Originally Posted by Ihatetochangeoil
Originally Posted by ST2008
Originally Posted by rubberchicken
Originally Posted by JHZR2
Black is some "black oxide" protective coating. Shining silver is usually zinc coated. Iridescent yellow-green-red-brown used to be cadmium plated, now is yellow zinc. Not sure I've seen a dull grey to my memory, but I may not be thinking straight.
All are corrosion protection to different levels/for different looks.
I was not aware the industry was moving away from cadmium. This is good to know.
Another warning about stainless steel- unless otherwise specified, SS is weak and brittle compared to generic steel. Make sure if you use SS you know exactly what alloy, and is it correct for that use. Pretty much the only "strong" SS I use would be from ARP.
Yeah... I always ask why it's so hard to find SS exhaust bolt kit in any general auto part store. Probably the mechanical properties of standard SS are not suitable for exhaust system.
If anyone had read my post and followed my links, you would see that ARP MANUFACTURED my 304 ss exhaust studs. I know what alloy they are and how correct they are for the use. And yes, it is true that while 300 series stainless is "weak" compared to hardened bolts, it IS strong enough and corrosion resistant to make excellent exhaust fasteners, else why would ARP make them? And stainless is ANYTHING but "brittle," having a percentage of elongation of 55%, over twice that of carbon steel, metallurgically speaking, it's more like a rubber band.
https://www.machinedesign.com/materials/comparing-stainless-steel-and-other-metals
My guess as to why it's so hard to find SS exhaust bolts in a general auto parts store is simply cost. My local Lowe's has a good supply of stainless bolts and nuts, and if you're unsure of what stainless alloy generic stainless bolts are, a pocket magnet will separate them. 400 series stainless is slightly magnetic and will rust a little, while 300 series is totally nonmagnetic and will NOT rust.
I used the term brittle when perhaps I should have used the term weak. Like you, when I need SS that is strong, I use ARP products. Most people that go to hardware stores and get SS fasteners are looking for corrosion resistance and are very price sensitive, and these products are not nearly as good as grade 8 , probably not even as good as grade 3. I did have a huge fup with ARP bolts in a boat engine exhaust manifolds, and ARP gave me excellent technical support for the problem. In the end, I had to pull the engine, cut off the heads of the bolts with a cut-off wheel which in turn ruined the manifolds. The bolts I used were too long by .25 inch, bottomed against blind holes, and could not be removed by impact wrench, and cutting the heads off then drilling the ARP bolts with cobalt bits was too expensive- I was going through about 3 cobalt bits for each fastener, so at that rate it would be about $500 for bits, or buy an expensive drill sharpener that can handle cobalt bits, or just write off the exhaust manifolds and replace them. Very costly mistake, and I should have spent about $20 more for proper exhaust studs rather than bolts.