The development history of color steel plate

Color-coated steel plates were born in the United States in the 1930s, and originated in my country in the late 1980s. The color-coated steel plate industry has grown rapidly for decades, and until 2005, there was a surplus of color-coated steel plates in my country. Especially after several years of adjustment after the economic crisis in 2008, the color-coated steel plate has recovered again.
The pencil scratch hardness tester is used to measure, that is, to plow through the coating with pen cores with known hardness in the range of 14 grades from 6H to 6B, among which: 6H is harder and 6B is softer. There are two methods for determination: manual pencil method and instrument pencil method. A Manual pencil method Use a pencil sharpener to sharpen the pencil until the 4-6mm cylindrical core is exposed, hold the pencil so that it is perpendicular to the surface of the 400 sandpaper, and grind on the sandpaper until the end surface is flat and the edge is sharp.
Damp heat test, also known as humidity test, is used to evaluate the resistance of coatings to high temperature and high humidity. Damp heat test is also a method to detect coating corrosion, so it is usually carried out at the same time as salt spray test. Since the main influencing factors in the heat and humidity test are temperature and humidity, special attention should be paid to the regulation of these two indicators in the temperature and humidity control box during the whole process of each test, so as not to affect the test results.