Toyota Tundra 2005 Service - Repair - Maintenance page 3517

CN-2
RUST-RESISTANT SHEET STEEL PARTS
Rust-Resistant Sheet Steel have zinc, tin or aluminum etc, plating over the base metal surface in order to improve the corrosion
resistance of the sheet metal. This sheeting is used on areas that require anti-corrosive abilities but there is no need to distinguish
the differences between rust resistant sheet steel and ordinary sheet steel in body repair.
Body panels on TOYOTA models are made of two different melted galvannealed sheet steel. The ordinary melted galvannealed
sheet has a zinc plating over the base metal surface and when heated a zinc-iron alloy plating. The zinc-iron double layered
galvannealed sheet has an iron rich and another zinc-rich layer above the sheet steel. These 2 layers improve paint adhesion.
These two melted galvannealed sheet steels are used selectively according to need.
Base
Metal
Double Layered Zinc-Iron Galvannealed Sheet Steel
The handling of Rust-Resistant Sheet Steel is the same as for ordinary sheet steel, but the following should be observed.
1. Panel Welding: The paint as well as the zinc portion must be removed completely from the welding area to guarantee
good welding integrity.
2. Anti-Rust Treatment: Since the zinc plating is lost after welding, anti-rust treatment of the welded area must be thor-
oughly performed (refer to section AR).
BODY PANEL CONSTRUCTION - Rust-Resistant Sheet Steel Parts
Fe-Zn Alloy (Iron Rich) improves
paint quality
Zn-Fe Alloy (Zinc Rich) improves
rust-resistant performance
Base Metal
Galvannealed Sheet Steel
: Rust-Resistant Sheet Steel
Zn-Fe Alloy
(Zinc-Rich)