Catalyst effects in heterogeneous nucleation of acicular ferrite

Grong, Ø.; Kluken, A. O.; Nylund, H. K.; Dons, Anne Lise; Hjelen, J.

doi:10.1007/bf02663903

Cited by 77 publications

(47 citation statements)

References 23 publications

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“…In the open literature, the following mechanisms have been suggested to cause nucleation of acicular ferrite at inclusions: -a reduction in the interfacial energy for simple heterogeneous nucleation on a surface of inclusions, [49][50][51][52][53][54] -an epitaxial nucleation on the inclusions, which have a good coherency with ferrite, [55][56][57] -a nucleation arising from the thermal strains at the inclusions, which is associated with the different thermal expansion coefficients of the inclusions and steel matrix, 58,59) -a nucleation arising from solute depletion of elements in the matrix near inclusions. 10,12,46,[60][61][62][63][64][65] It should be pointed out that it is, in many cases, difficult to decide which mechanism that is most important for formation of acicular ferrite.…”

Section: Mechanisms Of Acicular Ferrite Nucleationmentioning

confidence: 99%

“…According to this proposition, even the chemical composition of the inclusion is not important. 49) Grong et al 50) also suggested that the reduction of the energy barrier is the primary cause of nucleation. In addition, Zhang and Farrar, 51) Lee et al 52) and Furuhara et al 53,54) reported that the surfaces of inclusions acted as inert substrates, with the ability to reduce the free energy barrier to nucleation.…”

Section: Reduction In Interfacial Energymentioning

confidence: 99%

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On the Role of Non-metallic Inclusions in the Nucleation of Acicular Ferrite in Steels

2009

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The effects of non-metallic inclusions in nucleating acicular ferrite in steels during cooling from a weld or cooling from an austenitic temperature are reviewed. The influence of the acicular ferrite (AF) structure on mechanical properties of steels such as strength and toughness is briefly mentioned. The different factors affecting the formation of acicular ferrite, such as the soluble content of alloying elements in steel, cooling rate from austenitizing temperature, austenite grain size and inclusion characteristics in steel, are discussed. The mechanisms of acicular ferrite formation on non-metallic inclusions, such as reduction of interfacial energy, mismatch strain between the inclusion and ferrite/austenite, thermal strains at the inclusions and changes in matrix composition near the inclusions are also discussed. Finally, the effects of inclusion characteristics, such as size, number and composition are described and their effectiveness in nucleating acicular ferrite is discussed.KEY WORDS: non-metallic inclusions, intragranular acicular ferrite formation, strength and toughness, steel. 1063

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Section: Mechanisms Of Acicular Ferrite Nucleationmentioning

confidence: 99%

Section: Reduction In Interfacial Energymentioning

confidence: 99%

On the Role of Non-metallic Inclusions in the Nucleation of Acicular Ferrite in Steels

2009

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“…[7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26] Based on these research, it is possible to design welding consumables that maximize the formation of acicular ferrite in welds and thereby obtain better strength and toughness. However, the extension of this knowledge to a wide variety of welding processes, consumable compositions, and shielding gases still eludes welding metallurgist due to the complex interactions between inclu-sion formation, solidification, and solid-state transformations.…”

Section: Introductionmentioning

confidence: 99%

Inclusion Formation and Microstructure Evolution in Low Alloy Steel Welds.

Babu

David

2002

ISIJ International

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The paper presents an overview of research performed at Oak Ridge National Laboratory on inclusion-formation, weld-solidification, and solid-state transformations in low-alloy steel welds. The competition between oxide and nitride formation in Fe-C-Al-Mn self-shielded flux-cored arc steel welds was predicted using computational thermodynamics. Nonequilibrium austenite phase selection was monitored in a Fe-CAl-Mn weld using an in situ time-resolved X-ray diffraction technique. The competition between acicular ferrite and bainite formation from austenite was evaluated in Fe-C-Mn steel welds containing small amounts of titanium.KEY WORDS: steel welds; inclusion formation; weld solidification; nonequilibrium phase transformations; bainite; acicular ferrite.

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“…However, the probability that an AF crystal satisfies both the AF-TRZ and K-S orientation relationships within 5 degrees is only 18%, as determined using Grong's method. 9) Considering that three of nine AF crystals examined in this study exhibited the unique orientation relationships, it is difficult to envision that the coexistence of the AF-TRZ and K-S orientation relationships is accidental. It is likely instead that AF satisfies both the AF-TRZ and K-S orientation relationships simultaneously, through favorable variant selection.…”

Section: Formation Mechanism Of Af On Ti-rem-zr Complex Oxidementioning

confidence: 91%

“…[4][5][6] Many studies have been done to identify oxides that promote AF formation and to establish the mechanism of AF nucleation. [7][8][9][10][11][12][13][14] It is well known that Ti oxides have a positive influence on AF nucleation. 10,12,13,15,16) Researchers have pointed out that Ti2O3 incorporates Mn and forms a Mn depleted zone around the oxide, which increases the driving force for decomposition of the surrounding austenite matrix during cooling.…”

Section: Introductionmentioning

confidence: 99%

Acicular Ferrite Formation on Ti-Rare Earth Metal-Zr Complex Oxides

2015

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Acicular ferrite (AF) formation potency of Ti-Rare earth metal (REM)-Zr (TRZ) complex oxide has been investigated in the simulated heat affected zone of low carbon steel. The TRZ complex oxide shows higher AF formation potency than Ti and Al oxides. A TRZ oxide particle is composed of REM-rich and Zrrich phases. AF crystals nucleate on the interface between austenite and the Zr-rich oxide phase, having a crystal structure that is face-centered cubic with lattice parameter of 0.44 nm. The Zr-rich phase and AF have an orientation relationship described by (011)AF//(011)Oxide, [100]AF//[ ]Oxide (the AF-TRZ orientation relationship), which allows good lattice coherency. It is suggested that the formation of this orientation relationship promotes AF nucleation on TRZ complex oxides. The AF also satisfies the Kurdjumov-Sachs (K-S) orientation relationship with the austenite matrix. It is considered that the coexistence of the AF-TRZ and K-S "three phase" orientation relationships is caused by variant selection of AF in addition to the formation of a rational orientation relationship between the Zr-rich oxide phase and the austenite matrix during the HAZ thermal cycle.KEY WORDS: heat affected zone; Ti-Rare earth metal-Zr complex oxide; acicular ferrite.

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Catalyst effects in heterogeneous nucleation of acicular ferrite

Cited by 77 publications

References 23 publications

On the Role of Non-metallic Inclusions in the Nucleation of Acicular Ferrite in Steels

On the Role of Non-metallic Inclusions in the Nucleation of Acicular Ferrite in Steels

Inclusion Formation and Microstructure Evolution in Low Alloy Steel Welds.

Acicular Ferrite Formation on Ti-Rare Earth Metal-Zr Complex Oxides

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