Metallics G8HC584 Bolts 5/8-11 X 4 G8 Hxbt St-zn (Box 25)

It's a 5/8-11 UNC bolt, 11 threads per inch, with a measured shank diameter of 0.6170 to 0.6250 inch. So it threads into any standard 5/8-11 coarse nut or tapped hole. If your nut or insert is 5/8-18 fine thread, this won't engage.

Strength. The Metallics G8HC Grade 8 hex bolt is rated 150,000 psi minimum tensile and 130,000 psi minimum yield, hardened to Rockwell C33-39. Grade 5 is a lower tensile class, so if the engineer's detail calls out Grade 8, or the joint is a high-load automotive, fleet, or heavy equipment connection, Grade 5 is not a legal substitute. Going the other way is also a judgment call: Grade 8 is harder and less ductile, so for vibration-prone joints where some stretch is wanted, many specs deliberately stay at Grade 5.

No. The G8HC584 is sold as bolts only. You'll need to order matching 5/8-11 nuts and washers separately, and for a Grade 8 joint those should be matched in strength class, hardened washers and a Grade 8 (or Grade C) nut, so the nut is not the weak point in the assembly.

No. The G8HC584 is listed as not Buy American compliant and not ARRA compliant, with country of origin recorded as multiple. If your contract carries a domestic sourcing clause, you need a domestically produced Grade 8 bolt instead.

Head width across the flats measures 0.922 to 0.938 inch, which is a 15/16 inch socket or wrench. Head height is 27/64 inch, so allow for that in any recessed or counterbored pocket.

The bolt is medium carbon steel with a zinc finish, which handles indoor, damp, and sheltered exterior service. It is not stainless. For direct coastal exposure, chemical environments, or anything submerged, zinc-plated carbon steel will eventually corrode and a stainless or hot-dip galvanized fastener is the better call. Note that Grade 8 strength levels are not available in standard stainless, so a change in material also changes your load rating.

Boxed, 25 bolts to a box, with a stated order minimum of 50 each. So the practical buy is two boxes. Other sizes and quantities in the G8HC series are available by request.

Medium carbon steel in the AISI 1021 to 1045 range, quenched and tempered to Grade 8 hardness of Rockwell C33-39. That heat treatment is what gets it to the 150,000 psi tensile minimum. It also means you should not weld on it or reheat it, since that destroys the temper and drops the bolt's rating.