Investigation on the void closure efficiency in cogging processes of the large ingot by using a 3-D void evolution model

Cao, Feng; Cui, Zhenshan; Liu, Mingxiang; Shang, Xiaobang; Sui, Dashan; Liu, Juan

doi:10.1016/j.jmatprotec.2016.06.030

Cited by 31 publications

(16 citation statements)

References 29 publications

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“…e elimination of void defects can be divided into two stages: void closing and void healing. Void closure refers to the elimination of voids through deformation, which is basically based on the contact between the upper and lower surfaces of the void [1][2][3]. However, the internal cracks formed after void closure will seriously affect the mechanical properties of forgings.…”

Section: Introductionmentioning

confidence: 99%

Effect of Deformation Parameters on Microstructure and Mechanical Properties of Internal Crack Healing in As‐Cast 30Cr2Ni4MoV Steel

Jiao

Zhou

Liu

et al. 2021

Advances in Materials Science and Engineering

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Crack defects seriously affected the quality of heavy forgings, which needed to be eliminated by forging process. In this study, the healing process of internal crack defects was studied under different deformation parameters. The internal crack was produced by drilling the sample of 30Cr2Ni4MoV steel and then compressing the sample with different deformation. The microstructure of the crack healing zone was observed using an optical microscope. Meanwhile, the static and dynamic mechanical properties of the crack healing zone were tested by room-temperature tensile tests and impact tests, respectively. The results showed that dynamic recrystallization (DRX) and grain growth were the main factors for internal crack healing. When the forging ratio (FR) was 1.5, the cracks at the corner of the void began to heal, which was caused by DRX. At FR 2.0, the DRX was completed and the center crack was completely healed. The tensile properties of crack healing zones were restored to more than 95% of the base material. As the FR increased to 2.2, the elongation increased slightly and the yield strength decreased slightly, which indicated that the grain growth played an important role in the plastic recovery and DRX played an important role in strength recovery. The dynamic mechanical properties of the crack healing zone gradually increased with the increase of deformation. Furthermore, the maximum value of impact toughness reached FR 2.0, and the recovery rate of impact toughness was above 96%. When the deformation continues to increase, the grains grew up after DRX, which made the impact energy decrease.

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Section: Introductionmentioning

confidence: 99%

Effect of Deformation Parameters on Microstructure and Mechanical Properties of Internal Crack Healing in As‐Cast 30Cr2Ni4MoV Steel

Jiao

Zhou

Liu

et al. 2021

Advances in Materials Science and Engineering

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“…Harris et al [7] proposed a fast converging material-specific void closure model during ingot forging. Feng et al [8] used a 3D void evolution model to investigate the void closure efficiency in cogging processes of large ingots. Park [9] found that a closure criterion of the spherical void is a function of the effective strain and stress triaxiality.…”

Section: Introductionmentioning

confidence: 99%

Establishment and Application of the Void Closure Prediction Model of 316LN

Qin

Liu

2020

Advances in Materials Science and Engineering

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The presence of voids in the ingot affects the mechanical properties of the final products of the forging process. It is essential to establish a void closure model to predict cavity closure in the forging process to optimize the forging process and improve forging quality. The main purpose of this study is to obtain an accurate prediction model of void closure for 316LN stainless steel. Using the FEM simulation method to study the closure of spherical voids during forging compression of 316LN materials, we can accurately characterize the state of void closure. The void closure ratio K under different deformations at 1,200°C was counted, and the relationship between K and the effective strain was established to obtain the void closure prediction model of 316LN stainless steel. The void closure prediction model is implanted into DEFORM software through the secondary development method to generate the void closure ratio K. In the postprocessing module of DEFORM software, the void closure status of each part during the forming process can be directly observed. Comparing the results of large-scale upsetting experiments and simulation results, the closure error of each part was only 3%, which indicates that the void closure model established in this paper has higher accuracy, which is helpful for the optimization of the forging process and the control of forging quality.

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“…The literature reports on a multitude of process design approaches and on the modeling and numerical analysis of the effects of design parameters on the closure of internal voids in the open-die forging of large ingots. [19][20][21][22][23][24][25] Despite the large number of studies on the hot open-die forging of large ingots, there has been no reported research to date on the hot forging of large-diameter round blooms for use in the manufacture of heavy forgings like wind power system main shafts. To address this gap in the literature, this article reports on the feasibility of manufacturing shafts using solid round blooms and compares the proposed design with a conventional cast-ingot shaft in terms of raw material use and shaft mechanical properties.…”

Section: Introductionmentioning

confidence: 99%

Feasibility of using Continuously Cast Round Bloom as a Substitute to Cast Ingot in the Manufacture of Heavy Forgings

Kim

Kang

et al. 2020

steel research int.

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Continuously cast large round blooms have gained widespread attention due to the improved quality, enhanced economy, higher yields, and lower operating costs obtained through continuous operation. Because the continuous casting (CC) process combines the cleanliness and radial solidification symmetry of the ingot casting process with the higher axial symmetry obtainable through bloom casting, it can deliver a more homogeneous product than conventional ingot casting. Herein, the shop floor manufacturing of a main shaft is discussed to confirm the feasibility of using continuously cast round bloom in the manufacture of heavy forgings. For comparison, the characteristics of a 1000 mm‐diameter continuously cast round bloom are assessed against those of a conventionally cast 20.6 ton ingot. To eliminate cavities at the centerline of the cylindrical bloom, additional studies on void closure efficiency at the center of the billet under various forging die geometries (e.g., flat, V, and round dies) are conducted, and the results reveal that the V‐die geometry is most effective in consolidating centerline voids. A comparison of the respective operational characteristics reveals that the round bloom CC method could be feasibly applied in the manufacture of main shafts.

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Investigation on the void closure efficiency in cogging processes of the large ingot by using a 3-D void evolution model

Cited by 31 publications

References 29 publications

Effect of Deformation Parameters on Microstructure and Mechanical Properties of Internal Crack Healing in As‐Cast 30Cr2Ni4MoV Steel

Effect of Deformation Parameters on Microstructure and Mechanical Properties of Internal Crack Healing in As‐Cast 30Cr2Ni4MoV Steel

Establishment and Application of the Void Closure Prediction Model of 316LN

Feasibility of using Continuously Cast Round Bloom as a Substitute to Cast Ingot in the Manufacture of Heavy Forgings

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