The Combined Effect of Cold Work and Chloride Content on Corrosion Mechanism of 2101 Lean Duplex Stainless Steel in Citric Acid

2101 Lean duplex stainless steel (LDX) is emerging as a strong competitor to traditional austenitic stainless steels in the food industry, thanks to its superior corrosion resistance and cost-effectiveness. This study investigates the impact of 15, 30 and 45% cold working and chlorine content on the corrosion behavior of LDX 2101 exposed to citric acid as the most common electrolyte in food industries. Detailed electrochemical and characterization techniques have been used in this study. The results reveal that 2101 LDX is composed of γ and α phases, with Cr ₂ N and M ₂₃ C ₆ precipitates forming along grain and phase boundaries. Cold working primarily deforms the γ phase, leading to the formation of strain-induced martensite (SIM), and increases the hardness of α and γ phases. Galvanic and pitting corrosion was observed, especially in the α phase, where Cr ₂ N precipitates act as pit initiation sites. While the presence of chloride ions accelerated corrosion rate, cold working enhanced the materials corrosion resistance by promoting the surface passive layer characteristics. Electrochemical impedance spectroscopy results indicated that the as-annealed sample showed the lowest corrosion resistance after 24 h of immersion. In contrast, samples subjected to 15% and 30% strain exhibited improved resistance with 23.5 and 46.7% reduction in i _corr , with a significant passive behavior observed in the 45% cold-worked sample.