Effect of Si content on the microstructures and the impact properties in the coarse-grained heat-affected zone (CGHAZ) of typical weathering steel

Zhang, Yue; Shi, Genhao; Sun, Rui; Guo, Kai; Zhang, Chunyu; Wang, Qingfeng

doi:10.1016/j.msea.2019.138082

Cited by 30 publications

(27 citation statements)

References 31 publications

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“…The morphologies of the fiber and radiation zones were also observed at high magnification. With the increase in E j , the shape of the dimples in the fiber zone change from small, round, and deep to large, shallow, and parabolic, indicating a decrease in the degree of plastic deformation in this zone [14,32]. In the radiation zone, with the increase in E j , the size of the cleavage surface gradually increases.…”

Section: Effect Of E J On the Impact Fracture Characteristicsmentioning

confidence: 99%

Effect of heat input on the microstructure and impact toughness of submerged arc weld metal for high-performance weathering steel

Li,

et al. 2023

Mater. Res. Express

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This study aims to elucidate the appropriate heat input (Ej) range for submerged arc welding (SAW) of high-performance weathering steel. Generally, by increasing Ej, the welding efficiency can be improved, but the toughness of the weld metal may be deteriorated. Therefore, SAW was employed to produce the weld microstructure under varying Ej from 20 to 50 kJ/cm. The Charpy V-notch impact tests were conducted at −40℃, and the weld microstructures were characterized by optical microscopy (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and electron backscatter diffraction (EBSD). The results indicate that the weld microstructures consist of polygonal ferrite (PF), acicular ferrite (AF), granular bainitic ferrite (GBF), and martensite/austenite (M/A) constituents under each Ej. With the increase in Ej, the proportion of PF increases, while AF and GBF are coarsened, and the area fraction (fM/A) and mean size (dM/A) of M/A constituents increase monotonically. Further, the fraction (fMTA>15°) of high-angle grain boundaries (HAGBs) with the misorientation tolerance angles (MTAs) greater than 15° is reduced, while the mean equivalent diameter (MEDMTA≥15°) of ferrite grains with HAGBs increases. Accordingly, with the increase in Ej, the impact toughness of weld degrades from 128.4 to 47.6 J. The higher degree of micro-strain concentration caused by the increase in M/A size and area leads to the formation of larger microcracks under small plastic deformation, while the reduced HAGBs have a lower inhibition effect on crack propagation. Finally, the impact toughness decreases with the increase of Ej. Overall, the findings suggest that the Ej of SAW should not exceed 40 kJ/cm in the construction of high-performance weathering steel.

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Section: Effect Of E J On the Impact Fracture Characteristicsmentioning

confidence: 99%

Effect of heat input on the microstructure and impact toughness of submerged arc weld metal for high-performance weathering steel

Li,

et al. 2023

Mater. Res. Express

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“…Taillard et al [ 24 ] proved that the carbon enrichment of retained austenite in industrial E355 structural steels with the higher Si content can significantly promote the formation of the M–A constituents, leading to the local brittle zone during welding. Zhang et al [ 26 ] stated that with increasing Si addition in weathering steels, the LB decreases, whereas the GB increases. In addition, the amount of larger M–A constituents in CGHAZ increases and the fraction of high‐angled grain boundaries (HAGBs) decreases.…”

Section: Introductionmentioning

confidence: 99%

Effect of Si Content on the Microstructures and Toughness in Heat‐Affected Zone of Offshore Engineering Steels with Mg Deoxidation

Pan

Yang

Zhang

et al. 2022

steel research int.

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Herein, the effect of Si content on the microstructures and toughness in the heataffected zone (HAZ) with the heat input of 100 kJ cm À1 for Mg-deoxidized offshore engineering steels is presented. For the matrix, increasing Si content coarsens the lath bainites (LBs) in HAZ due to the higher A r3 and lower A r1 . Thus, the highangled grain boundary density (HAGBD) decreases from 0.88 to 0.53 μm À1 , and the effective grain size increases from 10.6 to 18.3 μm. M-A constituents are transformed from dotted and filmed ones to the stringer and blocky ones, with the area fraction increasing from 2.9% to 5.6%. Among them, the stringer M-A particles are likely to debond from the matrix, while the blocky M-A particles tend to initiate cracks because the interfacial energy of stringer particles is lower than that of blocky ones. Accordingly, increasing Si content from 0.0003 to 0.120 wt% results in both the increased crack initiation probability by more M-A constituents with the larger size and the lowered crack propagation barrier by the smaller HAGBD, thereby reducing the HAZ toughness at À40 °C from 202 to 58 J.

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“…To prevent the occurrence of hot cracks during the welding procedure, the wt-% P has been strictly controlled in the conventional weathering steels, so are the plate thickness, heat input and penetration rate [13]. The designed wt-% P of weathering mild steels proposed by Japanese Industrial Standard Committee (JIS) is usually lower than 0.15% [14].…”

Section: Introductionmentioning

confidence: 99%

Microstructure and mechanical properties of friction stir welded high phosphorus weathering steel

Wang

Tsutsumi

Kawakubo

et al. 2022

Science and Technology of Welding and Joining

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The mild steel with low phosphorus is vulnerable to corrosion while higher phosphorus often results in hot crack by fusion welding. The present study evaluated microstructures and mechanical properties of high phosphorus steels joined by friction stir welding below the A 1 temperature. The microstructure was analysed considering various phosphorus contents, and mechanical properties were assessed by digital image correlation. The results suggest that alloying elements (nickel, chromium and niobium) contribute to the refinement of pearlite in the base metal and cementite in the stir zone. The increasing phosphorus improves the microhardness and strength of friction stir welded joints but weakens the ductile behaviour. The added alloying elements can enhance the ductile behaviour and mechanical strength at the same time.

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Effect of Si content on the microstructures and the impact properties in the coarse-grained heat-affected zone (CGHAZ) of typical weathering steel

Cited by 30 publications

References 31 publications

Effect of heat input on the microstructure and impact toughness of submerged arc weld metal for high-performance weathering steel

Effect of heat input on the microstructure and impact toughness of submerged arc weld metal for high-performance weathering steel

Effect of Si Content on the Microstructures and Toughness in Heat‐Affected Zone of Offshore Engineering Steels with Mg Deoxidation

Microstructure and mechanical properties of friction stir welded high phosphorus weathering steel

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