The effect of non-metallic inclusions on the toughness of the weld metal of cold-resistant steels at low temperatures

Орыщенко, А. С.; Pimenov, A.V.; Shekin, S.I.; Sharapov, M. G.

doi:10.1080/09507116.2012.753279

Cited by 4 publications

(2 citation statements)

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“…e SEM and TEM observations show that the acicular ferrite nucleates around nonmetallic partials in the austenite grain and grows in all directions [16,17], as shown in Figure 4. e nonmetallic partials are mainly Ti -oxide (Figure 4(a)), (Figure 4(c)), which are denoted as martensite/austenite (M/A) constituents in the low-carbon microalloying steel fields [8,9]. e specific microstructure will affect the tempering transformation and its mechanical properties after the tempering.…”

Section: Microstructure and Charpy Impact Toughness Aftermentioning

confidence: 99%

“…e heavy-wall hot bends are usually made from longitudinal-seam submerged arc welding (LSAW) steel pipes by hot induction heated bending, on-line water cooling, and off-line tempering [5][6][7]. e microstructure and mechanical properties of the weld seam of LSAW steel pipes are different to the pipe body, and the acicular ferrite is obtained as an optimal microstructure to improve the impact toughness [8,9]. And yet for all that, the weld metal still has lower impact toughness than the pipe body.…”

Section: Introductionmentioning

confidence: 99%

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Transformation of M/A Constituents during Tempering and Its Effects on Impact Toughness of Weld Metals for X80 Hot Bends

Qiao

Han

Xiao

et al. 2019

Advances in Materials Science and Engineering

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Impact toughness of the weld metal is one of the important factors affecting the quality of hot bends, which is strongly dependent on the microstructure transformation during hot bending and tempering. In this study, three kinds of weld metals with different Ni contents were selected, and then the effects of tempering temperature on the microstructure impact toughness of weld metals for hot bends were investigated by simulation conducted on a Gleeble-3500 thermal simulator. The results show that the nonmetallic inclusion particles in weld metals can become the nuclear core of acicular ferrite like in as-welded metal. So, the overlapping acicular ferrite microstructure is obtained in the weld metal after direct cooling from the reheating temperature. During tempering, the overlapping acicular ferrite microstructure is degenerated, and martensite/austenite (M/A) constituents in the acicular ferrite microstructure decompose into ferrites and carbides. The resulting carbide particles mainly distribute along the acicular ferrite grain boundaries. With the increase of the tempering temperature, the carbide particles coarsen, which decreases the impact toughness of the weld metal of hot bends. Addition of Ni to weld metals can refine the acicular ferrite and improve the impact toughness.

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