Drawn Steel Wire Rusting Problems

[USCFan]

Problem: Customer produces drawn steel wire. It is rusting after being outside for one day. Rust inhibitor claims protection for 1 year. Problem just started recently.
Goal: Figure out why and put measures in place to prevent problem in the future.
Current Info: Obviously, water and oxygen are getting to and reacting with the metal more quickly than before and the first question is what has changed? I am going on the initial site visit this afternoon. I'll know more then, but right now I am looking for ideas and how to's.

i.e. if it could be biological. How do we know? Is there a type of bug we should try to isolate or a threshold bacteria count to look for in the bath?

Are there tests that we can run on the metal itself to narrow down possibilities?

Thanks in advance for your help.

 

[jck26]

USCFan, I did wire drawing at one time and here are some basic questions that I would ask of manufacturing to resolve the problem:

1. Did we change our anti-rust compound or drawing compound with rust inhibiter? Has this ever happened before, and if yes, what were the issues surrounding the problem. How did we resolve it then.

2. Do we have a new operator at the machine which might have caused: a lack of draw lube / inhibiter, improper draw lube concentration, or not physically turning on the system that adds the inhibiter or some other process related parameter.

3. What is the process and are we following it? Make them show you the process book on the floor and show you the related information concerning the application of the compound, the supplied form to the operator, the settings to used for the material, etc. If this not spelled out very specifically then there are problems not just with this process but with many other that they have.

I hope the problem is no deeper than these simple questions. Additionally, is there any way for the final inspection of the wire spools to verify the presence of the rust inhibiter? If not, then some addition to the process information book is in order. I Hope this helps.


jck26

 

[tnatale]

jck26 makes some very good points, I would add the following.
For the corrosion to be happening that quickly, there has to be some contaminate that is accerating the corrosion process. Therefore you need to isolate the source(s). Split a batch of wire into several areas and see if they are all corroding to a similar level. If so then the source is process related, if not, that would push me toward an enviromental issue.
If process related, pay really close attention to the process water (if there is any) or where else contamination is getting onto the wire.

 

[USCFan]

Thank you both for your comments. The plant has already played with variables in the process and storage environment. They have tasked us specifically to investigate the contamination side of the issue since our firm has a lab.

tnatale, they are thinking along the same lines as you are that something must be accelerating the corrosion. There are no visible problems with the wire after annealing. The last step is applying a water soluble oil/rust proofing. The thought is that either there is a contaminant on the wire that is activated when the oil is applied, or something in the made down oil is accelerating the corrosion.

Since our lab primarily works with water samples, we are running a battery of tests on the finishing oil, the water used to make it down and the made down solution. Since we have no background data it's hard to say what the results will tell us, but at least we can give them some information.

We also have samples of the wire at various points in the process. However, are at a loss as far as how to use them to get information. What contaminants would be of particular concern? Is there a way to look for them on wire samples? Is there a way to determine the cause of corrosion from an already rusted wire sample? Any thoughts are greatly appreciated.

 

[MikeHalloran]

Can your lab find any trace of the rust inhibitor on the rusted wire?

Mike Halloran
Pembroke Pines, FL, USA

 

[USCFan]

Excellent question, I wish I could answer it definitively. We don't know of a specific test to determine if the wire has the inhibitor on it. Visually (under a microscope) I have compared (1)wire that has not been through the inhibitor (2) "good" wire that has and (3) rusted wire that has. The biggest difference between the samples is a color change. If that is what determines the presence of inhibitor, then yes inhibitor is present on the rusty wire.

 

[USCFan]

For anyone who might be following this thread. There was a process change where the new lubricating soap had a higher pH. We also found high bacteria counts in the old rust inhibitor solution (prior to dumping the bath, cleaning the tank and making a new batch of inhibitor). When either of these two instances is isolated, the problem does not occur (at least not with the same severity). We believe the problem is a mechanism whereby the bacteria provides the source of moisture and perhaps also helps by reducing the iron from Fe3+ to Fe2+ and the higher pH soap residue provides the OH- creating ideal conditions to accelerate rust formation. We are now trying to help confirm this theory by isolating and identifing the bacteria found in the bath.

 

[kenvlach]

Interesting theory. The microbes also certainly degrade the rust inhibitor within the process bath and then continue doing so during storage of the wire.

Some environmentally-friendly aqueous cleaners use microbes to digest oils & greases lifted off metal parts by surfactants, giving much longer bath lives than emulsifying cleaners. One such bacterium naturally present in soil & water and found in oils & greases pseudomonas stutzeri

http://www.biocleanus.com/pdfs/AESFWeek2001.PDF

Similar products are used in greasetraps, plumbing drainlines, bilges of boats, e.g., Super Grease Eater™

http://www.eatoils.ca/productlist.html#bacterialproducts

There are biocides available for protecting solutions. These people have one of the few that is compatible with dye solutions used on anodized aluminum:

http://thor.adept.co.uk/usa/biocideproducts.asp?AppID=3

 

[TheBoss646]

We have a similar problem, however, we buy our rod in large quantities from overseas and it rusts long before it's drawn. Can this be a source of wire breakage during the drawing process? Can the application of a rust inhibitor on the rod prevent the rod from rusting, but not have any deliterious effects during the drawing process?

Thanks,
TheBoss646

 

[gerhardl]

Is change in material quality or structure in ingoing material (before drawing) resulting in different microstructure of thread surface or thread material excluded? Certification or analysis?

Traces of free steel particles contaminating surface?

 

[TheBoss646]

Thread material excluded.