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Yamane, Toshimi; Hisayuki, Koji; Kawazu, Yukio; Takahashi, Tatsuya; Kimura, Yuji; Tsukuda, Shin-ichi

doi:10.1023/a:1019695104094

Cited by 16 publications

(4 citation statements)

References 2 publications

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“…The fast air cooling rate during the normalizing cooling process caused insufficient carbon diffusion to develop continuous lamellae at some positions of the weld metal, then degenerated pearlite was formed finally. Addition of Nb to the weld metal was beneficial to the formation of degenerated pearlite, because the strong affinity of Nb and C made the C diffusion more difficult to form continuous lamellae, which was similar to the results in the Nb bearing steel reported by Shanmugam et al 12) Yamane et al 13) believed that as a microstructural constituent, degenerated pearlite could promote the toughness of steel. 1 200°C, respectively, the yield strength, tensile strength, elongation and Ϫ20°C impact energy of the weld metal as a function of normalizing temperature were shown in Figs.…”

Section: Microstructuresupporting

confidence: 77%

Effects of Normalizing Process on the Microstructural Evolution and Mechanical Properties of Low Carbon Steel Weld Metal with Niobium Addition

Wei

Liu

et al. 2010

ISIJ Int.

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The microstructure and mechanical properties of a Nb bearing weld metal under different normalizing processes had been evaluated and analyzed. The results showed that there was a great difference between the microstructure and mechanical properties of the as-welded and the as-normalized weld metals, and that the normalizing process played an important role in determining the microstructure and mechanical properties of a Nb bearing weld metal. The microstructure of the weld metal was converted from a columnar grain structure in the as-welded state into equiaxed grain, and the degenerated pearlite and NbC precipitates were observed in the weld metal after a 920°C normalizing treatment. Corresponding to the microstructure, the normalized weld metal had lower yield and tensile strengths, higher elongation and higher Ϫ20°C impact energy than the as-welded weld metal. With the prolonging of the holding time at the normalizing temperature of 920°C, the grain size in the weld metal remained almost constant, while the size of NbC precipitate increased. The mechanical properties of the weld metal showed no obvious change with the increasing holding time. With an increase of the normalizing temperature, the quantity of the NbC particles decreased and the proportion of Widmanstatten ferrite microstructure in the weld metal increased, which caused the yield and tensile strengths to increase obviously, while the elongation and impact toughness decreased significantly. When normalizing at 1 200°C, the NbC particles in the weld metal disappeared due to dissolution and the twin subplates were formed in the Widmanstatten ferrite.KEY WORDS: normalizing process; weld metal; microstructure; mechanical property; Nb-microalloyed steel.vided theoretical guidance for the design of microalloyed steel welding materials, as well as the microstructure and property controlling of Nb bearing weld metal. Experimental ProceduresA low carbon Nb bearing steel welding wire with a diameter of 1.2 mm was used in the experiment to weld a 12 mm thick S355J2G3 (base metal) steel plate by the automatic Gas Metal Arc Welding (GMAW) process. The joint was welded by 3 pass welding and the shielding gas was 85%Arϩ15%CO 2 . Table 1 gave the chemical compositions of the welding wire and the base metal. The chemical composition of the weld metal deposited by the welding wire was analyzed using chemical analysis as shown in Table 2. After welding, normalizing processes under different conditions were carried out on the welded plates as shown in Table 3.Tensile tests of the weld metal were conducted at room temperature using a computerized tensile testing system on an Instron-type testing machine. The tensile specimens were cut from the weld metal along the welding direction as shown in Fig. 1. The specimens for the impact property testing of the weld metal were extracted from these joints transversely to the welding direction by an electrical spark wire cutting machine and machined to a dimension of 55 mmϫ10 mmϫ10 mm. The V notch was machined in the center of t...

