Grade 8 J429 hex head bolt, UNC bolt

Gr 8, SAE J429 Mechanical and Material Requirements for Externally Threaded Fasteners


Grade 8, hex head bolt, grade 8 bolt, fasteners, machine bolt, A manufacturing Grade 8 screws and bolts by hot forging or machining from bar.



Grades are designated by numbers where increasing numbers represent increasing tensile strength and by decimals of whole numbers where decimals represent variations at the same strength level.

Bolts and screws are normally available in Grades 1, 2, 5, 5.2, 8, 8.2

Studs are normally available in Grades 1, 2, 4, 5, 8, 8.1


Chemical composition:

All fasteners shall be made of steel conforming to the chemical composition requirements in Table 2

Refer to SAE J403, J404, J1268 for chemical composition limits of standard steel grades. Other standard and non-standard steels not defined by the above standard are acceptable if the resultant fasteners comply with all of the requirements in this standard. For grades 5, 5.1, 5.2, 8, 8.1, 8.2 the maximum content of bismuth selenium, tellurium, or lead each shall be 0.02%.



Alloy and medium carbon steels with additive boron for manufacturing Grades 8 and 8.2 fasteners shall be fine grained steel.


Heading practice/ head forming: Hot forged


Threading practice/ thread forming: roll threaded


Coating: natural+oil, black, dacromet, zinc-plate, HDG, geomet, dorken


Machanical requirementd for Gr-8 bolts, screws, studs and U bolts

Grade designation Nominal sizeDia,in Proof load(stress), ksi Tensile strength(stress) Min, ksi yield strength (stress) Min, ksi ElongationMin, % Reduction of areMin, % Surface Hardness,Rockwell Core hardness Identification Marking
8 1/4~1-1/2 120 150 130 12 35 58.6 C33~C39  



Post time: May-09-2022