Analysis of Corrosion resistance of Heat Exchanger Plates Made of AISI 316L Steel

Analysis of Corrosion resistance of Heat Exchanger Plates Made of AISI 316L Steel

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For the corrosion resistance analysis of heat exchanger plates (made of AISI 316L steel) samples with visible damage were delivered. A major part of the surface damages was located at places of "close proximity" (or surface contact) of individual plates. Some of the samples submitted exhibited unequal layers of sediments, which indicated different flow velocities of the operating fluid through the plates. At some sedimentationfree sites in the upper part of the plates (high velocity flow), most of the surface damage was detected in the "near contact" areas as well as outside of them. On the other hand, in the area of the lower part of the plates, where the sediment deposition was massive (the lowest velocity flow), the least surface damage was observed. The results of the chemical composition analyses showed a lower amount of molybdenum and a higher amount of phosphorus for all samples. The contents of the key elements necessary for the corrosion resistance (chromium and nickel) were only just above the lower limit of the prescribed chemical composition interval. For a detailed study of surface damage, selected defects were observed and documented using scanning electron microscopy. Localized damage showed intercrystalline failure of material with a typical surface morphology degraded in consequence of cavitation damage under hydrodynamic stress.

For the corrosion resistance analysis of heat exchanger plates (made of AISI 316L steel) samples with visible damage were delivered. A major part of the surface damages was located at places of "close proximity" (or surface contact) of individual plates. Some of the samples submitted exhibited unequal layers of sediments, which indicated different flow velocities of the operating fluid through the plates. At some sedimentationfree sites in the upper part of the plates (high velocity flow), most of the surface damage was detected in the "near contact" areas as well as outside of them. On the other hand, in the area of the lower part of the plates, where the sediment deposition was massive (the lowest velocity flow), the least surface damage was observed. The results of the chemical composition analyses showed a lower amount of molybdenum and a higher amount of phosphorus for all samples. The contents of the key elements necessary for the corrosion resistance (chromium and nickel) were only just above the lower limit of the prescribed chemical composition interval. For a detailed study of surface damage, selected defects were observed and documented using scanning electron microscopy. Localized damage showed intercrystalline failure of material with a typical surface morphology degraded in consequence of cavitation damage under hydrodynamic stress.

AISI 316L steel; corrosion resistance; scanning electron microscopy; heat exchanger; metallography; fractography

AISI 316L steel; corrosion resistance; scanning electron microscopy; heat exchanger; metallography; fractography

JULIŠ, M.; KLAKURKOVÁ, L.; GEJDOŠ, P.

2021

16.11.2020

Trans Tech Publications Ltd

Switzerland

Metallography & Fractography 2019

1662-9507

Defect and Diffusion Forum

45

Švýcarská konfederace

245

250

6

https://www.scientific.net/DDF.405.245

2020-CONF-03--jul-klak-gej--Analysis of Corrosion Resistance of Heat Exchanger Plates--DDF.405.245-POSTPRINT