Laser processing of materials

Light amplification by stimulated emission of radiation (laser) is a coherent and monochromatic beam of electromagnetic radiation that can propagate in a straight line with negligible divergence and occur in a wide range of wave-length, energy/power and beam-modes/configurations. As a result, lasers find wide applications in the mundane to the most sophisticated devices, in commercial to purely scientific purposes, and in life-saving as well as life-threatening causes. In the present contribution, we provide an overview of the application of lasers for material processing. The processes covered are broadly divided into four major categories; namely, laser-assisted forming, joining, machining and surface engineering. Apart from briefly introducing the fundamentals of these operations, we present an updated review of the relevant literature to highlight the recent advances and open questions. We begin our discussion with the general applications of lasers, fundamentals of laser-matter interaction and classification of laser material processing. A major part of the discussion focuses on laser surface engineering that has attracted a good deal of attention from the scientific community for its technological significance and scientific challenges. In this regard, a special mention is made about laser surface vitrification or amorphization that remains a very attractive but unaccomplished proposition.

CW Nd:YAG Laser heating of silicon are modeled theoretically and
the heat diffusion equations solved numerically for estimation of the
temperature rise induced during these processes. The thermal properties
of the substrate silicon is assumed variations in the case of CW Laser
heating . Our results at estimation are agreement with experimental
value .

CW Nd:YAG Laser heating of silicon are modeled theoretically and the heat diffusion equations solved numerically for estimation of the temperature rise induced during these processes. The thermal properties of the substrate silicon is assumed variations in the case of CW Laser heating. Our results at estimation are agreement with experimental value .

Laser-based welding of thick17-4 precipitation hardening (PH)martensitic stainless steel(SS)plates in a tubular butt joint configuration with a built-in backing bar are very challenging because of the porosity and cracks are easily generated in the welds.

In the present study, laser assisted fabrication of 316L stainless steel has been attempted using a high power (1.5 kW) continuous wave diode laser. The main process variables for the present study were applied power density, scan speed and powder feed rate. A detailed microstructural study of the surface and cross-section of the fabricated layer were carried out using optical and scanning electron microscopy to understand the influence of laser parameters on microstructure of the surface and interface between the successive layers. The microstructure of the top layer was equiaxed, the near substrate region was fine dendritic, however, at the interface between two successive layers, it was coarsened. The morphology and degree of fineness of the microstructure was found to vary with laser parameters. The range of grain size (maximum grain size–minimum grain size) was taken as a measure of homogeneity. It was found that with increasing the scan speed, the range of grain size was minim...

In the present study, laser assisted fabrication of 316L stainless steel has been attempted using a high power (1.5 kW) continuous wave diode laser. The main process variables for the present study were applied power density, scan speed and powder feed rate. A detailed microstructural study of the surface and cross-section of the fabricated layer were carried out using optical and scanning electron microscopy to understand the influence of laser parameters on microstructure of the surface and interface between the successive layers. The microstructure of the top layer was equiaxed, the near substrate region was fine dendritic, however, at the interface between two successive layers, it was coarsened. The morphology and degree of fineness of the microstructure was found to vary with laser parameters. The range of grain size (maximum grain size–minimum grain size) was taken as a measure of homogeneity. It was found that with increasing the scan speed, the range of grain size was minimized. Micro-porosities were present in the microstructure that reduced with increasing scan speed and found to be minimum at a medium powder feed rate. The optimum processing conditions have been established by correlating the characteristics of the fabricated layer with process parameters.

Micro-texturing on the rake/flank face of the tool to obtain higher service life has emerged as a promising area of research. Micro-texturing assists in reducing contact area, and in-turn lowering wear and frictional heat. There are several methods to obtain micro-textures on tools. However, the quality of micro-texture depends largely on the manufacturing method used. Laser-induced surface texturing has been found more accurate and a cost-effective solution to enhance tribological properties and efficiency of the cutting tool. Ultra-short laser pulses can produce controlled ablation and micro-textures. However, obtaining accurate and ultra-clean micro-textures on cutting tools depends on the type of laser source, set of laser process parameters, and physical and mechanical properties of the cutting tool material. Several ablation models have been developed to predict the optimized set of laser parameters. This paper illustrates the simulation of laser surface texturing with the hel...

Light amplification by stimulated emission of radiation (laser) is a coherent and monochromatic beam of electromagnetic radiation that can propagate in a straight line with negligible divergence and occur in a wide range of wavelength, energy/power and beam-modes/configurations. As a result, lasers find wide applications in the mundane to the most sophisticated devices, in commercial to purely scientific purposes, and in life-saving as well as life-threatening causes. In the present contribution, we provide an overview of the application of lasers for material processing. The processes covered are broadly divided into four major categories; namely, laser-assisted forming, joining, machining and surface engineering. Apart from briefly introducing the fundamentals of these operations, we present an updated review of the relevant literature to highlight the recent advances and open questions. We begin our discussion with the general applications of lasers, fundamentals of laser-matter interaction and classification of laser material processing. A major part of the discussion focuses on laser surface engineering that has attracted a good deal of attention from the scientific community for its technological significance and scientific challenges. In this regard, a special mention is made about laser surface vitrification or amorphization that remains a very attractive but unaccomplished proposition.

High-speed steels (HSS) rolls are used in front finishing stands of hot strip mills. Good wear resistance and hardness at high temperature are defining features of HSS. Many types of carbides are present in these alloys, each having different effect upon the final properties of HSS. As a result, nature, morphology and amount of these carbides are factors of important concern. Identification and characterisation of HSS carbides are realised with optical microscopy combined with electron microscopy.