Bending Stainless

I want to bend 1mm stainless steel but in a curve will heating it to aneal it be required so that I can hammer over the lip to form the curve.

How about some idea of the radius of the curve ?

Roy

The piece will be circular and about 3 to 4 inches in diameter not yet fixed the size as it is something I am making from scratch not something for a model which needs to be made to a fixed dimension.

Possibly better to say bend a flange on a circular piece 3 to 4 inches diameter

Edited By Derek Lane on 29/01/2020 12:51:45

Edited By Derek Lane on 29/01/2020 12:53:04

How deep is the flange? Are you hammering it ? Assuming it's 300 series stainless, ie non-magnetic, bending a right-angled flange of any depth will be difficult. The annealed sheet material starts off quite ductile, but work-hardens very rapidly. Annealing requires a high temperature. >1000 deg. C. Not easy in a home workshop.

Edited By Clive Brown 1 on 29/01/2020 13:10:28

Hi Dereck, I agree with Clive, you would probably be better TIG welding a piece on, or find someone who could do it for you.

Regards Nick.

The flang will only be small 1/4" or a little less I know I have not given exact sizes I will also be attempting to silver solder or if not possible soft solder again no strength is needed or have any pressure involved.

I have in the past made things by building as I go but I still need to know how materials react to different procedures.

Where i worked many years ago we used to make a former in aluminium then put in lathe chuck and use the tail stock and a pressure plate and revolving centre to sandwich the sheet of 304 / 316 stainless steel and flange it over using a bearing mounted on a holder in the tool post. .The skill was to push it over quickly.

I didn't believe it would work until i saw it with my own eyes.

Steve

The 300 series stainless steels bend cold without a problem, if the fold is straight. On a curve is more complex. As the flange is formed the metal needs to compress, or more likely stretch, to accomodate the surplus metal. Of course there are methods involving spinning or forming dies that can be done cold. But to do it by hand would need heat. Here's a flange hot formed in 3mm cold rolled mild steel to give an idea. Note the increased depth of flange on the curve:

However, one needs to control the temperature. When hot stainless steel tends to absorb oxygen from the air. To some extent the chromium reacts with the oxygen leaving a scale that slows the absorption. Another issue is that if one melts the stainless steel it forms a black crystallised "sugar". When TIG welding it is normal to back purge the weld with argon to prevent this.

Andrew

Thank you gents for all the replies I will have a think and show once I can sort it out

I have tried to silver solder stainless, with the right flux it can be done but I would not recommend it. TIG welding is the way to go with stainless, it is easy to do and provided there is no gap, you often don't even need filler. I found when making tanks for my steam launch that flanges are not needed, in fact they are a liability, and a corner will weld very nicely.

If your piece is shaped like I think it is, I would look for piece of tube the right size and the length you want the flange, and cut a piece of flat to match. Then I would Tig weld around the edge.

John

316 will form, why muck about?

What about one of these as a starting point.

Stainless collar

Martin C

A friend of mine pointed out to me that stainless is a very ductile material, his example was the deep draw of a stainless steel sink which is done in one strike of a press. Of course work hardening especially of some grades is a very real problem frequently encountered.

Mike

Maybe, but it depends very much on which one of the stainless family it is. They vary from the soft sort used to press sinks to the extremely hard and tough varieties used to make knives, spanners and razors. Many of them work-harden in a blink too. Bend in one movement.

Dave