Talk:Brazing

Hi, I just wanted to say that the example given, with Nitinol and Niobium, is a very bad one. An excelent example for an eutectic alloy is Cusil (a Copper-Silver alloy), which is a very common brazing filler metal. If indeed Nitinol and Niobium form an eutectic it is not a simple one and i wouldn't give it as an example. I would also like to say that I find it hard to believe that Nitinol is a material regulary being brazed. At brazing temperatures (above 450C) Nitinol goes through extensive heat treatment and a radical change in properties is observed.It is possible that in certain specific applications Nitinol brazing is done, but as i said, not regulary. Also for this reason i find it a bad example for the introduction of "Brazing". —Preceding unsigned comment added by 79.177.128.185 (talk) 15:35, 24 November 2007 (UTC)

Hi Folks, I just wanted to say something about what Brazing was good for. Why use it instead of welding? - Lobstericus.


 * Welding will often distort the original metal part, although the final (warped) item will have nearly uniform strength with the original metal part. Brazing, on the other hand, causes no distortion of the original metal part, but is still roughly 1/3 as strong as if welded.  In many cases, this is strong enough, and the avoidance of distortion in the original metal parts is the key reason for using brazing instead of welding. Yaf 22:46, 8 February 2006 (UTC)

Soldering
Looking at this article and at Soldering, I can't see a specific difference between brazing and soldering. What is it, asside from being a different filler material with a hotter melting point? ― 05:50, 10 February 2006 (UTC)


 * The International Standard difference is 450°C, the traditional (meaning obsolete)difference is 425°C (800°F). For fillers that melt above this temperature, it is considered brazing.  For fillers that melt below this temperature, it is considered soldering.  Arbitrary, yes, but it is what Manko and other reference books have always defined as the difference.  Yaf 05:58, 10 February 2006 (UTC)
 * Thanks. Aside from that magic temperature, is there a qualitative difference between the processes? I'd imageine the important qualitative difference is the degree to which diffusion occurs between the filler and the material being brazed. Does that sound plausible?
 * I imagine there is another cutoff temperature to deliniate "braze welding" from "brazing". Is that correct? Do you know what temperature that is? Since it is "welding", I assume it is done hot enough to begin to melt the base material, or if not, at least cause significant diffusion. Is that right? ―BenFrantzDale 07:22, 10 February 2006 (UTC)


 * Definfing temp between soldering and brazing is 450C,842F. Quick references

http://www.technicalmaterials.umicore.com/en/bt/brazingCenter/lexikon_des_loetens/lexikon_des_loetens.htm http://www.linde-gas.co.uk/international/web/lg/uk/likelguk.nsf/DocByAlias/ind_mv_auto9 http://www.lucasmilhaupt.com/htmdocs/brazing_support/faqs.html http://www.materialsresources.com/mritech/mritech.htm http://www.weldingengineer.com/1soldering.htm http://www.jm-metaljoining.com/brazing/charts/terms/terms.htm as well the soldering page has the correct temperatures, and the HnadyBook that is referenced has the correct info on this page http://www.handyharmancanada.com/TheBrazingBook/Section%201/What%20brazing%20is%20all%20about/Part%201.htm#What%20is%20brazing (CanadianFirst 01:18, 30 March 2007 (UTC))


 * It appears that the defining temperature has moved up in some of the European and Canadian references. The traditional US references (Manko, et al) in their latest editions, still list the traditional 425°C (800°F) as being the defining temperature [Maybe it is time for modernize their obsolete habits.].  Perhaps the transition to higher temperature solders, needed for meeting European ROHS requirements (i.e., for lead-free solders), is what has pushed up the defining difference in the EU and Canadian references. Lead-based solders are still used in the US. The older lead-based solders have a liquidus at noticeably lower temperature, stressing components less.  Suggest we should list both sets of defining numbers, with references, as there are distinct differences in what the definitions are in different countries, to define the cut-off defining temperatures most accurately.  Yaf 02:53, 30 March 2007 (UTC)


