Search Results for laser surface melting

Laser surface hardening is a noncontact process that provides a chemically inert and clean environment as well as flexible integration with operating systems. This article provides a brief discussion on the various conventional surface-modification techniques to enhance the surface and mechanical properties of ferrous and nonferrous alloys. The techniques are physical vapor deposition, chemical vapor deposition, sputtering, ion plating, electroplating, electroless plating, and displacement plating. The article describes five categories of laser surface modification, namely, laser surface heat treatment, laser surface melting such as skin melting or glazing, laser direct metal deposition such as cladding, alloying, and hardfacing, laser physical vapor deposition, and laser shock peening. The article provides detailed information on absorptivity, laser scanning technology, and thermokinetic phase transformations. It also describes the influence of cooling rate on laser heat treatment and the effect of processing parameters on temperature, microstructure, and case depth hardness.

This article focuses on the directed-energy deposition (DED) additive manufacturing (AM) technique of biomedical alloys. First, it provides an overview of the DED process. This is followed by a section describing the design and development of the multiphysics computational modeling of the layer-by-layer fusion-based DED process. A brief overview of the primary governing equations, boundary conditions, and numerical methods prescribed for modeling laser-based metal AM is then presented. Next, the article discusses fundamental concepts related to laser surface melting and laser-assisted bioceramic coatings/composites on implant surfaces, with particular examples related to biomedical magnesium and titanium alloys. It then provides a review of the processes involved in DED of biomedical stainless steels, Co-Cr-Mo alloys, and biomedical titanium alloys. Further, the article covers novel applications of DED for titanium-base biomedical implants. It concludes with a section on the forecast of DED in biomedical applications.

Lasers evolved as a versatile materials processing tool due to their advantages such as rapid, reproducible processing, chemical cleanliness, ability to handle variety of materials, and suitability for automation. This article focuses on state-of-the-art laser applications to improve tribological performance of structural materials in lubricated and nonlubricated environments. It discusses the fundamentals of various laser materials interactions and reviews laser-based surface-modification strategies, including laser surface heating and melting, laser-synthesized coatings, and laser-based design approaches such as laser patterning and dimpling. Laser-surface modification of novel materials, such as high-entropy alloys and metallic glasses, is explored. The article provides an overview of hybrid techniques involving laser as a secondary tool, as well as a discussion on the improved capabilities of laser surface engineering for tribological applications by means of integrated computational process modeling.

Surface modification is the alteration of the surface composition or structure using energy or particle beams. This article discusses two different surface modification methods. The first, ion implantation, is the introduction of ionized species into the substrate using kilovolt to megavolt ion accelerating potentials. The second method, laser processing, is high-power laser melting with or without mixing of materials precoated on the substrate, followed by rapid melt quenching. The article also describes the advantages and disadvantages of the surface modification approach to promote corrosion resistance.

This article focuses on powder bed fusion (PBF) of ceramics, which has the potential to fabricate functional ceramic parts directly without any binders or post-sintering steps. It presents the results of three oxide ceramic materials, namely silica, zirconia, and alumina, processed using PBF techniques. The article discusses the challenges encountered during PBF of ceramics, including nonuniform ceramic powder layer deposition, laser and powder particle interactions, melting and consolidation mechanisms, optimization of process parameters, and presence of residual stresses in ceramics after processing. The applications of PBF ceramics are also discussed.

Surface hardening improves the wear resistance of steel parts. This article focuses exclusively on the methods that involve surface and subsurface modification without any intentional buildup or increase in part dimensions. These include diffusion methods, such as carburizing, nitriding, carbonitriding, and austenitic and ferritic nitrocarburizing, as well as selective-hardening methods, such as laser transformation hardening, electron beam hardening, ion implantation, selective carburizing, and surface hardening with arc lamps. The article also discusses the factors affecting the choice of these surface-hardening methods.

Laser beam machining removes, melts, or thermally modifies a material by focusing a coherent beam of monochromatic light on the workpiece. This article describes the principal lasers used in metal processing: neodymium-glass, carbon dioxide, and neodymium-doped yttrium aluminum garnet lasers. It discusses the operating parameters of concern in percussion drilling and trepanning. The process variables in surface treatment and laser cutting, as well as the operating parameters of concern in laser welding are reviewed. The article also explains the various categories of surface treatment: heat treating, cladding, surfacing, glazing, and marking.

This article covers in-line process monitoring of the metal additive manufacturing (AM) methods of laser and electron beam (e-beam) powder-bed fusion (PBF) and directed-energy deposition (DED). It focuses on methods that monitor the component directly throughout the build process. This article is organized by the type of AM process and by the physics of the monitoring method. The discussion covers two types of monitoring possible with the PBF process: monitoring the area of the powder bed and component and monitoring the melt pool created by the laser or e-beam. Methods for layer monitoring include optical and thermal methods that monitor light reflected or emitted in the visible and infrared wavelengths, respectively. Monitoring methods for laser directed-energy deposition (DED) discussed are those that measure the size and shape of the melt pool, the temperature of the melt pool, and the plasma generated by the laser as it interacts with the molten metal.

The additive manufacturing technologies in the casting of precious metals are divided into two groups: indirect metal methods and direct metal methods. Besides providing a process overview of both of these methods, the focus of this article is on the characteristics, process steps, applications, and advantages of direct metal methods, namely laser melting, material extrusion, binder jetting, material jetting, and vat photopolymerization methods.

Titanium alloys are known for their high-temperature strength, good fracture resistance, low specific gravity, and excellent resistance to corrosion. Ti-6Al-4V is the most commonly used titanium alloy in the aerospace, aircraft, automotive, and biomedical industries. This article discusses various additive manufacturing (AM) technologies for processing titanium and its alloys. These include directed-energy deposition (DED), powder-bed fusion (PBF), and sheet lamination. The discussion covers the effect of AM on the microstructures of the materials deposited, static and mechanical properties, and fatigue strength and fracture toughness of Ti-6Al-4V.

This article presents a general understanding of causes and possible solutions for defects in the most common metal additive manufacturing (AM) processes: laser powder-bed fusion (L-PBF), laser directed-energy deposition (DED-L), and binder jetting (BJ).