Transient thermal field in laser surface hardening treatment of medium carbon steel was analyzed by employing both three-dimensional analytical model and finite element model. In finite element model the laser beam was considered as a moving plane heat flux to establish the temperature rise distribution in the work-piece, while in analytical model laser beam was considered as an internal heat s...

The process of laser beam transformation hardening is principally controlled by two independent parameters, the absorbed laser power on a given area and the interaction time. These parameters can be transformed into two functional parameters: the maximum surface temperature and the hardening depth. It has been proved that with a constant hardening depth the results (hardness. residual stress. e...

In computed tomography (CT), the beam hardening effect has been known to be one of the major sources of deterministic error that leads to inaccuracy and artifact in the reconstructed images. Because of the polychromatic nature of the x-ray source used in CT and the energy-dependent attenuation of most materials, Beer's law no longer holds. As a result, errors are present in the acquired line in...

An experimental investigation with Nd:YAG laser system was carried out to study the effects of laser hardening process parameters on the microstructure and hardness during laser hardening of EN25 steel. The laser beam is allowed to scan on the surface of the work piece by varying the laser beam power (750–1250 W) and travel speed (500–1000 mm/min) of the work table. The microstructural features...

X-ray computed tomography (CT) is a non-destructive, radiographic scanning technique that enables the visualisation of both the internal geometry and the composition of a workpiece; X-ray CT is therefore well suited for non-destructive inspection tasks. Several physical processes reduce the quality of CT images, and therefore influence both qualitative and quantitative analyses made from CT dat...

The absorption law of Lambert-Beer gives rise to the linear relationship between the attenuation and the thickness of the material. However, this law is only true for a monochromatic beam. For polychromatic sources used in medical computer tomography (CT) and microtomography, this linear relationship no longer holds, which leads to beam hardening. When the beam hardening effect is not accounted...

In CT, the nonlinear attenuation characteristics of polychromatic X-rays cause beam hardening artifacts in the reconstructed images. When datasets contain multiple materials in the field of scan, the performance of state-of-the-art beam hardening correction approaches is limited by high computational load and reduced correction efficiency. An image based multi-material beam hardening correction...

as the turbine industries need to manufacture turbine blades made of martensitic stainless steel aisi 420 with high toughness and wear resistance, local laser hardening has become more and more important. in this research, surface of the samples was initially hardened by high-power pulsed laser beam; then, optimum parameters of hardening were calculated and wear resistance of surface hardened s...

We present a new method for correcting beam hardening artifacts in CT data. Software correction typically consists of a polynomial transform of the raw data, but determining optimal coefficients is not straightforward, especially if the material is not well known or characterized, as is the usual case when imaging geological materials. Our method lets an expert user guide an iterative optimizat...

Bone mineral density (BMD) measurements are critical in many research studies investigating skeletal integrity. For pre-clinical research, micro-computed tomography (microCT) has become an essential tool in these studies. However, the ability to measure the BMD directly from microCT images can be biased by artifacts, such as beam hardening, in the image. This three-part study was designed to un...