Annealing Mild Steel

I need ti bend a number it items in16" Mild Steel

Do I need to anneal it, or will it bend with ease ?

many thanks to all

Malcolm

If you mean 1/16" mild steel it's usually not too difficult with a vice and a soft hammer if the shapes aren't too intricate. I'd just try it and see. Of course ally's easier if you can use that instead.

Edited By Mick B1 on 17/12/2017 18:52:39

I use one of these for bending thin stuff, very good

**LINK**

Thank you both for your replies. There is nothing difficult in the bends I need to make.So will just give it a go in my Vice and a few gentlt taps.

Happy Christmas to you both

Malcolm

Is there a difference between annealing and normalizing?

this would be for any type of metal

Bri

Black hot rolled mild steel bends easily, the bright drawn strip with sharp edges will crack if bent to 90 degrees, cold rolled bright sheet usually bends easily, I do not know if it is still available but a long time ago rolled bright strip about 6 inches wide and up to .125 thick could be bought in varying conditions of hardness,when making prototype printer parts the trick was to saw a bit off the end of the strip and try to bend it,to make sure the stores had not cocked up the markings, it could be very annoying to make some part and then find it cracked on bending.

You could smooth the edges of the bend with a bit of 400 wet and dry paper before bending it so there is no sharp edge. This reduces the tendency to crack. Really sharp bends should be avoided if possible. Soft stainless steel is more ductile than mild steel.

As I understand it Normalisation is done by heating steel to the point where the grain structure breaks down and reforms with much smaller crystals by by allowing the steel to cool slowly in air. The purpose is to reverse ill-effects due to earlier heat treatments or the production process: these can leave steel with large grains, ie weaker, harder to machine, stressed etc. Normalisation wipes the slate clean, producing steel that's softer and tougher. Once returned to a known state, it can be confidently hardened & tempered again.

Annealing is a slower and more costly version of the same process. By cooling the steel extra slowly in an oven, the crystal structure can be made even finer.

The two processes are similar, and some books I've read confuse the two, usually by saying 'Annealing' is done in air or implying Normalisation is a steel-works process. Maybe the difference is a bit technical for most purposes - Normalisation is just Annealing to a basically acceptable state. I suspect what goes on in home workshops is normalisation rather than true annealing but that's good enough for most purposes.

Dave

That's a great reply Dave thank you. I had a sneaky feeling they were the same process.

Bri

Mild steel can’t be hardened and tempered like higher carbon steels or alloyed with other elements.. The stresses are confined mostly to the surface where the metal has been deformed, so affects cold-rolled steel and not hot-rolled.

BMS can bend awfully if the surface skin is machined from one side. So cracking is likely due to the surface stresses being further ‘shoved around’.

Heating to a suitable temperature for an appropriate time will certainly allow crystal structures to ‘even out’ and surface stresses to be relieved. Continued bending of hot-rolled strips, while cold, will cause cracks eventually, unless the new stresses are relieved and the crystal structure can relax.

So it is the cold rolling process which causes the problem and further cold bending simply exacerbates it.

Whether stress-relieved BMS is as stiff as when cold rolled might depend on how hot it gets. Too hot and it will certainly be no stiffer than hot-rolled.

We used to stress relieve steel at 190C for 4 hours and let cool naturally. Mild steel might benefit from this treatment which can be carried out in a domestic oven. As my old firm made aircraft parts, the steel we used was never mild.

Edited By old mart on 11/06/2019 11:59:41