Microstructural characterization of the HAZ in AISI 444 ferritic stainless steel welds

Silva, Cleiton Carvalho; Farias, Jesualdo Pereira; Miranda, Hélio Cordeiro de; Guimarães, Rodrigo Freitas; Menezes, John W.A.; Neto, Moisés A. Marcelino

doi:10.1016/j.matchar.2007.03.011

Cited by 102 publications

(53 citation statements)

References 22 publications

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“…The NbC precipitates were very close to each other and the EDX analysis confirmed higher concentrations of Nb and C than the surrounding ferrite matrix. From the literature [15][16][17], it is known that Nb can form Nb(C,N), Fe 2 Nb (Laves phase) and Fe 3 Nb 3 C (M 6 C) particles in Nb-containing ferritic stainless steel.…”

Section: Precipitates Containing Nb and Cmentioning

confidence: 99%

Characterization of NbC and (Nb,Ti)N nanoprecipitates in TRIP assisted multiphase steels

et al. 2011

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Multiphase steels utilising composite strengthening may be further strengthened via grain refinement or precipitation by the addition of microalloying elements. In this study a Nb microalloyed steel comprising martensite, bainite and retained austenite has been studied. By means of transmission electron microscopy (TEM), we have investigated the size distribution and the structural properties of (Nb,Ti)N and NbC precipitates, their occurrence in the various steel phases, and their relationship with the Fe matrix. (Nb,Ti)N precipitates were found in ferrite, martensite, and bainite, while NbC precipitates were found only in ferrite. All NbC precipitates were found to be small (5 -20 nm in size) and to have a face centred cubic crystal structure with lattice parameter a = 4.36 ± 0.05 Å. In contrast, the (Nb,Ti)N precipitates were found in a broader size range (5 -150 nm) and to have a face centred cubic crystal structure with lattice parameter a = 8.09 ± 0.05 Å. While the NbC precipitates were found to be randomly oriented, the (Nb,Ti)N precipitates have a well-defined Nishiyama Wasserman (N-W) orientation relationship with the ferrite matrix. An analysis of the lattice mismatch suggests that the latter precipitates have a high potential for effective strengthening. DFT calculations were performed for various stoichiometries of NbC X and Nb X Ti Y N Z phases and the comparison with experimental data indicates that both the carbides and nitrides are deficient in C and N content.

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Section: Precipitates Containing Nb and Cmentioning

confidence: 99%

Characterization of NbC and (Nb,Ti)N nanoprecipitates in TRIP assisted multiphase steels

et al. 2011

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“…They were thermodynamically less stable but kinetically more favourable. Silva and Farias (2008) observed the apparition of Laves or sigma phases in 444 grade that could have also decreased the corrosion resistance of ferritic stainless steels. Welding of FSS have also generated a grain growth in the HAZ due to the absence of allotropic transformation which had a detrimental effect on the fatigue strength.…”

Section: Introductionmentioning

confidence: 96%

Influence of filler wire composition on weld microstructures of a 444 ferritic stainless steel grade

Villaret

Deschaux-Beaume

Bordreuil

et al. 2013

Journal of Materials Processing Technology

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“…More recently, Ti and Nb rich carbide and nitride inclusions have been found in SS resulting from the preferential precipitation of stabilizing agents, as previously described. 4,13 Unlike the MnS inclusions found on austenitic SS, Ti and Nb C/N inclusions are inherently electrochemically stable. 14 The micron-sized inclusions have been reported to be involved in the initiation of corrosion fatigue 15 and stress corrosion cracking 16 in a Ti stabilized Ni alloy, 690TT.…”

Section: Introductionmentioning

confidence: 99%

The role of titanium in the initiation of localized corrosion of stainless steel 444

et al. 2018

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Titanium has been added to ferritic stainless steels to combat the detrimental effects of intergranular corrosion. While this has proven to be a successful strategy, we have found that the resulting Ti-rich inclusions present on the surface play a significant role in the initiation of other forms of localized corrosion. Herein, we report the effect of these inclusions on the localized corrosion of a stainless steel using macro and micro electrochemical techniques. Through the use of scanning electrochemical microscopy, we observe the microgalvanic couple formed between the conductive inclusions and passivated metal matrix. The difference in local reactivity across the material's surface was quantified using a 3D finite element model specifically built to respect the geometry of the corrosion-initiating features. Combined with electron microscopy and micro elemental analysis, localization of other alloying elements has been reported to provide new insight on their significance in localized corrosion resistance.

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Microstructural characterization of the HAZ in AISI 444 ferritic stainless steel welds

Cited by 102 publications

References 22 publications

Characterization of NbC and (Nb,Ti)N nanoprecipitates in TRIP assisted multiphase steels

Characterization of NbC and (Nb,Ti)N nanoprecipitates in TRIP assisted multiphase steels

Influence of filler wire composition on weld microstructures of a 444 ferritic stainless steel grade

The role of titanium in the initiation of localized corrosion of stainless steel 444

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