Effect of Ti-containing inclusions on the nucleation of acicular ferrite and mechanical properties of multipass weld metals

Fattahi, Mehdi; Nabhani, Nader; Hosseini, Mir Ghasem; Arabian, N.; Rahimi, Ehsan

doi:10.1016/j.micron.2012.11.004

Cited by 99 publications

(47 citation statements)

References 22 publications

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“…In the recent decades, considerable research has been conducted to evaluate different inclusion types regarding their capability for acicular ferrite: Ti-containing inclusions such as TiN and TiC, [16] titanium oxides [17][18][19][20] partly in combination with rare earth metals, [17] or Manganese [19] have been intensively studied. The effects of many inclusion types have already been well described in the literature, with some popular types, however, being left out, with conflicting results.…”

Section: Introductionmentioning

confidence: 99%

On the Capability of Nonmetallic Inclusions to Act as Nuclei for Acicular Ferrite in Different Steel Grades

Loder

Michelic

Mayerhofer

et al. 2017

Metall Mater Trans B

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Acicular ferrite nucleates intragranularly on nonmetallic inclusions, forming a microstructure with excellent fracture toughness. The formation of acicular ferrite is strongly affected by the size, content, and composition of nonmetallic inclusions, but also by the composition of the steel matrix. The potential of inclusions in medium carbon HSLA (high-strength low-alloyed) steels has been the main focus in the literature so far. The current study evaluates the acicular ferrite capability of various inclusions types in four different steel grades with carbon contents varying between 0.04 and 0.65 wt pct. The investigated steels are produced by melting experiments on a laboratory scale and subsequent heat treatment in a High-Temperature Laser Scanning Confocal Microscope. Inclusions are exclusively formed by deoxidation and desulfurization reactions. No synthetic particles are added to the melt. The inclusion landscape is analyzed by Scanning Electron Microscopy. Final ductility of the samples is evaluated based on performed tensile tests. Inclusion types in every steel grade are assessed regarding their nucleation potential always considering the interaction with the steel composition, especially focusing on the role of manganese. The effects of (Ti,Al)O x -, MnS-, and MgO-containing inclusions are discussed in detail.

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Section: Introductionmentioning

confidence: 99%

On the Capability of Nonmetallic Inclusions to Act as Nuclei for Acicular Ferrite in Different Steel Grades

Loder

Michelic

Mayerhofer

et al. 2017

Metall Mater Trans B

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“…The differences were attributed to carbonitride precipitation, higher dislocation density and the lath bundle size of acicular ferrite. In general, acicular ferrite is beneficial for mechanical properties and besides tensile properties it improves impact toughness and decreases the transition temperature [49,50]. Thus, methods are sought after to increase the volume fraction of acicular ferrite in welds [49,51].…”

Section: Diskusijamentioning

confidence: 99%

“…In general, acicular ferrite is beneficial for mechanical properties and besides tensile properties it improves impact toughness and decreases the transition temperature [49,50]. Thus, methods are sought after to increase the volume fraction of acicular ferrite in welds [49,51]. In this study, the weld metal microstructures were examined using two dimensional analysis.…”

Section: Diskusijamentioning

confidence: 99%

“…Razlike su pripisane talozima karbonitrida, većoj gustini dislokacija i veličini traka acikularnog ferita. U principu, acikularni ferit je od koristi za mehanička svojstva i osim zateznih svojstava poboljšava udarnu žilavost i snižava prelaznu temperaturu [49,50]. Dakle, metode su tražene posle da se poveća zapreminski udeo acikularnarnog ferita u šavu [49,51].…”

Section: Diskusijaunclassified

“…U principu, acikularni ferit je od koristi za mehanička svojstva i osim zateznih svojstava poboljšava udarnu žilavost i snižava prelaznu temperaturu [49,50]. Dakle, metode su tražene posle da se poveća zapreminski udeo acikularnarnog ferita u šavu [49,51]. U ovoj studiji, mikrostruktura metala šava je ispitana pomoću dvodimenzionalne analize.…”

