Abstract
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.
Highlights
Accepted: 28 December 2021Intergranular corrosion (IGC) is characterized by corrosion propagation along grain boundary regions with reduced chemical resistance, where it may lead to grain separation and, significantly reduced mechanical strength [1,2]
IGC is of particular interest for stainless steels, which typically exhibit excellent chemical resistance due to the formation of a passive layer of chromium oxide, but may be susceptible to IGC based on chromium carbide or nitride precipitation at grain boundaries [3]
4.4.Conclusions summary, the present findings demonstrate different precipitation behaviors
Summary
Accepted: 28 December 2021Intergranular corrosion (IGC) is characterized by corrosion propagation along grain boundary regions with reduced chemical resistance, where it may lead to grain separation and, significantly reduced mechanical strength [1,2]. Along with heat treatments to enable back-diffusion of chromium to sensitized regions [9], stabilization, i.e., the addition of alloying elements with pronounced affinity to form preferential carbides or nitrides without chromium, is a common method to mitigate the effects of IGC in FSS [10]. In this regard, titanium proved to be a promising stabilizing agent as it preferentially forms titanium-carbides (TiC) and titanium-nitrides (TiN) [11]. Recent findings indicate that IGC may form in Ti-stabilized FSS due to the segregation of unreacted chromium around Ti-precipitates and subsequent chromium depletion of the adjacent
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
