This chapter provides an overview of the various inspection methods used with metals and alloys, namely visual inspection, coordinate measuring machines, machine vision, hardness testing, tensile testing, chemical analysis, metallography, and nondestructive testing. The nondestructive testing methods discussed are liquid penetrant inspection, magnetic particle inspection, eddy current inspection, radiographic inspection, and ultrasonic testing.

Visual inspection is the most important method of inspection of materials. This chapter describes the procedures involved in visual inspection such as identification markings, identification of defects caused by heating problems, scaling of materials, cracking characterization, and measurement of material dimensions. It discusses the mechanisms, advantages, limitations, components, and applications of various visual inspection tools, namely magnifying devices, lighting for visual inspection, measuring devices, miscellaneous measuring equipment, record-keeping devices, and macroetching.

The coordinate measuring machine (CMM) is used for three-dimensional inspection of both in-process and finished parts. This chapter provides a detailed account of the operating principles, measurement techniques, capabilities, and applications of CMMs. The types of CMMs are described. Vertical CMMs include cantilever-type, bridge-type, and gantry CMMs; horizontal CMMs, such as the horizontal-arm type, are also covered. The CMM application for geometric measurement, contour measurement, and specialized surface measurement are discussed.

Machine vision is a means of simulating the image recognition and analysis capabilities of the human eye/brain system with electronic and electromechanical techniques. This chapter discusses four basic steps in the machine vision process, namely image formation, image preprocessing, image analysis, and image interpretation. Details of the processes involved, equipment used, and the factors to be considered are also presented. In addition, the applications of machine vision are discussed.

This chapter discusses the operating mechanism, applications, advantages, and limitations of Brinell hardness testing, Rockwell hardness testing, Vickers hardness testing, Scleroscope hardness testing, and microhardness testing. In addition, the general precautions and selection criteria to be considered are described and details of equipment setup provided.

This chapter is a detailed account of the tensile testing procedure used for evaluating metals and alloys. The discussion covers the stress-strain behavior of metals determined by tensile testing, properties determined from testing, test machines for measuring mechanical properties, and general procedures of tensile testing. Three distinct aspects of standard test methods for tension testing of metallic materials are discussed: test piece preparation, geometry, and material condition; test setup and equipment; and test procedure.

The overall chemical composition of metals and alloys is most commonly determined by x-ray fluorescence (XRF) and optical emission spectroscopy (OES). High-temperature combustion and inert gas fusion methods are typically used to analyze dissolved gases (oxygen, nitrogen, and hydrogen) and, in some cases, carbon and sulfur in metals. This chapter discusses the operating principles of XRF, OES, combustion and inert gas fusion analysis, surface analysis, and scanning auger microprobe analysis. The details of equipment set-up used for chemical composition analysis as well as the capabilities of related techniques of these methods are also covered.

This chapter describes the methods and equipment applicable to metallographic studies and discusses the preparation of specimens for examination by light optical microscopy. Five major operations for preparation of metallographic specimens are discussed: sectioning, mounting, grinding, polishing, and etching. The discussion covers their basic principles, advantages, types, and applications, as well as the equipment setup. The chapter includes tables that list etchants used for microscopic examination. It also provides information on microscopic examination, microphotography, and the effects of grain size on the structural properties of the material.

Liquid penetrant, magnetic particle, and eddy current inspection are used to detect surface flaws. This chapter is a detailed account of the physical principles, process description, equipment requirements, selection criteria, advantages, limitations, and applications of these surface flaw detection techniques.

This chapter discusses radiography methods using x-rays, gamma rays, and neutrons. It begins with a discussion on the applications and principles of radiography followed by sections providing information on the sources of radiation, classifications, and characteristics of x-ray tubes. Three primary attenuation processes of electromagnetic radiation, namely photoelectric effect, Compton scattering, and pair production, are covered. The chapter then discusses the principles of shadow formation, the process involved in the conversion of radiation into a form suitable for observation, and the characteristics of x-ray film. It provides information on various exposure factors in film radiography. The chapter provides a description of the characteristics that differentiate neutron radiography from x-ray or gamma ray radiography. The application of neutron radiography is described in terms of its advantages for improved contrast on low atomic number materials, discrimination between isotopes, or inspection of radioactive specimens.

