ANALYSIS OF THE INFLUENCE OF % VOLUME H2 IN GALVANIZED STEEL COATING PROCESS AS A MEDIUM IN A NON-OXIDIZING FURNACE

• Main Author: JULHARBI (NIM : 125 06 011)
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/22729
• Institution: Institut Teknologi Bandung

Galvanized steel is a type of steel that has been coated with zinc to prevent corrosion in steel. The most widely used method in the process of coating steel is a continuous hot dip galvanizing. Before the steel strip is inserted to a bath containing molten zinc, the steel strip must first enter the furnace to do the process of annealing and surface cleaning of steel strip. One type of furnace used is a non-oxidizing furnace (NOF). In the NOF exhaled H2, which serves to clean the oxide on surface of the steel strip. %volume of H2 used in the NOF is currently 40%. This value of % volume of H2 is considered too big and it makes the production cost expensive . Therefore, the use of H2 in NOF should be reduced to a limit of tolerance without causing defects on galvanized steel product. The sample has been obtained from the factory of galvanized steel PT FUMIRA and it has 10 x 10 x 0.02 cm in size. Measurement of the thickness, hardness and surface roughness of Zn coating performed to determine the effect of %volume of H2 on galvanized steel coating process. It was also observed by using SEM and EDS to determine the composition of the oxides contained in the Fe-Zn coating. The samples tested had benn used volume of H2 ranging from 38% to 20%. From the test results, it is found that Zn coating thickness will increase with the reduction of % volume H2 and further it also increase the hardness of the Zn coating. From the observation by using EDS, in 20 % volume H2 there are still 7.34 % amount of oxides in the Fe-Zn coating. In addition, % volume of H2 is also affecting the surface roughness of zinc coating. The higher % volume H2, the surface layer of Zn become rougher because there are more spangles in the surface layers. The decreasing of % volume of H2 until 20% is still recommended because the thickness and hardness of the zinc coating doesn’t change significantly.