Brazingprocesses and materials:SOLUTIONS with Effective, Powerful AdviceBrazing is a very old process already employed in prehistoric times to join gold jewelry. This new, edited and enriched page, summarizes the essential features of this group of processes, provides definition and explanations, assists with the understanding of critical aspects and requirements, and refers to specific additional pages where essential information is elaborated further on. Brazing Definition (AWS): The above definition clarifies that this process:
One well known example involving non metals is that of ceramic cutting points (sintered carbide tips) brazed to metallic supports, for machine tools like lathes and milling machines. This joining process lends itself to automatic operation, if the conditions are correct. Important Announcementa rich collection of valuable information on Materials, Volume 1, and Metals Welding, Volume 2, from expert Internet Sources, see our New Page on Metals Knowledge
What are these processes? They are those meeting the description above. Similar processes using temperatures below the said limit are called soldering.Alternatively Adhesive bonding is generally carried out at room temperature, except that low temperature curing may be used for completing the joint. When is this joining method preferred to welding? It should be preferred if joining:
As examples we may consider:
Advantages
Limitations
Processes are available for manual or automated brazing application. In typical mass production high frequency induction heating is used within the space of a coil, where well controlled high temperature is reached very fast. Complex constructions with different joints individually prepared (preplacing filler-alloy) beforehand, permit the realization of all of them at one time in a furnace, under protective atmosphere (from oxidation), or in a heated bath of salts (Dip processing is used for aluminum parts) as soon as Brazing temperature is reached. Other applications combine the heating for brazing with that needed for metallurgical purposes like heat treatments as aging or stress relieving. The use of filler alloys with progressively decreasing melting temperatures permits to perform sequential operations, called step operation, in a furnace, at different times, if the need arises because of assembling requirements, so that following joints are made at a lower temperature that does not compromise the earlier ones. See our new page on Brazing Joint Design Filler alloys For the largest part of base metals, three are the types of filler-alloys most used: Copper base, Nickel base and Silver base. For other alloys the base metal is either Aluminum, Magnesium or Gold. Within each type many alloys of various composition are available differing essentially in melting range and ease of flow at high temperature. An Article on the Selection of Silver Alloy based Filler Metal was included (4) in our Practical Welding Letter No. 03 of November 2003. To see the article click on PWL#03. An Article on Furnace-Brazing was published (7) in the May 2004, Issue No. 09 of Practical Welding Letter. Click on PWL#09 to read it. An Article on the Selection of High Temperature Filler Metal Alloys was published (4) in the September 2004, Issue No. 13 of Practical Welding Letter. To read the article, click on PWL#013. An Article on Filler Precious Metals was published (4) in the issue No.14 of Practical Welding Letter of October 2004. An Article on Induction_Brazing was published (7) in the issue No.14 of Practical Welding Letter of October 2004. To see the Article click on PWL#014. An Article on joining of Ceramic Materials was published (4) in the Issue 23 of Practical Welding Letter for July 2005. An Article on joining Heat Resisting Alloys was published (4) in the Issue No.24 of Practical Welding Letter for August 2005. An Article on Dew Point Measurement for Furnace Brazing Atmospheres was published (11) in the Issue No.24 of Practical Welding Letter for August 2005. To read it click on An Article reporting on recent development work by NASA on Brazing in Space was published (4) in Issue 28 of Practical Welding Letter for December 2005. To read the article (in Section 4) click on An Article on Electrolysers (that provide Hydrogen for Furnace processing) was published (11) in the Issue 33 of Practical Welding Letter for May 2006. To read it click on An Article on Filler Metal for Titanium Alloys was published (4) in Issue 46 of Practical Welding Letter for June 2007. An Article on Cleaning for joining was published (2) in Issue 52 of Practical Welding Letter for December 2007. An Article on Filler Metals for Diffusion Joining was published (4) in Issue No. 53 of Practical Welding Letter for January 2008. An Article on Brazing Defects was published (7) in Issue No. 62 of Practical Welding Letter for October 2008. To subscribe and receive regularly by e-mail at no cost the periodic publication above, click on Subscription. Filler metals are available in the form of foil, wire or paste (made up by a metal powder and a binder). Paste can be obtained in precharged dispensers for manual or machine application, or as a thick suspension to be applied by brush. Tip!: Pastes have an expiry date, because of the binder (usually six months from manufacturing date), and must be stored as recommended by manufacturers, possibly under refrigeration. For mass production, preforms of designed shape can be purchased, either bent from wire or blanked from strip, eliminating scrap and preparation work, and easing preplacement in the joint. See our new page on Brazing Heating. References and Specifications The following documents are important reference material for anyone involved in brazing operations. We recommend to learn and use the most significant of them for your activities. ANSI/AWS B2.2-91 ANSI/AWS C3.2M/C3.2:2001 ANSI/AWS C3.3:2002 ANSI/AWS C3.4M/C3.4:2007 ANSI/AWS C3.5M/C3.5:2007 ANSI/AWS C3.6M/C3.6:2008 ANSI/AWS C3.7:2005 ANSI/AWS C3.8M/C3.8:2005 ANSI/AWS D10.13/D10.13M:2001 ANSI/AWS A5.8/A5.8M:2004 AWS A5.31-92(R2003) AWS BRH AWS WHB-1.9 AWS WHB-2.9 AWS WHB-3.9 ISO 3677 BS EN 13347:2002 The following 12 brazing-Articles by R. L. Peaslee were published in the Welding Journal and are available online: Any questions or comments or feedback? Write them down and send them to us by e-mail.Click on the Contact Us button in the NavBar at top left of every page.
To reach a Guide to the collection of the most important Articles from Past Issues of Practical Welding Letter, click on Welding Topics. See also the following pages on Brazing: Brazed Joint Design For anyone of the following subjects, click on the underlined item:  POWERED BY:
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