Application of Hot Dip Galvanized Plate Subject to Inorganic Solid Lubrication in Automotive Industry

The work aims to reduce vehicle production costs and improve vehicle productivity. Friction coefficient of inorganic solid lubricated hot galvanized plate (GI-T) and common hot galvanized plate (GI) during drawing process was measured, and its time-dependant variation was analyzed in the method of flat-plate drawing; and difference in surface morphology of each steel sheet after drawing was analyzed; maximum drawing force and maximum cup height of GI-T and GI were compared under flat drawing test; weldable current section, weldable current width, maximum shear force and button diameter of the two were compared in the method of simulated welding; phosphating and electrophoresis properties were detected for samples hung on the BIW. The differences between GI-T and GI in stamping, welding and painting performance were evaluated respectively. As for stamping performance: compared to GI, the friction coefficient of GI-T decreased by 23% and no wear and scratch was observed on the surface. After the drawing test, the maximum drawing force decreased by 4.5% while maximum cup height increased by 9.5%, and the GI-T exhibited better stamping performance. As for welding performance: weldable current range of the former decreased by 0.6 kA while weldable current width was 1.2 kA, respectively, maximum shear force of GI-T and GI was 2.75 kN and 2.6 kN, respectively; and button diameter 5.8 mm and 5.2 mm, respectively; the welding performance was nearly the same. As for coating performance: the phosphate film weight of GI-T and GI was 3.12 g/mm2 and 3.09 g/mm2, respectively. The two were both qualified in electrophoresis membrane test. After 500 times of stamping tests, the GI-T could effectively prevent mold from adhering to zinc. Since GI-T exhibits better stamping performance, equivalent welding and coating performance compared with GI, and can prevent zinc layer from falling off effectively, GI-T can be used to replace GI, which can reduce production cost and improve production efficiency. © 2017, Chongqing Wujiu Periodicals Press. All rights reserved.