Laser beam welding significantly outperforms conventional joining techniques in terms of flexibility and productivity. The process benefits, in particular, from the highly focused energy and thus from a well-defined heat input. The high intensities of brilliant laser radiation, however, induce very dynamic effects and complex processes within the interaction zone. The high process dynamics require

Superhydrophobic surfaces have been attracting considerable attention due to potential applications in self-cleaning, anti-icing, water/oil separation, drag reduction, water collection, etc. However, to date, except for a few textile surfaces and coating products, only a limited number of superhydrophobic applications have been commercialized. The main reasons for the limited number of applications

In this work, laser cladding of a Ni-based superalloy powder (Inconel 718) on a Fe-based superalloy (A-286) substrate was performed. The microstructural evolution was studied by optical and electron microscopy techniques, aided by energy dispersive spectroscopy. Additionally, the microhardness along the as-deposited parts was analyzed and correlated with the observed microstructure. It was found that

The formation of self-assembled laser induced periodic surface structures (LIPSSs) after ultrashort pulsed laser ablation is still a matter of controversy in the literature. There is agreement that at least two different physical driving forces lead to ripples with distinguishable spatial periodicity. High spatial frequency LIPSSs with periodicity well below the incident wavelength are discriminated

A novel approach for the reconstruction of an equivalent volumetric heat source from a known weld pool shape is proposed. It is based on previously obtained weld pool geometries from a steady-state thermo-fluid dynamics simulation. Hereby, the weld pool dimensions are obtained under consideration of the most crucial physical phenomena, such as phase transformations, thermo-capillary convection, natural

In this study, using ultrafast lasers of 10 ps pulse duration as a precise and efficient method for cutting edge preparation is researched. Cutting edge preparation is an important step within cutting tool manufacturing, while unprepared sharp cutting edges show low stability, which leads to tool failure by high mechanical and thermal loads during the turning processes [C. F. Wyen, W. Knapp, and K

Material processing by ultrafast lasers is an attractive technology for high-precision fabrication, such as cutting, drilling, and surface modification, of a wide range of material, including dielectrics, semiconductor, metals, and polymer composites. However, it is still challenging to apply ultrafast laser processing in many applications because some key processes, such as absorption and heat accumulation

Problems related to component wear are one of the biggest challenges faced by industrial sectors such as agriculture, mining, and oil and gas. Coating application has been a good alternative to mitigate these problems. Ni-Cr-B-Si alloys are recognized for their abrasion and adhesion resistance properties. In this context, a comparison between the mechanical wear of Ni-Cr-B-Si 1545-00 deposited via

With the rapid development of high-power lasers, efficiency of laser cutting and thickness of cutting material have been greatly increased. In this study, a 10 kW fiber laser was used to cut 18 mm thick 316L stainless steel sheets. The surfaces and cross sections of samples were observed by an optical microscope and a scanning electron microscope. It was found that the quality of laser cutting was

Although different forms of renewable energy sources are in expansion, the oil and natural gas industry remains essential, maintaining its demand for more efficient methods for product transportation. The most productive and safe way is the flow through pipelines. However, pipeline usage directly involves several wear mechanisms, which contribute to pipeline degradation and, consequently, the need

Hybrid laser-arc welding (HLAW) is regarded as a promising joining process, since it can compensate disadvantages from laser autogenous welding and arc welding by uniting both techniques into a single melt pool. Such a process can achieve relative high quality metallurgical bonding, high speed, and low deformation. However, the process is considered complex and of difficult parametrization, as the

The aluminum alloy AA6082 is often used in high-voltage storage systems due to its favorable electrical and mechanical properties. Laser beam welding is a flexible process for producing the required welds. To protect the sensitive components of the battery cells, the required weld depth must be maintained in order to avoid destruction of the components and to reduce the number of defective parts. Optical