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Section: Microstructuresupporting

confidence: 77%

Effects of Normalizing Process on the Microstructural Evolution and Mechanical Properties of Low Carbon Steel Weld Metal with Niobium Addition

Wei

Liu

et al. 2010

ISIJ Int.

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“…It has been argued that N makes low-carbon steels more brittle. [36] The DBT temperature of the steels increases with an increase in the total N content. [37] Likewise, the interstitial nitrogen atoms gather to the dislocations and cause the strain-aging embrittlement of the steels.…”

Section: Discussionmentioning

confidence: 99%

Effect of V and N Precipitation on Acicular Ferrite Formation in Sulfur-Lean Vanadium Steels

Capdevila

García‐Mateo

Chao

et al. 2009

Metall Mater Trans A

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This article deals with the mechanical properties achieved in two S-lean laboratory-cast V steels with two different N content levels, as compared with commercial acicular ferrite steel. The designed heat treatments ensure an almost homogeneous microstructure consisting of acicular ferrite for N-rich and commercial steels and consisting of bainite for the N-lean steel. The results presented in this work demonstrate that, in the absence of sulfide inclusions, acicular ferrite is nucleated on V(C,N) precipitates. The mechanical tests indicate that N-rich acicular ferrite steel achieves the same toughness values as N-lean bainitic steel but with a substantial improvement in strength properties. The S-lean steels present better toughness properties than commercial acicular ferrite steel, which is consistent with the detrimental effect of inclusions on toughness.

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“…Based on the Equations. (5)(6)(7)(8), the values of different strengthening mechanisms in the DQT and DQQT processes could be obtained, Table 2. The results of calculation indicated that the primary factor affecting the yield strength was the grain boundary strengthening, whereas the subordinate factors were dislocation strengthening and precipitation strengthening.…”

Section: Tensile Propertymentioning

confidence: 99%

“…Thereby, it was necessary to improve the impact toughness and weldability. Generally, alloy composition, microstructure, grain size and non-metallic inclusion are the main factors that influence the impact toughness of steel [6][7][8][9][10]. The optimization of the chemical composition and steelmaking process could enhance the purity of the molten steel, and then the impact toughness of the steel could be significantly improved.…”

Section: Introductionmentioning

confidence: 99%

Microstructure and mechanical properties of 1000 MPa grade steel plate for hydropower station in different quenching processes

Chen

Ren

et al. 2022

Materialwissenschaft Werkst

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Strength and toughness of the ferrum-1.2manganese-1.4nickel steel plates in the DQT (direct quenching!tempering) and DQQT (direct quenching!reheated quenching!tempering) processes were investigated. This ferrum-1.2manganese-1.4nickel which possessed a relatively low alloy content and improved purity was used as the 1000 MPa grade high-strength steel plates for hydropower station. The flat prior austenite grains with the dislocation density of 4.86 × 10 14 m À 2 and nano-scaled precipitates were acquired in the DQT process. The grains and precipitates grew up and the dislocation density decreased to 4.26 × 10 14 m À 2 as a result of reheated quenching in the DQQT process. After tempering, the yield strength of the specimen treated by the DQT process was ~996 MPa, which was ~34 MPa higher than that of the DQQT sample. The difference of yield strength between these two quenching processes was primarily ascribed to grain boundary strengthening and partly caused by dislocation strengthening or precipitation strengthening. Due to the circular propagation path of cracks and matrix softening, the impact energy at À 60 °C in the DQQT process was superior to that of the DQT process.

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Untitled

Cited by 16 publications

References 2 publications

Effects of Normalizing Process on the Microstructural Evolution and Mechanical Properties of Low Carbon Steel Weld Metal with Niobium Addition

Effects of Normalizing Process on the Microstructural Evolution and Mechanical Properties of Low Carbon Steel Weld Metal with Niobium Addition

Effect of V and N Precipitation on Acicular Ferrite Formation in Sulfur-Lean Vanadium Steels

Microstructure and mechanical properties of 1000 MPa grade steel plate for hydropower station in different quenching processes

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