Relationship between Crystal Structure of Inclusions and Formation of Acicular Ferrites

Cui, Zhimin; Zhu, Lingkai; Li, Yuanliang; Zhang, Qingjun; Yan, Chunliang; Mo, Wenling

doi:10.1016/s1006-706x(16)30092-9

Cited by 11 publications

(4 citation statements)

References 14 publications

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“…The mean grain size of the ultra-NGMAGW welded joints is about 6.98 μm, while it is 12.80 μm in the NGSAW welded joints. In addition, Figure 7b shows that the AF grows in all directions around with inclusions or defects as the core [11,12], and in the growth process, due to the different nucleation directions or large growth angles of AF in the adjacent grains, cross-collision occurs to form a locking mechanism, which hinders the continued growth of the grains. In Figure 7d, only P and PF with a coarse grain structure were observed, while AF does not exist.…”

Section: Structure and Morphology Of Welded Jointsmentioning

confidence: 99%

Comparison of Microstructure and Mechanical Properties of Ultra-Narrow Gap Metal Active Gas Arc Welded and Narrow Gap Submerged Arc Welded Q235A Low Carbon Steel

Wu,

Xiao,

Gong

et al. 2023

Materials

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The 18 mm thick Q235A low carbon steel plates were welded via the ultra-narrow gap metal active gas arc welding (ultra-NGMAGW) and narrow gap submerged arc welding (NGSAW), and the microstructure and mechanical properties of the welded joints’ area were characterized. The results showed that there is acicular ferrite (AF) in the weld zone of the joint obtained via the ultra-NGMAGW. The AF grains are fine and have a great difference in growth direction, resulting in high local dislocation density. However, there is no AF in the welded joint obtained via the NGSAW. Using numerical simulation analysis of the temperature field distribution and the thermal cycle curve in the welding process of the ultra-NGMAGW, it was found that the mechanism of microstructure evolution is that during the welding process of the ultra-NGMAGW, the heat input is low, the cooling rate is quick, and the residence time in the high temperature region is short. Therefore, pearlite with coarse grains is basically not formed. AF nucleates in different directions with inclusions as the core. The tensile strength of the weld joint obtained via the ultra-NGMAGW is 643 MPa, which corresponds to 139% of that of the base metal, and 132% of that obtained via the NGSAW. The ultra-NGMAGW joints exhibited better tensile strength and higher microhardness than the NGSAW joints, which is mainly due to the existence of AF.

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Section: Structure and Morphology Of Welded Jointsmentioning

confidence: 99%

Comparison of Microstructure and Mechanical Properties of Ultra-Narrow Gap Metal Active Gas Arc Welded and Narrow Gap Submerged Arc Welded Q235A Low Carbon Steel

Wu,

Xiao,

Gong

et al. 2023

Materials

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“…In fact, the chaotic and interlocking nature of acicular ferrite introduced this microstructure as of relevant microstructures in achieving an appropriate combination of strength and toughness. PF is expected to be less efficient at making an interlocking structure compared to acicular ferrite [5][6][7][8].…”

Section: Introductionmentioning

confidence: 99%

Acicular ferrite nucleation and growth in API5L-X65 steel submerged arc welded joints

Milani

Saeid

2020

Materials Science and Technology

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In the present study, acicular ferrite nucleation and growth were investigated from a crystallographic point of view in API5L-X65 steel weld metals. It was observed that acicular ferrite was nucleated on inclusions in weld metal. The titanium-enriched layer around inclusions was characterised as the TiO phase by selected area diffraction patterns. A scanning electron microscope equipped with an electron backscatter diffraction technique was applied to investigate the crystallographic orientation relationship. The results showed that acicular ferrite lathes had a Baker–Nutting orientation relationship with the TiO layer on the inclusion surface in the nucleation of acicular ferrite. However, it is confirmed that the growth of acicular ferrite lathes depends on the deviation from the Kurdjumov–Sachs relationship between lathes and primary austenite.

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“…AF may be well nucleated if the non-metallic inclusions are more than 0.5 micron. Z. Cui et al [15] suggested that inclusion is surrounded by ferrite lath, which can be radial, symmetrical and acicular. The number of ferrite laths that are nucleated at one inclusion = 2, 4, 6.…”

Section: Introductionmentioning

confidence: 99%

“…AF provides high strength and excellent low-temperature impact toughness because this structure is characterized by interlocking morphology [12][13][14][15][16].…”

Section: Introductionmentioning

confidence: 99%

Microstructure and Impact Toughness Relationship for Different Nickel Level of Electrode in Multi-pass FCA Welded SM570-TMC Steel Joint

Winarto

Oktadinata

Siradj

et al. 2020

QUARTERLY JOURNAL OF THE JAPAN WELDING SOCIETY

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A study was carried out to evaluate the relationship of microstructure and impact toughness for different nickel level of electrodes in multipass flux-cored arc welded SM570-TMC steel joint. The base metal used in this study was SM570-TMC plate with 16 mm thickness. The multipass welds were run by using flux-cored arc welding (FCAW) with a flat position (1G). Three SM570-TMC welded plates were fabricated with varying amounts of the nickel content of electrodes, 0.4, 1.0 and 1.5% Ni. The effects of nickel were studied on the weld metals. The investigations consist of observation on the microstructure and mechanical tests. The results indicated that at a temperature of 25 °C and 0 °C there was no obvious different impact energy value of weld metal by using electrodes 0.4 and 1.0% Ni. Besides, at a temperature of -20 °C the impact energy of weld metal containing 1.0% Ni was superior to the other. It seems the acicular ferrite (AF) formation on the weld metal containing 1.0% Ni effectively improves low-temperature impact toughness. On the other hand, the impact energy of weld metal, 1.5% Ni was the lowest. It is found that the higher nickel content caused the microsegregation as observed by the electron probe micro analyzer (EPMA).

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Relationship between Crystal Structure of Inclusions and Formation of Acicular Ferrites

Cited by 11 publications

References 14 publications

Comparison of Microstructure and Mechanical Properties of Ultra-Narrow Gap Metal Active Gas Arc Welded and Narrow Gap Submerged Arc Welded Q235A Low Carbon Steel

Comparison of Microstructure and Mechanical Properties of Ultra-Narrow Gap Metal Active Gas Arc Welded and Narrow Gap Submerged Arc Welded Q235A Low Carbon Steel

Acicular ferrite nucleation and growth in API5L-X65 steel submerged arc welded joints

Microstructure and Impact Toughness Relationship for Different Nickel Level of Electrode in Multi-pass FCA Welded SM570-TMC Steel Joint

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