A contractor has stated that the 316SS (for SS tubing) cannot be heat treated and hardened to Brinnel 220-250. I'm questioning if that is so or not? Any comments? Also, they are recommending use of 416SS instead. The application is a roller in a rack assembly of some trash racks at a river gate near the ocean and exposed to salt water.

Alohatwou S.S 316 is generally not hardenable. However if the tubing is cold or hot worked - on some occasions hardness can go to 200-250 BHN. Normally this hardness will be lower than < 210 BHN. S.S 416 - if it is martensitic grade - is hardneable and is usally hardened and quench tempered to any desired hardness range - say from 200 BHN to even as close to 400-420 BHN If you use hardened & tempered SS 416 bolts for rack assembly - with hardness above 250 BHN in marine application for trash rack assembly with marine and salt water exposure, possibility of this developing SCC after some years or some months - if hardened > 300 BHN and left in such environment exposure has to be recognized now before use. S.S 316 may also be susceptible if cold worked to hardness > 220 BHN Hope this helps C.V.Srinivasan Nishi Engineers Pvt Ltd India Dec 2, 2008 E-mail: nishi@vsnl.com >A contractor has stated that the 316SS (for SS tubing) >cannot be heat treated and hardened to Brinnel 220-250. I'm >questioning if that is so or not? Any comments? Also, they >are recommending use of 416SS instead. The application is >a roller in a rack assembly of some trash racks at a river >gate near the ocean and exposed to salt water.