Welding Tips and Tricks

Hi guys,
I've read different opinions on the matter, so I'd like to hear your thoughts also: is it ok to flatten down weld beads on aluminum, or it takes away to much strenght from the weld, imposing too big of a cracking risk?
Many thanks!

Do you mean grinding down the welds or just laying a flat weld brad?

Grinding it down until it's flat.

Grinding it will definitely remove some strength, so you have to make a judgement call based on the application. Make sure you have good penetration to start with.

Grinding weld on any material will remove strength, this why it is not done in critical applications. If you are going to do it on aluminum a bevel greatly helps as well as.having full penetrations if allowed,.if it's not allowed, you will definitely want a bevel otherwise your weld will most likely crack.

Ok guys, thanks!

Nero.

I am assuming you are talking about a butt joint between two work pieces, and that you are not talking about other joints with fillet welds.

I am not distinguishing between the types of base metals (Al, SS, CS or whatever) being welded.

On the butt joint, and assuming that it is full penetration, usually the minimal required size (throat) of the weld is the thickness of the plate. So any weld material of the cap passes (reinforcement), that remains above the surfaces, would be excess. Excessive sized cap passes cost time and money. Obviously we cannot weld a cap pass that is perfectly flat, so we weld a cap pass as close to the surface as possible, without leaving undercut along the edges of the pass, nor concave areas across the pass that would make the through-thickness (throat) of the weld less than the thickness of the plate.

When we grind welds flat, it costs lots of time and money. This is done only if requested. For example, occasionally the weld can only be tested if the surface is flat. There are also other reasons, usually they are related to the interpretation of the test results.

When grinding welds flat is required, it is important to grind them in a way to not cause any damages to the remaining surface of the weld too. For example, overheating the surface that remains.

Alexa

And what about other types of joint, like an outside corner joint for example, where you have to smooth the weld out and round the corner for cosmetic reasons? Assuming you've got enough penetration, I would suppose that would not be a problem, wouldn't it?

Nero.

Depends upon what the Client and Fabricator agree upon.
It is important to have a clear acceptance criteria for the appearance of the finished weld.
The Clients know that the more work required for finishing, will also increase the cost of the product.

Some examples.
Grinding stainless steel flush is often a must in hospital, mess halls, and other sanitary jobs.
Small fabrication jobs often call for rounded corners, etc. ... the finishing requirements.

Alexa

Grinding down outside corners does work well as long as you are careful and do not "flatten" or remove to much of the fillet. Same goes for t and lap joint just becareful not remove to much of the fillet.

How thick and what kind of weld?

Well, let's say 1-3mm thick, outside corner weld. Something like this ramps, for example:

I am not to familiar with the metric system. But basically as long as your joint fit up is good, a true corner to, you should be fine. When I am,welding a outside corner that is going to be ground I make my welds convexed so all you are really doing when grinding is simple smoothing out your coins in your weld beads. If you have a flat or convexed weld bead you will have to over grind to.get a nice radius. I usually don't not like to grind down outside corner joints on thin aluminum like.040 and thinner. At my first shop we had problems with welds cracking on .030 aluminum outside corner joints that were ground down.

Thanks skater!

When welding outside corners that are going to be ground in thinner aluminum, you don't want to just fill the notch left by the open corner, but also keyhole weld it for penetration beyond the juncture of the inside of the corner. I see this neglected a lot. In this particular case, it cost this company millions of dollars in ecologic impact fines.



When I ground these welds off to repair it, not only was there no keyhole penetration, but you could still make out the inside edge of the material itself in places and these welds weren't even ground off. It was due primarily to inconsistent fit up and not paying attention to the weld penetration, but instead, just the physical appearance of the bead itself.

Hey,

I find that when some people tig, as TJ says, they get so wrapped up in the action of dip and move, they forget to actually watch out for the base metal melting.

Mick

When you see coupon tests presented as practice for outside corner welds, almost never do you see the back side. At the place where I work, the owner has multiple examples of my work, where pieces were cut out for other thru fittings and the back side shows ample penetration with it's own formed bead on the blind side. Multiple examples from different areas of the weldment, showing that each was neither selective, nor an accident.

Weld penetration was a big deal in school and we were grilled on that subject with all processes before we ever got to any destructive testing of our parts. I've never forgotten it.

Hi all,

Here they are flattening the weld faces (Grove and fillet types) with a TIG torch without filler material...they call this TIG Remelt....for me the name that is used is incorrect.

TIG remelt apply only on the weld toes....to improve the cyclic life of the item.