 * Have added in the traditional U.S. definitions, where the defining division between definitions of soldering and brazing was chosen as 800 deg F, from Manko and other references. Otherwise, we will mislead many readers who use that standard instead of the RoHS (reduction of hazardous substances, i.e., lead-free) definitions used in Europe and elsewhere outside the U.S. Both definitions need to be clearly stated in the article. Yaf 06:38, 1 June 2007 (UTC)

What follows is the defintion from the AWS Brazing Handbook

"BRAZING

DEFINITION AND GENERAL DESCRIPTION

Brazing joins materials by heating them in the presence of a filler metal having a liquidus above 84O0F (4500C) but below the solidus of the base metals. Heating may be provided by a variety of processes. The filler metal distributes itself between the closely fitted surfaces of the joint by capillary action. Brazing differs from soldering, in that soldering filler metals have a liquidus below 8400F (4500C).

Brazing with silver alloy filler metals is sometimes called silver soldering, a nonpreferred term. Silver brazing filler metals are not solders; they have liquidus temperatures above 8400F (4500C).

Brazing does not include the process known as braze welding. Braze welding is a method of welding with a brazing filler metal. In braze welding, the filler metal is melted and deposited in grooves and fillets exactly at the points where it is to be used. Capillary action is not a factor in distribution of the brazing filler metal. Indeed, limited base metal fusion may occur in braze welding."

My comments There are definite metallurgical reasons to use the 840 F figure. Others are used but this is the official AWS definition.

Brazing uses heat and, as with any other process involving heating metal, the possible distortion of the metal(s) involved as well as changes in the grain structure and other changes in basic material properties must be considered.

The flux does not interact with the materials being brazed but serves as a barrier and oxygen interceptor. It often has some cleaning properties including the ability to remove oxides but should not be counted on for this.

Titanium can be brazed several different ways. Titanium’s reactivity can make for very strong joints.

Ceramics can be brazed with a torch, induction, etc.

Using an abrasive to clean oil or grease physically removes some of it just as any wiping would. However to get the parts clean you need to use a saponifier that will change the oils and greases to soap. Oven cleaner woks well as do detergents.

The flux chars and adheres to the workpiece when it is used up and / or overheated. Warm flux can be extremely tenacious. Once the flux has cooled to room temperature it is much easier to remove. The goal is to use enough flux and a proper heating cycle so that the flux is not all used up.

When hot quenching remember that you are in effect, heat treating the materials. Quenching will change material properties.

Remember, also, that different materials have different coefficients of expansion and slow cooling will allow the joints to adjust slowly while fast quenching will lock in stress.

Pickling is widely used to remove oxides but pickling baths are generally not well maintained. Because it is a chemical reaction the bath gets used up and becomes less effective as does dishwater.

Tom Walz www.carbideprocessors.com   Nov 7, 2006

I pulled these comments from the actual entry: "Capilary attraction not involved" is used to distiguish braze welding from other brazing processes (ex. silver brazing) I think you will find this is in error; capillary attraction is fundamental to "whetting" in all brazing and soldering. When you go beyond the whetting action so necesarry for surface adhesion, using heat to "pull" the right kind of filler metal completely through a join, this is called capillary action (not attraction). I know the word similarity is a little confusing, but you do need to get your terms right. Michael Porter This certainly belongs here and not the main entry. Chris Otto 01:58, 12 September 2007 (UTC)

"Hard to wet"
Under Silver Brasing, there is the line "Pretinning gets around the problem that hardmetals are hard to wet." What does that mean? Literally wet, with water? Or does it mean whet, not wet? Could somebody please clarify/explain? Thanks. 24.78.106.209 (talk) —Preceding comment was added at 05:23, 12 July 2008 (UTC)

The term is Whetting, which is essentially the filler metal spreads evenly across the surface to be brazed. Technically it is when the force of adhesion between the base metal and the liquid filler metal is greater than the cohesion of the melted metal. --Pocketpencil (talk) 17:14, 26 August 2009 (UTC)

