Tool steel and methanol

[Hebe7671]

I am currently having corrosion issues with M42 tool steel parts that I am manufacturing. As a temporary fix, I have been placing the parts in WD-40 during any time the parts are not being machined. I would like to get away from the oil due to the messiness, it is difficult to dispose, and is pricey. I have done some testing with giving the parts a methanol rinse after they are washed to remove the water from the surface of the part and it seems to be working. I was wondering if there were any opinions on this method or other suggestion that may work better. Also, are there any negative effects that I am missing?

Any help would be greatly appreciated!

 

[tomwalz]

Flash rust or regular rust?

Flash Rust

Flash Rust is rust that happens really fast. Sometimes you can even watch it happen.

One cause of flash rust on saw blades occurs in window plants. The application is cutting vinyl in a window plant. PVC is vinyl is Polyvinyl chloride. The out-gassing of chlorine forms salts and can cause flash rust.

Flash rust is caused by chlorides and other soluble salts (such as sulfates and nitrates, ) located on the surface of steel. Phosphorus especially as iron phosphate can be a real problem. If these contaminants are present and water is added a bloom of flash rust quickly appears

Soluble salts initiate and accelerate corrosion of steel, and become deeply embedded within the corrosion product. The salts stimulate corrosion through an osmotic action by pulling moisture from the air and through any protective coatings. It is in this form that they achieve their highest level of chemical stability.

All liquid coatings are permeable, thereby allowing the salt on a substrate to "pull" moisture through the coating, causing active corrosion of the substrate long before the protective coating fails. This is commonly seen on structures or objects with blistered paint, which when removed, rust is seen on the surface. In nearly all cases, the coating was applied over salts.

Also, when the moisture is combined with chlorides, a mild hydrochloric acid is often formed, causing degradation of the substrate.

Salts left on a surface prior to the application of protective coatings can be the cause of several occurrences.

Prevention of Flash Rust
To prevent flash rust, the soluble salt contaminants must be removed from the steel.

It is nearly impossible to totally remove all contaminants from surfaces, there are usually some very low levels of salt contaminants remaining after decontamination. There are chemical soluble salt removers that may be added to aid in the removal of soluble salts. They are typically a liquid, organic, non-hazardous and biodegradable and are designed to solubilize both chlorides and sulfates. The soluble salt remover must come in contact with salt ions in order to solubilize them, therefore, any barrier, such as rust, must be removed.

To protect against flash rusting, a small amount of fluid concentrate (0.5% to 1.0%) should be added to the rinse water. This is done to prevent any flash rust.


This gentleman is an expert on flash rust and his company makes chemicals to prevent it.
James Ueberfluss
Applications Research Chemist
WPC Technologies, Inc.
300 South Barclay Street
Milwaukee, WI 53204
Tell: 414-225-2400
Fax: 414-225-2414
E-mail: jueberfluss@wpctech.com


Thomas J. Walz
Carbide Processors, Inc.

http://www.carbideprocessors.com

Good engineering starts with a Grainger Catalog.

 

[Hebe7671]

The parts usually rust in about 30-45 minutes so I assume that would be flash rust...thanks for the lead, I will look into that product. I have tried other corrosion inhibitors with no success but I'm willing to try another.

Now that still doesn't answer my question about the methanol though. Like I said, with testing I have noticed good results I am just not sure if it is a good idea to implement or not. I do not want these parts to get close to the end of the manufacturing process (or worse, to the customer) and start corroding or any other issues do to the methanol.

 

[EdStainless]

Methanol, ethanol, acetone, any of them can be used to dry parts.
However they are flammable and they must be stored in sealed containers because they will absorb moisture from the air and become less effective.
What are you washing the parts with?

A final rinse with high purity water and a small inhibitor addition should be the right answer. Then wipe the parts off and be done.
You should lightly oil the parts, but use a better oil. Some gun oils are excellent as they leave a very thin film, repel water, and will not dry and become tacky.

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Plymouth Tube

 

[swall]

The success of a methanol rinse depends on many factors, such as ambient humidity, rinse time and % water in the methanol. You may find that your recent success was a "we did it once and it worked" experience and then on a humid day and/or with a batch of methanol that picked up water, it won't work. I have seen a methanol swab used on metallurgical mounts where you throught every thing was fine until the evaporative cooling caused water droplets to form on the nicely polished mount, which you then had to re-do.

 

[Hebe7671]

Flammability won’t be an issue. These parts are not exposed to any heat or spark and they go through a final cleaning operation before they are sent to the customer. It is just when the parts sit in process that the problem occurs.

Currently, a heavy duty degreaser/soap and hot water is being used to clean the parts while they are in process. My idea was to have them washed/degreased the same way but after they are rinsed off dry them with forced air and give them a quick methanol bath to remove any water that may have remained on the parts and just let the methanol evaporate. After that I was just going to store them in a bag (possibly a VCI bag) with desiccant packs to keep out moisture.

 

[Hebe7671]

"We did it once and it worked" is one of my main concerns...I have done some research and did not find anyone else that was cleaning tool steel in this manor and wondered if there was a reason for that. I planned on keeping the methanol in sealed containers as EDStainless mentioned and possibly using a specific gravity test to determine the % water in the methanol. But this needs to have near perfect repeatability since rust=scrapped parts.

I requested samples for the additives but after my experience with VCI's im not holding my breath...I would really like to get away from using the oil but it looks like I am running out of other options. Any other leads or opinions?

 

[Maui]

I was responsible for the manufacture of M42 high speed steel at Crucible Materials Corporation for 10 years, and handled many different types of customer complaints and application issues. I never had a customer complain about corrosion issues with this grade, either during manufacturing or in application. This makes me wonder if you are exposing the material to chlorine during the manufacturing process. Are you mixing your own cutting fluids? Are you using city water for this purpose? During the summer months, municipalities often spike their water supplies with chlorine in order to kill bacteria that can otherwsie grow and spread disease. If you don't actively filter this excess chlorine out of the water (using charcoal filtration for example) before using it to mix your cutting fluids for machining, it will expose the M42 to a known corrosion agent.

Maui

http://www.EngineeringMetallurgy.com

 

[Hebe7671]

We do not mix our cutting fluids but we do use city water for washing the parts after each manufacturing operation. We have one sink that is DI water, I will do some testing with that to see if it makes a difference.

 

[EdStainless]

And then also rinse the parts with DI after machining.

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Plymouth Tube

 

[tomwalz]

Container chemistry?

I once had a problem when a galvanized funnel was used to replace a plastic funnel. Took a while to run down as its use was very limited and it was not the specified process.

Anybody adding or deleting a step in the process?

Tom

Thomas J. Walz
Carbide Processors, Inc.

http://www.carbideprocessors.com

Good engineering starts with a Grainger Catalog.

 

[Hebe7671]

Ok, I did a few trial runs of washing the parts in DI water afrer the machining operations and found that it greatly reduced, but did not completly eliminate, the corrosion issue. With the DI water, there was no flash rust but after a few hours a few small spots of rust could be seen. I have requested samples of additives and will see if using those with the DI water will eliminate the problem for good. If not, I will use the methanol approach of "drying" the parts. Thanks for all the information!!

 

[Maui]

Hebe7671, based on your preliminary results the city water is likely the root cause of your flash rust issue. I'd suggest adding a charcoal filtration system to your plant water supply to filter out any unwanted additives.

Maui

http://www.EngineeringMetallurgy.com