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About this book

Selective laser melting (SLM) has established itself as the most prominent additive manufacturing (AM) process for metallic structures in aerospace, automotive and medical industries. For a reliable employment of this process, it has to conform to the demanding requirements of these industries in terms of quasistatic and, especially, fatigue performance. Shafaqat Siddique identifies the influence of SLM processing conditions on the microstructural features, and their corresponding influence on the mechanical behavior of the processed AlSi12 alloy structures. The author also gives insight into integrated manufacturing by combining conventional and SLM processes to get the synergic benefits. Requirements for fatigue-resistant designs in additive manufacturing are highlighted, and a novel method is developed for agile fatigue life prediction.

About the Author

Shafaqat Siddique worked as Scientific Assistant at TU Dortmund University, Department of Materials Test Engineering (WPT), headed by Prof. Dr.-Ing. Frank Walther, and completed his Ph.D. research in cooperation with Laser Zentrum Nord (LZN) in Hamburg. He continues his post-doctoral research at TU Dortmund University, Germany.

Table of Contents

Frontmatter

Chapter 1. Introduction

Abstract
Selective laser melting process has the capability of producing intricate designs which, otherwise, would be quite difficult, time-consuming and costly to be manufactured. It also offers competitive advantage to decrease the product development cycle not only for ensuring geometrical integrity but for making prototypes for functional testing. Owing to the advancements in powder quality, laser technology and SLM machine systems, selective laser melting (SLM) cannot be now limited to prototyping only, but be extended to serial production.
Shafaqat Siddique

Chapter 2. State of the art

Abstract
Additive manufacturing (AM) is a free-form manufacturing technique which takes three-dimensional computer aided design (3D-CAD) model as input, adding raw material gradually, usually in a computer-controlled layer-wise manner, to build the part by consolidating the raw material applying an energy source. Additive manufacturing processes are in place for a number of decades; however, it is only possible since a number of years that metallic parts with relative densities higher than 99% can be manufactured, posing the opportunity to shift the potential of the technique from prototyping to serial production. This chapter gives a brief overview of the existing additive manufacturing processes regarding source of energy, type of raw material, processing capabilities and issues.
Shafaqat Siddique

Chapter 3. Investigation methodology

Abstract
To ensure reliability of the structural components in quasistatic and cyclic applications, it is important to understand the part parameters as a function of process parameters and post-processing steps. Understanding of process-structure-property relationships is important for part- and application-oriented processing of SLM parts. Every process parameter and step in the process chain until the end-use effects the part properties and, therefore, functional integrity. This chapter explains the process chain followed for manufacturing of test specimens including process parameters and post-processing steps.
Shafaqat Siddique

Chapter 4. Characterization of AlSi12 alloy

Abstract
Powder material is an important parameter in powder-based additive manufacturing which can affect the quality of the manufactured parts significantly. Therefore, fresh as well as recycled powder material was analyzed under scanning electron microscope to view the size, the morphology and the chemical composition.
Shafaqat Siddique

Chapter 5. Results and discussions

Abstract
The quasistatic tensile behavior of SLM-manufactured AlSi12 alloy of the investigated batches A-H (low energy density: A-D; high energy density: E-H) with low and high conditions of base plate heating and post-process stress-relief is portrayed in Fig. 5.1 as characteristic stress-strain curves.
Shafaqat Siddique

Chapter 6. Summary

Abstract
The current research aimed at determination of the mechanical behavior of AlSi12 alloy (Al4047) manufactured by SLM process, so that the potential of manufacturing tailored structures can be utilized to get the competitive advantages of SLM process in the era of fourth industrial revolution. These advantages include light-weighting potential, freedom-of-design, functional enhancement as well as drastically reduced time to market. It is important to understand the influence of different processing and post-processing conditions on the material properties in terms of their physical and microstructural features so that the corresponding mechanical properties can be controlled by controlling the processing conditions.
Shafaqat Siddique

Chapter 7. Outlook

Abstract
Results from the current study are encouraging that the SLM-manufactured AlSi12 alloy exhibits material properties responsible for improved quasistatic strength. After process optimization, remnant porosity has decreased to a very small level which has improved the fatigue reliability. The phenomena perceived in this study have suggested that several topics in this field have a potential to be investigated as comprehensive projects so that the complete capability profile of the process can be utilized for functional applications.
Shafaqat Siddique

Backmatter

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