Fasteners corrosion
Fasteners corrosion
(OP)
Will the original threads of modern cars rust over the years if anti-seize is not used? I don't think they put anything in the original assembly but I imagine there is still some air in between
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RE: Fasteners corrosion
As for modern vehicle fasteners, they typically have an inorganic zinc coating, Dacromet being an example. This provides good corrosion resistance.
RE: Fasteners corrosion
There are some thread lubes that have inhibitors in them but they are not used in automotive work.
Over the long term there will be some corrosion, especially in climates where they salt roads.
But having done some undercar work on by 2011 Toyota Avalon I can tell you that the modern treatments are very effective.
A bit of lubrication and some soak time and all fasteners came out fine.
That would not have been the case 20 years ago.
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P.E. Metallurgy, consulting work welcomed
RE: Fasteners corrosion
RE: Fasteners corrosion
In the marine industry it's standard practice to out anti-seize on the pipe threads for tank vent fittings (exposed to salt spray). These require regular removal so the tribe has decided anti-sieze is best. It's always an ordeal come load line inspection time. We switched our fleet to PTFE thread sealant and no longer have problems with removal.
RE: Fasteners corrosion
RE: Fasteners corrosion
https://cht-silicones.com/products/waxes/silicone-...
RE: Fasteners corrosion
Making sure that these can drain is the biggest help.
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P.E. Metallurgy, consulting work welcomed
RE: Fasteners corrosion
RE: Fasteners corrosion
Because I think is better to keep conductivity in bolt threads or it doesn’t matter?
What about the blue marine grease?
RE: Fasteners corrosion
Blue marine grease is petroleum based so it will damage bushings, hoses, and seals. The petroleum oils will also stain paints and plastics over time.
The blue "marine" grease is one of the worst performing greases I have worked with.
I would avoid soap based grease as they aren't stable and the oil separates from the thickener over time.
RE: Fasteners corrosion
There are really too many grease out there 😁
RE: Fasteners corrosion
https://www.daubertchemical.com/
RE: Fasteners corrosion
RE: Fasteners corrosion
"Everyone is entitled to their own opinions, but they are not entitled to their own facts."
RE: Fasteners corrosion
RE: Fasteners corrosion
What about Teflon grease? Is petroleum based? It harden or stay soft?
RE: Fasteners corrosion
RE: Fasteners corrosion
This is a fluorocarbon grease (short chain Teflon).
And they make versions with corrosion inhibitors.
https://www.krytox.com/en/-/media/files/krytox/kry...
This stuff is expensive, but totally inert and very slick.
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P.E. Metallurgy, consulting work welcomed
RE: Fasteners corrosion
Question to ask... not in any particular ranking/order...
Bolt/nut/washer configurations: what do these parts 'look like' by necessity. Example: hex-head bolts VS 2X-Hex VS Cap Bolts; plain, countersunk, split-lock, star-lock, etc washers; hex or 2X-hex or spanner or castellated etc Nuts... or tap-threaded holes with or without inserts and plain or self-locking, etc features.
Next Bolt, Nut and Washer alloys and corrosion protective finishes need to be considered. Carbon steel, Low alloy steel, stainless steels, heat resistant alloys, super alloys. Types of finishes such as zinc, zinc-nickel, cadmium, with extra chemical treatments such as chromates, phosphates, baked-on solid film lubricants, etc. Also installation lubricants for friction control: none, acetyl alcohol, lube-oil [often common to the vehicle systems], greases, CPCs [corrosion preventative compounds] or anti-seize ['wet' or dry/powdered [MoS2, graphite, etc]. Also Is the fastener install considered 'permanent' [no intention to remove], semi-permanent [remove for rare maintenance]; or an active maintenance remove/reinstall [such as wheels], etc.
CAUTION: Bolt, Washer and NUT alloys/strengths/finishes need to be in harmony with each other, IE: strength-durability-stiffness matching to prevent fastener failures due to 1-miss-matched part... and any materials miss-matches resulting in dissimilarities/corrosion or galling.
What is the environment: hot exposed to engine-oil, or coolant or other fluids, etc; hot-dry-dusty external; hot-humid-moist-salty external; salty-wet/slushy/snow/ice/rain; arctic external; exposed to exhaust/pollutants, etc. Is the fastener experiencing extreme thermal cycles or is it at long-term ambient?
How critical is assembly/re-assembly [long-term] torque-tension requirement? Configuration, alloys, finishes, surface damage, tools, etc all affect torque-tension. Friction increase usually translates to lower tension pre-load to a 'standard torque-value'... and yet increase shear stresses on head-fillets and threads; while reduced friction can result in excessive tension preload for the 'standard torque value' with increased tension load thru the head-filets and threads.
Now... does the fastener installation/assembly require 'locking' or is 'plain' OK. Self-locking parts are rarely re-useable after 10-15 assemblies. IF not self-locking, are they locked with a second/jam-nut, cotter-pins or lock-wire or thread-locking compound or external crimping, etc.
My head hurts and I have to go back to work.
Regards, Wil Taylor
o Trust - But Verify!
o We believe to be true what we prefer to be true. [Unknown]
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RE: Fasteners corrosion
rust encapsulator inside the thread would work but I think it would create too much friction material