This article describes the test methods of fracture toughness, namely, linear-elastic and nonlinear fracture toughness testing methods. Linear-elastic fracture toughness testing includes slow and rapid loading, crack initiation, and crack arrest method. Nonlinear testing comprises J IC testing, J-R curve evaluation, and crack tip opening displacement (CTOD) method. Other methods used include the combined J standard method, the common fracture toughness test, transition fracture toughness testing, and the weldment fracture testing method.

Welding codes and standards usually require the qualification of welding procedures prior to being used in production. This is to ensure that welds will meet the minimum quality and mechanical property requirements for the application. This article provides an overview of the welding procedure qualification guidelines and test methods. It also reviews the codes, standards, and specifications that govern the design and fabrication of welded structures for the procedure qualification details that are appropriate for a given application.

Qualification of welding procedures and personnel is an important step to assure the quality and performance of any welded component or structure. This article summarizes common welding procedures, personnel qualification variables, and test methods. Welding procedure qualification tests can be categorized as either standard or special. The article discusses the purpose of qualifying a welding procedure to demonstrate that the resulting welds will meet prescribed quality standards and the qualification of the personnel.

This article provides an overview of fractography as it applies to metal weldments and presents examples of various fracture surface morphologies to demonstrate how fractographic analysis can be used to determine the cause of weld failures. It identifies weld fractography principles and details several weldment-specific geometric and metallurgical considerations. The role of the weld-cracking mechanisms on the resultant fracture surfaces is described, along with example micrographs and fractographs of weldments. Common discontinuities related to welding processes and their impact on the resulting fracture behavior and surfaces are covered, as well as the common fractographic features related to fatigue failures of welds.

This article describes the formation of residual stresses and distortion, providing information on the techniques for measuring residual stresses. It presents a detailed discussion on the magnitude and distribution analysis of the residual stresses and distortion in weldments. The article briefly explains the effects of residual stresses and distortion on the brittle fracture and fatigue fracture of welded structures. It also provides information on the thermal treatments of weldments.

This article aims to survey the factors controlling the weldability of carbon and low-alloy steels in arc welding. It discusses the influence of operational parameters, thermal cycles, and metallurgical factors on weld metal transformations and the susceptibility to hot and cold cracking. The article addresses the basic principles that affect the weldability of carbon and low-alloy steels. It outlines the characteristic features of welds and the metallurgical factors that affect weldability. It describes the common tests to determine steel weldability. There are various types of tests for determining the susceptibility of the weld joint to different types of cracking during fabrication, including restraint tests, externally loaded tests, underbead cracking tests, and lamellar tearing tests. Weldability tests are conducted to provide information on the service and performance of welds. The major tests that are discussed in this article are weld tension test, bend test, the drop-weight test, the Charpy V-notch test, the crack tip opening displacement test, and stress-corrosion cracking test.

This article presents the structural attributes and internal characteristics of spot welds as well as the commonly inspected imperfections in resistance welds. It describes the industrial requirements for weld quality. Commonly performed destructive evaluations, namely, manual testing, quasi-static mechanical tests, dynamic mechanical tests, and metallographic examination, are reviewed. The article reviews weld-quality monitoring using various process signals and provides a discussion on the on-line and off-line nondestructive evaluation methods of spot weld quality.

This article discusses the standard test methods that can be applied to many types of welds: tension, bending, impact, and toughness testing. It provides information on four qualification stages, namely, the weld material qualification, base material qualification, the weld procedure qualification, and the weld service assessment. The article describes two general types of measurements for residual stress in welds: locally destructive techniques and nondestructive techniques. Locally destructive techniques include hole drilling, chip machining, and block sectioning. Nondestructive techniques include X-ray diffraction, neutron diffraction, Barkhausen noise analysis, and ultrasonic propagation analysis. The article concludes with an overview of weldability testing.

This article describes the formation of residual stresses and distortion and the techniques for measuring residual stresses. It provides a discussion on the magnitude and distribution analysis of residual stresses and distortion in weldments. The article considers the effects of residual stresses and distortion on the brittle fracture and fatigue fracture of welded structures. The thermal treatments of weldments are also discussed.

This article is a guide to the welding of commercially available aluminum-lithium alloys. It discusses the weldability issues created by weld porosity, hot cracking, and filler metal selection and presents the data revealed from weld characterization.

