The product characteristics of chromium-free fingerprint-resistant hot-dip galvanized steel sheets not only depend on the characteristics of the chromium-free fingerprint-resistant liquid itself, but are also closely related to factors such as the surface roughness of the steel plate, the thickness of the fingerprint-resistant film on the surface of the steel plate, and the uniformity of the film.
The design principle of the finishing process is to obtain a roughness on the surface of the strip that meets the dual requirements of corrosion resistance and electrical conductivity on the premise of ensuring the mechanical properties of the substrate. The control of strip surface roughness is affected by the surface roughness of the work rolls of the finishing machine, rolling speed and rolling force; among them, the surface roughness of the work rolls has the most significant impact.
The convex peaks with large surface roughness of the strip steel will cause the fingerprint-resistant film to be thin, and even the zinc layer will be exposed, and the coating film cannot be completely covered; the pits with smaller roughness will cause the fingerprint-resistant film to be thicker, and the coating film may not be fully covered. Full coverage.
Effect of curing time and temperature on fingerprint and corrosion resistance
Under normal production conditions of the hot-dip galvanizing production line, samples of 0.6 mm specifications and different film thicknesses were taken to determine the effects of curing time and temperature on fingerprint and corrosion resistance. The samples were placed in outdoor temperature (0℃) and air-conditioned rooms. A 72h salt spray resistance test was conducted under the conditions of (20℃). The test results are shown in Table 6. It can be seen that the fingerprint-resistant board only has a curing time of more than 48h, plus the curing temperature is 20℃. The film thickness can guarantee its salt spray performance.
