A study on the acicular ferrite formation in steel weld metals for gas metal arc welding

Uto, Kyohei; Nakayama, Koyo; Kisaka, Yuji; Kimura, Fumiaki; Terasaki, Hidenori

doi:10.2207/qjjws.38.6s

Cited by 6 publications

(4 citation statements)

References 10 publications

(4 reference statements)

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“…[4] Various inclusions after Ti-deoxidation have been found effective in stimulating AF nucleation, including MnTi 2 O 4, [21][22][23] TiO, [24,25] and Mn-Si-Al-Ti-O amorphous phases. [26] Despite the wide range of effective inclusions found…”

Section: Introductionmentioning

confidence: 99%

“…[ 4 ] Various inclusions after Ti‐deoxidation have been found effective in stimulating AF nucleation, including MnTi 2 O 4, [ 21–23 ] TiO, [ 24,25 ] and Mn–Si–Al–Ti–O amorphous phases. [ 26 ] Despite the wide range of effective inclusions found in the literature, only those compositions and structures confirmed by scanning transmission electron microscopy combined with energy dispersive spectrometry (EDS) and selected area diffraction pattern were listed here.…”

Section: Introductionmentioning

confidence: 99%

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Acicular Ferrite Identification in Heat‐Affected Zone of a Ti‐Killed High Strength Low Alloy Steel

Zhao,

Gao,

Huang

et al. 2024

steel research int.

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It is frequently found in the literature that an acicular ferrite (AF) dominant microstructure has unsteady or even low‐impact toughness. It is necessary to analyze whether they are qualified for real AF. Herein, a Ti‐killed high strength low alloy steel is prepared and subjected to heat‐affected zones simulation tests to induce various AF‐like microstructures. The morphological differences of these microstructures are compared, and their crystallographic characteristics are analyzed. It is found that even within a single prior austenite grain, the transformed microstructure can be heterogeneous. Local areas having clear lath boundaries and a chaotic or interlocking morphology should be classified as AF. Adjacent laths in these areas are from different close‐packed plane and Bain groups. In contrast, local areas having vague lath boundaries and a granular‐bainite‐like morphology should be classified as granular bainite. Neighboring laths in these areas are from the same Bain group, and a relatively low density of high‐angle grain boundaries can be found. The heterogeneous microstructure consisting of granular bainite and AF has a wider grain size distribution and a higher area fraction occupied by large grains, which can lead to the scatter of Charpy impact energy. Criteria for the identification of AF are also proposed in this research.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Acicular Ferrite Identification in Heat‐Affected Zone of a Ti‐Killed High Strength Low Alloy Steel

Zhao,

Gao,

Huang

et al. 2024

steel research int.

View full text Add to dashboard Cite

show abstract

“…AF nucleates intragranularly in the form of independent plates on the inclusions (Ricks et al, 1982), so the inclusion feature is a crucial factor affecting AF formation. The literatures (Wang et al, 2018;Zhang et al, 2018;Milani and Saeid, 2020;Uto et al, 2020) reported that some specific type Ti-containing inclusions can effectively promote AF nucleation by Mn depletion and/or crystallographic lattice match mechanisms. In addition, the hardenability of the weld metal also has a considerable effect on the AF formation (Lee and Pan, 1995) as a result of the competition relationships between AF and GBF, IF, SPF, etc., in the course of the austenite decomposition during cooling after welding (Ferrante and Farrar, 1982).…”

Section: Introductionmentioning

confidence: 99%

Effect of boron treatment on the microstructure and toughness of Ti-containing steel weld metals

Cui

Wang²

2022

revmetal

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Ti-containing steel weld metals with boron addition contents of 0-85 ppm were prepared, and their microstructural characteristics as well as the impact toughness were investigated. The results show that in these microstructures, compared to the weld metal without boron, the addition of 22-39 ppm boron results in a remarkable increase in the amount of acicular ferrite at the expense of grain boundary ferrite, idiomorphic ferrite and side-plate ferrite. However, with a further increase in the boron content up to 61-85 ppm, the bainitic ferrite is formed, accompanied with a drop in the amount of acicular ferrite. In the acicular ferrite, the size of martensite-austenite (M/A) islands is much smaller, and the amount is much lower than those found in the bainitic ferrite. In the case of the weld metals primarily composed of acicular ferrite, during the fracture of the impact specimens, the crack propagation path is more bent in comparison with the weld metals with large amounts of grain boundary ferrite, idiomorphic ferrite, side-plate ferrite or bainitic ferrite, which that the presence of acicular ferrite improves the toughness of the weld metals. The coarse martensite-austenite islands readily induce micro-cracks at the interface between martensite-austenite islands and ferrite matrix, deteriorating the toughness. The weld metals with B contents of 22-39 ppm exhibit outstanding impact toughness because of high amount of acicular ferrite, accompanied with fine martensite-austenite islands.

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“…: +86 24 56863067; e-mail address: wangbingxin@163.com pendent plates on the inclusions [4], so the inclusion feature is a crucial factor affecting AF formation. The literature [5][6][7][8] reported that some specific types of Ti-containing inclusions could effectively promote AF nucleation by Mn depletion and/or crystallographic lattice match mechanisms. In addition, the hardenability of weld metal also has a considerable effect on the AF formation [9] as a result of the competitive relationships between AF and PF, GBF, SPF, etc., in the course of the austenite decomposition during cooling after welding [10].…”

Section: Introductionmentioning

confidence: 99%

Effect of boron addition on microstructure and toughness of Ti-containing weld metals

Wang¹,

Li²

2022

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Ti-containing weld metals with boron (B) contents of 0-85 ppm were prepared, and the microstructural characteristics and impact toughness of weld metals were investigated. The results show that compared with the weld metal without B, in the weld metal with 22 ppm B, the fraction of acicular ferrite (AF) is increased from 26 to 76 %, accompanied by a remarkable decrease in the contents of pro eutectoid ferrite (PF), grain boundary ferrite (GBF) and sideplate ferrite (SPF). In the 39 ppm B weld metal, the microstructure basically consists of AF. However, a further increase in the B content up to 61 ppm decreases the fraction of AF to 66 % due to the formation of bainitic ferrite (BF). For the weld metal with 85 ppm B, the microstructure is wholly composed of BF. The size of martensite-austenite (M/A) islands distributed between AF plates is much smaller, and the amount is much lower than this between BF plates. In the case of the weld metals primarily composed of AF, during fracture of impact specimens, crack propagation deflects much more frequently in comparison to the weld metals with large amounts of PF, GBF and SPF, or BF, which improves the toughness of weld metals. The coarse M/A islands readily induce microcracks at the interface between M/A islands and the ferrite matrix, deteriorating the toughness. The weld metals with B contents of 22 and 39 ppm exhibit outstanding impact toughness because of a high fraction of AF accompanied by fine M/A islands.

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A study on the acicular ferrite formation in steel weld metals for gas metal arc welding

Cited by 6 publications

References 10 publications

Acicular Ferrite Identification in Heat‐Affected Zone of a Ti‐Killed High Strength Low Alloy Steel

Acicular Ferrite Identification in Heat‐Affected Zone of a Ti‐Killed High Strength Low Alloy Steel

Effect of boron treatment on the microstructure and toughness of Ti-containing steel weld metals

Effect of boron addition on microstructure and toughness of Ti-containing weld metals

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