Austenitic Grain Growth Behavior during Austenization in an Aluminum-Alloyed 5% Cr-Mo-V Steel

Li, Shasha; Liu, Yaohui; Song, Yulai; Kong, Lingnan; Li, Tuanjie; Zhang, Renhang

doi:10.1002/srin.201500427

Cited by 10 publications

(4 citation statements)

References 35 publications

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“…The result of Schino et al [ 6 ] by metallographic method showed that the austenite grains of a low nickel steel grew dramatically within the holding time of 0–5 min, but grains changed extremely slowly after ~5 min holding. The grain growth of a Cr–Mo–V Steel was investigated by Li et al [ 7 ] via interrupted quenching, and it showed that the austenite grains had grown dramatically after several hours holding. It was generally believed that in the holding time, holding temperature and initial microstructures had influences on the grain growth of steels.…”

Section: Introductionmentioning

confidence: 99%

In Situ Investigation of Grain Evolution of 300M Steel in Isothermal Holding Process

Chen

Zheng

et al. 2018

Materials

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The relationships between initial microstructures, process parameters, and grain evolutions in isothermal holdings have drawn wide attention in recent years, but the grain growth behaviors of 300M steel were not well understood, resulting in a failure in precise microstructure controlling in heat treatment. In this work, in situ observations were carried out to characterize the grain evolutions of 300M steel with varying holding time, holding temperatures, and initial microstructures. The intriguing finding was that the grain refinement by austenization of 300M steel was followed by a dramatic grain growth in the initial stage of holding (≤~600 s), and with increasing time (~600–7200 s), the average grain size appeared to have a limit value at specific temperatures. The austenization process accelerated the grain growth by generating large quantity of grain boundaries at the initial stage of holdings, and the growth rate gradually slowed down after holding for ~600 s because the driven force was weakened due to the reduction of grain boundary energy. The initial structure and the initial grain size of 300M steel had no obvious influences on the grain size evolutions. The mechanisms of grain growth were analyzed based on in situ observations and transmission electron microscope (TEM) characterizations. A grain evolution model considering the grain boundary migration of 300M steel was established for the isothermal holding process. Good agreement was obtained between the in situ observation results and the model calculation results. This investigation aimed to understand fundamentally the grain evolutions of 300M steel in the isothermal holding process.

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Section: Introductionmentioning

confidence: 99%

In Situ Investigation of Grain Evolution of 300M Steel in Isothermal Holding Process

Chen

Zheng

et al. 2018

Materials

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“…Kinetic model of austenite grain growth. The kinetics of grain growth has been intensively studied and it has been empirically known that the behaviors of grain growth obey the following Arrhenius type equation [17][18][19] )…”

Section: Resultsmentioning

confidence: 99%

Effect of Precipitates on Austenite Grain Growth Behavior in a Low-Carbon Nb-V Microalloyed Steel

Zhang¹,

Wen²,

Liu³

2017

MSF

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The effect of precipitates on austenite grain growth behavior in a Nb-V microalloyed steel was investigated. The precipitates were identified by selected area electron diffraction (SAED) and energy dispersive spectrometer (EDS) analysis. Because of pinning effect of NbC and/or VC on austenite grain boundaries, grains grew slowly at 850oC-1000oC. However, when temperature reached 1050 oC, abnormal grain growth was observed, which was attributed to dissolution of NbC particles. The NbC precipitates dissolved significantly at 1150 oC. However, grain sizes were still very small. Thus, austenite grains grew rapidly at 1050-1150 oC. The fully dissolution temperature of this steel was 1150-1250oC. Finally, the relationship between grain coarsening temperature (TGC) and fully dissolution temperature (TDISS) could be illustrated as follows: 100 oC≤TDISS -TGC≤200 oC. When heating temperatures were 850-1050 oC and 1050-1250 oC, grain growth activation energies (Q) were 59945 J/mol and 135813 J/mol, respectively. The different grain growth models were mainly caused by the gradual dissolution of NbC particles.

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“…The distribution of Al elements is uniform in the milled powder (Figure f), which results in uniform coarsening of the steel substrate during subsequent heating processes (Figure g,h). The grain coarsening of ODS steels due to the addition of Al has been reported in the literature …”

Section: Discussionmentioning

confidence: 99%

“…The grain coarsening of ODS steels due to the addition of Al has been reported in the literature. [42] In addition, in route #1, since the Al powder deforms more severely than the Fe-9Cr steel powder during ball milling (see Figure 11a), many Y 2 O 3 particles prefer to distribute in the Al-rich regions after the ball milling (see Figure 11b). Some of these Y 2 O 3 particles segregated in the Al-rich region react with Al upon subsequent heating processes to form the Y-Al-O particles (see Figure 11c,d).…”

Section: Influence Of Al Addition Strategy On Microstructurementioning

confidence: 99%

Influence of Al Addition Strategy on the Microstructure of a Low‐Cr Oxide Dispersion‐Strengthened Ferritic Steel

Zhou

Long

et al. 2019

Adv Eng Mater

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Herein, two kinds of Fe-9Cr-8Al oxide dispersion-strengthened (ODS) steels (prealloyed and postalloyed) are fabricated via mechanical alloying (MA), hot isostatic pressing (HIP), and subsequent hot forging. Microstructures of the milled powder and forged bulk materials are carefully characterized. The results show that the adding sequence of Al has a significant impact on the microstructure. For the postalloyed sample (adding Al during ball milling), a dual-phase structure composed of reticular Al-rich regions and a steel matrix is formed in the milled powder due to the highly mismatched deformability between the Al powder and the Fe-9Cr powder during ball milling. For the prealloyed sample (adding Al prior to ball milling), Al is solid solutionized into the steel matrix before ball milling, and there is no dual-phase structure in the milled powder. In the final bulk materials, the average grain size of the prealloyed sample is much larger than that of the postalloyed sample. Moreover, the matrix of the postalloyed sample has a bimodal grain structure consisting of coarse grains closely surrounded by fine grains, whereas the prealloyed sample has a relatively uniform distribution of coarse grains. The coarsening mechanisms of Al addition on the microstructure are also discussed.

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Austenitic Grain Growth Behavior during Austenization in an Aluminum-Alloyed 5% Cr-Mo-V Steel

Cited by 10 publications

References 35 publications

In Situ Investigation of Grain Evolution of 300M Steel in Isothermal Holding Process

In Situ Investigation of Grain Evolution of 300M Steel in Isothermal Holding Process

Effect of Precipitates on Austenite Grain Growth Behavior in a Low-Carbon Nb-V Microalloyed Steel

Influence of Al Addition Strategy on the Microstructure of a Low‐Cr Oxide Dispersion‐Strengthened Ferritic Steel

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