Stainless steel rod quality

Recent I bought a length of 3/32" diameter 303 grade stainless steel rod that is to be used for a valve rod on a steam engine. On inspection I found that it is badly scored with longitudinal grooves as shown in the picture.

I assume these were produced by a damaged die when the rod was drawn.

I have no idea what specs cover such rod but is this acceptable? Also would it be able to polish this out before the hardening of the steel prevents further finishing?

JA

I'm not sure that this grade can be hardened

Send it back. It will be very difficut to remove these marks and keep the rod round, and it will then be undersize anyway.

Being an 18/8 stainless I would have thought that 303 grade would work harden. If so polishing would produce a hard surface. According to a data sheet it cannot be hardened by heat treating. I think it can be annealed, though.

I am not sure about sending it back. The length cost about £0.70.

JA

How do you tell the different grades of Stainless steel, I notice 303 and 18/8 is mentioned, what does it all mean, ?.

Thanks, Ken.

The British Stainless Steel Association has a pretty good website. Seems that 303 is a slightly easier cutting version of 304 due to the addition of sulphur.

Although you can get through-hardening stainless steels (eg 420), most stainless steels don't contain carbon, so any hardening has to be surface treatments such as carburising, nitriding, chromising etc. Funny this should come, up as I discovered yesterday that a bearing part we had designed for through hardening had somehow been changed from 420 to 304L (the L denotes an almost total absence of carbon), rendering it only suitable for surface hardening. Not much use for a bearing, then.

Sounds as if you could machine it down. If the work hardening becomes an issue, you could anneal it as suggested.

Murray

Edited By Muzzer on 14/05/2016 19:56:04

Ken,

This is a good place to start **LINK**

MichaelG.

.

Edit: Muzzer beat me to it.

Edited By Michael Gilligan on 14/05/2016 19:57:32

Hi JA,

I had exactly the same experience some years ago though in my case was for boiler handrails. Other stuff 3/32" dia has been excellent and properly ground.

It is a case of sometimes you win, sometimes not.

Cheers,

Julian

I've used loads of 303, never had it harden. It's a fair bit easier to cut than 304.

Like night and day; 303 is easy-peasy to machine and gives an excellent finish without trying. On the other hand 304 is a complete pig; in my limited trials I never got anything approaching a good finish.

Andrew