Characterization of TiN, TiC and Ti(C,N) in titanium-alloyed ferritic chromium steels focusing on the significance of different particle morphologies

Characterization of TiN, TiC and Ti(C,N) in titanium-alloyed ferritic chromium steels focusing on the significance of different particle morphologies

Titanium-alloyed ferritic chromium steels are a competitive option to classical austenitic stainless steels owing to their similar corrosion resistance. The addition of titanium significantly influences their final steel cleanliness. The present contribution focuses on the detailed metallographic ch...

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Bibliographic Details
Published in:Materials characterization Vol. 100; pp. 61 - 67
Main Authors: Michelic, S.K., Loder, D., Reip, T., Ardehali Barani, A., Bernhard, C.
Format: Journal Article
Language:English
Published: United States Elsevier Inc 01-02-2015
Subjects:
AUSTENITIC STEELS
CARBONITRIDES
CHROMIUM STEELS
CORROSION RESISTANCE
Ferritic chromium steels
Ferritic stainless steels
FERRITIC STEELS
Heterogeneous nucleation
INCLUSIONS
Layer formation
LAYERS
MAGNESIUM
Manuals
MATERIALS SCIENCE
METALLOGRAPHY
Morphology
Non-metallic inclusion
Nucleation
OPTICAL MICROSCOPY
PRECIPITATION
SCANNING ELECTRON MICROSCOPY
SOLIDIFICATION
Titanium
TITANIUM ALLOYS
TITANIUM CARBIDES
Titanium nitride
TITANIUM NITRIDES
X-RAY SPECTROSCOPY
Heterogeneous nucleation
Scanning electron microscopy
Optical microscopy
Layer formation
Non-metallic inclusion
Ferritic chromium steels
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Summary:Titanium-alloyed ferritic chromium steels are a competitive option to classical austenitic stainless steels owing to their similar corrosion resistance. The addition of titanium significantly influences their final steel cleanliness. The present contribution focuses on the detailed metallographic characterization of titanium nitrides, titanium carbides and titanium carbonitrides with regard to their size, morphology and composition. The methods used are manual and automated Scanning Electron Microscopy with Energy Dispersive X-ray Spectroscopy as well as optical microscopy. Additional thermodynamic calculations are performed to explain the precipitation procedure of the analyzed titanium nitrides. The analyses showed that homogeneous nucleation is decisive at an early process stage after the addition of titanium. Heterogeneous nucleation gets crucial with ongoing process time and essentially influences the final inclusion size of titanium nitrides. A detailed investigation of the nuclei for heterogeneous nucleation with automated Scanning Electron Microscopy proved to be difficult due to their small size. Manual Scanning Electron Microscopy and optical microscopy have to be applied. Furthermore, it was found that during solidification an additional layer around an existing titanium nitride can be formed which changes the final inclusion morphology significantly. These layers are also characterized in detail. Based on these different inclusion morphologies, in combination with thermodynamic results, tendencies regarding the formation and modification time of titanium containing inclusions in ferritic chromium steels are derived. [Display omitted] •The formation and modification of TiN in the steel 1.4520 was examined.•Heterogeneous nucleation essentially influences the final steel cleanliness.•In most cases heterogeneous nuclei in TiN inclusions are magnesium based.•Particle morphology provides important information on inclusion formation.
Bibliography:ObjectType-Article-1
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ISSN:1044-5803
1873-4189
DOI:10.1016/j.matchar.2014.12.014