Stress corrosion cracking is an insidious form of damage that can occur when a susceptible metal is subjected to a tensile stress in a specific environment. To relieve tensile stresses at welded joints, postweld heat treatment can be helpful in reducing the susceptibility of carbon steel fabrications to SCC. When planning to use stainless steels in chloride-containing environments, it is advisable to select alloys that have been specifically developed to resist stress chloride cracking such as ferritic-austenitic (duplex) alloys, low-carbon ferritic alloys, and 6% Mo austenitic alloys or to select high-nickel alloys.

Emissivity is a term used to define the ability of a surface to emit and absorb radiation. At any given temperature, the emissivity of a body (or surface) equals its absorptivity. Development work on a vacuum carburizing process revealed the need to better understand the effect of workload surface emissivity and the proper use of dummy thermocouple test blocks. This article reports on the findings from this research effort.

Proper specification, measurement, and control of annealing furnace atmospheres are critical to reduce sooting, oxidation, sticking, and distortion. This article describes how to effectively design and utilize a nitrogen-hydrogen annealing atmosphere.

Atomic force microscopy studies show that sharp yield points in steels are explained by the existence of hard grain boundary walls, contrary to current accepted theories.

Induction heating is used to produce high quality, reliable aerospace components as well as unique combinations of engineering characteristics.

As industrial infrastructure continues to age, the risk of corrosion-related incidents becomes greater, increasing the need for detailed analysis of residual elements in steel framework and equipment. X-ray fluorescence is seeing greater use due to new smaller, lightweight equipment designs.

Conserving utilities is the simplest, most practical way for heat treaters to reduce costs and remain competitive. This article describes fuel-based nitrogen cogeneration systems that may offer efficiency benefits and reduced emissions for certain heat treating plants.

Active screen plasma nitriding and nitrocarburizing are relatively new processes in which a plasma discharge is applied to a metal screen surrounding the workload, generating highly reactive gas species that flow to the component surface. The active screen also radiates heat, resulting in a uniform temperature throughout the load. This article provides an overview of the two processes and presents examples of their use on stainless steel piston rings (nitriding) and 4142 and 1045 steels (nitrocarburizing).

Variable valve timing (VVT) plates are part of a system designed to optimize engine performance by changing the lift, duration, and timing of valve lift events. This article reviews a case study involving cracking of AISI 1045 steel VVT plates after heat treating.

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.

Significant advancements in metallurgy were highlighted at a special symposium presented at the Materials Science & Technology 2016 conference in Salt Lake City. This article summarizes the topics presented. All six speakers shared examples of the importance of understanding how the specific manufacturing process affects microstructure development in metals. The fundamental understanding of microstructure allows metallurgists to select manufacturing processes and schedules to tailor the microstructure, and therefore mechanical properties and performance, for a particular component.

Boriding is performed by diffusing boron atoms into a metal surface and allowing the boron to react with elements present in the substrate to form metal-boride compounds. Upon diffusing enough boron into the surface, a metal-boride compound layer with high hardness precipitates and grows below the surface of the part. This article discusses boriding of ferrous alloys, including a new deep case boriding method that produces wear layer depths comparable to competitive processes such as carburizing, nitriding, thermal spray coatings, and hardfacing.

Accurate measurement of retained austenite levels is important in the development and control of a heat treatment process.

Professor Induction answers a wide variety of questions regarding induction heating and heat treating. This article addresses differences between auto-tempering and self-tempering.

Understanding the forces behind decarburization is the first step toward minimizing its detrimental effects. This article reviews decarburization basics and results of experimental work on spring steels.

Metallographic examination and optical emission spectroscopy shed light on the origin of a lampshade found in the aftermath of Hurricane Katrina. The steels used for the ring and wire in the frame are typical of those made prior to WWII and the fabrication processes appear to be of a similar timeframe. Tassels on the lampshade were determined to be a more recent alteration and the fabric was found to be cow skin parchment based on DNA testing.

Phase coherence imaging is a new approach for processing ultrasonic signals generated during nondestructive testing. This article shows how it compares with amplitude-based focusing methods for detecting hydrogen-related microfissures, creep-induced damage, and stainless-steel weld voids.

Using advanced characterization techniques on surface hardened steels builds a richer understanding of the underlying metallurgical phenomena.

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.

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.