In the field of automotive manufacturing, it is pivotal to obtain a moderate penetration status when joining automotive parts by laser keyhole welding. As a typical characteristic of laser keyhole welding, keyhole behavior can directly reflect the penetration status of the weld bead. In this paper, a coaxial vision monitoring system with a laser auxiliary illuminant is established to collect the keyhole

Welding copper to itself and other metals is challenging using conventional welding techniques. The process window for welding copper with an infrared (IR) laser, resistance welder, or an ultrasonic welder is very narrow. In the case of the infrared laser, the high reflectivity at these wavelengths makes it difficult to couple the power into the material and control the temperature of the weld puddle

International thermonuclear experimental reactor correction coil cases are made of heavy, thick, high strength, and high toughness austenitic stainless steel 316LN. The BTCC (bottom and top correction coils) case has the dimension of 2.5 × 7 m2 and cross section of 239.8 × 146.7 mm2, side correction coil case has the dimension of 7.2 × 7.6 m2 and cross section of 147.8 × 168 mm2, and they will be closure

At Fraunhofer IWS Dresden, different, partially prototypic high-power continuous wave (cw) beam sources for the remote laser processing of nonmetals with galvanometric-driven scanner systems are available. The emitted wavelengths of the lasers cover the range from visible light to mid-infrared. A spectroscopic analysis was performed to gain insight into the processability of typical nonmetal materials

The authors report on the theoretical and experimental studies of laser-induced optical breakdown on the surface of fused silica to elucidate the influence of time delay and spatial separation between two ultrashort pulses on the position and size of the modification. Carriers involved in the damage formation including free electrons in the conduction band and self-trapped excitons (STEs) are investigated

The additional element from the filler wire in the laser beam welding is usually distributed inhomogeneously in the final weld due to the high solidification rate of weld pool. It has been found that the electromagnetic stirring produced by an external oscillating magnetic field can enhance the material mixing in the weld pool to achieve a more uniform element distribution. However, the magnetic field

Refined grain size structure is one of the most sought-after features during parameterization of welding processing. Refined grains in the region of the molten zone provide high tenacity in addition to high hardness, due to the dislocation blocking by grain boundaries. However, obtaining refined grain structure is not trivial, since a molten pool is formed during bonding of materials via welding, which

The control of friction and wear is a major concern in many industrial applications. A promising method for tailored surface modification is the so-called laser implantation technique. This method combines surface texturing and material optimization in one processing step by a localized dispersing of hard ceramic particles using pulsed laser radiation. Wear resistant, protruding micrometric features

Additive manufacturing technologies are characterized by complex process interrelations. Consequently, specifically adapted alloys are required to enable a robust building process. In particular, laser beam melting (LBM) is increasingly used for the fabrication of sophisticated functional parts for various applications in numerous industrial sectors, such as automotive and aerospace. However, process

Convoluted rough surfaces involving overhanging features can be a natural consequence of laser additive manufacturing and other spray techniques or can be generated deliberately by laser surface texturing, e.g., to aid osseointegration. Overhanging features add an extra level of complexity to the topography of a rough surface and can have a substantial effect on wettability, etc. However, features

Laser beam welding of aluminum die casting is challenging. A large quantity of gases (in particular, hydrogen) is absorbed by aluminum during the die-cast manufacturing process and is contained in the base material in solved or bound form. After remelting by the laser, the gases are released and are present in the melt as pores. Many of these metallurgic pores remain in the weld seam as a result of

To develop highly efficient and low-cost electrocatalysts based on earth-abundant elements for oxygen evolution reaction (OER) is a great challenge for electrocatalytic water splitting. Herein, a unique type of NiFe-based oxide catalyst with abundant defects is successfully synthesized via pulsed laser ablation in a specific atmosphere containing reductive NH3. The catalyst is self-supported and assembled

