Welding Tips and Tricks

Hey so I've been doing some maintenance work. And I've been welding some quarter inch steel as reinforcement for worn out large boats. Fitups aren't exactly ideal and I end up heating the plate up when I get it tacked up good at pivot points and hammering it after it gets nice and warm. While this has worked out, I'm looking for information on how to properly do this. Because I'm pretty sure if I heat it up too hot that the steel will become more brittle. And other things I'd like to know such as maybe heating it repetively affects the metal. Anyways, any input is appreciated!

Heating to bend steel is quite normal and as long as the steel is a low carbon type and not a specific alloy then it won't normally be harmed or damaged by this as long as you heat it as evenly as possible on and around the fulcrum to a dull red glow.

Cold-forming/bending steels at (too) acute angles actually has a bigger risk of cracks developing in and around the bend area.

But it sounds like you're only putting in small bends/kinks to better conform the repair plates to the shape underneath.

Alloyed steels or high carbon ones often harden under these conditions so they would need annealing if you have to keep some flexiblity/ductility and run the risk of cracking on the heated and bent section as they cool.

If you can tell us what steel type you are using (aka. plain mild steel or some specific type) then that would be great! Probably loads more people on here who do similar things daily.

Bye, Arno.

I’ll try to remember to post up a picture of a welding dog. It’s pretty much just a cut off c clamp. You weld it down and then use the screw to push down the plate before you tack it.

I beat the living stuff out of metal all the time, otherwise you can't fit properly.

I find tacking and tapping is useful, not beating it too crazy, just tack it, tap it down, tack next spot, tap it down, etc.

The thicker the metal the harder the tapping.

Sheet metal is the worst in this.

Cutting properly makes it easier to get proper seams, I learned that the hard way.

Arno, I'm almost certain I've been using mild carbon. I dont believe I've seen much other steel than mild carbon or stainless. And yeah mostly small bends. And is annealing the same as postheating the piece?

Poland, I don't regret googling that. I'm gonna have to make one, thanks for the idea! I'm curious if anyone's sold any with a strong magnet base like those portable magnet drills

Olivero, that makes sense. But is sheetmetal because of how much it distorts?

Sheet metal is worse than heavier plate because of how easy it bends and distorts. Every time you bend steel your actually stretching it. That’s why once it’s bent it’s almost impossible to get rid of the visible distortion.

Indeed they have Brett. Damage from welded on dogs is unacceptable on many jobs. Mine included. No weld allowed outside the fusion zone. https://youtu.be/FPtdUF0E97g

Brettmm92 wrote:
Olivero, that makes sense. But is sheetmetal because of how much it distorts?

Yes, but when doing sheetmetal you normally want a fusion weld which is done with no filler, that can only be done if the seam is tight, our rule of thumb is if you can see light through it, it won't fuse without filler, I've found this to be true in almost all cases.

You can tack a length of sheet, say 2' long seam, tack it every 3 inches and you still have to beat it down in between, it'll lift up.

So you tack and tap. then weld and tap.

Depending on the end purpose of the structure, heating to do fit-up is an absolute no-no. It is an absolute NEVER on structural elements of a Naval warfare vessel due to the grade of steel used. Putting heat into carbon steel could result in tempering it, meaning it gets softer and more pliable. When in doubt, cold-work it if you have no worry about cracks, otherwise get an engineer involved if there is any chance your work might cause any safety issue during or after the job.

Alloys in steel change the game, but temperature ranges need to be right and very high ('straw yellow was the old toolmaker's visual). Alloy steel is taken up to a critical temperature to get maximum hardness, but becomes brittle. A heat soak at a fairly high temperature then tempers back the hardness to achieve toughness. Stainless 300 series (non-magnetic) only work-hardens from cold-work, and tempering is used to stop the work-harden from cracking. Magnetic stainless grades use the method like carbon alloy steel. Quenching is the cooling process used to get specific about the hardness measurement desired from heat treating (cooling using water, oil, air). Case hardening for a hard skin with a tough, soft core is another way to play the game.