This article provides information on the process details that differ from general water atomization of metals as they relate to basic and engineering properties that are specific to stainless steel powders. The discussion focuses on the compacting-grade stainless steel powders. The process details include raw materials, melting method, and control of physical and chemical powder characteristics. The article describes the gas atomization of stainless steel powders and processes that are done after water atomization: drying, screening, annealing, and lubricating. It also discusses the two types of quality assurance testing measures for powder metallurgy stainless steels: tests for powder contamination and tests of chemical and physical properties.

Powder forging is an extension of the conventional press and sinter powder metallurgy process, which is recognized as an effective technology for producing a variety of parts to net or near-net shape. This article focuses on the material considerations, such as powder characteristics, alloy development, and inclusion assessment; and process considerations, such as process stages, tool design, and secondary operations; of ferrous alloy powder forging. The mechanical properties of powder forged materials are also reviewed. The article discusses the quality assurance tests for powder forged materials: the part dimensions and surface finish measurement, magnetic particle inspection, metallographic analysis, and nondestructive testing. It concludes with a discussion on the applications of powder forged parts with examples.

Powder forging is a process in which unsintered, presintered, and sintered powder metallurgy preforms are hot formed in confined dies. This article provides information on the basic forms of powder forging and describes the material considerations, process considerations, and mechanical properties of powder forged (PF) steels. It reviews the parameters involved in quality assurance tests for PF parts. The article includes examples of PF components and highlights the reasons for selecting them over those made by competing forming methods.

Forging is the process of working hot metal between dies, usually under successive blows and sometimes by continuous squeezing. This article describes the material selection criteria, quality assurance tests for forged components, and the dimensional tolerances of closed-die steel forgings. It provides an overview of the mechanical properties of wrought materials. The article also includes information on the fundamentals of hammer and press forgings and the design of hot upset forgings.

Maintainability is a function of the durability, damage tolerance, and repairability of a structure. This article discusses the configurations of composite structures, such as sandwich, stiffened-skin, and monolithic structures, used in commercial aircraft composites. It describes the considerations for maintainability of the composite structures during the conceptual design phase. Sources of the defects and damage, such as manufacturing defects and in-service defects, are reviewed. The article describes the nondestructive inspection methods that are used in the repair of composite structures to locate damage, characterize the extent of damage, and ensure post-repair quality. It lists suggestions that can be used as design guidelines for adhesive bonding, general composite structure, sandwich structure, material selection, and lightning-strike protection. The article also provides the basic considerations for personnel, facilities, and equipment during maintenance.

Heat treatment of aluminum alloys is assessed by various quality-assurance methods that include metallographic examination, hardness measurements, mechanical property tests, corrosion-resistance tests, and electrical conductivity testing. The use of hardness measurements in the quality assurance of heat treated aluminum products is effectively used in conjunction with the measurement of surface electrical conductivity. This article provides a detailed discussion of the error sources in eddy-current conductivity measurements. It also presents useful information on the variation of electrical conductivity of alloy 2024 samples as a function of aging time at different isothermal holding temperatures.

The purpose of accreditation is to evaluate and assure high-quality results from suppliers of products or services without incurring the costs associated with auditing each supplier. This article describes laboratory accreditation based on the general requirements of International Organization for Standardization/International Electrotechnical Commission (ISO/IEC) Guide 25, "General Requirements for the Competence of Calibration and Testing Laboratories." The Guide 25 is a balanced standard that addresses quality system requirements of ISO 9000 and the technical requirements needed to perform testing or calibration. The article describes an accreditation process that would enhance the international acceptance of test data for mechanical testing laboratories.

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 discusses the concepts of quality control (QC) and quality assurance (QA), and clarifies the differences and similarities in the roles and responsibilities of QC and QA personnel. It describes the inspection procedures used to verify proper surface preparation and installation of the protective coating/lining system. Prior to beginning surface-preparation operations, many specifications will require a presurface-preparation inspection to verify the correction of fabrication defects and removal of surface contamination such as grease, oil, cutting compounds, lubricants, and chemical contaminants. When inspecting concrete prior to coating installation, three areas of concern exist: surface roughness, moisture content in concrete, and acidity/alkalinity of the surface. The article provides information on the industry standards for assessing surface cleanliness. It details postcoating application quality requirements, including measuring of dry-film thickness, assessing intercoat cleanliness, verifying minimum and maximum recoat intervals, performing holiday/pinhole detection, conducting cure/hardness testing, and assessing adhesion of the applied coating system.

