What the hell is going on here?

[chunkolini]

I have been making a sculpture out of 1.6mm hot rolled sheet sheet for the last few days.
Tedious but things are working out.
A replica(ish) of my Seahorse from a few years back.
A complex assembly of sodding diamond shaped bits of sheet.

On a good day I can manage to make and fit 8 pairs of them.
Great fun.
Anyways.
Today I was pressing on working on the long panels on the head.
I am using 1.6mm cold rolled sheet. ie bright finish.
And I spotted this.


On the piece of sheet I was working on. Ignored it as a bit of weirdness in the rolling process.
Then it did this

Width of the wrinkly bit about 8mm.
What? plated? no cant be, I have been welding it.
The 'skin' layer is magnetic.
It goes rusty like mild steel when I put ammonium chloride on it.
What the hell is going on?
Has the rolling process loosened the surface?
WHTF???????
Not panicking but not far off it. It welds nicely, bends nicely and feels like bog standard mild steel.
Any ideas?

 

[julianthegypsy]

Bizarre. I have no idea but will be watching to see the replies!

 

[Paul.]

I've seen similar flaws a few times over the years, more common in hot rolled plates, but have had it in cold reduced, most likely a lamination caused by millscale / slag being trapped as the sheet is rolled, often you don't see it until its welded or shaped,

 

[CRB]

Imagine my joy finding a fly embedded in a large chunk of acrylic AFTER all the fabrication was done and the protective film removed. At least you can use your material.

?Rolled sheet starts as a really thick slab which is then thinned progressively? The fault should be repeated. Perhaps your supplier could shed some light on it.

Love the seahorses Chunkolini.

 

[chunkolini]

Typically it was in the most visible place possible, right in the middle of the hooter.
Could just as easily been on the back.
Tig Paul
You know more about this nonsense than I ever will.
I came to the same conclusion.
I was confident to carry on. Paul you have preserved my confidence.
Relieved.

 

[BuiltnotBought]

so I was discussing this with the old man (he is a materials nerd) and we were thinking its an inclusion. Pretty much an imperfection on the surface of the sheet when it is being rolled and it gets dragged along the surface. I have seen it before in normal sheets of mild steel. Never had any real problem with it myself but dad did mention its likely to cause localised rusting.
Hope this is a small help if any

 

[chunkolini]

Rusting is no problem. when I am finished I have to rust the whole thing.
My panic was that it would not go rusty on demand.
I confess I flipped. I lapsed into profanity, ranted, the whole caboodle.

 

[Hitch]

Cut the bit out, tell them it was right in the middle of the sheet, and ask for a discount next time round

Quite often see various flaws is thicker plates, where something has dragged through the rolls. Even had some once that near on looked like it split into 2 separate sheets once cut.

 

[BuiltnotBought]

Rusting is no problem. when I am finished I have to rust the whole thing.
My panic was that it would not go rusty on demand.
I confess I flipped. I lapsed into profanity, ranted, the whole caboodle.

Ha I know the feeling. Spent the day fixed a ram gaurd as best I could for the 45t machine thats a bit bent and having got it fitted and prettied up managed to sheer the ba****d off. Whole days work wasted. Though on the plus side it wasnt just my weld that went. It was also the 20mm steel twisting and ripping so that made me feel a little better. Took my anger out on an unsusspecting pallet

 

[roofman]

Iff you can find cigarete butts in sausage rolls just think what can fall on the rolling sheet from the mill roof or rafters...surprised you never turned it into an alien eye or summit anyway

 

[Wedg1e]

Iff you can find cigarete butts in sausage rolls just think what can fall on the rolling sheet from the mill roof or rafters...surprised you never turned it into an alien eye or summit anyway

My dad was on a squad installing telecoms systems in a tea factory some years back; he said they were working on a mesh catwalk some way above the factory floor, dropping copper strands, wire strippings, sweat, you name it - all of which fell through the mesh.
Straight into the wheelie-bins full of tea beneath them.