Search Results for brazements

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.

Diffusion brazing (DFB) is a process that coalesces, or joins, metals by heating them to a suitable brazing temperature at which either a preplaced filler metal will melt and flow by capillary attraction or a liquid phase will form in situ between one faying surface and another. This article discusses the two critical aspects of DFB, namely, a liquid filler metal must be formed and become active in the joint area and extensive diffusion of filler metal elements into the base metal must occur. It schematically illustrates a diffusion process that results in the loss of identity of original brazed joint. The article also discusses the advantages of DFB.

This article is intended to assist the development of procedures for the brazing of ceramic-to-ceramic or ceramic-to-metal joints for service under elevated temperatures, mechanical or thermal stresses, or corrosive atmospheres. It describes the factors considered in preparing a procedure for the brazing of graphitic materials.

The various methods of furnace, torch, induction, resistance, dip, and laser brazing are used to produce a wide range of highly reliable brazed assemblies. However, imperfections that can lead to braze failure may result if proper attention is not paid to the physical properties of the material, joint design, prebraze cleaning, brazing procedures, postbraze cleaning, and quality control. Factors that must be considered include brazeability of the base metals; joint design and fit-up; filler-metal selection; prebraze cleaning; brazing temperature, time, atmosphere, or flux; conditions of the faying surfaces; postbraze cleaning; and service conditions. This article focuses on the advantages, limitations, sources of failure, and anomalies resulting from the brazing process. It discusses the processes involved in the testing and inspection required of the braze joint or assembly.

This article provides a discussion on filler metal selection, brazing procedures, and brazing equipment for brazing refractory metals. These include molybdenum, tungsten, niobium, and tantalum, and reactive metals. Commercially pure and alpha titanium alloys, alpha-beta alloys, zirconium alloys, and beryllium alloys are some reactive metals discussed in the article.

Aluminum, a commonly used base material for brazing, can be easily fabricated by most manufacturing methods, such as machining, forming, and stamping. This article outlines non-heat-treatable wrought alloys typically used as base metals for the brazing process. It highlights chloride-active and fluoride-active types of fluxes that are used for torch, furnace, or dip brazing processes. The article explains the steps to be performed, including the designing of joints, preblaze cleaning, assembling, brazing techniques (dip brazing, furnace and torch brazing, fluxless vacuum brazing), flux removal techniques, and postbraze heat treatment processes. It concludes with information on the safety precautions to be followed during the brazing process.

Inductors used for brazing can be machined from solid copper shapes or fabricated out of copper tubing, depending on the size and complexity of the braze joint geometry to be heated. This article provides information on inductors (coils) that are generally classified as solenoid, channel (slot), pancake, hairpin, butterfly, split-return, or internal coils. It discusses the variables pertinent to the design of inductors for brazing, soldering, or heat treating. The article presents various considerations for designing inductors for brazing of dissimilar materials that present a unique challenge in the field of induction brazing.

This article describes the dip brazing process and the principal types of furnaces used for molten-salt-bath dip-brazing applications. It provides information on equipment maintenance, which is divided into temperature control, control of the liquid, and maintenance of the vessel. The article presents the typical salts used for molten-salt dip brazing of carbon and low-alloy steels with selected filler metals in tabular form. It concludes with information on dip brazing of stainless steels, cast irons, and aluminum alloys and safety precautions of the process.

This article focuses primarily on the various steps involved in the brazing of heat-resistant alloys (nickel- and cobalt-base alloys). The major steps include the selection of brazing filler metals, surface cleaning and preparation, brazing processes and their corresponding atmospheres, and fixturing. The article also provides an overview of the brazing of blow-alloy steels and tool steels and oxide dispersion-strengthened alloys.

This article describes the factors considered in the analysis of brazeability and solderability of engineering materials. These are the wetting and spreading behavior, joint mechanical properties, corrosion resistance, metallurgical considerations, and residual stress levels. It discusses the application of brazed and soldered joints in sophisticated mechanical assemblies, such as aerospace equipment, chemical reactors, electronic packaging, nuclear applications, and heat exchangers. The article also provides a detailed discussion on the joining process characteristics of different types of engineering materials considered in the selection of a brazing process. The engineering materials include low-carbon steels, low-alloy steels, and tool steels; cast irons; aluminum alloys; copper and copper alloys; nickel-base alloys; heat-resistant alloys; titanium and titanium alloys; refractory metals; cobalt-base alloys; and ceramic materials.

This article presents an overview of resistance brazing (RB) used for many applications involving small workpieces, for small joints that are part of very large equipment, or for low-volume production runs. It lists the advantages and limitations of RB and outlines the factors that contribute to high quality in an RB joint. The article discusses the classification of RB such as manual RB or automatic RB. It describes the selection of metal electrodes and filler metals for RB. The filler metals include silver alloys, aluminum-silicon alloys, and copper-phosphorus alloys.

Brazing and soldering are done at temperatures below the solidus temperature of the base material but high enough to melt the filler metal and allow the liquid filler metal to wet the surface and spread into the joint gap by capillary action. This article discusses the common advantages of both brazing and soldering. It describes the brazing and soldering of cast irons, as well as the selection of brazing filler material. The article discusses various brazing methods: torch brazing, induction brazing, salt-bath brazing, and furnace brazing. It concludes with information on the application examples of brazing of cast iron.