scispace - formally typeset
Search or ask a question
Author

Khalid Rafi

Bio: Khalid Rafi is an academic researcher from University of Louisville. The author has contributed to research in topics: Selective laser melting & Risk analysis (engineering). The author has an hindex of 9, co-authored 9 publications receiving 1406 citations. Previous affiliations of Khalid Rafi include Nanyang Technological University.

Papers
More filters
Journal ArticleDOI
TL;DR: In this article, the defect characteristics are discussed with respect to defect generation mechanisms; and effective process windows for SLM and EBM system are discussed. But they do not consider the defect generation mechanism.
Abstract: Ti–6Al–4V parts made using additive manufacturing processes such as selective laser melting (SLM) and electron beam melting (EBM) are subject to the inclusion of defects. This study purposely fabricated Ti–6Al–4V samples with defects by varying process parameters from the factory default settings in both SLM and EBM systems. Process parameters are classified according to their tendency to create certain types of porosity. Finally, defect characteristics are discussed with respect to defect generation mechanisms; and effective process windows for SLM and EBM system are discussed.

766 citations

Journal ArticleDOI
TL;DR: In this article, the mechanical properties of Ti-6Al-4V samples produced by selective laser melting (SLM) and electron beam melting (EBM) were evaluated for hardness, tensile, and fatigue tests.

620 citations

DOI
01 Jan 2013
TL;DR: In this paper, the influence of energy density on porosity and microstructure of SLM 17-4PH stainless steel parts was investigated using the Archimedes method and image analysis.
Abstract: Energy density, which directly impacts the properties of as-built parts, is a key factor in the metal selective laser melting (SLM) process. This paper studies the influences of energy density on porosity and microstructure of SLM 17-4PH stainless steel parts. Experiments were carried out by varying processing parameters to change energy density. Porosity was estimated using the Archimedes method and image analysis. Microstructures were investigated through optical and electron microscopy. The experimental results were discussed regarding porosity formation and microstructure characterization.

163 citations

Journal ArticleDOI
TL;DR: In this paper, sound multi-layered deposits in various ferrous materials were realized using friction surfacing in both single-and multi-track approaches, and samples with fully enclosed internal cavities were also successfully produced.
Abstract: In this work, we explore the possibility of utilizing friction surfacing, an emerging solid-state surface coating process, for layer-by-layer manufacture of three-dimensional metallic parts. One possibility in this regard (single-track friction surfacing) is to utilize friction surfacing for depositing a track or layer of material (sufficiently wide to cover the entire layer area), which is subsequently shaped to its corresponding slice counter using CNC machining. Another possibility (multi-track friction surfacing) is to generate a layer from multiple overlapping tracks of friction surfaced material, which is subsequently shaped as required using CNC machining. In the current work, sound multi-layered deposits in various ferrous materials were realized using friction surfacing in both single- and multi-track approaches. Samples with fully enclosed internal cavities and those consisting of different materials in different layers were also successfully produced. The deposits showed fine-grain wrought micr...

84 citations


Cited by
More filters
Journal ArticleDOI
TL;DR: A review of the emerging research on additive manufacturing of metallic materials is provided in this article, which provides a comprehensive overview of the physical processes and the underlying science of metallurgical structure and properties of the deposited parts.

4,192 citations

Journal ArticleDOI
TL;DR: In this paper, the authors describe the complex relationship between additive manufacturing processes, microstructure and resulting properties for metals, and typical microstructures for additively manufactured steel, aluminium and titanium are presented.

2,837 citations

Journal ArticleDOI
TL;DR: In this article, a review of additive manufacturing (AM) techniques for producing metal parts are explored, with a focus on the science of metal AM: processing defects, heat transfer, solidification, solid-state precipitation, mechanical properties and post-processing metallurgy.
Abstract: Additive manufacturing (AM), widely known as 3D printing, is a method of manufacturing that forms parts from powder, wire or sheets in a process that proceeds layer by layer. Many techniques (using many different names) have been developed to accomplish this via melting or solid-state joining. In this review, these techniques for producing metal parts are explored, with a focus on the science of metal AM: processing defects, heat transfer, solidification, solid-state precipitation, mechanical properties and post-processing metallurgy. The various metal AM techniques are compared, with analysis of the strengths and limitations of each. Only a few alloys have been developed for commercial production, but recent efforts are presented as a path for the ongoing development of new materials for AM processes.

1,713 citations

Journal ArticleDOI
TL;DR: In this paper, the recent progress on Ti6Al4V fabricated by three mostly developed additive manufacturing techniques-directed energy deposition (DED), selective laser melting (SLM) and electron beam melting (EBM)-is thoroughly investigated and compared.

1,248 citations

Journal ArticleDOI
TL;DR: A review of published data on the mechanical properties of additively manufactured metallic materials can be found in this paper, where the additive manufacturing techniques utilized to generate samples covered in this review include powder bed fusion (eBM, SLM, DMLS) and directed energy deposition (eBF3).
Abstract: This article reviews published data on the mechanical properties of additively manufactured metallic materials. The additive manufacturing techniques utilized to generate samples covered in this review include powder bed fusion (e.g., EBM, SLM, DMLS) and directed energy deposition (e.g., LENS, EBF3). Although only a limited number of metallic alloy systems are currently available for additive manufacturing (e.g., Ti-6Al-4V, TiAl, stainless steel, Inconel 625/718, and Al-Si-10Mg), the bulk of the published mechanical properties information has been generated on Ti-6Al-4V. However, summary tables for published mechanical properties and/or key figures are included for each of the alloys listed above, grouped by the additive technique used to generate the data. Published values for mechanical properties obtained from hardness, tension/compression, fracture toughness, fatigue crack growth, and high cycle fatigue are included for as-built, heat-treated, and/or HIP conditions, when available. The effects of test...

1,093 citations