General Motors Corrosion Engineer Christa Cooper and her team know that rust never sleeps, so they look for corrosion in places the typical automobile owner never sees – underneath welded brackets and joints and among the thousands of spot welds that help hold together a vehicle body.
The Crime Scene Investigation-style effort was performed recently on the 2012 Chevrolet Cruze. The outcome should mean years of little or no rust. Cooper’s corrosion quest takes place inside the Vehicle Teardown Facility at GM’s Milford (Mich.) Proving Ground. Cooper and her team analyzed Cruze test vehicles subjected to extreme durability testing representing 10 years of wear, tear and elements. “We test to the 95th percentile environment, which is the most-severe customer environment we can replicate in our labs and road courses,” said Cooper. The cars are then disassembled piece by piece.
Skilled trade mechanics drill out 2,000 to 3,000 individual spot welds by hand seeking out corrosion in the sheet metal structure. It takes a two-person team two weeks to completely tear down a car to its base elements.
When Cooper and her team find even a trace of rust, they look for ways to prevent it. Rust is a natural result of steel contacting water and oxygen, and the corrosion accelerates when road salt is present. The solution most often is finding a way to keep water out. Sealers and alternative materials are often prescribed.
While Cruze was under development, Cooper and her team uncovered corrosion where the inner panel of the rear door is joined to the safety beam. The team recommended switching out an uncoated steel bracket with a rust-resistant coated steel stamping. The change eliminated corrosion in that area.
