Wire for Grade 8 Fasteners
Grade selection guide for SAE J429 Grade 8 bolt production — alloy CHQ wire with the hardenability and tempering resistance for 150,000 psi minimum tensile.
Grade 8 fasteners are the high-strength tier of SAE J429, with a minimum tensile of 150,000 psi. They show up in heavy equipment, automotive driveline, structural connections, and any application where a Grade 5 isn’t strong enough. Getting reliable Grade 8 performance requires the right alloy chemistry, careful cold-heading, and consistent heat treatment.
Grades we commonly stock for Grade 8 production
4037 — our primary Grade 8 wire grade. Chromium-molybdenum alloy with proven response to oil-quench and temper heat treatment. Suits Grade 8 bolts across the standard diameter range.
10B21 — boron-treated alternative for smaller-diameter Grade 8 fasteners where its hardening behavior fits the geometry.
Special-order options
Larger or more demanding Grade 8 applications sometimes call for grades outside our standard stock — 4140, 8740, and other low-alloy options. We can source these on a special-order basis with mill certs and full traceability.
Condition
Grade 8 wire is generally supplied SAFS. Customers running multi-station headers with tight forming tolerances sometimes prefer SAIP. See the SAFS vs SAIP guide for detail.
Building a Grade 8 program?
Need help specifying the right wire for a high-strength application? Request a quote or check current stock.