This article, prepared under the auspices of the ASM Thermal Spray Society Committees on Accepted Practices, describes a procedure for evaluating residual stresses in thermal spray coatings, which is an extension of the well-known layer removal method to include the Young’s modulus and Poisson’s ratio properties of the thermal spray coating material and the substrate. It presents questions and answers that were selected to introduce residual stresses in thermal spray coatings. The article describes equipment and the laboratory procedure for the modified layer removal method and provides the description of the residual stress specimen. It also describes the procedures for applying or installing bonded resistance strain gages, the dimensions of the test specimen, the procedure for removing layers, and the method for interpreting the data to evaluate residual stresses. The spreadsheet program, “ MLRM for Residual Stresses ,” is available as a supplement to this document.

Users of steel castings establish performance requirements for specific characteristics of the castings based on the planned use. They express tolerance for variation in those characteristics to the producer of the castings. One issue which should never be taken for granted in considering capability and tolerances is the ability to measure with accuracy and precision (repeatability and reproducibility). This chapter discusses the methods for measuring accuracy and precision. It describes the variation of process characteristics, capability indices in general use, and factors related to process performance and tolerance specification.

Tensile tests are performed for several reasons related to materials development, comparison, selection, and quality control. The properties derived from tensile tests are used in selecting materials for engineering applications. Tensile properties often are used to predict or estimate the behavior of a material under forms of loading other than uniaxial tension. This chapter provides a brief overview of tensile specimens and test machines, stress-strain curves, true stress and strain, and test methodology and data analysis.

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 presents the fundamentals of tensile testing of fiber-reinforced polymer composites. Basic tensile testing of polymer composites is divided into lamina and laminate testing. The chapter focuses on tensile testing of laminates. It discusses the most common tensile test methods that have been standardized for fiber-reinforced composite materials. It also briefly reviews considerations in tensile testing of metal-matrix composites.

This chapter discusses the methodology of the tensile test and the effect of some of the variables on the tensile properties. The methodology and variables discussed are shape of the item being tested, method of gripping the item, method of applying the force, determination of strength properties other than the maximum force required to fracture the test item, ductility properties to be determined, speed of force application or speed of elongation, and test temperature. The chapter presents the definitions of the basic terms and their units, along with discussions of basic stress-strain behavior and the differences between related terms, such as stress and force and strain and elongation. It considers the parts of a tensile test, namely, test-piece preparation, geometry, and material condition; test setup and equipment; and test procedures. The chapter provides information on post-test measurements and describes the effect of strain concentrations and strain rate on tensile properties.

High strain rate tensile testing is used to understand the response of materials to dynamic loading. The behavior of materials under high strain rate tensile loads may differ considerably from that observed in conventional tensile tests. This chapter discusses the processes involved in determining strain rate effects in tension by conventional tensile tests and covers expanding ring tests, flat plate impact tests, split-Hopkinson pressure bar tests, and rotating wheel tests.

This chapter focuses on mechanical behavior under conditions of uniaxial tension during tensile testing. It begins with a discussion of properties determined from the stress-strain curve of a metal, namely, tensile strength, yield strength, measures of ductility, modulus of elasticity, and resilience. This is followed by a section describing the parameters determined from the true stress-true strain curve. The chapter then presents the mathematical expressions for the flow curve. The chapter reviews the effect of strain rate and temperature on the stress-strain curve and describes the instability in tensile deformation and stress distribution at the neck in the tensile specimen. It discusses the processes involved in ductility measurement and notch tensile test in tensile specimens. The parameter that is commonly used to characterize the anisotropy of sheet metal is covered. Finally, the chapter covers the characterization of fractures in tensile test specimens.

