How can I treat or replace steel bolts in aluminum nuts to avoid corrosion?


I have a structure originally built from aluminum extrusion with channels using aluminum T-nuts and steel bolts. Over the years, the steel bolts have rusted, making them prone to stripping at the head and getting stuck in the nut. I'm going to replace a lot of the bolts to get rid of the rust. Worst case, I replace them with bare steel again, and accept that they will rust again over the next decade or two. I would prefer to avoid that. Can I grease the threads or cover the bolt head with plastic or wax or something like that? Is there a cheaper material than titanium that I could upgrade the bolts to? Are there other solutions I should be considering?

PS: The solution needs to be...

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It is no doubt that stainless steel screws are the best when it comes to holding together materials such as aluminum sheets so that when faced with a variety of elements they do not break open. However, the dissimilar nature of these two metals puts them at risk of getting corroded resulting in their destruction altogether. At Marsh Fasteners , we believe that the steel screws can be used with aluminum but some precautions must be taken if they are to work well together.

Tips to consider when using stainless screws on aluminum

Salty water is an electrolyte that can easily corrode either the aluminum or stainless steel material when they come into contact with each other. Therefore, it is important to always separate the two metals as soon as possible especially if the environment has salty water or anything close to it.

To reduce chances of the metals getting corroded reduce the contact the two metals have by creating a non-reactive barrier. The best barrier...

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Text: David Nikel

photo: Ullustrations - Dan Hambe, Justus Hultgren

It’s lightweight, strong, recyclable, and the most abundant metal in the earth’s crust. However, there is much to consider when using aluminium.

First published in Bolted #2 2014.

Aluminium has dominated the aerospace industry for over half a century. Now other industries are turning to the miracle metal.
Ford recently launched a revamp of its iconic F-150 pickup truck with an all aluminium body. In 2008, Apple launched an anodised aluminium casing for its new MacBook laptops, widely regarded as a design classic, while one year later, in the USA, the packaging industry began using more aluminium than the transport industry.

Why is aluminium the miracle metal?

David Harris from ALFED, the aluminium federation representing the industry in the UK, explains some of the metal’s benefits:

“Aluminium is light, strong and easily fabricated into extrusions and other...

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How to Avoid Cracking in Aluminum Alloys

March 26, 2014

The majority of aluminum base alloys can be successfully arc welded without cracking related problems, however, using the most appropriate filler alloy and conducting the welding operation with an appropriately developed and tested welding procedure is significant to success. In order to appreciate the potential for problems associated with cracking, it is necessary to understand the many different aluminum alloys and their various characteristics. Having this advance knowledge will help avoid cracking situations.

The primary cracking mechanism in aluminum welds

There are a number of cracking mechanisms associated with the welding of metallic alloys. One of the most notorious is hydrogen cracking, also referred to as cold cracking. Hydrogen cracking is often a major concern when welding carbon steels and high strength low alloy steels. However, when welding aluminum alloys hydrogen cracking cannot...

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Stainless steels are generally very corrosion resistant and will perform satisfactorily in most environments. The limit of corrosion resistance of a given stainless steel depends on its constituent elements which means that each grade has a slightly different response when exposed to a corrosive environment. Care is therefore needed to select the most appropriate grade of stainless steel for a given application. As well as careful material grade selection, good detailing and workmanship can significantly reduce the likelihood of staining and corrosion.

Pitting corrosion

Pitting is a localised form of corrosion which can occur as a result of exposure to specific environments, most notably those containing chlorides. In most structural applications, the extent of pitting is likely to be superficial and the reduction in section of a component is negligible. However, corrosion products can stain architectural features. A less tolerant view of pitting...

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How to prevent uniform corrosion?Uniform corrosion or general corrosion can be prevented through anumber of methods:

Use thicker materials for corrosion allowance

Use paints or metallic coatings such as plating, galvanizing or anodizing

Use Corrosion inhibitors or modifying the environment

Cathodic protection (SA/ICCP) and Anodic Protection

Uniform Attack

Generalized Corrosion - This 40 year old sample of 8 in. schedule 80 pipe, while clearly containing depositsof iron oxide, shows very even wall loss and long remaining service life. The pipe was cleanedusing high-pressure water jet and returned to service.

Galvanic Corrosion

What is galvanic corrosion?

Galvanic corrosion




Dissimilar Metal Corrosion

, as sometimes called, isdefined as the accelerated corrosion of a metal because of anelectrical contact...

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All of our equipment mounts are of aluminum and are fastened together with stainless bots and nuts. When the things were originally designed by the Navy they passed their salt spray test.

One thing I would reccomend from experience is to use stainless flat washers on either side of the aluminum and then a ss lock washer and a ss elastic stop nut in your assembly.

This is not just Navy overkill, it promotes long life in the assembly.

You tighten the bolt and nut just until they are snug and the lock washer closes up. That way you don't stretch the rather weak bolt beyond it's elastic limit. The assembly stays tight becuse the elastic stop nut won't loosen from vibration.

Some other things I learned the hard way.

Use stainless Heli-Coils with stainless fasteners in aluminum.
Aluminum hates the fine thread series, always Heli-Coil those threads.

Never use self locking Heli-Coils or any other self locking inserts or clinch nuts with stainless...

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Some of the frequently asked questions we get asked are presented below:

What are the marks shown on the head of a bolt?
When tightening stainless steel bolts - they tend to seize - what's happening?
I can't find the shear strength of a fastener in the specification, can you help?
What is the best way to check the torque value on a bolt?
What are the benefits of fine threaded fasteners over coarse threaded fasteners?
What methods are available for calculating the appropriate tightening torque for a bolt.
Does it matter whether you tighten the bolt head or the nut?
How do you select a fastener size for a particular application?
Does using an extension on a torque wrench change the abliity to achieve the desired torque value?
Is it okay to...

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Handling Moisture in RVs (updated 6/2007)
Phred Tinseth © 1999-2002 Reproduction permitted
Web site:

First things first. You've got to keep moisture from getting in. After that, you deal with what you make on your own.

Simple emergencies—broken window, tear in skin or roof, cracked vent cover, etc. Most of these can be temporarily patched with "aluminum duct tape." NO, not that grey cloth xxxx.

• Aluminum sealing tape is aluminum tape with a peel-off sticky back (A-Seal) . If you put it on a reasonably clean, dry surface, it'll work for months. Every RVer should carry a roll—it's good for lots of other things.

• A roll of Eternabond RoofSeal If the problem is simple (a crack or tear) aluminum tape will usually get you by.

More complicated emergencies—Bigger stuff (like a shattered vent cover, antenna torn off,...

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Hello, and thank you for visiting my site…a personal tribute dedicated to the finest American automotive creation in history: the wonderful Jeep Grand Wagoneer.

My name is Norbert and it has been my mission to produce the highest quality, full, professional, ground-up restorations of Grand Wagoneers in the world, for over 15 years.

There are already plenty of Grand Wagoneer “retailers”, or used car dealers that have labeled themselves as “Grand Wagoneer specialists”, in the US, that clean up and detail 21-30 year old vehicles and call them recertified, refurbished or renewed. Regardless of the label that they use, all of these retailers and dealers have one thing in common….they are selling old, used cars with countless mechanical and cosmetic deficiencies that, more or less, look their age and are just fixing the obvious deficiencies and replacing some simple, inexpensive "wear" components.

My business philosophy, and my purpose...

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