Regaining surface finishing after hardening stainless steel

bamek

Hi!

We are going to machine some stainless steel parts that will require hardening afterwards.
The parts are going to be hardened in an oven at 600 degrees celcius for 4 hours and then air cooled. This procedure is given in the suppliers data sheet.

Because i'm new in the game of hardening stainless steel, I wonder how the surface finish will turn out? And -if it turns out bad, how can we regain it? I was thinking about treating it with some kind of acid, but i don't know if it will work.

Best Regards
Daniel

Danger

Welcome to PF, Bamek.
I have no experience with this, but the only downside that I can think of from your heat-treatment might be a bit of surface discolouration from contaminants in the atmosphere. If that's correct, then a very light surface grinding or even maybe power sanding should eliminate it. Polishing compound on a buffer wheel might bring the original smoothness back, if the scratches aren't too deep.
All that I can say for sure from personal experience is that SS is a total ******* *** **** ***** to work with.
When I designed and built modifications to the normal locking devices for the '88 Winter Olympics athletes' village, I made the very serious mistake of ordering the 16# stainless backing plates for the deadbolts from the machine shop with the holes for the deadbolts themselves, but neglected to get the smaller corner holes for the mounting screws. I probably spent more on drill bits than I earned from the job.

jim mcnamara

In part, the resulting finish is a function of the type of original finish. For example, a brushed finish has more surface irregularities (surface area) than a polished finish for oxygen and trace contaminants to react with. Newly acid-washed surfaces have less existing oxidation than does old stock.

The oxidation on SS is not super evident, and resists further oxidation, which is why we call it stainless.

The manufacturer can certainly tell you what the side effects of hardening will be.