Stainless steel contamination?

[ronstafari]

Has anyone here had any issues with iron contamination and corrosion after installing a non-stainless gas block and muzzle device on a stainless steel barrel? I am considering whether or not I need to buy either stainless or aluminum to avoid any potential corrosion issue.

[Dogbite]

Has anyone here had any issues with iron contamination and corrosion after installing a non-stainless gas block and muzzle device on a stainless steel barrel? I am considering whether or not I need to buy either stainless or aluminum to avoid any potential corrosion issue.

[ronstafari]

Hmm ok. My concerns stems from two issues: 1) My understanding is that an electrical potential would develop between the two metals since they are far apart in the galvanic series. Any introduction of moisture into the system can create the opportunity for corrosion. 2) Will iron contamination depassivate the protective passive oxide layer?

I'm just curious if anyone has actually had a corrosion issue with any of this.

[russ69]

Electrolysis usually occurs when there is an electrical charge between 2 dissimilar materials...

The electrolysis flow is created by the dissimilar metals and moisture (it's a battery). Moisture is always present because it's in the air. To answer the OPs question: Barrel steels have iron in them, they are not stainless they are CRES (Crosssion REsistant Steels). They will stain. The best solution is to use the same materials and finishes the military uses. I believe the military requires parkerizing of the barrel under the gas block. That is a somewhat effective barrier given the fact that barrels are wear items and replaced before corrosion becomes an issue.

[FMJBT]

In marine environments, I've seen rust migrate from steel to adjacent surfaces made from extremely corrosion resistant 300 series stainless, so it is possible. However, unless you are doing the "Over the beach" test with your firearm, repeatedly, I doubt it will ever be an issue.

[ronstafari]

Barrel steels have iron in them, they are not stainless they are CRES (Crosssion REsistant Steels). They will stain.

Is this true for barrels advertised as "stainless steel?" I assumed the stainless barrel I bought is actually 304 or some other lower-cost stainless.

[ronstafari]

In marine environments, I've seen rust migrate from steel to adjacent surfaces made from extremely corrosion resistant 300 series stainless, so it is possible. However, unless you are doing the "Over the beach" test with your firearm, repeatedly, I doubt it will ever be an issue.

ok cool. All my knowledge on corrosion is more or less theoretical so I was unsure of how significant of an issue it is. Thanks

[Fjold]

Electrolytic corrosion is only a worry if the dissimilar metals are submerged in an electrolytic solution. Winchester has been screwing stainless barrels on to carbon steel actions since the late 1950's without issues.

[Dezrat]

Is this true for barrels advertised as "stainless steel?" I assumed the stainless barrel I bought is actually 304 or some other lower-cost stainless.

Virtually all Stainless Firearm barrels these days are 416ss.
As Russ69 mentioned, no such thing as "true stainless" steels, only more stain(corrosion) resistant.

[uechikid]

The barrel on my Aero M5 308 is made from 416R Stainless Steel with an A2 bird cage style flash hider. This is a very common combination that I have not heard of any issue.

[russ69]

Electrolytic corrosion is only a worry if the dissimilar metals are submerged in an electrolytic solution...

Wrong, moisture from the air becomes the "electrolyte" for electrolysis action, unless you are hermetically sealed, which you aren't.

[Fjold]

Wrong, moisture from the air becomes the "electrolyte" for electrolysis action, unless you are hermetically sealed, which you aren't.

Wrong, It's not water that is the issue, there has to be enough solution to support electrical current flow and the solution has to be of a high current carrying composition (an electrolytic solution). The amount of current (transfer of ions) is what determines the rate of corrosion. That's why boats in freshwater lakes don't worry about galvanic corrosion like ocean craft have to. The freshwater doesn't allow enough current flow to let the corrosion develop fast enough to worry about it. If moisture in the air was enough to cause galvanic corrosion at a rate that you had to worry about there wouldn't be any old steel structures standing in the world. Just about every metal structure in the world has a mix of different alloys, such as structural steel, rivets, bolts, nuts, washers, decorative trim, etc..