Due to increased absorptivity of laser light at 515 nm wavelength in copper materials, welds with low formation of spatters and homogeneous weld depths can be performed.1 However, depending on the used process parameters, a process regime with strong formation of pores is observed. These pores are not resulting from instabilities of the capillary (process pores), but they are observed to result from

The rapidly growing technological innovation of directed energy deposition leads to an increase in part complexity as well as quality and mechanical properties of manufacturable components. However, the variety of process parameters and influencing factors still requires skilled operators, who observe the machine tools. For an unobserved use of deposition welding machines, well parametrized and validated

The phenomenon of thermal focus shift in optical systems, mainly caused by thermal lensing, is well known. There are numerous publications dealing with this effect, but they do not answer the question of how relevant this problem is to the practical application of lasers in laser cutting machines. In this paper, we examine the effect of the thermally induced change of the focus position on the quality

Additive manufacturing using preplaced powder became a widely used processing method during the last few years to build complex and precise structures. The laser beam is often used as a heat source to selectively melt the powder and create the structure layer by layer. However, during the processing, imperfections can occur. The spattering, accumulation of powder particles, and denudation effects lead

The geometrical characteristics of the weld end crater are commonly used as a means of validating numerical results in welding simulations. In this paper, an analytical model is developed for calculating the cooling stage of the welding process after the moving energy source is turned off. Solutions for various combinations of heat sources and heated bodies are found. It is shown that after turning

The present paper deals with short-pulse laser welding of copper and aluminum alloys in dissimilar configuration. In particular, a 100 W nanosecond-class pulsed fiber laser is exploited as a source for welding lap-joints both with linear and spt strategy. The investigation is aimed at understanding the role of the main process parameters, such as pulse shape, duration and energy, peak power, and welding

Laser polishing of metals consists of irradiating the part's surface with a laser beam, thus generating a molten layer that is redistributed and resolidified to create a surface with reduced roughness. However, the process is also characterized by an instantaneous formation of heat-affected zones with consequent microstructural changes that influence the mechanical properties. In order to understand

Excessive heating of the metal sheet during laser oxygen cutting can cause quality deterioration and even lead to cut loss and possible machine idle time, especially for cutting of thick plates, where the cutting speed is slower. There are at least three different strategies to handle quality deterioration by heat accumulation in flame laser cutting of thick plates: to optimize the process parameters

The authors report on the rapid fabrication of an axicon array, consisting of 37 individual axicons in a hexagonal arrangement, made of fused silica by an all laser-based manufacturing method within only 23 min. Therefore, a two-step process is used, first to ablate the silica substrate in a layer-by-layer process, generating the predefined geometry of the axicon array with a femtosecond laser, and

Surface roughness (Ra) after the laser micro-cutting process plays an important role in the quality of the final product. On the other hand, this surface roughness depends on complex laser process parameters such as laser power, laser repetition rate, and laser scanning speed. Therefore, it is important to propose a reliable model to predict the surface roughness as well as to correlate it with important

A one step functionalization of large surfaces and layers could be enabled by high power ultrashort pulsed lasers. Despite today's availability of high power ultrashort pulsed lasers (up to several hundred watts), it is still a challenge to structure large surface areas, which is required on embossing rollers, within an acceptable processing time for industrial roll-to-roll production. Furthermore

This study aims to analyze four different telescope pointing correction models to verify the highest accuracy of the laser ranging telescope corrected by the back propagation (BP) neural network model optimized by the proposed genetic algorithm and Levenberg–Marquardt. In this process, first, the observation data of 95 stars are used to solve the coefficients of the four models, and then the pointing

The utilization of ultrashort pulsed laser radiation enables the precise generation of microstructures and the processing of a wide variety of materials. However, for massive parallel processing, the raw intensity distribution of the beam emitted by the laser source usually has to be transformed into an arrangement of multiple laser beams with specific intensity distributions. Here, sophisticated,

