Notes from the Bay #2 - Gen 3 Steels Are Here

Sep 2

2 min read

Designed for technicians. There's more repair news out there than anyone has time to read, so each issue I pull out one that's worth knowing; stuff you'll be glad didn't slip past. Short, on purpose.

Gen 3 Steels: Strong, Formable, Replace-Only

A did-you-know from Collision ProAssist, drawn from WorldAutoSteel's AHSS Insights

(Courtesy of WorldAutoSteel)

Third Generation Advanced High-Strength Steel (Gen 3 Steel) is making its way into more vehicles. It's the newest step in a line you already know parts of. 1st-Gen AHSS gave us dual-phase, TRIP, martensitic, and boron press-hardened steels. Gen 3 steels are giving us:

• DH — dual-phase, high formability

• TBF — TRIP-assisted bainitic ferrite

• QP — quenching & partitioning

• CH — complex-phase, high ductility

• CFB — carbide-free bainite

The recipes differ; the point doesn't. All are engineered to be strong and formable; which is exactly why you can't judge them by the part, its location, or its design.

Look at the steel "formability diagram" (Courtesy of WorldAutoSteel) and you'll see the old rule: as strength went up, formability went down. For years that meant a deeply formed, complex part was a reasonable bet to be milder steel, because ultra-high-strength steels couldn't form that way. Gen 3 steels fill in the top-right of that chart, offering formability, while maintaining, or exceeding, the strength of earlier UHSS. So a part that looks like it should be mild steel could be 1180 MPa or more. The body repair manual is the only way to know what you're working with.

And the part that matters most: you can't straighten it. On these parts, the only answer if damaged is replacement, following the OEM repair procedures.

This Month in BackBay: The Part Fits. The Insurer's Logic Doesn't.

A BackBay member needed the uniside replacement procedure for a 2023 Silverado — and an insurer used the lack of a published complete-replacement procedure to demand section-only on a panel GM sells (and builds) as one piece. The docs were already on the tech's side: replacing the B-pillar reinforcement calls to remove the body side outer panel (roof and all), and there's published labor time for the complete uniside. When that still didn't move the needle, I took it straight to a GM body/structure engineer, who confirmed it — full uniside replacement is allowed.

Read it on Fender Bender / ABRN →