting temperature

A novel continuous directional freeze casting technique derived from LMC (liquid metal cooling) is developed in the present study, which is named as “LMC-like freeze casting”. In this novel freeze casting method, a quartz mold containing slurry is dipped into a low-temperature bath with a constant rate to achieve directional freezing of the slurry. Under quasi-steady state conditions, the solidification

Residual stress plays an important role in controlling the performance of high-precision martensitic steel parts, as it affects the properties of the material in various ways. At present, the dynamic evolution of the phase transition mechanism in residual stress generation is not yet fully understood, and there have been few quantitative studies on the effect of phase transitions on the residual stress

In gas tungsten arc welding (GTAW) based additive manufacturing (AM), omni-directional deposition with side feeding is common when depositing complex parts, which is different from the gas metal arc welding (GMAW). While side feeding may lead to unstable deposition process and deposition deviation. In this paper, a wire melting simulation model was established to analyse the behaviour of the wire in

Single Point Incremental Sheet Forming (SPISF) is a well-known flexible alternative to conventional generative manufacturing processes. In SPISF, the geometry to be formed is fragmented into series of 2D slices and the plastic deformation is achieved through layer by layer movement of a Numerically Controlled (NC), hemispherical or ball end forming tool. The whole plastic deformation is the sum of

Al/steel butt joints were successfully obtained using a dual–spot laser welding–brazing process with different R (R = EFe:EAl = 4:6, 5:5, and 6:4; EFe and EAl represented the energy ratios of the laser near steel and Al, respectively). The molten filler metals wet and spread well along the front and back surfaces of the steel when R was 5:5 and 6:4, whereas an undercut occurred when R was 4:6. The

The laser ablation has been proved to be an effective way to machine carbon fiber reinforced plastic composites (CFRPs). Previous experimental studies on laser drilling of CFRPs are usually limited to thin plates. For thick (above 10 mm) CFRPs plates, the studies on feasibility, efficiency and dimensional accuracy of laser drilling processes are still missing. This study presents a novel dual-beam

For the purpose of grain refinement and improvement of the hot formability of duplex stainless steel, a new concept of the thermomechanical processing method using the austenite phase transformation from the δ ferrite phase in the hot working temperature range was proposed. The supercooled δ ferrite phase is generated by rapid cooling immediately before hot working, and crystal grains are refined by

Incremental sheet forming (ISF) is considered as an advanced sheet metal forming process for flexibly producing complex sheet metal parts. In the present work, a novel three-sheet incremental forming (TSIF) process is developed. For better understanding the forming characteristic and deformation mechanism of this new variant of incremental sheet forming (ISF), the surface quality and forming limit

TiN nanoparticle reinforced AlSi10Mg composite powder was produced by a novel ultrasonic vibration dispersion technique. The TiN/AlSi10Mg composites were fabricated via selective laser melting (SLM). The effects of scanning speed on the microstructure, particle distribution state, and tribological properties of the as-built composites were studied. Experimental results showed a better SLM processibility

A re-rolling method was successfully developed to add more layer of carbon fibers into the composite plate that already contained one layer fibers. The thickness and state of covering-layer were synchronously controlled to achieve a subtle equilibrium between the solidification and deformation behaviors. It could offer sufficient infiltration effects on the upper fibers and protection effects on the

The grain structure and texture of metal parts fabricated by selective laser melting (SLM) are of interest for their effect on the properties. The study of the SLM single track can reduce the variables to be concerned and, hence, facilitate the understanding of the development of grain and texture in the SLM process. In this work, the austenitic stainless 316 L single tracks are fabricated at different

Because of its excellent properties, such as good corrosion resistance, high specific strength and important ductility, the AA5383 aluminum alloy is largely employed for naval applications. In this work, the mechanical behavior of the AA5383 alloy at elevated temperatures, which is an important aspect for the control of forming operations, is investigated. For this purpose, an experimental campaign

Machining processes with main thermal impact like electro discharge machining (EDM) result in a change of temperature in the workpiece with temporal and spatial temperature gradients which have a large influence on the thermo-chemically modified surface microstructure and therefore a high impact on the functional properties of the workpiece. However, as most state variables (like the temperature) cannot

Reduction of friction and wear is a key aspect in saving materials and energy of moving components. The tribological mechanism response for the ultralow frictional behaviors should be paid enough attention. In the present work, the polyimide (PI) composites were obtained by in-situ adding with multiwalled carbon nanotubes (CNTs). It is disclosed that the incorporation of CNTs enhanced the strength