Improvement Corrosion Resistance of Carbon Steel by Laser Surface Alloying within Nickel and Chromium Powders

摘要

Low carbon steel ST-37 had poor corrosion resistance in several environment. Therefore, Laser Surface Alloying (LSA) is done by using Ni and Cr powders. LSA is perform in two steps. The first, powder is stick on the surface by preplace method. The second step is laser processing to melt both powder and base metal to form an alloy on the surface. Solid state Nd:YAG laser pulse mode within specify laser parameter is used. Microstructure, surface alloy composition, corrosion behavior and regions depth after laser processing are study. Energy Dispersive Spectroscopy (EDS) optical microscope and potentialstate polarization technique are used in this study. Corrosion test is perfrom in 3.5% NaCl solution. Different corrosion parameters are studied (i _( corr. ) , E _( corr. ) , i _( passive ) , E _( passive ) , i _( transpassive ) , E _( transpassive ) ). The aim of this research is to investigate the effect of laser alloy surface layer within different composition on corrosion behavior of steel. Different surface layer composition of Fe-Ni and Fe-Cr alloys are formed. The results show improving in corrosion resistance of steel due to form passive layer when the surface is alloying with Ni or Cr powders. The depth of melted and heat affected zones within Cr-powder is clearly more than Ni-powder samples.