Because alloy steel hardenability is such an important factor in part manufacturing, the Center for Heat Treating Excellence (CHTE) is conducting research through simulations and laboratory testing aimed at learning more about the performance of gas quenching systems used to harden newer alloy steels. The primary goal of the study is to establish a standard method to evaluate gas-quench steel hardenability. Heat transfer coefficients will be determined for different gas pressures and during the cooling phase.

New methods evaluate steel hardenability in a standard gas quench test and heat transfer coefficient variation within a furnace gas quench chamber.

This article explains why defining gas quenching in terms of bar pressure no longer applies and how a new definition based on heat transfer and cooling rate leads to a better understanding of which steels and what cross-sections can be hardened via gas quenching.

A digital refractometer gives more accurate quench concentration readings thereby reducing maintenance, increasing productivity, and ensuring desired metallurgical properties.

This article demonstrates how FEA-based tools are used to model residual stress and distortion in a full-float truck axle induction hardened and cooled at different rates. The effect of cooling rate on axial displacement is discussed.

Tests conducted on vacuum carburized and quenched shafts identify variables that increase distortion and the magnitude of residual stresses.

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.

Application of heat treat simulation using the finite element method is ideal to troubleshoot, improve, and design heat treating processes. This article presents examples of heat treating simulation used in the design of a tooling component and in refining a low-pressure carburizing 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.

Engineers at the Ford Motor Co. are using integrated computational materials engineering (ICME) tools, allowing them to accurately simulate the heat treatment of gears and predict phase transformation kinetics and distortion.

This article focuses on five common reasons for distortion and cracking during heat treatment and recommended remediations: (1) Nonuniform and uncontrollable heat transfer during heating and cooling; (2) Structural changes during phase transformation; (3) Residual stresses in the part that occur due to forming, welding, or machining before heat treatment; (4) Macro or micro steel structure; and (5) Fixturing and loading errors.

A new design and welding process may extend the life of furnace rolls in hot-dip coating lines, which often fail in less than one year. This article is a case study of analysis of a failed furnace roll that led to a proposed improved design to extend component life.

Experimentally derived surface heat flux rate data and computational fluid dynamics (CFD) software are helping researchers more accurately simulate liquid quenching processes. This article describes an approach where surface heat flux rates are determined experimentally in a precisely controlled flow boiling test system. This data is then used to build CFD models that are proving to be quite accurate in quenching process simulations.

This article provides a brief review of thermal spray technology along with examples of where and how it used in steelmaking equipment and operations.

This article considers the effect of atomic oxygen exposure in low earth orbit on thin film solid lubricants of molybdenum disulphide and diamond-like carbon nanocomposites, a silica-containing diamond-like carbon film. Advances in deposition methods over the past few decades enable dense films to be created that are more resistant to oxidative degradation and the effects of adsorbed moisture than their predecessors. Further, incorporating additional phases improves the tribological performance of the films in a range of atmospheres.

Advancements in nanoscience are making it possible to metallically glue two solids together at room temperature, in air, and under a small amount of mechanical pressure. Metallic glues can serve as excellent conductors for heat dissipation and electrical current in electronic devices and also as leak-resistant seals for vacuum environments.

Field assisted sintering technology (FAST) enables cost-effective manufacturing of metal, ceramic, and composite components with sub-micron grain microstructures and tailored properties.

This article evaluates the sliding wear behavior of fiber-reinforced 7075 Al alloy composites. It explains how the composite samples were made and shows how different fiber materials, volume percentages, and orientations affect hardness and wear resistance. It also interprets wear test results and what they reveal about wear mechanisms in metal-matrix composites.

This work describes the development of a model to simulate the compound layer growth kinetics for nitriding AISI 4140 steel based on a customized Lehrer diagram. The model can be used to calculate concentration profiles of nitrogen as a function of time and position during the nitriding process and to predict the thickness of the compound layer. Winner of the 2012 HTS-Bodycote Best Paper in Heat Treating Award endowed by Bodycote Thermal Process-North America.

In this article, the authors demonstrate the use of simulation software to optimize low-pressure carburizing (LPC) processes for high-alloy steels with strong carbide-forming elements.