1. The effect of heat treatment on the interface of 155 PH martensitic stainless steel and SAF 2507 duplex steel in functionally graded AM componentsMartina Koukolíková, Pavel Podaný, Sylwia Rzepa, Michal Brázda, Aleksandra Kocijan, 2023, original scientific article Abstract: Multi-material components, also known as functionally graded materials (FGMs), are innovative materials that possess unique properties due to their composition and have many potential applications in engineering and science. The effect of the heat treatment (HT) of functionally graded materials 15–5 precipitation-hardened (PH) martensitic steel and SAF 2507 duplex stainless steel (and the opposite order of deposition, i.e. SAF 2507 first followed by 15–5 PH stainless steel) on the interface microstructures was systematically investigated in the presented research. The choice of HT followed the trend of optimum post-processing for the individual alloys. A significant modification in the interface microstructure, characterized in the microstructural transition zone (MTZ) formed above the fusion line. Mechanical properties by miniaturized testing method including hardness measurement characterized both types of interfaces. The sequence of the materials’ application did not have a significant effect on their final mechanical tensile properties in the heat-treated states. Nevertheless, the microstructural change at the MTZ led to drop in the hardness at the interface. The research presents heat-treated FGMs in a horizontal configuration to form a high-quality metallurgical joint between heterogeneous materials manufactured by powder-based directed energy deposition method.
Keywords: heat treatment, additive manufacturing, martensitic stainless steel, duplex steel, microstructure, mechanical properties
Published in DiRROS: 04.04.2024; Views: 64; Downloads: 17
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2. Pitting corrosion on highly alloyed stainless steels in dilute sulphuric acid containing sodium chlorideElina Huttunen-Saarivirta, Elisa Isotahdon, Zaiqing Que, M. Lindgren, Ahmad Mardoukhi, Jean-Baptiste Jorcin, Petra Močnik, Tadeja Kosec, Yassine El Ouazari, Sukanya Hägg Mameng, Lena Wegrelius, 2023, original scientific article Abstract: Stainless steels are widely used in industrial assets and equipment. Despite their good corrosion resistance under a wide range of operating conditions, there is the possibility of pitting corrosion in the presence of chlorides. However, very few studies have identified the safe operating conditions for various high-alloyed stainless steel grades by comparing their pitting susceptibility. In this research, the susceptibility to pitting attack of five stainless steels with austenitic and duplex microstructures was examined in dilute sulphuric acid solution with varying amounts of NaCl at the temperatures of 50, 90 and 130◦C. Based on potentiodynamic polarization scans, none of the test materials underwent pitting corrosion at 50◦C, but differences in susceptibility to pitting attack were clear between the test materials and NaCl concentrations at the temperature of 90◦C, and further tem- perature increase facilitated uniform corrosion. 28-day immersion tests at 90◦ C confirmed the pitting suscepti- bility of duplex grades 1.4662 (PREN 33) and 1.4462 (PREN 35) in the presence of at least 2000 mg/L NaCl, but not the susceptibility of a corresponding austenitic grade 1.4539 (PREN 34). The grades 1.4547 (PREN 43) and 1.4410 (PREN 44) were not susceptible to pitting corrosion under any of the studied conditions. The results from materials microstructural and electrochemical characterization are presented and discussed in this paper.
Keywords: stainless steel, austenitic stainless steel, duplex stainless steel, pitting atttack
Published in DiRROS: 12.07.2023; Views: 304; Downloads: 380
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