Additive manufacturing (AM) methods for rapid prototyping of 3D materials (3D printing) have become increasingly popular with a particular recent emphasis on those methods used for metallic materials. These processes typically involve an accumulation of cyclic phase changes. The widespread interest in these methods is largely stimulated by their unique ability to create components of considerable complexity. However, modeling such processes is exceedingly difficult due to the highly localized and drastic material evolution that often occurs over the course of the manufacture time of each component. Final product characterization and validation are currently driven primarily by experimental means as a result of the lack of robust modeling procedures. In the present work, the authors discuss primary detrimental hurdles that have plagued effective modeling of AM methods for metallic materials while also providing logical speculation into preferable research directions for overcoming these hurdles. The primary focus of this work encompasses the specific areas of high-performance computing, multiscale modeling, materials characterization, process modeling, experimentation, and validation for final product performance of additively manufactured metallic components.

Linking process, structure, property, and performance for metal-based additive manufacturing: computational approaches with experimental support

Since the discovery of X-rays at the end of the 19th century and the first works on diffraction of X-rays by crystals, huge developments were achieved in the application of these methods for material characterization. In particular, in the field of materials science and engineering, several applications were developed to become state of the art techniques. This chapter first presents a condensed overview of the production of X-rays as well as of the theory of diffraction of X-rays by crystals. A short survey of the hardware for X-ray diffraction (XRD) measurements is given. The methods of phase analysis, residual stress measurements, and texture investigations of polycrystalline materials are then described with examples, and finally, special methods and future trends are presented.

X-ray diffraction (XRD) techniques for materials characterization

Laser surface hardening is a well-established process for enhancing the mechanical properties of selected surface areas of engineering parts made of different types of steel Since this was first reported in the early seventies, much research has been done since to develop a deeper understanding of the process, process modeling for determining operating parameters, laser beam shaping, and online process monitoring It still continues abated In this paper, after presenting a brief description of the basic principle of laser hardening and the scientific work reported prior to the first decade of this century, the more recent research on its various aspects has been reviewed

Laser Transformation Hardening of Steel

The state of laser transformation hardening in surface modification of steel and its alloys is reported in this review paper. The laser hardening process involves the use of high-intensity laser ra...

Status of laser transformation hardening of steel and its alloys: a review

Spatially resolved temporal stress evolution during laser surface spot hardening of steel

An in situ stress analysis by means of synchrotron x-ray diffraction was carried out during laser surface hardening of steel. A single exposure set-up that based on a special arrangement of two fast silicon strip line detectors was established, allowing for fast stress analysis according to the sin2ψ x-ray analysis method. For the in situ experiments a process chamber was designed and manufactured, which is described in detail. First measurements were carried out at the HZG undulator imaging beamline (IBL, beamline P05) at the synchrotron storage ring PETRA III, DESY, Hamburg (Germany). The laser processing was carried out using a 6 kW high power diode laser system. Two different laser optics were compared, a Gaussian optic with a focus spot of o 3 mm and a homogenizing optic with a rectangular spot dimension of 8 × 8 mm2. The laser processing was carried out using spot hardening at a heating-/cooling rate of 1000 K/s and was controlled via pyrometric temperature measurement using a control temperature of 1150 °C. The set-up being established during the measuring campaign allowed for this first realization data collection rates of 10Hz. The data evaluation procedure applied enables the separation of thermal from elastic strains and gains unprecedented insight into the laser hardening process.

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R. Rössler

Papers

Fast in situ phase and stress analysis during laser surface treatment: a synchrotron x-ray diffraction approach.