Stainless Steel and Anodised Aluminium

In summary, the conversation discussed the use of stainless steel bolts in an anodised aluminium clamp, with concerns about potential corrosion. It was recommended to use silicon grease on dissimilar metal contacts and to check fasteners on the mast. The use of an anti galling compound was also suggested for all contacts between dissimilar metals in a marine environment. It was also advised to use a stainless steel thread insert when threading a steel bolt into aluminium. The conversation concluded with a request for guidance on the proper torque for the bolts, with suggestions to check the manufacturer and grade of the stainless steel used.
  • #1
TL;DR Summary
Stainless Steel Bolts in an Anodised Aluminium Block
Hello engineers,

Is it ok to use stainless steel bolts in an anodised aluminium clamp? I know that I should avoid using stainless steel with plain aluminium because of risk of corrosion.

Also, what torque would you recommend that I apply to an M10 stainless steel bolt in an anodised aluminium block?

Many thanks in anticipation...
 
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  • #2
Welcome to PF.

What is the anodised aluminium "clamp" or "block" ?
Does it have a thread cut, or a thread insert in the aluminium, or does the bolt pass through to a nut ?

Use silicon grease on dissimilar metal contacts.

What stainless grade alloy is the M10 ?
Who is the manufacturer ?
 
  • #3
Hello Baluncore

It's a clamp that attaches a tiller to the rudder stock on my boat, so in use in a marine environment (photo
attached)

A X332 Mardy Gras Clamp.jpg


Bolt B passes through the clamp to a nut, the hole is not threaded..

The second bolt locates in a thread insert right through the block at C.

There are also grub screws located in threaded inserts in each side of the clamp.

All of these bolts/screws are currently stainless. The bolts are DIN912 M10 socket head screws CH A2, the grub screws are A2 (304), DIN 916.

I do not have any corrosion between the metals at the moment seeking advice to make sure I am doing the right thing?

Also, critically, I have been unable to get any advice on how many Nm I should torque the bolts and crews to. Any advice on that score would be greatly appreciated?

Thank you...
 
  • #4
Use anti galling compound on all contacts between dissimilar metals. Do that anywhere on your boat. Check fasteners on the mast.
 
  • #5
Baluncore said:
What stainless grade alloy is the M10 ?
Are you in a marine environment with chlorine, or in fresh water? The marks on the head of the bolt will identify the manufacturer and the grade of steel. Then the maximum torque can be found in the tables. Is the bolt a 316 marine stainless bolt or some other type of lower cost stainless steel like 304?

Where a steel bolt is threaded into aluminium, a stainless steel thread insert should be used. That should protect the aluminium surface from physical damage.
https://en.wikipedia.org/wiki/Threaded_insert#Helical_insert
 
  • #6
Thank you very much, you've been very helpful

Best wishes..
 

What is the difference between stainless steel and anodised aluminium?

Stainless steel is a type of metal alloy that contains at least 10.5% chromium, which gives it its corrosion-resistant properties. Anodised aluminium is a process in which a layer of oxide is formed on the surface of aluminium, making it more durable and resistant to corrosion.

Which one is more durable, stainless steel or anodised aluminium?

Both stainless steel and anodised aluminium are highly durable materials. However, stainless steel is generally considered to be more durable due to its high resistance to corrosion and wear. Anodised aluminium may be more prone to scratching or chipping, but it is still a durable option for many applications.

Can stainless steel and anodised aluminium be used together?

Yes, stainless steel and anodised aluminium can be used together in certain applications. However, it is important to consider the potential for galvanic corrosion when using these two metals together. This can be mitigated by using proper insulation or coatings between the two materials.

Which one is better for outdoor use, stainless steel or anodised aluminium?

Both stainless steel and anodised aluminium can be suitable for outdoor use, but stainless steel is generally preferred due to its higher corrosion resistance. Anodised aluminium may be more prone to fading or discoloration over time when exposed to UV rays.

What are some common uses for stainless steel and anodised aluminium?

Stainless steel is commonly used in kitchen appliances, cookware, and construction materials. Anodised aluminium is often used for outdoor furniture, window frames, and electronic casings. Both materials are also used in various industrial applications due to their durability and resistance to corrosion.

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