Stainless Steel and Anodised Aluminium

Click For Summary

Discussion Overview

The discussion revolves around the compatibility of stainless steel bolts with anodised aluminium clamps, particularly in a marine environment. Participants explore concerns regarding corrosion, torque specifications for fastening, and the appropriate materials to use in such applications.

Discussion Character

  • Technical explanation
  • Debate/contested
  • Experimental/applied

Main Points Raised

  • One participant questions the suitability of using stainless steel bolts in anodised aluminium due to potential corrosion issues, particularly in marine environments.
  • Another participant asks for clarification on the type of anodised aluminium clamp and its threading configuration to provide more tailored advice.
  • It is suggested to use silicon grease and anti-galling compounds at dissimilar metal contacts to mitigate corrosion risks.
  • Participants inquire about the specific grade of stainless steel used for the M10 bolts, noting that different grades may have varying corrosion resistance.
  • There is a discussion about the necessity of using stainless steel thread inserts when steel bolts are threaded into aluminium to protect the aluminium from damage.
  • Participants express uncertainty regarding the appropriate torque specifications for the bolts and screws, indicating a need for further information on this topic.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the best practices for using stainless steel bolts with anodised aluminium. Multiple viewpoints regarding materials and torque specifications remain unresolved.

Contextual Notes

The discussion highlights the importance of identifying the specific stainless steel grade and the environmental conditions (marine vs. fresh water) that may affect corrosion. There are also unresolved questions regarding torque values and the implications of using different materials in contact.

Who May Find This Useful

Engineers and hobbyists involved in marine applications, particularly those working with metal fasteners and materials in corrosive environments.

Fred Mundle
Messages
3
Reaction score
0
TL;DR
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...
 
Engineering news on Phys.org
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 ?
 
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...
 
Use anti galling compound on all contacts between dissimilar metals. Do that anywhere on your boat. Check fasteners on the mast.
 
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
 
Thank you very much, you've been very helpful

Best wishes..
 

Similar threads

  • · Replies 6 ·
Replies
6
Views
2K
Replies
2
Views
2K
  • · Replies 6 ·
Replies
6
Views
3K
  • · Replies 10 ·
Replies
10
Views
5K
  • · Replies 3 ·
Replies
3
Views
4K
  • · Replies 10 ·
Replies
10
Views
4K
  • · Replies 18 ·
Replies
18
Views
3K
  • · Replies 2 ·
Replies
2
Views
5K
  • · Replies 3 ·
Replies
3
Views
6K
  • · Replies 5 ·
Replies
5
Views
2K