Why is 316 grade stainless steel more corrosion resistant than 304 grade stainless steel?

Question

I make trolleys and bits for use on and around the beaches and tried using 304 grade stainless steel for the cost savings but it rusted up very quickly?

Answer 1

316 grade has a higher molybdenum percentage than 304, which provides higher corrosion resistance

Answer 2

Stainless Steel Grades 304 316

Answer 3

In general, the austenitic stainless steels are considered to have the best overall corrosion resistance of all the stainless steels and to be the most resistant to industrial atmospheres and acid media. As the corrosion conditions become more severe (e.g. higher temperatures and stronger acids), more alloy content above that in type 304 is required.

The addition of over 2% Mo to austenitic stainless steels increases resistance to pitting. Type 316 is a popular alloy in this class and contains 2.5% Mo.

Answer 4

The molybdenum gives 316 better overall corrosion resistant properties than Grade 304, particularly higher resistance to pitting and crevice corrosion in chloride environments.

Answer 5

Unfortunately the stainless property does not make a 100% superior blade, unless you are not too concerned with how it performs. Generally speaking the mineral that allows steel not to stain is chromium so the higher content of chromium the more shiny and less likely to stain. The best performing blades however are the ones resistant to fatigue that usually contain high silica levels like japanese blades. Chromium on the other hand does make a less flexible and lower quality blade that also needs to be thicker, so it comes down to what will you be using it for.

Answer 6

316 has Moly in it, 304 doesn't.

Answer 7

It's because there are 12 more numbers