Need help with H11 and H13 material to be used for headstud fasteners.

[NattyBoh74]

Hi guys,
Im not an Eng. by any means, but Im looking for your opinions on the materials H11 and H13 ( specifically for use as headstuds on diesel engines ). I dont know anywhere else to look, and the places that I have looked are pretty much forums with gearheads, and no one with true info or experience.

Im looking at using either an H11 or H13 stud for my truck. As we know these diesels now days operate under very high pressures within the cylinders. These are two very popular options now for their strength versus ARP's proprietary alloy ARP2000 ( which I believe is 8740 chrome-moly ).

Can someone explain the difference between the H11 studs that are available and the H13 studs? What are some points worth noting on the two versus each other? Does one have a little more stretch when yielded versus the other? Any and all info here guys, Id appreciate it.

Thanks,
Anthony.

 

[Screwman1]

Natty,
What is your target clamp load for each stud and what are their diameters and thread sizes? Then we can give you a better idea of what sort of strength that you need. Just trying to make the strongest bolt possible is not generally a great idea because you end up trading tensile breakage for other failure modes like Stress Corrosion Cracking or notch sensitivity.

 

[NattyBoh74]

Thanks

 

[TVP]

H11 and H13 are very similar when compared to other fastener steels like 8740, ARP2000, etc. Both H11 and H13 are quenched and tempered to very high strength and hardness, typically ~ 50 HRC (tensile strength ~ 280 ksi or 1900 MPa) for this application, which makes them sensistive to stress corrosion cracking (SCC). ARP sells their H11 fasteners wrapped in a special paper that is soaked with a rust preventive oil in order to minimize corrosion during handling prior to assembly.

 

[tbuelna]

NattyBoh74-

For an H11 or 8740 steel stud having equal profiles, they should experience a similar amount of "stretch" for a given torque preload. When it comes to engine fasteners a primary consideration is cost. Highly stressed studs benefit from having the threads roll formed. But it is not practical to roll form threads when the material is harder than around Rc38. So it can be quite costly to make studs from a material like H11 when it is quenched and tempered to high hardness/strength levels.