316L Chain Eroding/Stretching
316L Chain Eroding/Stretching
(OP)
We use 316L stainless chain to drop Zinc Ingots into a galvanizing bath. The bath temperature is 880F. Bath chemistry is 99.5%Zn 0.30%Al 0.005%Fe 0.015%Sb. The chain is submerged beneathe the bath while the ingots melt. The chain is only removed from the bath when more ingots are needed. On average the chain is out of the bath for a matter of minutes every 2-3 hours.
The problem is the chain which holds the ingots used to last 6 months without showing signs of deteriation, we changed it out to err on the side of caution. Now we have to change the chain every 3 months and many chain links are elongated and/or eroded at the time of change. We are trying to find the reason for the change. Why is the chain eroding so quickly when in the past it would last 6 months or longer and show pracitcally no wear. The problem has been ongoing for ~9months. With one chain completly failing after 3 months in service.
We have not changed chain supplier, the stamping is the same, we have not changed bath temperature, ingot supplier nor bath chemistry.
The problem is the chain which holds the ingots used to last 6 months without showing signs of deteriation, we changed it out to err on the side of caution. Now we have to change the chain every 3 months and many chain links are elongated and/or eroded at the time of change. We are trying to find the reason for the change. Why is the chain eroding so quickly when in the past it would last 6 months or longer and show pracitcally no wear. The problem has been ongoing for ~9months. With one chain completly failing after 3 months in service.
We have not changed chain supplier, the stamping is the same, we have not changed bath temperature, ingot supplier nor bath chemistry.





RE: 316L Chain Eroding/Stretching
Mike Halloran
Pembroke Pines, FL, USA
RE: 316L Chain Eroding/Stretching
RE: 316L Chain Eroding/Stretching
If the links are weaker than they were before they may have switched to low carbon alloy from a higher carbon grade.
or....it may not even be 316.
you need to do some analysis and talk with your supplier.
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Plymouth Tube
RE: 316L Chain Eroding/Stretching
Mike and Ed we did try a second chain from a different supplier and had the same results. Forgot to note this above. However they are both from the same vendor. The stampings are different from chain to chain. In the end we will likely make sure we are getting 316L but we are stumped at this point.
Blacksmith, We do monitor bath chemistry closely. We have seen nothing abnormal.
We recently checked for a potential difference from the chain to the pot and found nothing there as well.
RE: 316L Chain Eroding/Stretching
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Plymouth Tube
RE: 316L Chain Eroding/Stretching
http://www.mae.wvu.edu/barbero/pdf/2007-Xu-MMT.pdf
You have some time of process change that must be identified or use an alternative chain material.
RE: 316L Chain Eroding/Stretching
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"The richer we have become materially, the poorer we have become morally and spiritually." Martin Luther King Jr
RE: 316L Chain Eroding/Stretching
RE: 316L Chain Eroding/Stretching
Carbon content is unlikely to be the issue. All, or 99% of all, 316 is really 316L (S31603) with enough process modifications that it meets the strength requirements of 316 (S31600). It is then dual certified to meet both specifications.
I am pleased to hear that 253 MA performs well in molten zinc, presume it is the 1.7% silicon that provides resistance. Would love to know the source of this information.
AL-6XN with 6% molybdenum has much better resistance to molten zinc than does 316L. Base metal cost of AL-6XN is roughly 2-1/2 times that of 316L, the cost of the finished chain may or may not be in that ratio.