Corrosion monitoring and materials selection for automotive environments by using Atmospheric Corrosion Monitor (ACM) sensor

• Atmospheric Corrosion Monitor (ACM) sensor is applicable to automotive environment.
• The cause of corrosion of respective parts is identified by ACM monitoring.
• Corrosion rate of materials is estimated from the correlation with ACM outputs.
• We demonstrate corrosion life prediction for respective parts in use environments.

Severity of corrosion damage in automobiles depends on use environments and parts. Corrosion life prediction is a key technology for the optimum selection of materials. The Fe–Ag type Atmospheric Corrosion Monitor (ACM) sensor has been the object of many studies from this viewpoint. In the present study, ACMs were installed on various parts of a monitoring test vehicle and the corrosivity of the environments of those parts was evaluated. To simulate different use environments, pure water and salt water were sprayed on the right and left halves of the vehicle body. The corrosion behavior in each part was characterized by the output of the ACM sensor against atmospheric parameters and driving history. Corrosion of test coupons (cold-rolled steel, Zn-coated steel) was also measured at the same positions. The corrosion rates of these exposure test specimens showed a good correlation with the average daily charge calculated from the sensor output. These results demonstrated the possibility of corrosion life prediction and materials selection based on ACM monitoring results. It was concluded that ACM monitoring is applicable to corrosivity evaluation of automotive environments, including both specific parts of automobiles and automobile use environments.