I know that these comments date a little now, but "whetting" is a sharpening process while "wetting" is a physical description of the behaviour of molecules. Water can "wet" things (IIRC you need 7 molecules of water to do so) and the process of tinning is the same. JonSenior (talk) 05:45, 25 March 2012 (UTC)

Advantages
Im going to be re-working the advantages section and adding references. --Pocketpencil (talk) 17:33, 26 August 2009 (UTC)

EDIT DONE, section has been re-worked with citations --Pocketpencil (talk) 18:08, 26 August 2009 (UTC)

Further rework
I will be reworking the disadvantages and the processes section next. After that i think the whole article needs more work, and additional references added. Some of the examples used are poor and do not adequately describe or characterize brazing. It also feels like very slanted towards torch brazing, with little insight into industrial brazing which occurs quite frequently. I will also try to make the article more general with regards to the theory of brazing. It seems there are many rules of thumb and anecdotal evidence given, many of which are incorrect. Will update when completed --Pocketpencil (talk) 16:58, 28 August 2009 (UTC)
 * Everything done except techniques section, should have time to get to that in a day or so. --Pocketpencil (talk) 21:34, 18 September 2009 (UTC)
 * All finished...let me know if something needs editing/revising --Pocketpencil (talk) 14:25, 22 September 2009 (UTC)


 * I have restored all of the "common technique" subsections that were deleted because those seem like legitimate brazing techniques to me, unless I'm missing something. I think the vacuum section needs to be merged into the vacuum furnace section to reduce redundancy, otherwise the rest only need references. I've also added a prose and expand-section template to the sections that need the respective clean-ups. Hope that helps. Wizard191 (talk) 20:27, 22 September 2009 (UTC)


 * They are not legitimate brazing techniques. They are all special types of torch brazing.  Vacuum brazing can be merged with the furnace section (though there is some incorrect info in there), but the other 3 techniques (braze welding, cast iron and silver) are all torch brazing with different substrates of fillers.  calling these brazing techniques is incorrect.  Perhaps a section could be created listing some special types or applications of torch brazing and then incorporate some of these there.  Not only that, but the sections seem to have a lot of anecdotal type statements which dont really contribute to an understanding of the brazing process. --Pocketpencil (talk) 22:24, 22 September 2009 (UTC)
 * Also, the sections you added the expansion and cleanup templates to were already cleaned up by me. There is not much else to go into there unless you want this article to be really long and drug out. --Pocketpencil (talk) 22:27, 22 September 2009 (UTC)

Soldering vs Brazing
The mains points coming out are the higher temperatures in brazing compared to soldering. But this has the affect, from the operators point of view of greatly changing the tools used. In my experience hand brazing uses some form of gas torch that applies the flame directly to the work pieces.

Soldering, especially for electronics, would almost always use a small (<5mm) tipped soldering iron. Usually electric, but sometimes the tip is heated by butane or similar gas. But the gas flame is NEVER (for cicuit board work anyway) applied directly to the surface. One exception might be where a steel chassis is having items soldered directly to it. Even that would be uncommon now days. The heat has to be applied very precisely, or your component or circuit board would be destroyed. --220.101.28.25 (talk) 10:21, 25 October 2009 (UTC)

Heating
In an otherwise useful article, no mention is made of the use of the oxy-acetylene process commonly used with brazing. More specifically, what flame should be used, oxydising, nuetral or carburising? —Preceding unsigned comment added by 212.93.199.154 (talk) 07:02, 19 January 2010 (UTC)

General advice on flame
In the most general way, it is not possible to give you specific recommendation on the flame adjustment to use. This depends upon the base metal, filler metal and type of flux. In the most theoretical way and to be safe, go for neutral to slightly oxidising. Normally, oxidizing is the best. Think of it this way - you use a flux in order to clean the oxides off the base metal. If you use an oxidizing flame, you help the flux by also using the oxidizing flame. In contrast, if you clean the surface with a flux and then keep getting it dirty with a carbarizing flame, well you are defeating the purpose of the flux. But this rule of thumb is not always true. So to be on the safe side, go for neutral flame. But when the base metal and filler metal support it, oxidizing is the best way to go. —Preceding unsigned comment added by 178.198.133.52 (talk) 20:57, 12 October 2010 (UTC)

