Color-coated steel sheets were born in the United States in the 1930s and originated in my country in the late 1980s. The color-coated steel sheet industry has grown rapidly for decades. Until 2005, there was a surplus of color-coated steel sheets in my country. Especially after several years of adjustment after the 2008 economic crisis, color-coated steel sheets have recovered again.
Measured with a pencil scratch hardness tester, that is, using a refill with known hardness in the range of 6H to 6B to plow through the coating, wherein: 6H is harder and 6B is softer. The manual pencil method and the instrument pencil method can be used for the determination. A Manual pencil method Use a sharpener to sharpen the pencil until the 4-6mm cylindrical refill is exposed, hold the pencil so that it is perpendicular to the surface of the 400-grit sandpaper, and scratch on the sandpaper until the end surface is flat and the edge is sharp.
Damp heat test, also known as damp test, is used to evaluate the resistance of coatings to high temperature and high humidity. The damp heat test is also a method for detecting the corrosion resistance of the coating, so it is usually carried out at the same time as the salt spray test. Since the main influencing factors in the damp heat test are temperature and humidity, special attention should be paid to the regulation of these two indicators of the temperature and humidity control box during the whole process of each test, so as not to affect the test results.
