Search Results for exothermic brazing

Exothermic brazing is a process that utilizes the heat produced in a solid-state chemical reaction to melt a conventional filler metal or to produce molten filler metal as a product of the reaction. This article provides the pros and cons of exothermic brazing, describes procedure of the process, and illustrates a typical arrangement for the exothermic brazing of tube. It provides information on the exothermic compounds used for brazing refractory metals and aluminum alloys.

This article describes the physical principles of brazing with illustrations and details elements of the brazing process. The elements of brazing process include filler-metal flow, base-metal characteristics, filler-metal characteristics, surface preparation, joint design and clearance, temperature and time, rate and source of heating, and protection by an atmosphere or flux. The article explains the different types of brazing processes: manual torch brazing, furnace brazing, induction brazing, dip brazing, resistance brazing, infrared (quartz) brazing, exothermic brazing, electron-beam and laser brazing, microwave brazing, and braze welding.

This article provides information about the selection of brazing processes and filler metals and describes the brazing (heating) methods, including manual torch brazing, furnace brazing, induction brazing, dip brazing, resistance brazing and specialized brazing processes such as diffusion and exothermic brazing. The article explains joint design, filler materials, fuel gases, equipment, and fluxes in the brazing methods. The article also describes the brazing of steels, stainless steels, cast irons, heat-resistant alloys, aluminum alloys, copper and copper alloys, and titanium and titanium alloys.

This article describes the effects of furnace atmospheric elements on steels. These elements are air, water vapor, molecular nitrogen, carbon dioxide, and carbon monoxide. The article provides useful information on six groups of commercially important prepared atmospheres classified by the American Gas Association on the basis of method of preparation or on the original constituents employed. These groups are designated and defined as follows: Class 100, exothermic base; Class 200, prepared nitrogen base; Class 300, endothermic base; Class 400, charcoal base; Class 500, exothermic-endothermic base; and Class 600, ammonia base. These are subclassified and numerically designated to indicate variations in the method by which they are prepared. The article also contains a table that lists significant furnace atmospheres and their typical applications.

Controlled atmosphere chambers are used to control the surface chemistry of the metals that are being processed. This article focuses on the various types of controlled atmospheres used in induction heat treating and brazing, namely, inert gas atmospheres based on argon and helium; prepared and commercial nitrogen-base atmospheres; and brazing atmospheres. It provides detailed information on two types of controlled atmosphere chambers: atmosphere and vacuum. The article also describes the selection factors, advantages, and disadvantages of these chambers.

This article overviews the classification of welding processes and the key process embodiments for joining by various fusion welding processes: fusion welding with chemical sources for heating; fusion welding with electrical energy sources, such as arc welding or resistance welding; and fusion welding with directed energy sources, such as laser welding, electron beam welding. The article reviews the different types of nonfusion welding processes, regardless of the particular energy source, which is usually mechanical but can be chemical, and related subprocesses of brazing and soldering.

Control of temperature and furnace atmospheres has become increasingly critical to successful heat treating. Temperature instrumentation and control systems used in heat treating include temperature sensors, controllers, final control elements, measurement instruments, and set-point programmers. This article describes these items and discusses the classifications and control of furnace atmospheres. The article also describes the surface carbon control devices available for the wide variety of furnace atmospheres and evaluation of carbon control. Finally, the article provides a set of guidelines for safety procedures that are common to all industrial heat treating furnace installations.

This article provides a detailed discussion on the types of furnace atmospheres required for heat treating. These include generated exothermic-based atmospheres, generated endothermic-based atmospheres, generated exothermic-endothermic-based atmospheres, generated dissociated-ammonia-based atmospheres, industrial gas nitrogen-base atmospheres, argon atmospheres, and hydrogen atmospheres. Atmospheres for backfilling, partial pressure operation, and quenching in vacuum are also discussed. Furnace atmospheres constitute four major groups of safety hazards in heat treating: fire, explosion, toxicity, and asphyxiation. The article reviews the fundamentals of principal gases and vapors. It describes how the evaluation of the atmospheric requirements of heat treating furnaces is influenced by factors such as cost of operation and capital investment.

Corrosion is often thought of as rusting, the process of deterioration undergone by a metal when it is exposed to air or water. This article provides the fundamentals of joints corrosion and primarily addresses the various forms of corrosion observed in brazed and soldered joints and their causes. It describes the role of proper brazing procedures in controlling corrosion. The article concludes with information on the corrosion resistance of various brazing alloy systems.

Copper, copper alloys, and precious metals are probably the most easily brazed metals because of their resistance to oxidation at high temperatures. This article provides a brief discussion on the metallurgy of copper, copper alloys, and precious metals and discusses the filler metals, brazing fluxes, joint clearance and design, and different brazing processes used in brazing of copper, copper alloys, and precious metals.

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.

Thermite welding (TW) is a fusion welding process in which two metals become bonded after being heated by superheated metal that has experienced an aluminothermic reaction. This article describes the thermite welding principles by presenting equations of the aluminothermic reaction that occurs in thermite welding. It provides information on the applications of thermite welding: rail welding, electrical connections, and railroad applications. The article concludes with a discussion on the associated safety aspects.

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.

The quality of brazed stainless steel joints depends on the selection of the brazing process, process temperature, filler metal, and the type of protective atmosphere or flux. This article provides a detailed discussion on the applicability and brazeability of stainless steel and lays an emphasis on the selection of suitable filler metal, brazing processes, and its corresponding furnace atmosphere for brazing different grades of stainless steel. The types of brazing processes include torch brazing, furnace brazing in different atmospheres (dissociated ammonia, dry hydrogen, and vacuum atmosphere), dip brazing in salt bath, and high-energy-beam brazing. A complete list of the typical compositions and properties of standard brazing filler metals for brazing stainless steel is also provided.

The atmosphere within a furnace chamber is a basic factor in achieving the desired chemical reactions with metals during heat treating. This article presents the fundamentals of heat treating atmospheres, and describes two groups of atmosphere control, namely, furnace atmosphere control and supply atmosphere control. The two basic types of atmospheric supply systems are generated atmospheres and nitrogen-base atmospheres. The article provides a brief overview of the gas reactions associated with oxidation and carbon control to ensure either carburization, or to prevent decarburization. It demonstrates how the carbon potential control is achieved by controlling water vapor concentration, carbon dioxide concentration, or oxygen partial pressure. The article also describes the various devices and analyzers used to monitor sampled gas from furnace atmospheres, namely, chromatographs, oxygen probes, Orsat analyzers, infrared analyzers, dewpoint analyzers, and hot-wire analyzers. Finally, it discusses the advantages, disadvantages, and limitations of these analyzers.