scholarly journals Transmission Electron Microscopy Study on the Precipitation Behaviors of Laser-Welded Ferritic Stainless Steels and Their Implications on Intergranular Corrosion Resistance

Metals ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 86
Author(s):  
Niklas Sommer ◽  
Clementine Warres ◽  
Tarek Lutz ◽  
Martin Kahlmeyer ◽  
Stefan Böhm
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Grain Boundaries ◽  
Stainless Steels ◽  
Intergranular Corrosion ◽  
Microscopy Study ◽  
Precipitation Behavior ◽  
Acid Media ◽  
Ferritic Stainless Steels ◽  
Transmission Electron

The intergranular corrosion susceptibility of ferritic stainless-steel weldments is strongly dependent on chromium carbide precipitation phenomena. Hence, stabilization is widely used to mitigate the aforementioned precipitation. In contrast, stabilization has proved ineffective to fully prevent intergranular corrosion due to segregation of unreacted chromium during solid-state heat-treatments. To analyze the precipitation behavior of 17 wt.-% chromium ferritic stainless steels during laser welding, sheets of unstabilized and titanium-stabilized ferritic stainless steels were welded in a butt joint configuration and characterized with special consideration of precipitation behavior by means of transmission electron microscopy. While unstabilized ferritic stainless steels exhibit pronounced chromium precipitate formation at grain boundaries, titanium-stabilization leads to titanium precipitates without adjacent chromium segregation. However, corrosion tests reveal three distinctive corrosion mechanisms within the investigated ferritic stainless steels based on their inherent precipitation behaviors. In light of the precipitation formation, it is evident that immersion in sulfuric acid media leads to the dissolution of either grain boundaries or the grain boundary vicinity. As a result, the residual mechanical strength of the joint is substantially degraded.

Effects of Ti and Nb Stabilization on the Recrystallization and the Pitting Potential in Fe-21%Cr Ferritic Stainless Steels

2007 ◽  
Vol 561-565 ◽  
pp. 77-80
Author(s):  
Wen Bo Dong ◽  
Li Ma ◽  
Lai Zhu Jiang
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Stainless Steels ◽  
Recrystallization Temperature ◽  
Ferritic Steels ◽  
Pitting Potential ◽  
Ferritic Stainless Steels ◽  
Transmission Electron ◽  
Scanning Electron

Effects of Ti and Nb stabilization on the recrystallization and the pitting potential in Fe-21%Cr ferritic stainless steels were studied by using optical microscopy, scanning electron microscopy, transmission electron microscopy and polarization curve measurement. The results show that both Ti and Nb, either in solution or as precipitates, retard the recrystallization and enhance the recrystallization temperature. Substitution of Nb for Ti in Fe-21%Cr ferritic stainless steels increases the recrystallization temperature by 30 to 50°C. Nb and Ti stabilized ferritic steels present higher pitting potential than Ti stabilized steels.

Transmission Electron Microscopy Study of YBa2Cu3O7-x Thin Film Multilayer Devices

1997 ◽  
Vol 474 ◽  
Author(s):  
M. A. Barnett ◽  
J. S. Abell ◽  
M. Aindow ◽  
N. G. Chew ◽  
P. J. Hirst ◽  
...  
Keyword(s):  
Thin Film ◽  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Grain Boundaries ◽  
Slope Angle ◽  
Microscopy Study ◽  
Electron Microscopy Study ◽  
Base Layer ◽  
Transmission Electron Microscopy Study ◽  
Transmission Electron

ABSTRACTPatterned thin film multilayer structures, consisting of superconducting YBa2Cu3O7-x (YBCO) and insulating PrBa2Cu3O7-x (PrBCO), deposited onto (001) MgO substrates by electron beam co-evaporation, have been examined using Transmission Electron Microscopy (TEM). It is shown that PrBCO films grown over 30° steps in YBCO layers are free of tilt-grain boundaries. The PrBCO is c-oriented everywhere and shows pronounced faceting on the steps. Strain contrast features are present where the PrBCO has to adapt to large variations in the slope angle of the underlying YBCO layer. However, tilt-grain boundaries in YBCO or PrBCO layers are nucleated when depositing over small MgO steps formed by unintentional milling into the substrate. It is shown that grain boundaries associated with milled steps on MgO can be eliminated by the use of a PrBCO buffer layer beneath the superconducting base layer.

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