Stainless steel replacement bolt kits.

old-git

Moderator
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From
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Elan & Robin Hood
A word of caution:

Stainless steel can unpredictably sustain galling (cold welding). Stainless steel self-generates an oxide surface film for corrosion protection. During fastener tightening, as pressure builds between the contacting and sliding, thread surfaces, protective oxides are broken, possibly wiped off, and interface metal high points shear or lock together. This cumulative clogging-shearing-locking action causes increasing adhesion. In the extreme, galling leads to seizing - the actual freezing together of the threads. If tightening is continued, the fastener can be twisted off or its threads ripped out.

I wouldn't recommmend their use where torque settings are critical.
 

T9 man

TC ModFather
Moderator
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1,137
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Saab 9-3SS T9
:blink: Thanks for sharing the wisdom OG. I have copied and pasted this in my car notes for future reference material.
 

Loz

Torque King
Points
252
From
Wolverhampton, U.K.
Car
MX-5
A word of caution:

Stainless steel can unpredictably sustaing galling (cold welding). Stainless steel self-generates an oxide surface film for corrosion protection. During fastener tightening, as pressure builds between the contacting and sliding, thread surfaces, protective oxides are broken, possibly wiped off, and interface metal high points shear or lock together. This cumulative clogging-shearing-locking action causes increasing adhesion. In the extreme, galling leads to seizing - the actual freezing together of the threads. If tightening is continued, the fastener can be twisted off or its threads ripped out.

I wouldn't recommmend their use where torque settings are critical.
It's a fair point & thank you for the reminder Og :embarrest:

I would add that the use Stainless fasteners on an aluminium engine block should be avoided as there could be a risk of bimetallic corrosion between the two dissimilar metals as ally is anodic to St/steel it could sacrificially corrode, possibly leading to seizing or breakage.

What you describe above though, sounds to me like a stainless fastener deforming a more ductile material (Eg. low carbon steel) past its elastic range & permanently deforming the threads, further tightening would then lead to shear?

In fairness to the company above their kits seem designed to replace the rusty nuts & bolts used to attach ancillary parts to the cars engine bay & with the use of an anti seize compound & a little care when tightening I don't see there being an issue.

It did seem like an appealing solution at the time, but if you still think it's a bad idea using stainless steel fasteners on a car, I'll take the link down. No biggy. :bigsmile:
 

old-git

Moderator
Points
617
From
Essex
Car
Elan & Robin Hood
Your comments are valid, Loz, and I had forgotten about the corrosion issue.

I think this thread should stay. Stainless bolts, like any fixing, are useful when used correctly, so the above should help potential users to make an informed decision.
 

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