What is the purpose of the salt spray corrosion test?

Corrosion is the damage or deterioration of a material or its properties caused by the action of the environment. Most corrosion occurs in the atmospheric environment, which contains corrosive components and factors such as oxygen, humidity, temperature changes, and pollutants.

Salt spray corrosion is a common and destructive form of atmospheric corrosion and is a manifestation of the aging of metal products. Like the field of weathering testing, the automotive industry has seen many innovations in corrosion testing.

Automotive cyclic corrosion testing in the 1980s and 1990s added condensing high humidity to the previously advocated wet and dry cycles. Corrosion Solutions recreates the harsh road conditions that use salt to melt snow and ice. These tests typically use conventional compressed air atomizing nozzles to spray the corrosion solution and then dry it.

The salt residue on the specimen dissolves in the condensing high humidity environment and reacts again on the specimen surface and paint scratches. These tests generally correlate well with outdoor corrosion in many environments, especially for cars driven on salt-treated roads in winter, and greatly improve corrosion resistance, which is of great help to the industry.

In modern corrosion aging Test Chambers, the control of environmental conditions is more stringent, and manual operation is no longer required to meet test needs, such as GMW 14872. The first improvement is the addition of relative humidity control, which is important for testing phases that require "dry" or "lab environment" conditions. Laboratory environmental conditions vary with geographic climatic conditions and often cannot achieve the precision required to control phase transition times. Since the relative humidity control system and the air supply pretreatment unit of the salt spray Tester provide dry heat or cold air to the Test Chamber, the salt spray Tester can almost meet all the test conditions specified by the automotive corrosion engineer.

Another advancement in salt spray testing is the control of corrosion spray. Users can program spray on/off times so they can precisely control the amount of sediment sprayed onto their samples. Traditional salt spray application emphasizes the uniformity of the spray and avoiding "direct impact", while the new method emphasizes quickly wetting the sample by spray and rinsing away the salt residue for a long transition to other test stages.