Sheet metal forming operations consist of a large family of processes, ranging from simple bending to stamping and deep drawing of complex shapes. Because sheet forming operations are so diverse in type, extent, and rate, no single test provides an accurate indication of the formability of a material in all situations. However, as discussed in this chapter, the uniaxial tensile test is one of the most widely used tests for determining sheet metal formability. This chapter describes the effect of material properties and temperature on sheet metal formability. Information on the types of formability tests is also provided. The chapter discusses the processes involved in uniaxial and plane-strain tensile testing. Examples include the uniaxial tensile test and the plane-strain tensile test which are subsequently described.

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 testing of plastics includes a wide variety of chemical, thermal, and mechanical tests. This chapter reviews the tensile testing of plastics, which has been standardized in ASTM D 638, "Standard Test Method for Tensile Properties of Plastics," and other comparable standards. It describes the fundamental factors that affect data from tensile tests, examines the stipulations in standardized tensile testing, and discusses the utilization of data from tensile tests.

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.

The tensile test provides a relatively easy, inexpensive technique for developing mechanical property data for the selection, qualification, and utilization of metals and alloys in engineering service. The tensile test requires interpretation, and interpretation requires a knowledge of the factors that influence the test results. This chapter provides a metallurgical perspective for such interpretation. The topics covered include elastic behavior, anelasticity, damping, proportional limit, yield point, ultimate strength, toughness, ductility, strain hardening, and yielding and the onset of plasticity. The chapter describes the effects of grain size on yielding, effect of cold work on hardness and strength, and effects of temperature and strain-rate on the properties of metals and alloys. It provides information on true stress-strain relationships and special tests developed to measure the effects of test/specimen conditions. Finally, the chapter covers the characterization of tensile fractures of ductile metals and alloys.

The mechanical behavior of a material, in the most practical sense, is how it deforms or breaks under load; in other words, how it responds when stressed. This chapter provides a brief review of the properties associated with mechanical behavior, including stress, strain, elasticity, plastic deformation, ductility, hardness, creep, fatigue, and fracture. It also describes the primary components of a Charpy impact tester and the role they serve.

This chapters discusses the basic steps in the failure analysis process. It covers examination procedures, selection and preservation of fracture surfaces, macro and microfractography, metallographic analysis, mechanical testing, chemical analysis, and simulated service testing.

This chapter discusses the factors that govern the mechanical properties of titanium, beginning with the morphology of the alpha phase. It explains that the shape of the alpha phase has a significant effect on many properties, including hardness, tensile strength, toughness, and ductility as well as creep, fatigue strength, and fatigue crack growth rate. It also discusses the influence of other titanium phases and the properties of titanium-based intermetallic compounds, metal-matrix composites, and shape-memory alloys.

Fracture is the separation of a solid body into two or more pieces under the action of stress. Fracture can be classified into two broad categories: ductile fracture and brittle fracture. Beginning with a comparison of these two categories, this chapter discusses the nature and causes of these failure modes. Some body-centered cubic and hexagonal close-packed metals, and steels in particular, exhibit a ductile-to-brittle transition when loaded under impact and the chapter describes the use of notched bar impact testing to determine the temperature at which a normally ductile failure transitions to a brittle failure. The discussion then covers the Griffith theory of brittle fracture and the formulation of fracture mechanics. Procedures for determination of the plane-strain fracture toughness are subsequently covered. Finally, the chapter describes the effects of microstructural variables on fracture toughness of steels, aluminum alloys, and titanium alloys.

This chapter describes the use of standardized tests to determine the susceptibility of aluminum alloys to specific forms of corrosion, including pitting, intergranular corrosion, filiform corrosion, exfoliation corrosion, and stress-corrosion cracking.

This chapter provides an overview of the state of the art in high-pressure cold spray equipment, including both spray systems and gas supply systems. The chapter describes the commercial cold spray systems developed by companies such as Cold Gas Technology (CGT) GmbH, Plasma Giken Company Ltd, Impact Innovations GmbH, and ASB Industries. Typical helium and nitrogen gas systems used in high-pressure cold spray processing are reviewed.