This study presents a comprehensive scale-bridging characterization approach to investigate acicular ferrite nucleation in electron beam welded S355 ML steel, demonstrating the critical role of titanium oxide particles in promoting fracture-resistant microstructures for offshore wind monopile applications. Using a multi-technique methodology spanning light microscopy, scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), energy dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), and transmission Kikuchi diffraction (TKD), the researchers identified and analyzed particles that serve as nucleation sites for acicular ferrite formation. This entry won the prestigious 2024 Jacquet-Lucas Award for Excellence in Metallography at the International Metallographic Contest held during IMAT in Cleveland, October 2024.

This study characterizes a historical Decauville narrow-gauge rail from Argentina (circa 1884) using metallographic analysis, chemical composition testing, and microhardness measurements. The rail, manufactured by French engineer Paul Decauville's company for portable agricultural and industrial transport, exhibited a hypoeutectoid steel composition (0.52% C) with ferrite-pearlite microstructure showing cold deformation patterns from service stress. Chemical analysis revealed a composition comparable to modern European rail steels, while microhardness values met current rail standards. Macrographic examination confirmed excellent material quality with no manufacturing defects. The study demonstrates that this 19th-century rail achieved contemporary quality standards through controlled manufacturing processes, with service-induced cold deformation enhancing mechanical strength and wear resistance.

Forensic metallurgy investigations in archaeology and aerospace engineering follow similar technical protocols but serve different objectives. Archaeometallurgical analyses focus on artifact provenance and cultural heritage management with minimal invasive sampling, while aerospace investigations prioritize rapid failure analysis for operational problems. Four case studies illustrate the approaches: noninvasive macrophotographic analysis of an ancient silver cup revealed stress corrosion cracking, noninvasive investigation of a Boeing 747 accident identified fatigue failure in fuse pins due to inadequate load knowledge, invasive lead isotope analysis successfully provenanced Chinese bronzes using kernel density methods, and comprehensive testing of F-16 wing bolts ruled out hydrogen embrittlement. Both fields employ similar analytical techniques, including microscopy, fractography, and chemical analysis, but differ in sampling constraints, time pressures, and reporting goals, with successful investigations in both domains requiring interdisciplinary teamwork.

This article highlights some of the best metallographic practices from a laser powder bed fusion laboratory and provides practical observations of the more universal aspects of powder testing.

This article summarizes the more common analytical techniques for studying ancient metal artifacts, illustrated by case histories. There are two main classifications: noninvasive and invasive techniques. This distinction is of prime importance because some heritage objects may be too rare or valuable for invasive sampling, or there may be ethical objections to certain types of examination. Noninvasive examination of ancient metal artifacts is important, yet it cannot provide the detailed information obtainable from invasive techniques. This is especially true when artifacts contain “hidden” damage and there is also a need for accurate quantitative analyses.

A world-renowned archaeometallurgist reflects on his career within the discipline and the technological advancements he witnessed during five decades out in the field and at the microscope.

Although stress corrosion cracking (SCC) accounts for just a fraction of all engineering failures, its prevention is a major problem, particularly in the aerospace industry. Recent archaeometallurgical studies show that stress corrosion cracking occurred in ancient metallic artifacts. This article describes investigations that revealed definite evidence for SCC in ancient silver and bronze alloys and a probable case of SCC in low-carat (13K) gold. Diagnostic methods included visual inspection, metallography, and fractography.

This article describes a metallographic and SEM study of a Spanish silver coin. The study verified the coin's authenticity and determined its alloy composition. The investigation is an example of a unique archaeometallurgical collaboration between a university and a museum.

This article reports on development of a versatile new technique that fills the need for grain etching in multiple aluminum alloy series. The procedure is a two-step etch that combines an attack etchant with a stain etchant to reveal grain structure of 2000, 5000, 6000, and 7000 series aluminum alloys. This entry won the prestigious DuBose-Crouse Award for unique, unusual, and new techniques in microscopy at the 2022 International Metallographic Contest.

A recent metallographic and historical analysis of two parts from the Buenos Aires to Pacific Railroad railway looked at possible manufacturing techniques of the parts in question. The information collected is useful for comparison with techniques and materials used at that time as well as with current techniques. The analysis questioned whether the material itself has varied or evolved from the metallurgical point of view, and confirmed the quality of raw material used to construct the historic railway line.

This article describes sample preparation to create a visually impressive micrograph image of single-phase cartridge brass, C26000, an alloy composition of 70% copper and 30% zinc. C26000 was chosen due to the striking twins and large grain size that are easily generated by annealing a cold-worked sample, the large range of contrast and colors that can be created by etching, and the wide availability of the material. This entry won the Jacquet-Lucas Award for Best in Show at the 2021 International Metallographic Contest.

Identifying metallographic TSC artifacts, specifically in air plasma spray zirconia-based thermal barrier coatings.

A scientific study of two copper coins from 1851 and 1853 reveals well-preserved symbols of a growing, newly independent Chile nation.

Two case studies highlight the strengths and weaknesses between traditional metallurgical techniques and 3D micro-computed tomography, as well as the interplay between the two.

A metallurgical study of a 10th century iron-base nail from the central-East coast of Tunisia reveals how early metallurgists without modern scientific knowledge created parts with engineered properties.

The production and processing of advanced materials, namely metals and alloys, began in the Old World about 8000 years ago and developed over many millennia, providing a lasting legacy for modern civilizations. This article gives a brief overview of the production and processing of ancient bronzes and silver in the Old World, and also mentions post-processing problems including corrosion and embrittlement, owing to long-term burial before archaeological recovery.

This entry won the prestigious Jacquet-Lucas Award for Best in Show in the 2020 International Metallographic Contest. In the research discussed in this article, light microscopy was applied to a Co28Cr6Mo alloy for a biomedical application processed by laser bed powder fusion (LPBF) additive manufacturing.

A study of metal artifacts from the Mendoza region of Argentina reveals the influences of native migration and European conquest.

Despite decades of research, fundamental questions still exist regarding the role of microtexture on the deformation, fatigue, and fracture behavior of titanium alloys. This article describes the microstructural evolution processes that result in microtexture formation, while Part II of this series will further elaborate on the effects of microtexture on deformation behavior.

Vision-based machine learning systems for microstructural characterization and analysis are being successfully used for image classification, semantic and instance segmentation, and object detection, leading to accurate, autonomous, objective, and repeatable results.