Cr-Mo steels are preferred in the construction of high-temperature components because they possess excellent strength, toughness, and corrosion resistance relative to carbon steels and most low-alloy steels. This article discusses the composition and metallurgy of the heat-resistant Cr-Mo steels. It details the Charpy V-notch (CVN) toughness properties of Cr-Mo steels relevant to fatigue and fracture resistance. The fracture mechanics of Cr-Mo steels are reviewed. The article analyzes the characterization of low-cycle fatigue based on fatigue damage calculations. It concludes with information on fatigue crack growth and fatigue behavior of weldments.

This article examines the factors influencing the fatigue behavior of an individual weldment, using extensive experimental data and a computer model, which simulates the fatigue resistance of weldments. It discusses the process of fatigue in weldments. The service conditions, which favor long crack growth and the conditions, which favor crack nucleation are contrasted. The article presents experimental data, which is used to show the effect of weldment geometry on fatigue resistance. Several useful geometry classification systems are compared. The article analyzes a computer model, which is employed to investigate the behavior of two hypothetical weldments, namely, a discontinuity-containing weldment and a discontinuity-free weldment.

Fracture toughness is an empirical material property that is determined by one or more of a number of standard fracture toughness test methods. This article describes the fracture toughness test methods in a chronological outline, beginning with the methods that use the linear-elastic parameter. After this, the methods that use the nonlinear parameters are discussed. The article reviews some of the work in progress to update the standard test methods, namely, common fracture toughness test method and transition fracture toughness test method. Finally, an overview of fracture toughness testing for ceramic and polymer materials is provided.

This article describes some of the welding discontinuities and flaws characterized by nondestructive examinations. It focuses on nondestructive inspection methods used in the welding industry. The sources of weld discontinuities and defects as they relate to service failures or rejection in new construction inspection are also discussed. The article discusses the types of base metal cracks and metallurgical weld cracking. The article discusses the processes involved in the analysis of in-service weld failures. It briefly reviews the general types of process-related discontinuities of arc welds. Mechanical and environmental failure origins related to other types of welding processes are also described. The article explains the cause and effects of process-related discontinuities including weld porosity, inclusions, incomplete fusion, and incomplete penetration. Different fitness-for-service assessment methodologies for calculating allowable or critical flaw sizes are also discussed.

This article briefly reviews the general causes of weldment failures, which may arise from rejection after inspection or failure to pass mechanical testing as well as loss of function in service. It focuses on the general discontinuities observed in welds, and shows how some imperfections may be tolerable and how the other may be root-cause defects in service failures. The article explains the effects of joint design on weldment integrity. It outlines the origins of failure associated with the inherent discontinuity of welds and the imperfections that might be introduced from arc welding processes. The article also describes failure origins in other welding processes, such as electroslag welds, electrogas welds, flash welds, upset butt welds, flash welds, electron and laser beam weld, and high-frequency induction welds.

This article briefly reviews the factors that affect the fatigue strength of aluminum alloy weldments. It discusses a number of factors influencing the fatigue performance of welded aluminum joints. The article describes the effects of fatigue behavior on weldments based on parent alloy selection, weld joint configuration, and residual stress. The two categories of techniques that can result in improved fatigue life, such as modification of weld toe geometry and introduction of compressive residual stresses in the surface material, are detailed. The article analyzes the influence of section size on fatigue performance of aluminum alloy weldments.

This article discusses the various options for controlling fatigue and fractures in welded steel structures, with illustrations. It describes the factors that influence them the most. The article details some of the leading codes and standards for designing against failure mechanisms. Codes are presented for fitness-for-service and standards for fatigue and fracture control.

This article describes the fundamental and specific factors that control the properties of steel weldments in both the weld metal and heat-affected zone (HAZ) of carbon and low-alloy steels. It provides information on steel types and their weldability. The article also explains the influence of welding procedure factors on the weldment properties. These procedure factors include preheat temperature, interpass temperature, postweld heat treatment, and heat input.

This article focuses on the tests for evaluating the weldability, cracking susceptibility, weld pool shape, fluid flow, and weld penetration of base materials. These tests include different types of self-restraint tests, externally loaded tests for evaluating cracking susceptibility and weld penetration tests, weld pool shape tests, and Gleeble testing for evaluating weld pool shape, fluid flow, and weld penetration.

This article begins with a discussion on the classification of hydrogen embrittlement and likely sources of hydrogen and stress. The article describes several hydrogen embrittlement test methods, including cantilever beam tests, wedge-opening load tests, contoured double-cantilever beam tests, rising step-load tests, and slow strain rate tensile tests. It also describes the interpretation of test results and how to control hydrogen embrittlement during production.