Influence of cooling paths on microstructural characteristics and precipitation behaviors in a low carbon V–Ti microalloyed steel

Chen, Jun; Lv, Mengyang; Tang, Shuai; Liu, Zhenyu; Wang, Guodong

doi:10.1016/j.msea.2013.09.086

Cited by 89 publications

(30 citation statements)

References 15 publications

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“…Most early studies [8,[25][26][27] generally emphasized that only interphase precipitation morphology could occur within the ferrite matrix. However, it is worthy to note that not only the present study but also more and more research has demonstrated the coexistence of interphase precipitation and random precipitation [16,[19][20][21][28][29][30][31][32]. The above metallurgical phenomenon is associated with the kinetics of austenite decomposition in different processes, which will be discussed in detail later.…”

Section: Precipitate Morphology Observed By Transmission Electron Micmentioning

confidence: 48%

“…Although the random precipitation morphology has been verified by many studies [16,17,[19][20][21], ϰ the root cause of the random precipitation morphology is still under debate. For example, some researchers have proposed that interphase precipitates will appear to have a random distributed morphology when the direction of the incident electron beam and the planes on which the carbides precipitated are not parallel to each other [19,20].…”

Section: Introductionmentioning

confidence: 99%

“…suggested that random array carbides can achieve a better strengthening effect if distributed as finely as in interphase precipitation [14]. Jun et al examined a Ti-V microalloyed steel and found that both interphase precipitation and random precipitation, separated by about 20~30 nm, occur simultaneously in the same ferrite grain [16]. Furthermore, unlike the traditional isothermal holding approach, Chen et al found that both interphase precipitation and random precipitation can occur during continuous cooling or interrupted cooling processes [17].…”

Section: Introductionmentioning

confidence: 99%

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Control of precipitation morphology in the novel HSLA steel

Chen

et al. 2015

Materials Science and Engineering: A

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Section: Precipitate Morphology Observed By Transmission Electron Micmentioning

confidence: 48%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Control of precipitation morphology in the novel HSLA steel

Chen

et al. 2015

Materials Science and Engineering: A

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“…The effect of cooling rate was recently studied. [14][15][16][17] However, the effect of the finish cooling temperature in UFC has not been explored.In the present work, we focus on the effect of finish cooling temperature on microstructural evolution and precipitation behavior in Nb-V-Ti microalloyed steel, with particular focus on the nucleation site, chemical composition, size distribution, and crystallography. Furthermore, the contribution of the precipitation strengthening to yield strength was calculated using empirical equation.…”

mentioning

confidence: 99%

“…The effect of cooling rate was recently studied. [14][15][16][17] However, the effect of the finish cooling temperature in UFC has not been explored.…”

mentioning

confidence: 99%

The Determining Role of Finish Cooling Temperature on the Microstructural Evolution and Precipitation Behavior in an Nb-V-Ti Microalloyed Steel in the Context of Newly Developed Ultrafast Cooling

Wang

Deng

et al. 2016

Metall Mater Trans A

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We have studied here the impact of finish cooling temperature on the microstructural evolution and precipitation behavior in Nb-V-Ti microalloyed steel through thermo-mechanical simulation in the context of newly developed ultrafast cooling system. The microstructural evolution was studied in terms of morphology and crystallography of precipitates using high-resolution transmission electron microscopy. At finish cooling temperature of 933 K and 893 K (660°C and 620°C), the microstructure primarily consisted of polygonal ferrite, together with a small amount of wedge-shaped acicular ferrite and lamellar pearlite, while, at 853 K and 813 K (580°C and 540°C), the microstructure consisted of lath bainite with fine interlath cementite and granular bainite with martensite/ austenite (M/A) constituent. In all the finish cooling temperatures studied, the near-spherical precipitates of size range~2 to 15 nm were randomly dispersed in ferrite and bainite matrix. The carbide precipitates were identified as (Nb,V)C with NaCl-type crystal structure. With a decrease in the finish cooling temperature, the size of the precipitates was decreased, while the number density first increased with a peak at 893 K (620°C) and then decreased. Using Ashby-Orowan model, the contribution of the precipitation strengthening to yield strength was~149 MPa at the finish cooling temperature of 893 K (620°C).In the last few decades, high-strength low-alloy (HSLA) steels have been widely used in buildings, bridges, and ships because of their potential to obtain high strength-toughness combination. [1] Superior mechanical properties were obtained through optimization of alloy design in conjunction with thermo-mechanical processing (TMCP). [2][3][4][5] The improvement in mechanical properties was a consequence of grain refinement together with microstructural control and precipitation strengthening. The carbide-forming elements include titanium and niobium that facilitate grain refinement and contribute to dispersion hardening through carbide precipitation in the matrix. The relative contribution of the microalloying elements is determined by the solubility of carbides in the microstructure. Titanium is beneficial because it combines with nitrogen at relatively high temperature, preventing grain growth, while niobium can effectively retard recovery and recrystallization during hot rolling leading to grain refinement. Moreover, these two elements can precipitate as carbides from the supersaturated ferrite solid solution or precipitate as interphase precipitates during austenite-to-ferrite transformation increasing strength. Vanadium is less effective in grain refinement but contributes to strength via precipitation hardening because of higher solubility in austenite as compared to niobium, leading to precipitation at lower temperature. [6] TMCP involving ultrafast cooling (UFC) technology developed by our laboratory is being currently applied to industrial production, [7][8][9] with the aim to reduce the consumption of alloying elements and make the s...

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Effect of Cooling Rate on Microstructure and Centerline Segregation of A High-Strength Steel for Shipbuilding

Ye¹,

Liu²,

Wang³

2015

HSLA Steels 2015, Microalloying 2015 &Amp; Offshore Engineering Steels 2015

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Ultra-fast cooling (UFC) has been increasingly applied in industry, but accompanying with great changes of rolling strategy. It is therefore of importance to evaluate the characteristics of steels produced by UFC as compared to those processed by conventional accelerated cooling (ACC). The present study examines the microstructure through thickness and centerline segregation of solute elements between UFC and ACC steels, both of which were rolled at a final rolling temperature at around non-recrystallized temperature. UFC steel showed the pronounced microstructural transition from lath-type bainite with Widmanstätten ferrite at subsurface to acicular ferrite in an average size of ~5 Pm dispersed with degenerate pearlite in the interior. In contrast, ACC steel had the homogeneous microstructure through the thickness, which was distinguished with coarser polygonal ferrite grains and pearlite nodules. Moreover, the centerline segregation was significantly suppressed by applying UFC at a higher cooling rate of 40 K/s compared to 17K/s for ACC steel. The significant differences in the microstructure and centerline segregation caused by various cooling rate is discussed from the view of JoD transformation.

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Influence of cooling paths on microstructural characteristics and precipitation behaviors in a low carbon V–Ti microalloyed steel

Cited by 89 publications

References 15 publications

Control of precipitation morphology in the novel HSLA steel

Control of precipitation morphology in the novel HSLA steel

The Determining Role of Finish Cooling Temperature on the Microstructural Evolution and Precipitation Behavior in an Nb-V-Ti Microalloyed Steel in the Context of Newly Developed Ultrafast Cooling

Effect of Cooling Rate on Microstructure and Centerline Segregation of A High-Strength Steel for Shipbuilding

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