Regarding stainless vs plain steel and flushing...
The Achilles heel of most stainless steel is chlorine, either as the element or as part of a salt. The element, found in chlorine bleach, is quite corrosive to stainless - there are numerous tales of home brewers disinfecting their stainless equipment with chlorine bleach solution, but failing to rinse it completely out. What happens is that droplets of bleach solution left inside the vessels can slowly dry out, increasing the chlorine concentration to the point where it causes pinhole corrosion in the vessels, leading to pinholes, which means they can no longer be used to hold liquids esp not under pressure.
The main element in stainless steel that gives it corrosion resistance is chromium. Upon exposure to air, it creates a very thin layer of chromium oxide, which prevents the iron in the metal from combining with oxygen and rusting. However, salt water or chlorine bleach can attack the chromium oxide, resulting in corrosion of the metal underneath it. Very cheap stainless has only chromium for corrosion resistance, and that cheap stainless will fairly quickly corrode (rust) if left in contact with salt water for a prolonged time. More expensive stainless has nickel in addition to the chromium, and the nickle acts to protect the chromium as well as provide its own corrosion resistance. In terms of corrosion resistance, from lousy to pretty good, you go from 18-0 (18% chromium, 0% nickel), to 18-8, 18-10, then up to 18-12. 18-10 is what I usually look for in flatware and such. The usual alloy is #304. A few percent of molybdenum also helps to protect the chromium oxide layer, and according to the sources I've seen, that's generally called 316 grade and may be preferred for marine environments. Above that, you start to get into the high nickel alloys like Inconel, Monel, which are very corrosion and heat resistant, but as you might imagine, much more expensive than the usual consumer grades. Very high nickel alloys are used in such things as jet engine turbine blades and afterburners, because they are so heat resistant. They are also very difficult to machine, but that's another story. And as you might imagine, there are a lot of different alloys produced by tweaking the percent and type of alloying elements added.
The reason why I bring this all up is from Panthera's recommendation to flush the drain thoroughly after using a disposer. I would imagine, based on the above, while it's important for normal food scraps, it's even more important if one cleans a sink with a chlorine containing bleach. You don't want droplets of a bleach solution drying out on stainless (or regular steel, for that matter), becoming more and more concentrated as they dry, and causing pinhole leaks/fractures/mayhem.
Many years ago when I didn't know better, I bought a set of flatware that turned out to be 18-0 stainless. It worked fine as long as I kept it clean and dry. But I got a taste of how vulnerable it can be, when I lost a spoon in the garden. I found it a few weeks later, and it looked quite corroded and rusted. I was a bit surprised. After that I got some 18-8 flatware and have kept better track of its whereabouts

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