Search Results for exothermic brazing

Brazing and soldering processes use a molten filler metal to wet the mating surfaces of a joint, with or without the aid of a fluxing agent, leading to the formation of a metallurgical bond between the filler and the respective components. This chapter discusses the characteristics, advantages, and disadvantages of brazing and soldering. The first part focuses on the fundamentals of the brazing process and provides information on filler metals and specific brazing methods. The soldering portion of the chapters provides information on solder alloys used, selection criteria for base metal, the processes involved in precleaning and surface preparation, types of fluxes used, solder joint design, and solder heating methods.

This chapter discusses furnace atmospheres. It describes how furnace atmospheres protect metals, transfer heat, and supply alloying elements (carbon and nitrogen). The chapter focuses on the different types of atmospheres that are available to the heat treater: combustion products, air, exothermic, salt, nitrogen, endothermic, ammonia, hydrogen, inert gas, and vacuum.

This chapter discusses joining atmospheres that are used for brazing, along with their advantages and disadvantages. It discusses the processes, advantages, and disadvantages of chemical fluxing, self-fluxing, and fluxless brazing. Information on stop-off compounds that are considered as the antithesis of fluxes is also provided.

This chapter, a detailed account of furnaces and related equipment for heat treating, begins by describing three basic modes of heat transmission, namely conduction, convection, and radiation, followed by a discussion on the working principle, applications, advantages, and disadvantages of furnaces classified based on the heat transfer medium employed. The types of furnaces covered are batch-type, continuous-type, liquid bath, fluidized bed, and vacuum. The subsequent sections provide information on furnace parts, fixtures, quenching mediums, and quenching systems. The final section of the chapter describes the types of atmospheres available, emphasizing their applications and limitations.

Beryllium has been successfully joined by fusion welding, brazing, solid-state bonding, and soldering. This chapter describes these processes in detail along with their advantages and disadvantages. It also addresses application considerations such as surface preparation, joint design, and testing.

Brazing and soldering jointly represent one of several methods for joining solid materials. This chapter summarizes the principal characteristics of the various joining methods. It then discusses key parameters of brazing including surface energy and tension, wetting and contact angle, fluid flow, filler spreading characteristics, surface roughness of components, dissolution of parent materials, new phase formations, significance of the joint gap, and the strength of metals. The chapter also describes issues in processing aspects that must be considered when designing a joint, and the health, safety, and environmental aspects of brazing.

All superalloys, whether precipitation hardened or not, are heated at some point in their production for a subsequent processing step or, as needed, to alter their microstructure. This chapter discusses the changes that occur in superalloys during heat treatment and the many reasons such changes are required. It describes several types of treatments, including stress relieving, in-process annealing, full annealing, solution annealing, coating diffusion, and precipitation hardening. It discusses the temperatures, holding times, and heating and cooling rates necessary to achieve the desired objectives of quenching, annealing, and aging along with the associated risks of surface damage caused by oxidation, carbon pickup, alloy depletion, intergranular attack, and environmental contaminants. It also discusses heat treatment atmospheres, furnace and fixturing requirements, and practical considerations, including heating and cooling rates for wrought and cast superalloys and combined treatments such as solution annealing and vacuum brazing.

This chapter reviews materials issues encountered in joining, including challenges involved in welding of dissimilar metal combinations; joining of plastics by mechanical fastening, solvent and adhesive bonding, and welding; joining of thermoset and thermoplastic composite materials by mechanical fastening, adhesive bonding, and, for thermoplastic composites, welding; the making of glass-to-metal seals; and joining of oxide and nonoxide ceramics to themselves and to metals by solid-state processes and by brazing. The classification, types, applications, and the mechanism of each of these methods are covered. The factors influencing joint integrity and the main considerations in welding dissimilar metal combinations are also discussed.

Ceramics normally have high melting temperatures, excellent chemical stability and, due to the absence of conduction electrons, tend to be good electrical and thermal insulators. They are also inherently hard and brittle, and when loaded in tension, have almost no tolerance for flaws. This chapter describes the applications, properties, and behaviors of some of the more widely used structural ceramics, including alumina, aluminum titanate, silicon carbide, silicon nitride, zirconia, zirconia-toughened alumina (ZTA), magnesia-partially stabilized zirconia (Mg-PSZ), and yttria-tetragonal zirconia polycrystalline (Y-TZP). It also provides information on materials selection, design optimization, and joining methods, and covers every step of the ceramic production process.

Steel is broadly classified as plain-carbon steels, low-alloy steels, and high-alloy steels. This chapter begins by describing microconstituents of low- and medium-carbon steel, including bainite and martensite. This is followed by a section discussing the effect of alloying elements on steel. Then, it provides an overview of steel casting applications. Next, the chapter reviews engineering guidelines for steel castings and feeder design. The following section provides information on feeding aids. Further, the chapter describes the elements of gating systems for steel castings. It also describes the alloys, properties, applications, and engineering details of steel. Finally, the chapter explains defects in steel castings and presents guidelines for problem solving with examples.

This appendix is a compilation of terms and definitions related to metallurgy.

Aluminum has many outstanding properties, leading it to be used for a wide range of applications. It offers excellent strength-to-weight ratio, good corrosion and oxidation resistance, high electrical and thermal conductivity, exceptional formability, and relatively low cost. This chapter examines the metallurgy, composition, processing, and mechanical properties of aluminum and its alloys, both cast and wrought forms. It also covers heat treating and basic temper designations, including annealed, work hardened, solution heat treated, and solution heated treated and aged. The chapter concludes with information on corrosion and oxidation resistance.

This chapter discusses the advantages and disadvantages of metal matrix composites and the methods used to produce them. It begins with a review of the composition and properties of aluminum matrix composites. It then describes discontinuous composite processing methods, including stir and slurry casting, liquid metal infiltration, spray deposition, powder metallurgy, extrusion, hot rolling, and forging. The chapter also provides information on continuous-fiber aluminum and titanium composites as well as particle-reinforced titanium and fiber metal (glass aluminum) laminates.

This chapter discusses the factors that influence the cost and complexity of machining titanium alloys. It explains how titanium compares to other metals in terms of cutting force and power requirements and how these forces, along with cutting speeds and the use of cutting fluids, affect tool life, surface finish, and part tolerances. The chapter also includes a brief review of nontraditional machining methods.

Titanium and its alloys are used chiefly for their high strength-to-weight ratio, but they also have excellent corrosion resistance, better even than stainless steels. Titanium, as the chapter explains, is protected by a tenacious oxide film that forms rapidly on exposed surfaces. The chapter discusses the factors that influence the growth and quality of this naturally passivating film, particularly the role of oxidizing and inhibiting species, temperature, and alloying elements. It also discusses the effect of different corrosion processes and environments as well as hydrogen, stress-corrosion cracking, liquid metal embrittlement, and surface treatments.

This chapter covers the basic steps of the powder metallurgy process, including powder manufacture, powder blending, compacting, and sintering. It identifies important powder characteristics such as particle size, size distribution, particle shape, and purity. It compares and contrasts mechanical, chemical, electrochemical, and atomizing processes used in powder production, discusses powder treatments, and describes consolidation techniques along with secondary operations used to obtain special properties or improve dimensional precision. It also discusses common defects such as ejection cracks, density variations, and microlaminations.

This chapter details the types of heat treating furnaces. It discusses energy sources and modes of heat transmission. The chapter’s focus is on the different types of batch furnaces and continuous furnaces, including box furnaces, integral-quench batch furnaces, pit furnaces, furnaces for heat treating with fluidized beds, and straight chamber continuous furnaces.