The crystallographic texture, thermal conductivity, and microhardness of the Cu-2.4Ni-0.7Si alloy processed by selective laser melting (SLM) were investigated. The SLM sample shows columnar grains with stronger (100) preferred orientation, and the content of high-angle grain boundaries (HAGBs) is 64.6%. It owns the lower microhardness of 89.73 Hv and the higher thermal conductivity of 187.83 W/m K

The nearly rapid solidification and high-temperature thermal cycles associated with laser directed energy deposition of titanium alloys using laser solid forming (LSF) lead to the formation of coarse prior β columnar grains and continuous coarse-grain-boundary α (αGB) phases, which result in anisotropic properties and poor ductility. The influence mechanisms of trace B (up to 0.3 wt. %) on the solidification

Visual detection and color discrimination become more challenging tasks when laser eye protection (LEP) is worn. This is due to the reduced light transmission and wavelength-blocking characteristics of LEP filters. LEP can, however, provide valuable protection against laser eye dazzle—the temporary reduction of vision caused by visible wavelength lasers. To understand this compromise, a model has been

The deep penetration laser welding of a thick section of austenitic stainless steel by a 20 kW laser is systematically evaluated. The welding phenomena of bead-on-plate and butt-welding of 20 and 30 mm thick steel plates are examined. The results show that the penetration depth of bead-on-plate welding can reach 32 mm and that wide processing windows exist to obtain defect-free butt-welding of 20 mm

The decay of thermal emission of rough surface layers of different carbon materials under the pulsed laser excitation is analyzed both theoretically and experimentally. For pulsed laser heating of rough surfaces, computer simulations revealed that laser-induced thermal radiation is mainly emitted by peaks of the surface relief, and the emission decay time depends on the relation between the laser penetration

The effect of welding parameters on the pore formation in laser-pulsed metal inert gas (MIG) hybrid welding of A7N01P-T4 aluminum alloy was investigated. The formation and dynamic behavior of keyholes at different wire feeding speeds were studied using a “sandwich” structure consisting of GG17 glass and A7N01P-T4 aluminum alloy. The types and morphology of pores were analyzed using scanning electron

For safety reasons, the need of a fast in situ technique for measuring change in surface hardness of nuclear reactor vessel walls due to ion bombardment has great importance. Material hardness measurement using laser induced breakdown spectroscopy has been demonstrated as a new promising technique. The effect of the material matrix is one of the challenges that this technique for hardness measurement

Porous TiO2 ceramic coatings with high contents of Si and P were fabricated on a Ti6Al4V alloy using hybrid processing of laser surface melting (LSM) and microarc oxidation (MAO). The effect of LSM pretreatment on the growth behavior and mechanical properties of the MAO coating was studied. The results showed that the MAO coating on LSM pretreatment Ti6Al4V (LSM-MAO) had quite different surface morphologies

A study is conducted on the detailed static and dynamic characteristics of plasma and the resulting emission spectral qualities generated by a femtosecond (fs) laser irradiation compared with those produced by nanosecond (ns) laser irradiation at a reduced ambient air pressure of 0.65 kPa. It is shown that both plasmas feature a tiny primary and a much larger secondary plasmas, which share the same

Single-shot femtosecond laser ablation experiments with linearly and circularly polarized light were conducted in order to investigate the morphological characteristics of surface nanostructures in lithium borate crystals and glasses, a strontium borate crystal, lanthanide containing borate crystals, and aluminate silicate crystals: Li2B4O7 (LTB) and LiB3O5 (LBO) crystals and Li2O⋅2B2O3 (LTB) and Li2O⋅3B2O3

In this study, the characterization of laser weld joint on transformation-induced plasticity (TRIP) steel sheets coupled with Nd:YAG laser welding was investigated, and the influence of welding conditions like angle of weld, power of laser, and welding speed on the strength of the joint was measured. The microstructure, tensile behavior, and microhardness of TRIP laser-welded sheets were examined in

