Privious Issue

Volume 46 Number 1 (2015.3)

Special Feature

Metal Forming and Processing

Part I. Special Feature


Research Reports

  • 2. A New Model for Growth and Dissolution of Grain-boundary Cementite during Cyclic Vacuum CarburizationPDF(2,470kB)

    pages 1-16
    Hideaki Ikehata, Kouji Tanaka, Hiroyuki Takamiya, Hiroyuki Mizuno and Takeyuki Shimada


    We have developed a model to predict the growth and dissolution of grain-boundary cementite (θGB ) during vacuum carburization by characterizing the microstructures formed upon vacuum carburization and the simulation results. The model fairly accurately reproduces carbon profiles and θGB distributions after cyclic vacuum carburization and diffusion processes.

  • 3. Solidification Analysis of Al-Si Eutectic Alloy with Consideration of Undercooling and Solidification RatePDF(1,217kB)

    pages 17-26
    Jun Yaokawa, Yasushi Iwata, Norihiro Amano and Takashi Nakamichi

    Solidification analysis has been used for simulating die-casting processes to determine proper casting design and conditions. This paper describes a simple calculation scheme for solidification analysis based on the modified temperature recovery method that can simulate undercooling during the eutectic solidification of Al-Si eutectic alloys.

  • 4. Stamping Simulation for Surface Deflection of Automotive Outer Panels PDF(1,020kB)

    pages 27-32
    Noritoshi Iwata, Takamichi Iwata, Masatomo Niihara and Kenichi Takeda

    A calculation method that can consider restriking is proposed. The results using our proposed method are equivalent to the measurement results in both range and magnitude for the sheet metal forming of a fender. Therefore, we confirm that the proposed method for the restriking process is practical.

  • 5. Measurement Methods for Flow Stress of Metallic Materials in Large Strain RangePDF(711kB)

    pages 33-41
    Yasuhiro Yogo, Takamichi Iwata, Michiaki Kamiyama, Masatoshi Sawamura, Noritoshi Iwata and Takashi Ishikawa

    Two methods were developed for measuring a stress-strain curve. One is a ring compression test for thin sheet metals. Using this method, a stress-strain curve can be measured up to a strain of 1.0 considering the plastic anisotropy. The other method is a high-pressure torsion test for bulk metals. With this method, due to very high hydrostatic stress, a specimen can be continuously deformed without fracture. This enables us to measure a stress-strain curve up to a strain of 10.0.

Part II.

Special Review

  • 6. Current Status of Power Device DevelopmentPDF(918kB)

    pages 43-56
    Tetsu Kachi

    The current status of Si, SiC, and GaN power devices is reviewed. Recently developed device structures and the theoretical limit of on-resistance in Si power devices are discussed. For SiC and GaN power devices, experimental performance and issues remaining to be solved are reviewed.

Research Report

  • 7. Resonant Dielectric Gratings for the Control of Light Propagation and Thermal RadiationPDF(846kB)

    pages 57-63
    Kota Ito, Takayuki Matsui and Hideo Iizuka

    This paper is an overview of our recent studies on resonant dielectric gratings. Firstly, we present an asymmetric grating that exhibits novel reflection and transmission characteristics. Secondary, resonant modes in gratings coupled to surface modes of specific substrates are demonstrated to control thermal radiation characteristics.

Brief Report

  • 8. High-density Magnetic Composite for Reactor in Hybrid VehiclePDF(687kB)

    pages 65-67
    Takeshi Hattori, Masaki Sugiyama, Hidefumi Kishimoto and Takanobu Saito

    A new powder magnetic core was developed for the reactor used in the boost converter of a hybrid vehicle. Through advances in three technologies, (1) high-density powder compacting, (2) particle shape control, and (3) high-heat-resistance insulator coating, large cost reductions were achieved while maintaining magnetic properties comparable to those of high-grade magnetic steel.