As per title, has anyone any idea where I might get M10 x 70 1.5 12.9 grade bolts?
I only need 3 - ATP manifold to turbo.
I only need 3 - ATP manifold to turbo.
I've managed to get some, but with an allen rather than a hex head - being delivered Monday so that's the job postponed another week.
For future searchers, I have ordered 3 spare.
Everywhere I've read, it says you musn't re-use 12.9 grade bolts.
For future searchers, I have ordered 3 spare.
Everywhere I've read, it says you musn't re-use 12.9 grade bolts.
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Wouldn't bother with 12.9, at high temperatures they are only a little bit stronger than 10.9. You'd be better off using stainless grade 316.
Bernard
Bernard
Thank you. I had got the impression that the only advantage of SS was corrosion resistance. Am I likely to get a better performance from SS under the heat conditions?
Out of genuine interest, can you point me to why the strength of 12.9 deteriorates under extreme heat and why 316 SS performs better?
Out of genuine interest, can you point me to why the strength of 12.9 deteriorates under extreme heat and why 316 SS performs better?
Due to the fact that the class 12.9 won't be 12.9 after been used at high temperatures the hardness will change during cooling down.
I was under the impression that 316 stainless was only equivalent to a grade of 4.6?
The reason you re-use 12.9 bolts is the proper way to tighten them is to torque them right up to thier 90% of proof load limit (which is the ".9" bit in their name and the point at which they permanently stretch).
The reason you re-use 12.9 bolts is the proper way to tighten them is to torque them right up to thier 90% of proof load limit (which is the ".9" bit in their name and the point at which they permanently stretch).
Code:
Metric Class Marks on Head Material Tensile Strength Yield Strength
N/mm2 psi N/mm2 psi
8.8 8.8 Steel 800 116,000 640 93,000
10.9 10.9 Steel 1040 151,000 940 136,000
12.9 12.9 Alloy Steel 1220 177,000 1100 160,000
A2-70 A2-70 302 Stainless 700 102,000 450 65,000
A4-80 A4-80 316 Stainless 800 116,000 600 87,000
Bearing in mind the state of the 12.9 bolt that snapped, I'm heavily persuaded by Bernard. It's not the strength of the bolt, it's how it copes with the heat.
Me too!
Corky Bell says
"The idea of holding parts together at the operating temperatures induced by a flat-out turbocharger system is a cause for some thought. Almost any mild steel will have its heat treat cooked out of it. Mild steel will eventually oxidize to the point where fasteners are corroded virtually to the base materials. Cadmium plating will burn away at these temperatures. The most reasonable solution to fastener problems is stainless steel. Stainless steel bolts work better at temperatures above 1200 degrees F. Below that, stainless steel is nice but not cost-effective."
316 SS has a maximum service temperature of 870 degrees C
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For corrosion purposes 12.9 bolts won't be zinc plated due to hydrogen embrittlement that occurs at class 9.6 and above. Nearly all 9.6, 10.9 an d 12.9 bolts are coated with zincprimers.
Further in high-temp applications brons or copper fasteners are used. Bolts that are a higher class than 8.8 will tend to snap quicker instead of bend. The higher the number the larger the chance.
Also cadmiumplating has long been banned
Further in high-temp applications brons or copper fasteners are used. Bolts that are a higher class than 8.8 will tend to snap quicker instead of bend. The higher the number the larger the chance.
Also cadmiumplating has long been banned
Dave, let me know what companies your lookin at as i need some bolts, high tensile jobbies for me, M12x1.5 65mm length. Cheers.
Any thoughts on what issues I'm likely to face using A4 stainless steel bolts, Niall?
Next weekend's job is to remove my turbo to extract the broken ends of 12.9 bolts. It's a job I want to do only once.
Next weekend's job is to remove my turbo to extract the broken ends of 12.9 bolts. It's a job I want to do only once.
I too have broken 12.9 bolts at high temps. They may be strong at 25C but they are not much good at 800C !
Bernard
Bernard
Dave, let me know what companies your lookin at as i need some bolts, high tensile jobbies for me, M12x1.5 65mm length. Cheers.
12.9's Phil? How many, I'll get you a price.
Any idea what the standard VAG bolts are, Bernard? RIBE S D.
Dave theyre for my calipers to the hub fitment, so whatever you reccomend really.
Total length of thread is 40mm - then a shaft length of 25.5mm(same dia as the thread) So a total of ~65mm length from end to the head.
17mm hex head would be fine.
Thanks.
Total length of thread is 40mm - then a shaft length of 25.5mm(same dia as the thread) So a total of ~65mm length from end to the head.
17mm hex head would be fine.
Thanks.
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