Metallics JG8HC31 Bolts 3/8-16 x 2-1/4 G8 HXBT St-zn (Jar 50)

Grade 8 here means 150,000 psi minimum tensile and 130,000 psi minimum yield, with a case hardness of Rockwell C33-39. A Grade 5 of the same diameter tops out lower on both counts, which is why Grade 8 gets specified on automotive, fleet, and heavy equipment work where the joint is loaded harder. Same 3/8-16 thread, so it drops into the same tapped hole or nut.

Both the ARRA and Buy American compliance flags on the JG8HC31 read C for compliant. Country of origin is China, so if your contract language requires domestic melt and manufacture rather than ARRA-style compliance, verify the specific clause you're working to before you submit.

It's 3/8-16, a fine-thread (UNF) 3/8 inch bolt at 16 threads per inch. That matters because the common 3/8 coarse thread is 3/8-16's cousin at 16 TPI for UNF versus 16 for UNC on other diameters, so pair it only with 3/8-24 or 3/8-16 nuts that match. Check the nut marking: it must read 16 TPI. Shank outside diameter runs 0.3690 to 0.3750 inch.

The finish is zinc plating over medium carbon steel, which handles indoor, mechanical room, and sheltered exterior duty. For constant wet exposure, salt spray, or direct weather, zinc plated carbon steel will eventually corrode; a hot dip galvanized or stainless fastener is the right call there. Note also that Grade 8 strength comes from heat treatment, so don't substitute stainless and assume equal strength.

They ship 50 to a jar, and 50 counts is the order minimum, so the jar is the smallest unit. Total packed weight is 1828 g. Other sizes and quantities can be had by request within the G8HC and JG8HC series.

Material is medium carbon steel in the AISI 1021 to 1045 range, quenched and tempered to reach Grade 8 hardness of Rockwell C33-39. That heat treatment is what carries the 150,000 psi tensile rating, and it's also why you should not reuse a Grade 8 bolt that has been torqued to yield.