Rust Issues on Stainless Steel
Are You Experiencing Rusting with your Stainless Steel?
Beer tanks, hospital equipment, acid tanks, etc. are just a few of the many products that are made from stainless steel. One reason for stainless steels’ popularity is because of its high tolerance to corrosion. But, have you ever noticed rusting on or near your stainless weld?
You may think: is it my power supply, my welding wire or rod, or my welding process? But in reality, it could be something as simple as your wire brush. The rusting appearance occurs when operators are switching back and forth between carbon steel and stainless steel production work. Contact with a carbon steel forming roll can cause a “rust” appearance on stainless. Or, simply grinding or polishing a stainless steel weld with a wire brush can start a “rusting” process. That’s because most wire brushes are made from carbon steel and while cleaning with the brush you deposit free iron onto the surface – which creates rust.
When welding stainless steels, it is important to only use stainless steel brushes for your cleaning needs. Also, when grinding, it is important to use new or uncontaminated grinding wheels. If this is not followed, contamination from carbon steels can occur. Another safeguard, is to positively identify your tools, such as painting the wire brush handles or grinder. This helps operators clearly know the appropriate tools to use for each metal type.
You can enhance stainless corrosion resistance by pickling (cleaning with acid) to remove the chromium oxides, scale and slag formed during welding followed with a neutralizing treatment and finally passivation (clean and allow to air dry). Similar to a scab, this re-oxidization will protect the material from further damage.
What techniques do you use to eliminate corrosion on stainless? Let me know…post your comments and vote on the poll question.
Average (Not Rated)
July 16th, 2006 at 11:42 am
You touched on carbon steel contact with SS. All carbon must be avoided, oil, grease, paint and even some markers. Carbide formation is to be elininated!
August 3rd, 2006 at 10:08 am
Sensitisation must also be avoided. Excessive interpass temps may cause carbide precipitation which will lead to corrosion problems.
August 4th, 2006 at 5:06 am
Eliminating all contact with carbon steel is critical. Our shop welded a complex stainless steel piping system for a major computer corporation. Once the system was on site all areas around the welds started to rust. I was given the task of finding out why this happened and what to do about it. All stainless steel welds have a certain amount of magnetism. The piping was stored in the weld shop after welding and passivation. Carbon steel grinding dust from other projects attracted to all the welding areas on the piping. We solved the problem by sending a high strength passivation paste to the job site and all the weld areas were repassivated. It saved the project and the rust never returned. Customer and my boss were totally satisfied.
August 17th, 2006 at 1:02 pm
We made ever sandblasting on welds.
Be careful with silica sand your aspiration cause silicosis (Lung disease)
August 21st, 2006 at 3:21 pm
Once an inspector put a magnet on a SS wire brush, and then rejected the brushes stating they were not stainless. Contacted Weiler Brush company, and they told me when they “draw” the wire, that that can cause some magnetic properties, but the brush was not carbon.
September 1st, 2006 at 7:23 am
We are a large stainless steel frame manufacturing company in san jose ca. We specialize in clean room robotic frames. We have had all the issuses discussed in this topic. We have implemented all the changes to our process from haveing stand alone brake dies for only sst forming and a complete beadblasting system that only does sst products. We have found that it is really easy to contaminate sst in a job shop. From grinding, wire brushing, waterjet, tumbleing, using the wrong weld rod, forgeting to change the liner in the mig or robot gun, etc. It takes a bullet proof process and disciple to control all these operations to make sure you dont have rust issues at the customers site.
December 4th, 2006 at 11:59 am
Y am Welding Engeneer and in these moments Y am working an Cellulose erection Plant with a big quantity of materials , Titanium included
July 25th, 2007 at 12:36 pm
Hello I was looking for someone with some extensive experience with high strength steels such as hasteloy and various nickel alloys used in the manufacturing of engine and engine componets that experience high heat input during operation.
Thanks Al