The process of coating plastics with metals for functional purposes is called metallizing of plastics. This article discusses the metallizing of plastics, provides information on its history, and gives a short note on applications and adhesion properties of metallic coatings. It also discusses the selection of plastics for plating. This article also describes metallizing techniques, including plating (electrolytic or electroplating), vacuum metallizing and thermal spraying, and environmental considerations. The article discusses the quality assurance procedures for metallized plastic parts which include tests that assess the quality of the finish, coating thickness, adhesion, and corrosion resistance, and gives a short note on service performance, which includes service condition classifications.

This article defines quality, quality assurance, quality control, and quality management of processes, products, and services. It describes the evolution of quality control and quality assurance in the coatings industry. The article also discusses the standards, quality programs, and certifications in the coatings industry.

The characterization, testing, and nondestructive evaluation of ceramics and glasses are vital to manufacturing control, property improvement, failure prevention, and quality assurance. This article provides a broad overview of characterization methods and their relationship to property control, both in the production and use of ceramics and glasses. Important aspects covered include the means for characterizing ceramics and glasses, the corresponding rationale behind them, and relationship of chemistry, phases, and microconstituents to engineering properties. The article also describes the effects that the structure of raw ceramic materials and green products and processing parameters have on the ultimate structure and properties of the processed piece. The effects that trace chemistry and processing parameters have on glass properties are discussed. The article describes mechanical tests and failure analysis techniques used for ceramics.

This article presents the importance of progressing from post-manufacturing inspection/verification to in-process inspection/verification methods. It lists the various quality assurance factors considered for typical composite laminate lay-up process. The article provides information on composite cure tooling that is fabricated from steel, aluminum, or high-temperature composite materials. The quality assurance for commercial applications is reviewed. The article concludes with a discussion on data fusion systems designed to provide nondestructive analysis data from fabrication and assembly processes for each individual composite part.

This article outlines the requirements and methods associated with the inspection of brazements. It emphasizes the incorporation of these requirements into the overall quality system. The article reviews the acceptance limits, design limitations, and nondestructive and destructive inspection techniques involved in the brazement inspection. Selected case studies are also provided for further reference.

This article describes the characterization techniques, mechanical tests, and nondestructive evaluation methods that are commonly used for metal-matrix composites. It also tabulates typical methods of particle size and size distribution measurement, as well as mechanical test specifications for aluminum-matrix composites.

This article describes the four basic steps of the purchasing process of cast components. These steps include defining requirements and developing a purchasing plan; requesting and evaluating bids from potential sources; selecting a source and negotiating contract terms; and carrying out the contract and pursuing continuous improvement. It provides guidance on purchasing cast components and explains specific issues and approaches that have proven to be useful in purchasing castings. The article presents a list of the most significant considerations when attempting to determine the overall cost and design requirements of a metal casting.

This article discusses the standard conduct of coating failure investigation. As each failure is different, a specific coating failure may require increased emphasis on a given step, or additional work and/or steps may be required. This article covers the following topics: obtaining and analyzing background information, preliminary determination of site conditions, inspection equipment requirements, coating failure site investigation, sampling techniques, sample chain of custody, coordination with the coatings laboratory, report preparation, and sample retention.

The basic elements of control design are safety, process control, process verification, machine control, productivity, repeatability, and ease of setup. Effective systems of quality control/quality assurance are essential for heat treating practices. This article provides information on process control modes, as well as on process signatures of some items that require control, monitoring, verifying, and logging methods. It provides information on programmable logic controllers that have become efficient in machine control and monitoring. The article describes possible noise issues, National Electric Code clearance requirements, monitoring requirements, and machine accuracy that need to be considered when designing induction equipment.