Work-Hardened Stainless Steel

[Stemar]

I've managed to work harden a plate of SS while attempting to drill a hole in it. (blunt drill, and my drill press running a bit fast). Nothing I've got will make any impression on it. Is there a way to unharden it with stuff I'll have in the workshop. which doesn't include any welding kit, or am I going to be better off taking it to an engineering shop and admitting my incompetence?

 

[waynes world]

Done it many a time myself when rushing and to lazy to change drill speed, i have managed to sort it using a countersink bit. real slow speed though with cutting fluid.
.

 

[paulajayne]

Anneal it - heat to cherry red and allow to cool.

 

[earlybird]

Is there a way to unharden it with stuff I'll have in the workshop. which doesn't include any welding kit, or am I going to be better off taking it to an engineering shop and admitting my incompetence?

Not easy, it's got to be hot, hot, hot; >1000 degC. Best held for a few minutes and then quenched. A workshop with a carbide end mill in a milling machine might do it. How big is the intended hole?

 

[john_morris_uk]

My guess is you need to grind away the hardened layer. Perhaps a grinding bit in a Dremel? It depends how big the hole is that you’re trying to drill?

 

[Fr J Hackett]

You can anneal but it's not quick, it should be heard at 750°C to 800°C for an hour or so for a thin plate then allow to cool slowly. An alternative would be to use a plasma cutter to make the hole.

 

[sarabande]

Now that the steel is hardened, probably quickest to hand it to a workshop with a plasma cutter/ water jet or a punch in a biiiiiiig press. You may have to abrade the edges of the hole as they will be sharp.

 

[coopec]

My guess is you need to grind away the hardened layer. Perhaps a grinding bit in a Dremel? It depends how big the hole is that you’re trying to drill?

I've got a die grinder and I'm sure an appropriate burr (if it wasn't too big) would handle it.

But a better way is to use a sharpened masonry bit in a drill press (i.e. plenty of force)

When I was drilling the work-hardened SS chain-plates in situ on the yacht my B-I-L and I used a sharpened masonry bit and I applied pressure with a timber plank across the back of the drill . (We had them done quite quickly)

There are a number of video clips on YouTube. Here is just one of them.

 

[coopec]

This may help too. (particularly how to sharpen the bit)

(The Caterpillar Diesel Fitters in West Australia use sharpened masonry drill bits to drill out broken engine studs)

 

[Graham_Wright]

You can try drilling from the other side if you can locate the right spot. Use a fluid (even water will help), lots of pressure and slow speed. If you can't slow down the drill press, start it, stop it and press on the run down.