This paper reports the 3D microprocessing of Si using a femtosecond laser at a wavelength of 1552.5 nm. As Si is optically transparent at this wavelength, the authors attempted to machine the back surface and interior of a Si substrate by a nonlinear absorption process, similar to the nonlinear process used to treat dielectric materials using visible and near-infrared ultrashort lasers. The femtosecond

Laser surface structuring is becoming increasingly important in the industry for tool and mold making. While structured surfaces contribute to minimizing friction in combustion engines or to increasing efficiency of light-emitting diode-based lighting systems, surface texturing is evolving a quality feature of products with regard to optical and haptic properties. Currently used manufacturing processes

This work presents the design and optimization of a cascade nano-laser using CH3NH3PbI3 perovskite. Due to increasing threshold gain with decreasing device size and high Auger losses, the use of perovskite as the active medium in the cascade nano-laser was proposed, as the material possesses a high emission rate in the visible wavelength region, with relative ease of device fabrication. By optimizing

It is necessary to understand the light-matter interaction for application of femtosecond laser micro/nanoprocessing. In this work, the authors investigated the melting and disintegration behavior of a Cu film irradiated by a femtosecond laser with different pulse durations in the range of 35–500 fs by using a combined two temperature model (TTM) and molecular dynamics (MD) method. On the basis of

Hot-dipped galvanized steel is processed with short- and ultrashort-pulsed lasers in air at near-infrared wavelengths with pulse durations ranging from 350 fs to 241 ns. The morphology of the ablated craters (processed over a range of laser fluence levels and a number of laser pulses) is analyzed by confocal laser scanning microscopy and scanning electron microscopy. The ablation threshold of galvanized

In this paper, the authors report a method for continuous trench micromachining on polymethylmethacrylate (PMMA). Visible laser-induced backside wet etching (v-LIBWE) on PMMA using a potassium permanganate (KMnO4)-based absorber liquid was studied. PMMA is widely used in microfluidic devices for chemical and biological applications. Conventional micromachining of channels in the PMMA substrate using

Laser trimming has become one of the powerful tools for precise manufacturing of alloy resistors that are widely used in electrical vehicles, electrical controlling, and in appliances. In this work, the influence of femtosecond laser trimming is compared with nanosecond laser trimming. The authors found that lasers focused on different heights relative to the sample surface induced significant changes

In this study, the effects of laser volumetric energy density (η) on the metallurgical defect behavior and microstructure evolution of H13 die steel fabricated by selective laser melting (SLM) additive manufacturing are systematically studied, and underlying thermal mechanisms are revealed. The results indicate that the metallurgical defect behavior is significantly affected by the applied η, which

Laser perforations are formed in packaging to control the rate of gas exchange and maintain a balance between the respiration of the product and the permeation of the package. The air permeability of the packaging materials is typically measured using air-driven methods, but these do not allow for online measurement during the rapid production of perforations. The required permeability is generally

The authors conducted this meta-analysis of randomized controlled trials (RCTs) to assess the effects of photobiomodulation therapy (PBMT) in the treatment of androgenic alopecia (AA). RCTs published in Pubmed, Web of Science, and Embase were systematically reviewed to identify the effects of PBMT in AA patients. The outcome measures included hair density and hair growth. Results were expressed as

In order to reveal the fluctuation mechanism of the plume induced during fiber laser keyhole welding, dynamic behaviors of both the plume and the keyhole were simultaneously observed by using the multiple-imaging method. The results show that the fluctuation period of the plume was the same as that of the laser-induced vapor moving down on the keyhole front wall (KFW). The tilt angle of the plume was

The surface of a eutectic BiSn target was ablated by several series of pulses at different spots using an excimer laser with a wavelength of 351 nm and a pulse duration of 20 ns. Morphology of ablation craters formed under a different number of pulses was analyzed with a scanning electron microscope, an optical profilometer, and an energy dispersion spectroscope (EDS). Laser-induced breakdown spectroscopy