Search Results for Current testing

This chapter explains how metallography and hardness testing are used to evaluate the quality and condition of metal products. It also discusses the use of tensile testing, fracture toughness and impact testing, fatigue testing, and nondestructive test methods including ultrasonic, x-ray, and eddy current testing.

Welded joints in any component or structure require a thorough inspection. The role of nondestructive evaluation (NDE) in the inspection of welds is very important, and the technology has become highly developed as a result. This article describes the applications, methods, evaluation procedures, performance, and limitations of NDE. It provides information on the training and certification of NDE operators, evaluation of test results, and guidance to method selection. Typical examples of various NDE methods for welds are also described.

This chapter discusses the methods and procedures used for inspecting induction-hardened parts. It provides information on hardness and case depth measurements, nondestructive testing and surface analysis, the effect of various hardening errors, and relevant test standards.

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.

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.

This chapter discusses the types of sensors used in sheet forming operations and the information they provide. It explains how force sensors protect equipment from overloads due to tool wear, friction, and misfeeds, how displacement and proximity sensors help to prevent die crashes, how acoustic emission, ultrasonic, and eddy current sensors detect tool breakage and part defects such as cracks, and how roller ball and optical sensors measure material flow. It also discusses the role of draw-in, wrinkle, oil-monitoring, and vision sensors and explains how material properties can be derived in real time from various sensor outputs.

This chapter reviews the current technology and examines force application systems, force measurement, strain measurement, important instrument considerations, gripping of test specimens, test diagnostics, and the use of computers for gathering and reducing data. The influence of the machine stiffness on the test results is also described, along with a general assessment of test accuracy, precision, and repeatability of modern equipment. The chapter discusses various types of testing machines and their operations. Emphasis is placed on strain-sensing equipment. The chapter briefly describes load condition factors, such as strain rate, machine rigidity, and various testing modes by load control, speed control, strain control, and strain-rate control. It provides a description of environmental chambers for testing and discusses the processes involved in the force verification of universal testing machines. Specimen geometries and standard tensile tests are also described.

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.

Corrosion testing and monitoring are powerful tools in the fight to control corrosion. This chapter provides a general overview of three major categories of corrosion tests, namely laboratory tests, pilot-plant tests, and field tests. It begins with brief sections describing the purposes of corrosion tests, the logical steps in a test program, and the preparation and cleaning of test specimens. The focus then moves on to discuss the types and applications of these test categories and the associated evaluation procedures. Excluding electrochemical tests which are addressed separately in this chapter, the other laboratory tests covered under this category are simulated atmosphere tests, salt-spray tests, and immersion tests. Only corrosion testing in the atmosphere is discussed in the section on field tests. Corrosion monitoring techniques are finally considered, covering the characteristics of corrosion monitoring techniques, the factors to be considered in selecting a corrosion-monitoring method, and the strategies in corrosion monitoring.

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.

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.

Transistors are the most important active structure of any semiconductor component. Performance characteristics of such devices within the specifications are key to ensuring proper functionality and long-term reliability of the product. In this article, a summary of the semiconductor technology from design to manufacturing and the characterization methods are discussed. The focus is on two prominent MOS structures: planar MOS device and FinFET device. The article covers the device parameters and device properties that determine the design criteria and the device tuning procedures. The discussion includes the effects of drain induced barrier lowering, velocity saturation, hot carrier degradation, and short channel on these devices.