cybernation said:
I juz know there are few different grade of Stainless steel....SUS 304 ( those material used for thermo ) and SUS 430 ( the best of stainless steel grade, looks like mirror,very chrome and shiny!!)...kekeke
You're right that there are many different grades of SS and that SUS304 are used in thermoflusk. This is primarily because 304 are cheap and very common.
But SUS430 isn't the best SS you can find in the market. I can name you at least 50 or more grades that are better than the 430. Also, the better the grades doesn't mean its more mirror and shiny. The mirror finish that you see on most railings, gates, poles and etc are mainly because the steel goes thru many layers of polishing. As i mention in my earlier threads, to produce a mirror finish, you need to polish using sandpaper of different grades, from the roughest sand paper, to the smoothest. Any grades of SS can achieve such mirror finish providing the right polishing technique is used. When you buy SS material in a bar or a pipe or strip form, its actually very rough and unpolished, its the polishing that makes it look good. Also, sometimes we've actually been cheated by some goods proclaiming to be stainless steel but in actual its actually galvanised steel which actually doesn't last as long as SS.
Back to the issue of SS grades, i wouldn't see there's one grade of SS that is the best but rather when we're talking about SS, its the mechanical properties that counts most. Some want it to be more resistive to corrosion, some want a high strength SS, some want a SS that can withstand high temperature, some want a SS that can withstand cracking at low temperature. So all these criteria are important for a foundry to produce that right composition of metals or formula to be used to produce the desired end product. Some of the more expensive SS that are in the market are called Duplex and Super Duplex. These SS have very high resistance to corrosion and are used in submerged sea water pipes. As much as we think SS won't rust, it'll happen. Seawater are very high in salt content and over the years, it'll corrode the metal so a higher grade SS is needed. Similarly, people who work in the port for a long time will find that their car gets rusty much easier and the paint is very likely to fade much faster than a person working in the city. Its because of the sea water salinity.
I hope i do not bore you guys with these metal talk. Just sharing whatever i know.