Section: Diskusijaunclassified

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Characterisation of local grain size variation of welded structural steel

Lehto¹,

Romanoff²,

Remes³

et al. 2016

Zavarivanje i zavarene konstrukcije

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Previously, it has been shown that the grain size distribution plays an important role in the mechanical properties of welded steel. In the previous investigation, the volume-weighted average grain size has been shown to capture the influence of grain size distribution, resulting in a better fitting Hall-Petch relationship between grain size and hardness. However, the previous studies exclude the effects arising from local variation in grain size. In this paper, the grain size measurement methods are extended for the characterisation of the local grain size variation, which is significant for welded joints and can have an adverse effect on mechanical properties. The local gradient of grain size variation and its dependency on measurement direction are considered. In addition, examples of grain size and hardness variation are shown for S355 base metal and two weld metals, and characteristic differences are highlighted and discussed. The coarse-grained areas of a heterogeneous microstructure are found to have lower hardness than fine-grained areas. However, the surrounding microstructure, i.e. local grain size gradient, has an influence on the measured hardness values. RezimeRanije je pokazano da distribucija veličine zrna igra važnu ulogu vezanu za mehanička svojstva zavarenog čelika. U prethodnom istraživanju, zapreminski procenjena prosečna veličina zrna je pokazala uticaj distribucije veličine zrna, što je rezultovalo u boljem ispunjenju Hall-Petch-og odnosa između veličine zrna i tvrdoće. Međutim, prethodne studije isključuju učinke koji proizlaze iz lokalnih varijacija u veličini zrna. U ovom radu, metode merenja veličine zrna su proširene na karakterizaciju varijacije lokalne veličine zrna, što je značajno za zavarene spojeve jer mogu imati negativan uticaj na mehanička svojstva. Razmatraju se lokalni gradijent varijacije veličine zrna i njegova zavisnost od smera merenja. Osim toga, primeri veličine zrna i varijacije tvrdoće su prikazani za S355 kao osnovni materijal i dva šava metala, a karakteristične razlike su istaknute i o njima se diskutuje. Za područja krupnozrne heterogene mikrostrukture utvrđeno je da imaju manju tvrdoću od sitnozrnog područja. Međutim, okružujuća mikrostruktura, t.j. gradijent lokalne veličine zrna, ima uticaj na izmerene vrednosti tvrdoće.

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High Toughness Independent of Low‐Medium Heat Inputs in Coarse‐Grain Heat‐Affected Zone of a Designed HSLA Steel

Luo

Chen

Wang

2017

steel research int.

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In the present work, low‐medium heat inputs of 15, 30, and 50 kJ cm−1 are adopted to simulate Coarse‐Grain Heat‐Affected Zones (CGHAZ) of a designed HSLA steel by Gleeble‐3500 thermal simulator. Microstructures are characterized by optical microscope (OM), scanning electron microscope (SEM), and transmission electron microscope (TEM). Charpy impact tests are performed to evaluate toughness of CGHAZs. Results show that impact toughness (−50 °C) of CGHAZs with heat inputs of 15, 30, and 50 kJ cm−1 is 156.18, 172.86, and 181.49 J, respectively. Toughness stays in high level though heat input varies within low‐medium range. Evolution of microstructures is investigated and micro‐mechanisms of high toughness in all of the three heat inputs are discussed in detail. An original alloy design for HSLA steels with high toughness CGHAZ is proposed as well.

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Effect of Ti-containing inclusions on the nucleation of acicular ferrite and mechanical properties of multipass weld metals

Cited by 99 publications

References 22 publications

On the Capability of Nonmetallic Inclusions to Act as Nuclei for Acicular Ferrite in Different Steel Grades

On the Capability of Nonmetallic Inclusions to Act as Nuclei for Acicular Ferrite in Different Steel Grades

Characterisation of local grain size variation of welded structural steel

High Toughness Independent of Low‐Medium Heat Inputs in Coarse‐Grain Heat‐Affected Zone of a Designed HSLA Steel

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