Strength of a brazed joint is excellent !
I just want to state here that the text in the original page is completely and utterly wrong ! A brazed joint properly executed is the strongest joining method possible. To verify this, you must only look at material deformation in a constrained two dimensional plane. This principle is readily shown in every book on brazing by giving the joint strength as a function of the brazed gap. At a large gap size, yes the joint is normally very weak as most common brazing materials have low strength (though not all like Ni-based alloys). But as the size of gap decreases, the joint strength will rapidly increase. At recommended gaps sizes like 0.05-0.10 mm, the braze joint strength far exceeds that of the base material.

I can add literally hundreds of references here when I have time.

Although not based upon the same deformation mechanisms as metallic materials (where the two dimension deformation plane is influencing dislocation motion), you can explain this effect in very simple layman terms. Put a drop of water between two plates of glass, and then try to pull the glass apart. Correct, nearly impossible. Although the tensile strength of water is essentially zero, put a thin layer between glass and it behaves completely differently (though when you shear the plates apart, you find again very low strength). So in this analogy, you can easily demonstrate that a properly designed brazing joint will always be of higher strength than the base material.

Basic principle.

Disappointing that Wiki would let such a strikingly wrong article exist in the system. Nonsense is being spread.

By the way, welded joints are normally rather weak due to the undesired effects of the HAZ or heat affected zone. But this is topic for another comment. . . —Preceding unsigned comment added by 178.198.133.52 (talk) 22:21, 22 September 2010 (UTC)


 * While I don't have a ref handy, I was taught the same thing in college, so if you could supply 2 or 3 good refs we can change it. Wizard191 (talk) 12:20, 23 September 2010 (UTC)


 * You're both correct; the statement in the article is utter rubbish. I recall reading earlier this evening that a brazed joint is several times stronger than the thinner metal in the joint (for brazing tubing, anyway). It was on an engineering website, but, alas, I've my browser set up to clear my history occasionally and it has done so in the interim. I'll try to find this reference and post it at a later date as I, ironically, have to get up early tomorrow and repair dozens of weak and leaking brazed joints that were put together by pipefitters that need to stay away from installing refrigerant piping.
 * AntarcticFox (talk) 02:21, 9 October 2010 (UTC)

References on strength
wish I could easily give appropriate references. Maybe I can email offline with the author of this article and revise the main text. I am not sure how this process works. Wish I could sign it also so you could contact me, but I am not sure how to do this. There are alot of references in the text and I am 100% sure that some of them must contain required info. Any brazing book with its weight in peanuts will give the famous graph of tensile strength as a function of the brazed joint. They all have this ! It readily shows for large gaps, the strength of the joint will drop down to the tensile strength of the brazing filler metal. While these are often soft (soft solders, silver alloys, pure copper), they must not be. Think of Ni-base braze where strength is rather high and alloys are brittle. Anyhow, this is common knowledge of anyone with practice in brazing. Take really any combination of materials, and do a proper braze joint. Do a tensile test and you see easily that you break in the base metal. Always. I have been out of academic studies 20 years and no longer have access to my text books or library. But my PhD in metallurgy gives me good reason to believe that I make no mistake here. The explanation for this is also pretty easy to find. You get any sophmore level book on mechanics of dislocations. When you look at the influence of the stress state on deformation, you see that when you constrain deformation to two dimensions you get infinitely increasing strength. A narrow brazed gap has the same effect and creates this two-dimensional stress state within the braze material. So theory readily explains what is empirically observed and it all makes sense. BRAZING gives the highest strength joining technique that we know (compared to welding, gluing, rivets, etc). —Preceding unsigned comment added by 178.198.133.52 (talk) 21:07, 12 October 2010 (UTC)

References for brazed joint strength
I can probably provide some references for brazed joint strength: Design_and_strength_brazed_joints see fig 7 and associated paras for showing that silver-copper (the most widely used brazing alloy) can exceed both the UTS of Silver, coppper AND steel. There are other reasons for this other than just "because it is brazed not welded". Firstly it involves triaxial stresses associated with brazed joints; in a very narrow joint gap the filler metal will be prevented from necking, which if you study your fracture mechanics is an important part of the fracture mechanism.

