Stainless steel bolts, galvanic corrosion?????

[franciscocl7]

Here is the issue. I plan to restor my short fleet side box that I bought one year ago. I thing to change all the bed bolts by stainless steel, but here is the problem. If the stainless bolt and the iron bolt are in contac they form a galvanic cuople, so one of them will tend to corred in a short time....Is a good idea to replace such bolts????

Please help me!!!!!!!

[silverstreak]

I've heard of disimilar metals causing corrosion, yet I've seen a fair amount of stainless fasteners used at car shows and on motorcycles. If your panels have a good coat of paint on them (and no bare metal to contact the bolts)and you use stainless nuts as well I think you should be fine. You could even use some nylon / plastic flat washers as cheap insurance.

[franciscocl7]

Ok...thanks sirverstreak. I guess I shall use similar bolts to avoid corrosion in my truck.

Originally Posted by silverstreak

I've heard of disimilar metals causing corrosion, yet I've seen a fair amount of stainless fasteners used at car shows and on motorcycles. If your panels have a good coat of paint on them (and no bare metal to contact the bolts)and you use stainless nuts as well I think you should be fine. You could even use some nylon / plastic flat washers as cheap insurance.

[cdowns]

i've had no serious problems with steel and stainless// i've had cars put together with stainless fasteners and taken them apart 25years later with no problems to either metal

[franciscocl7]

Thanks. The main problem is if they are in contact metal to metal. Its importanto to avoid an electrified interface between them.

Originally Posted by cdowns

i've had no serious problems with steel and stainless// i've had cars put together with stainless fasteners and taken them apart 25years later with no problems to either metal

[capev86]

stainless is stainless......

less normal steel means less rust......

as long as the sheet metal is clean and painted you won't have problems for a long while.

[Willys47]

I don't think you would have a problem I have stainless welded to regular mild steel and it held up just fine as floors in a 4x4

[franciscocl7]

I think if I put stainless bolts on my bed, the fenders, and the bed holes could star to corroed in a short time......stainless should protect hitself by the galvanic couple formed. So the mid steel holes will begin to corroed in a shor time even if they are coated....
I guess

Originally Posted by Willys47

I don't think you would have a problem I have stainless welded to regular mild steel and it held up just fine as floors in a 4x4

[mbgmike]

stainless steel depending on grade is actually not really considered a Dissimilair metal in the industry. There is still Carbon in the stainless in lower grades. I would not worry about it at all. We have welded stainless pipe and carbon pipe together in process plants. We try not to any more but it still is required at times. The metals are just too close on the scale to matter.

[fishingjred73]

I agree with cdowns and mbgmike. I had some stainless bolts that held the spare tire carrier on my stepside and the mirror arms. They had been on the truck for 18 years and I just took them off a couple of months ago. The stainless bolts were fine and the regular steel captured nuts look like they did 18 yrs ago.

[joeelutz]

Really about the only time you need to worry about it on a vehicle is if you have bare aluminum and steel in contact.

[Roland]

You really should not have a problem with using stainless hardware as through bolts for the fender to bed joint. As someone has stated, paint the mild steel well to seal away moisture (oxygen) without oxygen there can be no "rust". So grease the threads before assembly to make an oxygen free joint between the bolt and the nut threads and this will also coat the edge of the hole through the bedside eliminating oxygen there.

True Galvanic corrosion (I think) must take place in an electrolyte AND with some electrical charge. That charge can be generated by a boat hull sliding through salt water or by the movement of fluids through a pipe, etc..

There is a "Galvanic chart" of metals which shows the tendency of metals to react with each other. The more noble of the two will corrode the less noble. I believe the two extremes are graphite and zinc, with zinc being the most sacrificial.

Just my three cents -sorry, I go back to reading posts now

[MVHandy]

They are both forms of carbon steel, stainless has a higher content of nickel and chromium but they are not dis-similar metals in terms of a galvanic cell. You need to have a difference in reactivity between the metals to have a galvanic cell.

[tcb-1]

400 series stainless steel can and will oxidize. granted it will take a while and will need to be submerged, but it happens.

300 series to mild carbon steel should hold up well and will not cause one another to corrode/oxidize under normal use.

[franciscocl7]

Wooo.....Roland that´s a scientific explanation.....I agree with you. I just was thinking about the diferential of potential created between stainless and iron, One will behavies as cathode an the other one as anode.... and yes we need to avoid contac with oxygen to prevent rust....

Thanks.

Originally Posted by Roland

You really should not have a problem with using stainless hardware as through bolts for the fender to bed joint. As someone
has stated, paint the mild steel well to seal away moisture (oxygen) without oxygen there can be no "rust". So grease the threads before assembly to make an oxygen free joint between the bolt and the nut threads and this will also coat the edge of the hole through the bedside eliminating oxygen there.

True Galvanic corrosion (I think) must take place in an electrolyte AND with some electrical charge. That charge can be generated by a boat hull sliding through salt water or by the movement of fluids through a pipe, etc..

There is a "Galvanic chart" of metals which shows the tendency of metals to react with each other. The more noble of the two will corrode the less noble. I believe the two extremes are graphite and zinc, with zinc being the most sacrificial.

Just my three cents -sorry, I go back to reading posts now