Influence of the as-cast and cold rolled microstructural conditions over corrosion resistance in an advanced TWIP steel microalloyed with boron

Abstract

As a high-performance material, advanced TWIP steels have recently received considerable attention, particularly promising to form parts of complex geometry due to the superior mechanical properties. In the present research work, the study of the corrosion resistance of an experimental advanced TWIP steel was carried out with the purpose of establishing the relationship between its chemical composition and processing condition. The aforementioned was achieved by evaluating the effect of boron microaddition and the as-cast and cold rolled microstructural conditions on the corrosion resistance of a low carbon highly-alloyed TWIP steel. The electrochemical tests for corrosion analysis were performed in a 3%-NaCl solution at room temperature. Results reveal that after 30 min of immersion, boron-free TWIP steel in both as-cast and cold rolled microstructural conditions present the better corrosion resistance against boron-containing TWIP steel in almost 0.2 V in its anodic behavior, being more prone to corrosion in almost 7%. Because the strain-induced deformation, a complex interaction is assumed to take place among second-phase particles and boron-rich precipitates with high strain energy active sites in promoting electrochemical reactions at grain boundaries and even into austenitic grains. Thus, a pitting corrosion mechanism is evident as black cavities and agglomerated compounds form on steel surface. Furthermore, a beneficial effect of boron on corrosion performance on this chemically complex TWIP steel is expected to occur after a fully microstructure conditioning, retaining its outstanding mechanical properties.

Keywords

• TWIP steel
• Boron microaddition
• Dendritic structure
• Cold rolled microstructure
• Corrosion resistance