How to distinguish 304 stainless steel and 316 stainless steel?

The two most commonly used stainless steel 304,316 (or corresponding to the German/European standard 1.4308,1.4408), 316 and 304 in the chemical composition of the main difference is that 316 contains Mo, and it is generally recognized that 316 corrosion resistance is better than 304 in high temperature environment more corrosion resistance. Therefore, in a high temperature environment, engineers generally choose parts of 316 material. But the so-called thing is not absolute, in the concentrated sulfuric acid environment, then the high temperature do not use 316. Otherwise it can be a big thing. People who learn machinery have learned threads, remember that in order to prevent thread bite at high temperatures, you need to apply a black solid lubricant: molybdenum disulfide (MoS2), from which you can draw two conclusions: one: Mo is indeed a kind of high-temperature material (know what crucible to melt gold? Molybdenum crucible!) . Two: Molybdenum is easy to react with high sulfur ions to produce sulfide. So no stainless steel is super resistant to corrosion. In the end, stainless steel is a piece of impurities (but these impurities can be more corrosion resistant than steel) more steel, steel can react with other substances.