Abstract This article introduces "Smart Repair," an integrated scan-to-repair workflow that advances robotic cold spray additive manufacturing (CSAM) beyond the traditional trade-off between flexible manual repair and rigid, pre-programmed robotic repair. Built on CSIRO's Continuous3D software platform, the system uses in-cell 3D scanning to generate a live digital model of a damaged component, automatically identifying repair regions and generating collision-free, optimized robotic toolpaths without manual coding or reliance on CAD files. A case study restoring a PT6 gearbox housing demonstrates that this approach enables efficient, high-quality automated repair of one-off and variably damaged parts that were previously impractical to automate.
Abstract This technical spotlight examines how rotating beam fatigue (RBF) testing can be a faster and more economical alternative to conventional axial fatigue testing for characterizing material endurance limits. The article contrasts the high setup costs, alignment sensitivity, and time-intensive nature of axial testing with RBF's self-centering collet design, higher testing frequencies (up to 100 Hz), and surface-sensitive stress measurement, which together enable dramatically reduced test times and costs. While acknowledging that axial-torsion testing remains necessary for applications requiring complex, multi-axis loading replication, the authors argue RBF is democratizing fatigue data generation for materials researchers, quality managers, academic labs, and testing facilities alike.
Abstract The second installment of a three-part series traces the expansion of nickel-based superalloy 718 beyond aerospace turbines into critical applications, including large power turbine rotors, rocket engines (notably the Space Shuttle Main Engine), cryogenic systems, nuclear reactors, oil and gas production tooling, and high-strength fasteners. The article highlights how alloy 718's combination of high strength, weldability, corrosion resistance, and performance across extreme temperature ranges—from liquid helium to 1200 °F—drove its adoption. It also details key metallurgical developments, such as delta-phase control and specialized heat treatments, that enabled its use in increasingly demanding environments.
Abstract From the 1930s through the 1950s, Metal Progress — the flagship publication of the American Society for Metals (now ASM International)—featured bold, distinctive cover designs. The artwork ranged from oil paintings and geometric abstractions to exquisite photography, all unified by a common thread: some reference, however stylized, to the processing or application of metals. This article features several striking examples of covers from that period.
Abstract The Aluminaire House, the first all-metal residence in the U.S., pioneered aluminum and steel construction as a scalable, affordable housing prototype. Designed in 1930-1931 by A. Lawrence Kocher and Albert Frey, the structure demonstrated that factory- produced components—aluminum columns, steel decking, sheet metal cladding, and plate glass—could be rapidly and affordably assembled into a habitable dwelling. The house was recently restored and reinstalled at the Palm Springs Art Museum.
Abstract A thermomechanical treatment widely used to enhance the mechanical properties of steel rebar creates a microstructural gradient — a tempered martensitic outer shell for strength and a ferritic-pearlitic core for ductility — that enables rebars to meet required tensile properties even in steels with high inclusion content. This article examines the trade-off inherent in that approach: while the treatment reliably meets mechanical performance targets, the tempered martensitic outer layer is more susceptible to corrosion than the ferritic-pearlitic core, exhibiting intergranular corrosion and pitting at MnS inclusions under early chloride exposure. Because rebar quality and treatment completeness can vary by producer and country, on-site inspection remains necessary, and the corrosion vulnerability of the outer shell raises concerns for infrastructure designed to meet 100-year service life requirements.
Abstract This article, the third in a series, describes an eight-step failure investigation process developed by the author. It is a systematic approach to ensure that the investigation is properly performed, the true root cause of the failure is identified, the documentation is thorough, the results are properly reported, and appropriate corrective action is implemented.
Abstract Additive brazing produces dense, wear-resistant, crack-free, and corrosion-resistant coatings that often do not require further processing.
Abstract This article examines how advances in portable phased-array ultrasonic testing (PAUT) are expanding aerospace NDT capabilities across the full aircraft lifecycle—from raw-material verification and manufacturing quality control to in-service maintenance. Key developments covered include local immersion scanning for large composite panels, near-surface-optimized probe and wedge configurations for thin skins and bonded structures, and advanced imaging techniques such as the Total Focusing Method (TFM) and Phase Coherence Imaging (PCI), which improve defect characterization beyond traditional amplitude-based methods.
Abstract The first installment of a three-part series traces the origins and early aerospace adoption of Inconel alloy 718, the highest-volume nickel-base superalloy in aircraft engines today. Invented in the mid-1950s by Herbert Eiselstein at Huntington Alloys — originally for coal-fired power plant tubing — the alloy’s niobium-induced gamma double prime strengthening phase delivered superior yield strength and weldability compared to incumbent superalloys, while its slow aging kinetics enabled forming and welding reliability that Waspaloy and René 41 could not match. Inco’s decision to freely license the patent drove competitive process innovation across the supply chain, rapidly maturing vacuum melting, remelting, and forging technologies. Early engine programs, from the SR-71 Blackbird’s J58 diffuser case to GE’s TF39 and Pratt & Whitney’s JT9D, established alloy 718 as the structural workhorse of aero-engines — a position reinforced by its cobalt-free composition, lower intrinsic cost, and broad fabricability that continue to sustain its dominance today.
