Corrosion Resistance Enhancement of Stainless Steel Powder Metallurgy in Artificial Body Fluids by Reinforcement of Boron and Niobium

The usage of powder metallurgy technology has been extended until nowadays due its flexibility and practical use in mixing with other alloying elements. This research investigate the analysis of the corrosion behavior of powder metallurgy alloy AISI 316L stainless steel with variations in the elemental content of Niobium in human body simulation fluid (SBF) at 25 °C. The various elements of niobium are 0.5, 1.0, 1.5, 2.0 wt%. After mixing and compaction, the green compacted samples were sintered in nitrogen atmosphere at 1150 °C. The corrosion testing used in this research were electrochemical methods consisting of open circuit potential and anodic polarization. In addition, characterization testing was also carried out in this study using an optical microscope and an scanning-electron microscope (SEM–EDS). The results obtained from this test are based on the corrosion rate, the general corrosion resistance of the alloy increases with the variation of niobium from 0.5, 1.0 and 1.5 wt Nb. However, it decreased in the variation of 2.0%wt Nb. Each sample are still showed susceptibility to pitting corrosion. Based on its repassivation capacities, the increase of Nb content tend to cause detrimental effect on alloys. SEM–EDS observations predict a decrease in corrosion resistance in AISI 316L alloy with the addition of 2.0%wt Nb due to the concentration of the Nb element at a certain point so that there is a failure in preventing the depletion of chromium elements at the grain boundaries resulting in chromium carbide at grain boundaries.