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welding vs brazing

smcdonaldaz

smcdonaldaz

NAXJA Forum User
Location
Litchfield Park, AZ
Hi gang,

I have a roof rack and would like to add a floor of expanded steel. I have no welder but do have a MAP gas torch. Would brazing this work? I learned brazing a long time ago in Boy Scouts and can sweat copper in my sleep. Do I bother trying?

Thanks in advance for your help.
 
FordGuy said:
Actually it will work great if you buy the right rod. Don't use the copper brazing rod, bronze or nickel silver.
Click to expand...

And the MAP gas is hot enough?
 
I would not use brazing for anything structural (like adding load-bearing elements to the rack,) but it should work fine for what you're doing (adding a floor, with load-bearing elements already in place.)

Welding is a "fusion process" for steel - it takes two bits of steel and makes them one. Brazing is a high-powered version of gluing two bits together - they're still two bits of steel, and can be separated relatively easily. For strength, brazing would fall in between soldering (much softer alloy) and welding (direct fusion.)

Concur on the bronze or nickel-alloy rod. MAPP gas should be hot enough, but you're still better off if you can combine it with oxygen...
 
mapp gas burns at 5300* F

i have the little mapp/oxygen torch from home depot, even comes with brazing rods.
 
Brazing will be just fine for what you want it to do. Depending on the application a brazed joint may be more desireable than a welded one. The braze will cover a larger area than the weld would so it spreads the force out over a larger area, uses less heat and will flex before it cracks and breaks. Depending on the type of braze rod and the quality of the brazed joint the strength can be from 40,000 psi to 85,000 psi.
Here is an interesting article on brazing vs welding
http://machinedesign.com/ContentItem/61255/WhenBrazingBeatsWelding.aspx

~Alex
 
Thanks for the info guys, guess I'll get it all preped and cut to size, and get'er done!
 
smcdonaldaz said:
Thanks for the info guys, guess I'll get it all preped and cut to size, and get'er done!
Click to expand...

That article makes it sound like brazing would be good for stuff like unibody strenghtening and welding on armor because it's not hot enough to affect the structural properties of the metal, and it doesn't have to melt anything but the "adhesive" metal. Is that feasible? Why doesn't anybody do it?
 
winkosmosis said:
That article makes it sound like brazing would be good for stuff like unibody strenghtening and welding on armor because it's not hot enough to affect the structural properties of the metal, and it doesn't have to melt anything but the "adhesive" metal. Is that feasible? Why doesn't anybody do it?
Click to expand...

Because brazing isn't a fusion process, and the joint can still be sheared by applied stresses.

Quite often, fabrication processes involve a tradeoff - you lose desireability somewhere and gain it somewhere else - and you just have to figure out which you want more.
 
alex22 said:
uses less heat and will flex before it cracks and breaks.
Click to expand...
Id love to know how you figure that?I can weld the whole thing with a "quench" welder and you can pick it up when Im done!With any gas welder,your likely to warp the crap out of it,and you wont be able to touch it for hours.Bring it to me,well have it done in like 10 minutes,ready to go!There are going to be more stress issues with the "dis-simular" metals than any "same" material welding,"done properly".
 
Last edited:
Could you explain how a quench welder works, I havent heard the term before and couldnt find it in my book, not trying to sound like a dick, i'm currious now. In order to weld two pices of metal together you have to melt them, when a joint is brazed only the braze rod is melted.

~Alex
 
alex22 said:
Could you explain how a quench welder works, I havent heard the term before and couldnt find it in my book, not trying to sound like a dick, i'm currious now. In order to weld two pices of metal together you have to melt them, when a joint is brazed only the braze rod is melted.

~Alex
Click to expand...
Its an old generic term for a MIG welder!
 
Why doesn't anybody do it?
In many cases it's cheaper, faster, even easer to do some form of welding
 
badron said:
Why doesn't anybody do it?
In many cases it's cheaper, faster, even easer to do some form of welding
Click to expand...
Maybe,not even close,I dont think so!
 
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