Quote:
Originally Posted by DLRIDES
Tensile strength doesn’t necessarily give the complete story as to the “hard vs. soft” of the two alloys. Many scales can be used, but for this instance, let’s use the Brinell.
) 316L has a Brinell hardness of 146
) 904L has a Brunel hardness of 122
This dispels the internet hype that 904L is harder therefore more scratch resistant. Better corrosive properties, but not harder.
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Brinell hardness is rarely used on austenitic steels. Rockwell B (HRBW) is a far better and more widely accepted scale for alloys like 316L and 904L. And, depending on
how they're alloyed, Rockwell harness might only be 5 points apart between the two and typically fall somewhere in the HRBW 70 to 95 range -- likely 90~95 in this case. This still isn't "soft" to the point where 904L is like gold and 316L like steel as it seems to be assumed here.
904L might be
slightly softer than 316L but in no way is it a "soft" metal. That's the main point I was making above.
Besides, if both steels are forged in manufacturing then their Brinell hardness (if using that scale for debate purposes) will be closer together than the 146/122 numbers you posted above. I suspect they'd only be a few points apart. The numbers you quoted are for raw materials, not forgings. Rolex forges their cases but might not forge their bracelets, which are likely made from extrusions. We'd need to test each part before claiming the end-all debate on hardness numbers. This is why I went with tensile strength.
IMO this debate in "904L softness" is WAY overblown. Any event that will scuff, scratch or dent 904L will equally affect 316L.
