Nondestructive Evaluation of Materials
Nondestructive testing is a multidisciplinary area of endeavor that has its origins in materials science and is critical to safety, quality, and reliability of many engineering parts and systems. The history of the various measurement modalities and first applications of nondestructive testing/evaluation goes back many decades. The Metals Handbook, 8th Edition, Volume 11, Nondestructive Inspection and Quality Control was published in 1976 and provided a comprehensive overview of the technologies. Nondestructive testing (NDT) is now a mature industry, with global equipment sales fast moving towards $2 billion per year. The use of conventional NDT is growing in developing countries, and challenges facing developed countries include an aging workforce, preserving industry knowledge, and maintaining an aging infrastructure. In addition to on-going use of NDE defined in codes and standards, the future will include structural health monitoring, more advanced methods for material state awareness, and integration of online measurements in manufacturing.
In the 1970s, there were major advances as NDT moved from a workmanship standard to a key element in quality technology. The 9th Edition Volume published in 1989, known as ASM Handbook, Volume 17, Nondestructive Evaluation and Quality Control and online updates in 2015, reflect the evolution of NDT to nondestructive evaluation (NDE). Since this time, the fundamental physics on which NDT/NDE is based has not changed significantly, although there have been major advances in some areas of theory, in particular some aspects of energy-defect interactions. Since the time of the previous printed edition, NDT/NDE has seen major advances in instrumentation, signal processing, and display forms and technologies in large part due to advances in electronics, analog-to-digital (A/D) conversion capabilities, and readily available computing power. During these years the science base for NDT/NDE has become more quantitative as it was seen to be necessary to better detect, locate, type, and size defects, improve the reliability of inspection, and add measures of people and equipment performance with probability of detection (POD). Such defect characterization data is being used to inform retirement-for-cause and prognostics (remaining life). There is particular interest in estimating the potential defects could have on degrading performance or potential for loss of structural integrity, under various loading or stressor conditions, and ultimately implementation of risk-based reliability life assessments.
NDE has become an area of science and technology that must be seen more as a part of the wide field of engineering; as an interdisciplinary endeavor that brings together the expertise of materials science and metrology, together with the underlying physics for inspection methods, as well as statistics, computers, robotics, and software. The adoption of advanced manufacturing is requiring new metrology tools and methods to provide data for assessing new materials including powder metals (as used in additive manufacturing) and various composites.
This Volume is a complete revision and restructuring of content from the 9th Edition which seeks to benchmark the current state of the art where new types of transducers and much improved A/D and powerful computers have revolutionized the field. There are new approaches to NDT being utilized and more basic measurement physics is being more fully understood, to give new insights which are needed to provide the data needed to solve many real-world NDE problems, to understand and measure early degradation and to give the required data for remaining safe life or prognostic prediction. Modeling and real-time digital technology, along with computed tomography provide a guide for improved and safe product. Simulation-based engineering and science lend themselves to detailed visualization for optimizing the process.
This Volume is organized into seven divisions: an introduction to NDE, visual examination and optical inspection, thermal methods, sonic and ultrasonic techniques, radiography electromagnetic inspection, and then articles which address selected applications of NDE to manufactured products.
This Volume represents the collected efforts of scores of authors and reviewers. The editors wish to extend their heartfelt thanks to all who participated in volume development and for the insightful and extensive contributions provided for the wider engineering community.
Leonard J. Bond