Search Results for flux inclusions

This chapter discusses the effects of metallurgical factors on the corrosion resistance of magnesium alloys. The factors are chemical composition, heat treating, grain size, and cold-work effects. The chapter describes the causes of corrosion failures in magnesium alloys, namely heavy-metal contamination, blast residues, flux inclusions, and galvanic attack.

This chapter discusses the critical soldering faults that lead to quality degradation and potential failure of a soldered connection. It then describes the types of nondestructive evaluations used to inspect soldered and brazed joints, including dimensional and visual inspection, ultrasonic testing, radiographic examination, dye penetrant inspection, and leak testing, including overpressure tests. The chapter also provides an overview of destructive physical analysis.

This chapter focuses on factors that influence the mechanical properties of a soldered joint, including solder material, base material, solder joint design, soldering surface, soldering temperature, and test methodology.

Porosity in aluminum is caused by the precipitation of hydrogen from liquid solution or by shrinkage during solidification, and more usually by a combination of these effects. Nonmetallic inclusions entrained before solidification influence porosity formation and mechanical properties. This chapter describes the causes and control of porosity and inclusions in aluminum castings as well as the combined effects of hydrogen, shrinkage, and inclusions on the properties of aluminum alloys. In addition, it discusses the applications of radiography to reveal internal discontinuities in aluminum.

This chapter highlights the different melting, holding, and dosing furnaces that are available for the alternative casting processes used for the production of aluminum castings. Melting furnaces are grouped into four broad categories: crucible furnaces; reverberatory furnaces (or reverbs); stack melting furnaces (also called stack melters), tower melting furnaces, or jet melting furnaces; and electric coreless induction furnaces are detailed in this chapter. Factors influencing the choice of the melting, holding, and dozing equipment are presented. Equipment for recycling machined chips is also addressed.

This chapter describes various aspects of the billet making process and how they affect the quality of aluminum extrusions. It begins with an overview of the direct-chill continuous casting technique and its advantages over other methods, particularly for hard aluminum alloys. It then discusses the influence of casting variables, including pouring temperature and cooling rate, and operating considerations such as the make-up of charge materials, fluxing and degassing procedures, and grain refining. The chapter also provides information on vertical and horizontal casting systems, billet homogenization, and the cause of casting defects, including cracking and splitting, segregation, porosity, and grain growth.

Weldment failures may be divided into two classes: those identified during inspection and mechanical testing and those discovered in service. Failures in service arise from fracture, wear, corrosion, or deformation. In this article, major attention is directed toward the analysis of service failures. The discussion covers various factors that may lead to the failure of arc welds, electroslag welds, electrogas welds, resistance welds, flash welds, upset butt welds, friction welds, electron beam welds, and laser beam welds.

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.

Steels contain a wide range of elements, including alloys as well as residual processing impurities. This chapter describes the chemical composition of low-alloy AISI steels, which are classified based on the amounts of chromium, molybdenum, and nickel they contain. It explains why manganese is sometimes added to steel and how unintended consequences, such as the development of sulfide stringers, can offset the benefits. It also examines the effect of alloying elements on the iron-carbon phase diagram, particularly their effect on transformation temperatures.

This chapter describes the basic steps in the steelmaking process. It explains how iron is reduced from ore in the liquid state through the classic blast furnace process and in the solid state by direct reduction. It discusses the conversion of iron to steel and the technological advancements that led from open hearth steelmaking to basic oxygen processes and ultimately the electric arc furnace (EAF). It describes the versatility, efficiency, and scalability of the EAF process and its impact on recycling and sustainability. It explains how EAF refining and deoxidation practices have changed over time, and describes secondary refining processes such as degassing, homogenization, rinsing, and remelting.

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 how aluminum and other alloying constituents are added to prepare a furnace charge for the melting process, and how it is cast into billets of various aluminum alloys. Fundamental aspects of billet casting are covered to give an overview of the casting process. The melting practice is discussed, as well as grain refining and degassing. Charge material, grain refining, degassing, filtration of melt, casting systems, and casting variables are discussed. The chapter concludes with a discussion of casting defects.

This chapter describes the processes involved in alloy production, including melting, casting, solidification, and fabrication. It discusses the effects of alloying on solidification, the formation of solidification structures, supercooling, nucleation, and grain growth. It describes the design and operation of melting furnaces as well as melting practices and the role of fluxing. It also discusses casting methods, nonferrous casting alloys, and atomization processes used to make metal powders.

This chapter discusses the basic steps of a failure investigation. It explains that the first step is to gather and document information about the failed component and its operating history. It advises investigators to visit the failure site as soon as possible to record damages and collect test specimens for subsequent examination and chemical analysis. It also discusses the role of mechanical property testing, the use of nondestructive evaluation, and the final step of generating a report.

This chapter examines the effects of welding on the structure of metal, particularly the changes induced in the isothermal regions adjacent to the weld. It presents more than 150 images identifying structures and features associated with fusion and solid-state welding processes, including electroslag, TIG, gas, electron-beam, and arc welding as well as vacuum diffusion, forge, friction, electrical-resistance, and explosive welding. It also discusses the effect of welding temperature, pressure, and composition on the transformations that occur in and around the weld, and it includes a short section on brazing and braze welding.

The manufacture of all aluminum wrought products begins with an ingot or a continuous strip solidified from the liquid state. During molten metal processing (MMP), aluminum undergoes a series of operations that are described in this chapter including melting and alloying, recycling, molten metal treatment, control of inclusions, ingot grain refinement, and direct chill (DC) or continuous casting.

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.

Arc welding applies to a large and diversified group of welding processes that use an electric arc as the source of heat to melt and join metals. This chapter provides a detailed overview of specific arc welding methods: shielded metal arc welding, flux cored arc welding, submerged arc welding, gas metal arc welding, gas tungsten arc welding, plasma arc welding, plasma-GMAW welding, electroslag welding, and electrogas welding. The basic characteristics of gases used for shielding during arc welding are briefly discussed.