Martempering involves cooling steel from the austenitizing temperature and rapidly cooling into either specially formulated petroleum oil or a molten salt bath with a specific composition to a temperature slightly above the martensite start (Ms) transformation temperature of the steel. Martempering is performed to reduce distortion problems that may be encountered with conventional quenching methods. This article, adapted from the latest ASM Handbook on quenching and quenchants, describes suitable steels for martempering and variables that influence the process.

Both shape memory and elastocaloric effects are related to the reversible martensitic phase transformation. For the shape memory effect, thermal energy is used to drive the material through the phase transformation and recover its original shape. For the elastocaloric effect, mechanical energy is used to induce phase transformation, and the associated latent heat is used to pump heat for cooling or heating. Heat pumps based on the elastocaloric effect have a low environmental impact and are highly efficient. However, designing a prototype to harvest the full potential of the elastocaloric effect has been challenging. This article summarizes prototyping efforts undertaken by three different research groups.

John J. Croat and Masato Sagawa simultaneously and independently invented the world’s most powerful permanent magnet, the neodymium (NdFeB) magnet, and established two different manufacturing methods to produce it. Their achievement is recognized by the 2023 Honda Prize, awarded by the Honda Foundation. This article highlights each inventor’s research contributions.

Annealing and normalizing both involve heating metal to a temperature and cooling back to room temperature and are differentiated by the metals involved and rate of cooling. This article is an overview of annealing and normalizing processes.

Ni-ion irradiated NiTi is nearly 50% harder, retains 85% recoverable deformation, and has reduced hysteresis. This work explores the feasibility of using ion beam modification to modulate the austenite to martensite phase transformation in NiTi, thereby achieving novel or localized properties in near-surface regions.

The second article in this series looks at materials testing, microstructural evaluation, mechanical testing, and residual stress and distortion using the DANTE Controlled Gas Quenching process.

A new method to control distortion in difficult-to-quench geometries addresses the nonuniform cooling inherent in most gas quenching processes. This article describes the development of a controlled gas quenching prototype unit design and its operation. The prototype unit constructed was able to achieve great control within the temperature range of 400 to 100°C, using varying rates of temperature change.

Novel methods for altering the mechanical properties of functionally graded orthodontic medical devices leads to new applications. This article highlights recent applications of selective vaporization to enable functional grading of shape memory alloys in medical devices for the dental industry.

Creep strain behavior during cooling was investigated by physical simulation, giving insight into the relationship of flow stress behavior and microstructure as a function of temperature and cooling rate.

New research explores a zirconia-based shape memory ceramic that exhibits a unique type of electrically triggered martensitic transformation.

Through a series of case studies, the benefits of micro x-ray fluorescence (XRF) over traditional XRF are demonstrated in the power generation industry for informing weld procedures, identifying root cause, and providing materials or component specifications.

Induction hardening parts with small grain size achieves higher fracture strengths, but close control of thermal cycles is required to prevent grain growth.

Deformation-induced martensite phase transformation during room temperature forming of austenitic stainless steel leads to higher residual stress. This article discusses the results of a study to determine the relationship between deformation-induced martensite phase transformation and residual stress in AISI Type 304 austenitic stainless steel (nominal 18% Cr, 8% Ni) after stamping.

New methods for processing titanium alloys offer the potential to enhance mechanical properties while reducing component cost. This article discusses innovative and potentially lower cost fabrication processes including additive manufacturing (AM), superplastic forming/diffusion, hot isostatic pressing (HIP) near-net shapes from prealloyed powder, injection molding, rapid solidification, mechanical alloying, and thermohydrogen processing.

Using virtual tools to study aluminum cylinder head quenching processes delivers valuable information for process design and optimization. In this study, cooling curves and temperature gradients generated by air and water quench modeling methods were used to evaluate quenching performance for various quenching configurations.

A new process called nanofunctionalization was successfully used to control the solidifying microstructure during additive manufacturing and produce crack-free 7000 and 6000 series aluminum alloys for the first time.

Affordable bulk production of a newly developed nanostructured bainitic steel is possible without using severe deformation or complex heat treatments. This article discusses the characteristics and significance of nanostructured bainite in terms of the transformation mechanism.

Production techniques based on net shape forming from the liquid or semisolid state offer advantages in terms of manufacturing simplicity, cost, and energy consumption compared with current complex solid state forming processes. Engineering molten alloys to change their solidification process improves part integrity and alloy microstructure, leading to better component performance.

This article presents a broad overview of key annealing processes such as recovery, recrystallization, and grain growth in magnesium and its alloys. It explores the role of recovery in recrystallization behavior, evolution of recrystallization microstructure and texture, current understanding of grain coarsening in magnesium alloys, and concludes with a perspective on future research.

There is growing interest in steels microalloyed with titanium, niobium, and molybdenum for use in high-temperature carburizing applications. This article describes methods for control of grain coarsening and work to commercialize microalloyed coarsening-resistant steels.