3D Observation of Micro-cracks as Cleavage Fracture Initiation Site in Ferrite-pearlite Steel

Nemoto, Yoshiki; Shibanuma, Kazuki; Suzuki, Katsuyuki; Sadamatsu, Sunao; Adachi, Yoshitaka; Aihara, Shuji

doi:10.2355/isijinternational.isijint-2016-607

Cited by 9 publications

(1 citation statement)

References 37 publications

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“…However, no cracks were observed while bending the strips at 870, and 880 • C, as shown in Figure 7f,g, respectively. The formation of the cracks can be divided into three distinct stages; in the first stage, shear micro-cracks are formed in the PBS; in the second stage, the crack extends to the adjacent ferrite grain; in the third stage, the crack propagates to the boundary of the ferrite grains [20][21][22]. Hence, the hot-rolled strip with an 860 • C finishing rolling temperature which was bent to 90 • , still exhibited small cracks (Figure 7e) due to the appearance of a few PBSs in the grains (Figure 5e).…”

Section: Verification Of the Bending Testmentioning

confidence: 99%

Optimization of Hot Rolling Scheduling of Steel Strip with High Bending Performance

Feng¹,

Lin²,

Chuang³

et al. 2022

Materials

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Poor formability in hot-rolled strips may be attributed to the many pearlite-banded structures (PBSs) that develop in steel during the hot-rolling process. The challenge of manufacturing strips with minimum PBSs is that multiple factors influence the amount and distribution of the PBSs. This study used the Taguchi method to find the optimum hot-rolling parameters to obtain strips with a reduced number of PBSs. The strips were then subjected to bending tests to evaluate their ductility. The first part analyzes the contribution of selected parameters to the hot-rolling process: (1) finishing rolling temperature, (2) finishing rolling speed, (3) coiling temperature, and (4) coiling speed. The second part confirms, using bending tests, the influence of the finishing rolling temperatures 780, 800, 820, 840, 860, 870, and 880 °C on the formability of an A36 hot-rolled strip. Based on the experimental protocol for the study, the optimal process parameters were determined to be the finishing rolling speed (0.80 m/s), finishing rolling temperature (870 °C), coiling speed (2.80 m/s), and coiling temperature (650 °C). When the A36 strip was prepared at the optimum parameters, the average length and thickness of the PBS were 108.61 ± 0.11 μm and 10.18 ± 0.12 μm, respectively. According to the Taguchi analysis, the finishing rolling temperature had the most significant influence on the dimensions of the PBS. In tests where the hot-rolled A36 strip was bent to 90° and 180°, at the finishing rolling temperatures of 870 °C and 880 °C, no cracking was observed at the R angle.

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Section: Verification Of the Bending Testmentioning

confidence: 99%