A whole host of our literature is available here: JM_literature If anyone is interested in further reading.

Here is a slide taken from a presentation I have given: slide

NOTE: these are NOT test results, I have mocked this data up from test results (just quickly from a presentation). I just thought it was a nic graphical way to articulate the effect I am trying to describe.

I can be contacted directly at will.clark@matthey.com if more sources/source verification is required.

Regards,

Will E4xit (talk) 11:23, 27 January 2012 (UTC)

Side note re soldering vs brazing
I suppose the temperature difference may be the "accepted" dividing line, however there are fundamental differences between soldering, brazing, and welding with regards to the ways those techniques are used. In traditional soldering, a physical connection is first created between the 2 pieces to be joined (two wires twisted together to make an electrical contact, a component attached to a circuit board by its leads, copper plumbing and a tight fitting). Then the work to be joined is heated to a temperature above the solder's melting point and solder is brought into contact with the work. The solder stabilizes the existing physical bond and prevents oxide from forming and the conductor-conductor contact point remains highly conductive. (Note that modern electronics uses very low currents so the higher resistance of conduction through solder or high resistance circuit traces are less relevant. Most manufacturing uses solder paste adhesive or silver epoxy for physical contact and conduction.) Brazing is used to create a strong physical bond between two pieces to be joined and it is the braze that is heated to melting and not the pieces to be joined. (Hence your confusion in calling some brazes "high temperature solder".) Welding. Construction welding e.g. 8" steel beam to 6" thick 6' diameter steel tube uses filler metal similar to the pieces to be joined and melts both the filler metal and the surfaces of the metals to be joined. Thinner pieces can be melted/joined without filler metal. Indeed metals will weld when held against each other under pressure at well below their melting point: like spot welds or picking up a 1000°C Platinum crucible with Iron tongs. I spent some years working at an Industrial Testing Laboratory doing failure analysis for legal cases. The distinction between soldering and brazing was important for a deposition I did. The Testing Lab had subscriptions to ASME and ASTM documentation, and non-web NIST or ANSI information was free. These Standards agencies now charge several hundred dollars for information. (I note that a majority of citations here come from "Industrial brazing practice - Google Books. Books.google.com. 2004. ISBN 9780849321122. http://books.google.com/?id=LHOsJGu9WUAC&pg=PA272&dq=brazing+alloys+types&cd=1#v=onepage&q=brazing%20alloys%20types" which is NOT in the public domain and refer to pages not even displayed by Google.) Very good information about brazing et al can be obtained from Copper.org, most documents being free/gratis or a token $1 Shjacks45 (talk) 21:04, 1 November 2010 (UTC)

Huge table removal
diff


 * 1) The table was completely unreadable even on a standard screen.
 * 2) Possibly excessive use of information from a few sources - ie copyright issues
 * 3) also What_Wikipedia_is_not, and What_Wikipedia_is_not - possibly suitable for a separate "list of" article, but caution as regards excessive copying remains.Sf5xeplus (talk) 18:50, 12 January 2011 (UTC)