The simple act of firing the rifle will heat the barrel up enough to dry out any residual moisture. You have to have condensation such as near the seashore where fog and salt water spray condenses on cold surfaces on a regular basis or you have to submerge the gun regularly in dirty water.



An electrolyte is a substance that produces an electrically conducting solution when dissolved in a polar solvent, such as water. The dissolved electrolyte separates into cations and anions, which disperse uniformly through the solvent. Electrically, such a solution is neutral. If an electrical potential (voltage) is applied to such a solution, the cations of the solution would be drawn to the electrode that has an abundance of electrons, while the anions would be drawn to the electrode that has a deficit of electrons. The movement of anions and cations in opposite directions within the solution amounts to a current. This includes most soluble salts, acids, and bases. Some gases, such as hydrogen chloride, under conditions of high temperature or low pressure can also function as electrolytes. Electrolyte solutions can also result from the dissolution of some biological (e.g., DNA, polypeptides) and synthetic polymers (e.g., polystyrene sulfonate), termed polyelectrolytes, which contain charged functional groups. A substance that dissociates into ions in solution acquires the capacity to conduct electricity. Sodium, potassium, chloride, calcium, magnesium, and phosphate are examples of electrolytes, informally known as lytes.

[arnie19]

I know if you have a barn with galvanized roofing and replace one panel with aluminum .The aluminum will corrode away from some kind of galvanic action .

[Dogbite]

Wrong, It's not water that is the issue, there has to be enough solution to support electrical current flow and the solution has to be of a high current carrying composition (an electrolytic solution). The amount of current (transfer of ions) is what determines the rate of corrosion. That's why boats in freshwater lakes don't worry about galvanic corrosion like ocean craft have to. The freshwater doesn't allow enough current flow to let the corrosion develop fast enough to worry about it. If moisture in the air was enough to cause galvanic corrosion at a rate that you had to worry about there wouldn't be any old steel structures standing in the world. Just about every metal structure in the world has a mix of different alloys, such as structural steel, rivets, bolts, nuts, washers, decorative trim, etc..

The simple act of firing the rifle will heat the barrel up enough to dry out any residual moisture. You have to have condensation such as near the seashore where fog and salt water spray condenses on cold surfaces on a regular basis or you have to submerge the gun regularly in dirty water.



An electrolyte is a substance that produces an electrically conducting solution when dissolved in a polar solvent, such as water. The dissolved electrolyte separates into cations and anions, which disperse uniformly through the solvent. Electrically, such a solution is neutral. If an electrical potential (voltage) is applied to such a solution, the cations of the solution would be drawn to the electrode that has an abundance of electrons, while the anions would be drawn to the electrode that has a deficit of electrons. The movement of anions and cations in opposite directions within the solution amounts to a current. This includes most soluble salts, acids, and bases. Some gases, such as hydrogen chloride, under conditions of high temperature or low pressure can also function as electrolytes. Electrolyte solutions can also result from the dissolution of some biological (e.g., DNA, polypeptides) and synthetic polymers (e.g., polystyrene sulfonate), termed polyelectrolytes, which contain charged functional groups. A substance that dissociates into ions in solution acquires the capacity to conduct electricity. Sodium, potassium, chloride, calcium, magnesium, and phosphate are examples of electrolytes, informally known as lytes.

[russ69]

Wrong, It's not water that is the issue, there has to be enough solution to support electrical current flow and the solution has to be of a high current carrying composition (an electrolytic solution)....

In aircraft design this is prohibited. Putting dissimilar metals together is a total no no, regardless of where on the aircraft the parts reside. The dissimilar metals have current potential and all they need is some moisture in the air and the current starts to flow. Normal humidity is enough do do the trick. Perhaps this is overly cautious but one of the first things I do during a design is choose compatible materials. It's poor design practice to place materials with large electrical potential against each other.