Abstract Recent advances in bioelectronics, power supply miniaturization, and targeted energy delivery are enabling a new generation of true in vivo shape memory implantable devices that go beyond the self-expanding superelastic implants that have dominated the field for three decades. The central challenge—human tissue damage at temperatures achievable in relatively short durations—has historically limited the clinical use of Nitinol's shape memory properties, since common binary Nitinol alloys require temperatures up to 90°C for full actuation. This article reviews three devices currently under development that demonstrate viable approaches to safe in vivo actuation: Myra Vision's CalibrEye glaucoma shunt, the V-Wave Magical interatrial shunt, and Adona Medical's Delphi shunt. The recent innovations represented by these examples may signal an inflection point analogous to the early development of superelastic stents, with particularly promising opportunities in pediatric devices where implant sizing must adapt as patients grow.
Abstract This study investigates how the degradation of yttria suspensions over time affects coating quality in suspension plasma spraying (SPS), comparing coatings produced from a fresh batch at six months post-delivery with those from a significantly aged batch at eighteen months. While particle velocity and temperature in the plasma plume remained largely unchanged between batches, the aged suspension produced distinct coating defects colloquially termed “speckles”—localized agglomeration artifacts seeded by incompletely melted particles that propagate and develop internal cracking with successive deposition passes. The findings underscore the importance of suspension shelf life as a process variable and highlight the risk of quality degradation when expired or improperly stored suspensions are used in SPS applications.
Abstract For heat treaters working with high-carbon steels such as AISI 1050–1095 and 52100, grain size is a critical process variable that directly affects austenitizing temperatures, soak times, hardness penetration, and overall production costs. This article examines the metallurgical differences between coarse-grain (ASTM 2–4) and fine-grain (ASTM 5–8) steels, explaining how finer grain structures impede carbon diffusion during austenitization and require higher temperatures and longer soak times than coarse-grain equivalents. The article quantifies the real financial impact of these constraints and offers practical recommendations for heat treaters, including material verification, development of material-specific processing recipes, and engineering specifications that account for reduced hardenability.
Abstract Thermal management is one of the most critical and difficult challenges in next-generation sustainable aviation, where hydrogen fuel cells, hybrid-electric systems, and battery-electric propulsion all generate significant heat that conventional heat exchangers cannot efficiently handle without unacceptable weight and size penalties. This article describes an approach for leveraging additive manufacturing to produce intricate, lightweight heat exchangers with optimized internal channels and exceptionally thin walls that conventional manufacturing cannot achieve. Three examples are presented to illustrate the approach in practice.
Abstract This article demonstrates the complementary value of combining electron backscatter diffraction (EBSD) and x-ray diffraction (XRD) for materials characterization through two case studies. EBSD provides localized crystallographic information from micron to millimeter-scale areas within a scanning electron microscope, while XRD characterizes larger centimeter-sized regions using a diffractometer, with both techniques capable of revealing texture and phase composition. The first case study examined texture measurements in oxide dispersion strengthened (ODS) and non-ODS additively manufactured nickel-based superalloys. The second case study focused on phase identification of desert soil samples serving as lunar analogues for radio frequency property investigations. Together, the studies illustrate how EBSD's site-specific sensitivity and XRD's bulk representativeness create a comprehensive characterization approach where each technique validates and complements the other, ensuring that neither minor phases nor overall composition are overlooked in materials analysis.
This article, the second in a series, provides an overview of the phases of a failure examination: identification of the true root cause, failure mechanism, and failure mode. The article includes definitions of key terminology used in metallurgical failure analysis.
Meet Elizabeth Hoffman, the new president of ASM, and learn about her professional background, service, and contributions as a leader.
This article addresses the challenge of achieving ultra-high purity standards—"five-nines" (99.999%) or better—in precious metal recycling from electronic waste, where trace amounts of light element impurities (carbon, sulfur, oxygen, nitrogen) can critically impact material performance. Traditional analytical methods are inadequate for detecting contamination at parts-per-million or parts-per-billion levels, prompting the adoption of advanced combustion and inert-gas fusion techniques that rapidly measure impurities by heating samples in controlled atmospheres and detecting evolved gases. A case study using specialized analyzers demonstrated successful implementation and high-precision results. This rapid, non-destructive analytical approach enables accelerated quality assurance, provides definitive purity certification, supports high-throughput operations while preserving valuable material, ultimately making urban mining of precious metals from e-waste an economically viable component of the circular economy.
Abstract From machining scrap to recycled powders and polymers, upcycling is rapidly moving into mainstream additive manufacturing. It reduces dependence on virgin feedstock while enabling local, closed-loop manufacturing. This article is an overview of the processes, current state, impacts, and future view.