 * I disagree with the removal and find it quite useful. As to point 1, I can read it just fine. Point 2: I've reviewed a few of the sources (not all) and found that no copyvio occurred. Point 3: I wouldn't call it an "indiscriminate" list because it is directly applicable to this article and, going back to my first comment, I find it quite useful. As such, I restored it and feel that it should remain. Wizard191 (talk) 20:37, 12 January 2011 (UTC)
 * This is what it looks like for me on a screen maximised and 1280 pixels wide Brazingscreenshot.JPG - that's not acceptable.
 * I think it would be better split into a separate article - what methods were used for inclusion on the list - or has every single mixture mentioned in the two books been replicated here, as I suspect.?
 * Either as a separate article or on this page the table needs fixing - it is an unreadable mess. I won't argue against the inclusion of the data (excluding my resevations already stated above) - but as is it needs to get mended soon, or be removed to this talk page for re-inclusion when fixed. Sf5xeplus (talk) 20:58, 12 January 2011 (UTC)
 * I think the table should remain since it is relevant and useful. However, I can see how some may have difficulty viewing it. My screen resolution is 1680x1050 and it just barely fits with the window maximized. Perhaps the width of the list could be reduced by removing the redundancy of listing the composition both in its name and in a data cell.Alister 77 (talk)
 * A column "other elements" could be used for the less common additives, however that would reduce the sortability that others may find useful. Additionally the page is about ~324kB in size and this would be an obvious split - (note scrolling vertically that table uses ~85% of the pageheight at 1280px wide). But it really needs a solution.83.100.230.154 (talk) 21:16, 12 January 2011 (UTC)


 * I've split the table to List of brazing alloys and created links to and from, plus additional relevant categories. However it still needs some way to make it more generally accessible - I assume that combining elements is not an option due to sorting issues - are there any technical software solutions.? Sf5xeplus (talk) 21:37, 12 January 2011 (UTC)


 * I've asked at Help_desk, a request has been made for addition headers.83.100.230.154 (talk) 22:51, 12 January 2011 (UTC)


 * Well the name column can be forced to be a narrower width. And instead of moving it to a new article, why don't you just make it a collapsible table? Wizard191 (talk) 23:26, 12 January 2011 (UTC)
 * I didn't want to split the formulas but if you think that's ok then do it if it helps. 2nd question - simple answer Article size, more complex answer - splitting to a separate article appeared to be a good solution to the problems of page display on the main article, article size, overwide article width, and coverage of 'expert' information. Sf5xeplus (talk) 00:00, 13 January 2011 (UTC)


 * Actually WP:SIZE states: "Readers may tire of reading a page much longer than about 30 to 50 KB, which roughly corresponds to 6,000 to 10,000 words of readable prose." "'Readable prose' is the main body of the text, excluding material such as: Footnotes and reference sections ("see also", "external links", bibliography, etc.), Diagrams and images, Tables and lists, Wikilinks and external URLs, and Formatting and mark-up". Therefore, (using Dr PDA's script) this article doesn't qualify for splitting because the prose is 25 kB. Give me some time to see if I can improve the formatting of the table so that it's not so wide and then I'll move it back per the above. Wizard191 (talk) 19:49, 13 January 2011 (UTC)
 * There's more to the size considerations than a single metric - I really don't think you are getting that such a large list of data (even if formatted to properly fit within a page) is not best suited for inclusion in the main article Brazing. I'll seek a third opinion.83.100.230.154 (talk) 20:06, 13 January 2011 (UTC)
 * (dispute) : The only issue is whether List of brazing alloys should be a separate page, or re-incorporated into the page Brazing. Thanks83.100.230.154 (talk) 20:06, 13 January 2011 (UTC)


 * OK, another article it is then. Wizard191 (talk) 15:44, 14 January 2011 (UTC)

lead
Hi, I've rewritten the lead and will be back in a week or so to remove the flag. In addition added proper names and links to the various filler materials for clarity. Marc — Preceding unsigned comment added by 80.219.53.103 (talk) 10:26, 9 May 2015 (UTC)

As annonunced here, removed the "Lead too short" comment, as the rewrite has not been challenged nor been discussed.

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Dubious
As far as I know, retort furnaces cannot be used "semi-continuously" due to the nature of the retort -- it must be run in a batch. I don't have any citations to back this up, but it seems obvious to me from my experience and reading of the article.65.24.142.205 (talk) 13:55, 1 December 2021 (UTC)

No History
This article has no history. I wanted to know the history of brazing, but there is nothing significant in the article. It would be good if someone who knows anything about this topic could add a history section.

Lkingscott (talk) 12:42, 7 April 2023 (UTC)