My Dad was a senior metalurgest with the United kingdom Atomic Energy Authority for over 30 years, working on fuel enrichment for atomic bombs at Capenhurst in the 50's to energy production at Dounreay until the late 80's,
We often talked about stainless steel & it various properties, its a most fascinating material, as you probably know, nuclear reactors & all there associated pipework etc are totally made of the stuff & the UKAEA actually came up with & patented many special grades for there specific purposes. many are still covered under The Official Secrets Act.
To explode a few myths:
Certain grades are magnetic, others not.
Certain grades oxidise, other do not.
Certain grades are nigh-on unmachineable even with carbide tipped tools, others turn, drill, tap & mill like MS.
certain grades are unweldable, usually the HT grades, other weld beautifully.
A2 is medium tensile & used for fastners on non-load bearing applications.
A4 is equivalent to HT in MS.
303 machines well but does not weld.
21-4-N is used for engine valves, commonly referred to as Nimonic Steel.
What makes SS SS & not MS is simply a few % more of Chromium & Nickel in the alloy, the amounts are very subtile, it was discovered by accident by a Sheffield cutlery maker in about 1900, looking for a metal for knives & forks that would not rust, the rest as they say is history!
There are as many grades of SS as there are days in a year.
Im a big fan of SS on motorcycle applications as I live only a few yards from The Pentland Firth but it must be used correctly for safety reasons.
Early SS car exausts cracked when the cooled down as it was not the correct grade used for the pipework, I have SS systems on my Alfa & Jag & SS silencers on the Alpino, they give no trouble whatsoever & weigh about 50% of the equivalent MS items. All the fastners & many of the brackets on both the 500's & the 7R are SS.
I hope this clears up a few myths.
Ross.
