Before starting an auto body repair it is necessary to identify the material of the parts to be repaired in order to choose the most suitable tool, processes and products. The most common materials in bodywork are steel, aluminum and galvanized metal, but do you know how to tell them apart?
In order to tell the difference between steel, aluminum and galvanized metal, we will have to do some tests on the surface to identify the material. In general, identification methods can be invasive or non-invasive. Invasive methods require a certain amount of damage to be done to the part in order to carry out the analysis, while non-invasive methods allow a simple identification that can sometimes be carried out without the need to have the vehicle available.
Invasive methods to identify the substrate material:
- By the color of the material
- By means of a filing test using a grinder
- Through heat input
Non-invasive methods to identify the substrate material:
- Consultation of the manufacturer’s technical documentation
- Consultation of technical publications of credible bodies or organizations in the sector
- If there is visible rust
- By weight
- Using a magnet
ALUMINUM
Aluminum in auto bodywork is used in loose parts such as hoods or bumpers and also in the chassis and/or bodywork of high-end cars.
- This material does not rust
- It has a lower weight compared to steel and galvanized metal.
- If a magnet test is performed, aluminum is not magnetic
- It has a silver-gray color
- It does not give off sparks when filed with a grinder.
- It does not change color as it approaches its melting temperature.
STEEL
In the automotive industry, steel is used mainly in car cladding components and the structure of the car. The following characteristics of steel will help us to recognize it:
- If the part shows signs of rusting, this will be an orangey color
- It has a medium-high weight compared to other materials, such as aluminum
- It is a magnetic metal
- Steel is a bluish gray color
- If it is filed with a grinder, it will give off sparks
- When it approaches melting temperature, it turns a cherry red color.
GALVANIZED OR ZINC-COATED METAL
Galvanized or zinc-coated surfaces are normally used for the car’s structure and cladding. The main difference from steel is that galvanized steel shows no visible rust and the surface color is streaked or watery. These are the main characteristics of galvanized parts:
- There is no visible rust
- It has a medium-high weight, similar to steel
- It is magnetic
- It is a watery or streaked gray color, although it depends on the type of process used
- It gives off sparks when filed with a grinder
- When welded, a white layer peels off and it turns cherry red before melting
Other materials used in bodywork
Plastic is also a very common material in bodywork, especially in parts such as wings, bumpers or semi-structural parts for energy absorption, and it stands out for its low weight.
In more specific cases, and especially in very high-end vehicles, manufacturers have started to introduce other materials such as magnesium, in components such as alloy wheels or hoods, or carbon fiber in roof panels or door sills. In both cases, the reason for its use is the weight reduction compared to aluminum and the good mechanical performance of carbon fiber.
