is 904l supposed to be non-magnetic? while 316l is? i have some 316l and 904l watches at home, if magnetism can be used as a way to distinguish them then it's easy, right?
Sort of but Not exactly... you’ll need a good quality magnet to tell the differences although I’ve had a standard fridge magnet be attracted to some of my stated 904L watches haha which indicated they are most likely not 904L. 316L can become magnetic through cold working... as metal that’s worked below it’s recrystallisation temperature to put it in simple terms.
When case blanks are punched out by a press it’s similar to an extrusion process along with other categories such as bending, sheering and squeezing. These processes are used more often with stainless because hot working stainless can cause stress fracturing and making it harder on tooling and machining accuracy.
Proper 904L is austenitic does not magnetise under theses manufacturing processes as in the ones involved in making watches. Other high quality stainless steels like 316L do become magnetic through these processes and most of the time go through processes to demagnetise at the final
Stages of manufacturing or production... obviously rep factories would not do this.
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