Ultrasonic inspection is a nondestructive method in which beams of high frequency acoustic energy are introduced into a material to detect surface and subsurface flaws, to measure the thickness of the material, and to measure the distance to a flaw. This chapter begins with an overview of ultrasonic flaw detectors, ultrasonic transducers, and search units and couplants. It then discusses the principles of operation, presentation, and interpretation of data of pulse echo and transmission methods. This is followed by sections providing information on general characteristics of ultrasonic waves and the factors influencing ultrasonic inspection. The advantages, disadvantages, and applications of ultrasonic inspection are finally compared with other methods of nondestructive inspection of metal parts.

The inspection of castings normally involves checking for shape and dimensions, coupled with aided and unaided visual inspection for external discontinuities and surface quality. This chapter discusses methods for determining surface quality, internal discontinuities, and dimensional inspection. Casting defects including porosity, oxide films, inclusions, hot tears, metal penetration, and surface defects are reviewed. Liquid penetrant inspection, magnetic particle inspection, eddy current inspection, radiographic inspection, ultrasonic inspection, and leak testing for castings are discussed. The chapter provides information on the procedures involved in the inspection of castings that are limited to visual and dimensional inspections, weight testing, and hardness testing. It also discusses the use of computer equipment in foundry inspection operations.

This chapter focuses on the inspection of steel bars for the detection and evaluation of flaws. The principles involved also apply, for the most part, to the inspection of steel wire. The nondestructive inspection methods discussed include magnetic particle inspection, liquid penetrant inspection, ultrasonic inspection, and electromagnetic inspection. Eddy current and magnetic permeability are also covered.

Wrought tubular products are nondestructively inspected chiefly by eddy current techniques (including the magnetic flux leakage technique) and by ultrasonic techniques. The methods discussed in this chapter include eddy current inspection, flux leakage inspection, ultrasonic inspection, magnetic particle inspection, liquid penetrant inspection, and radiographic inspection of resistance welded tubular products, seamless steel tubular products, and nonferrous tubular products. This chapter discusses the fundamental factors that should be considered in selecting a nondestructive inspection method and in selecting from among the commercially available inspection equipment. The factors covered are product characteristics, nature of the flaws, extraneous variables, rate of inspection, end effect, mill versus laboratory inspection, specification requirements, equipment costs, and operating costs.

In forgings of both ferrous and nonferrous metals, the flaws that most often occur are caused by conditions that exist in the ingot, by subsequent hot working of the ingot or the billet, and by hot or cold working during forging. The inspection methods most commonly used to detect these flaws include visual, magnetic particle, liquid penetrant, ultrasonic, eddy current, and radiographic inspection. This chapter provides a detailed discussion on the characteristics, process steps, applications, advantages, and limitations of these methods. It also describes the flaws caused by the forging operation and the principal factors that influence the selection of a nondestructive inspection method for forgings.

Fabricated powder metallurgy (P/M) parts are evaluated and tested at several stages during manufacturing for part acceptance and process control. The various types of tests included are dimensional evaluation, density measurements, hardness testing, mechanical testing, and nondestructive testing. This chapter is a detailed account of these testing methods. It describes the four most common types of defects in P/M parts, namely ejection cracks, density variations, microlaminations, and poor sintering. The chapter discusses the capabilities and limitations of various nondestructive evaluation methods to flaw detection in P/M parts. The nondestructive evaluation methods covered are mechanical proof testing, metallography, liquid penetrant crack detection, filtered particle crack detection, magnetic particle crack inspection, direct current resistivity testing, x-ray radiography, computed tomography, gamma-ray density determination, and ultrasonic techniques.

Weldments made by the various welding processes may contain discontinuities that are characteristic of that process. This chapter discusses the different welding processes as well as the discontinuities typical of each process. It provides a detailed discussion on the methods of nondestructive inspection of weldments including visual inspection, liquid penetrant inspection, magnetic particle inspection, radiographic inspection, ultrasonic inspection, leak testing, and eddy current and electric current perturbation inspection. The chapter also describes the properties of brazing filler metals and the types of flaws exhibited by brazed joints.

This appendix contains figures that illustrate specimen orientation and crack plane codes for rolled plate, drawn bars, and hollow cylinders.