Search Results for residual stress

This article series explores the indispensable role of characterization in the development of cold spray coatings and illustrates some of the common processes used during coating development.

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.

Residual stress exists in all classes of materials and significantly impacts many facets of product design and manufacturing. This article reviews residual stress formation, types of stresses, and measurement techniques. ASM International is launching a technical committee on residual stress to enable industry-wide collabration and to advance the science of this important phenomenon.

This case study measures residual stress on a truck axle housing as it goes through the manufacturing process.

Because residual stress has a significant impact on engine component service life, understanding its cause helps optimize fabrication processes to ensure quality. X-ray diffraction is often the only viable technique to measure residual stresses at certain failure-critical locations. This article gives some guidelines for XRD analysis to understand and control residual stresses in processing of engine components.

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.

Residual stress is generally defined as the stress that is retained in equilibrium in a body or material after manufacturing or processing operations or component usage in the absence of any external forces. This article provides an overview of residual stress measurement methods, including diffraction-based, piezo-spectroscopic/Raman, mechanical, ultrasound, and magnetic techniques. It includes a discussion of measurement planning and execution considerations.

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.

Process optimization and optimal component performance can be achieved when multiple variables are measured and studied as a whole. In the investigation described in this article, fatigue performance of AISI 8620 H steel was characterized as a function of carburization case depth, hardness, residual stress, and retained austenite to demonstrate that an optimized carburization process could be engineered to meet specific application requirements.

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

This study looks at whether adding an annealing step to the heat treating process has an effect on residual stress and distortion on hypoid gear sets. Test results indicate that the annealing heat treatment introduced between gear set soft cutting and case carburizing helped to minimize distortion.

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.

Development of wear-resistant hardfacing materials using powder metallurgy/hot isostatic pressing technology offers an alternative to today's cobalt-based materials and those that suffer delamination damage. Ongoing research and development at the Electric Power Research Institute (EPRI), detailed in this article, examines the application of wear-resistant hardfacing materials using the PM/HIP process. The hope is to eliminate weldability and residual stress challenges associated with some hardfacing alloys, as well as to provide a wider range of potential alloy solutions to reduce cobalt use and to address delamination issues with incumbent materials.

Laser shock peening is a novel surface engineering method that improves component performance by introducing deep compressive residual stress. It has demonstrated significant benefits in safety-critical applications such as aerospace engines. Ongoing research focuses on lowering the cost and increasing equipment flexibility.

Neutron-based imaging and measurement techniques are an ideal complement to x-ray methods for characterizing additively manufactured materials and components. This article presents examples showing how neutron radiography and residual strain measurements reveal the internal structure and stress distributions in highly engineered turbine blades produced by additive processes. It also discusses the development of neutron characterization tools at ORNL and a recent effort in which they were used to evaluate stress-relief treatments for large-scale metal AM structures.

Modeling shows that achieving required gear performance in a reduced gear size is possible by changing the steel grade and heat treatment parameters during the design stage. This article describes work in which virtual computer models using DANTE software are applied to help achieve gear size reduction by including steel grade hardenability and heat treatment parameters in the design process.

In this brief case study, finite element analysis and linear elastic fracture mechanics are used to evaluate new weld designs for large marine engines.

The Center for Heat Treating Excellence (CHTE) was founded with the goal of bringing the industrial sector and university researchers together to find solutions to real-world problems. The Center, located at Worcester Polytechnic Institute (WPI) in Massachusetts, has 19 members from all areas of industry working together with WPI researchers to improve both heat treat and thermal processing methods worldwide. This article describes some of the current CHTE research projects.

This new article series explores the indispensable role of characterization in the development of cold spray coatings and illustrates some of the common processes used during coatings development. This article provides a list of techniques to be covered in subsequent articles.

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.