Stainless Screws for Deck Gear

[elhix]

Does anyone know if the fasteners I use to attach winches, clutches, cleats etc need to be A4 stainless or will A2 do the job?

[GordMay]

Yes, I’d certainly recommend type A4 (316) S/S over type A2 (304).

[David M]

Never use the cheap stainless if you can avoid it. For others, one way to detect the cheap stuff if you are not certain is to place a magnet on it. The cheapo stuff has a higher iron content.

[mikereed100]

Of necesity I used 304 for many of my deck fittings as 316 simply was not available or was too expensive (the local jewelry store wanted the equivalent of 15USD for a 2 1/2" x 5/16 bolt. When you need 40 it adds up). No rust to date but time will tell.

Mike

[egemen]

Originally Posted by elhix

Does anyone know if the fasteners I use to attach winches, clutches, cleats etc need to be A4 stainless or will A2 do the job?

dear elhix;

ı can say that for A4 (316) and A2(304), are the same mechanical properties. look at the bolt quality if it is A4-70 or A2-70, tensile strength is 700 N/mm2,
A4-80 or A2-80 tensile strength is 800 N/mm2.
chemical properties is
Austenitic
GradeMaterial
No. to AISI C Si Mn P S Cr Mo Ni
A2 304 0.08 1.0 2.0 0.05 0.03 17.0 to 20.0 - 8.0 to 13.0
A4 316 0.08 1.0 2.0 0.05 0.03 16.0 to 18.5 2.0 to 3.0 10.0 to 14.4

chemical properties says that; 304 SS can be rust in the long time.

[jamieh]

316 or A4 definitely for decking fittings. 304 will be o.k but will probably get tea-staining. Magnetism can also occur in 316 as well as 304. It depends how the fastener is made. Threaded Rod for example is cold drawn and often 316 will become magnetized. 316 castings also commonly become magnetic so no easy way to tell.