• Journal of the Korean Society for Heat Treatment
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• v.21 no.4
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• pp.189-198
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• 2008

The production of automotive chassis parts requiring both high hardness and good shape-holdability is better realized by using press quenching technology, comprising the austenitizaton and the subsequent press quenching in a specially designed stamping tool. The effect of press quenching mold shape on the hardness distribution, bending height, and degree of planeness of automotive flexible plate during press quenching and tempering has been investigated. The preferable shape of the projections of punch and die in contact with the flexible plate was close to oval to improve the flow of cooling oil, leading to the higher hardness. The press quenching mold with three separate parts was more effective to control the dimensional change due to thermal deformation during press quenching. Some decrease in the bending height during tempering may be related to some recovery of the residual stress at $400^{\circ}C$.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.10a
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• pp.185-189
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• 2009

Recently, ultra high strength products can be manufactured by the hot press forming process of Boron steel in automotive and electronics industries. In order to get high strength, the hot press forming should be accompanied by quenching process inducing phase transformation. There are several types of the hot press forming processes according to the quenching method, water quenching and die quenching, etc. In the study, the process was numerically and physically simulated to compare the two types of quenching processes, and then the strength, hardness and dimensions of the products were compared with try-outs.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.05a
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• pp.337-340
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• 2009

In hot press forming process, the desired high strength can be obtained through quenching process after cold forming of product. The quenching process, however, accompanies undesired distortion due to the volume change during the phase transformation as well as by thermal contraction. In this study the numerical simulation with DEFORM3D-Microstructure is used to predict the deformed shape during the quenching for the quenching fixture design.

• Transactions of Materials Processing
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• v.20 no.8
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• pp.588-594
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• 2011

A new manufacturing process is presented for automotive drive plate using a boron-containing carbon steel sheet, which is hot-formed and press quenched. Particular attention was given to the capability of the process in minimizing dimensional change.

• Transactions of Materials Processing
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• v.22 no.2
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• pp.101-107
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• 2013

The heat transfer characteristics between die and sheet and die and coolant are important parameters in hot press forming process. The determination of the quenching time that guarantees full martensitic transformation requires proper understanding of these heat transfer characteristics. The contact area changes drastically during the quenching process due to volume changes of both die and sheet by temperature drop as well as phase transformation. Several types of modeling techniques are tested in order to select the most suitable. The effect of quenching time as well as die heat conductivity on martensitic transformation is investigated and predictions are compared to experimental results.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.10a
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• pp.186-189
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• 2008

The flex plate, an automotive part which mounts to the automotive engine to transfer torque to transmission, should have considerable hardness and shape accuracy. As a way to produce the flex plate, the hot press forming technology which takes advantages of high formability at elevated temperature, enhanced strength and shape stability was introduced. Therefore, as one of major process parameters the heat treatment condition should be determined to obtain appropriate hardness in the range of manufacturer's specifications. In this study, two heat treatments, austempering and quenching and tempering (QT), were compared as feasible conditions fur the hot press forming of high-carbon tool steel and the hardness and toughness after heat treatments were evaluated. The study showed that both heat treatments resulted in improved hardness but only quenching and tempering showed practicable range of toughness.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.10a
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• pp.181-184
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• 2009

The hot press farming process, which is the press hardening of steel parts using cold dies, can utilize both ease of shaping and high strength due to the hardening effect of rapid quenching during the pressing. In this study, a thermo-elastoplastic analysis of the hot press forming process using the finite element method was performed in order to investigate the deformation behavior and temperature history during the process and the mechanical properties of the pressed parts.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.10a
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• pp.367-370
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• 2009

Recently, ultra high strength products can be manufactured by the hot press forming process of Boron steel in automotive and electronics industries. In order to get high strength, the hot press forming should be accompanied by quenching process inducing phase transformation. In the study, the heat conductive die and the cooling channel were designed by the numerical simulation and the effect of three different parameters were determined to improve cooling characteristics.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1355-1360
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• 2007

The use of high strength steels are gradually increasing to reduce the weight of automobile to improve the environmental problems and collision safety. To encounter the traditional disadvantages of high strength steels like as a poor formability and high springback, hot press forming has been developed. By this method, the strength of steel sheet is increased about three times of original one through die quenching process. In order to the design of hot press forming tools by using numerical simulation, the knowledge of mechanical and microstructural characteristics are required. This study show the mechanical and microstructural characteristics of a high strength boron-alloyed steel according to the various quenching conditions.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1995.06a
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• pp.25-34
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• 1995

Large-scale low-alloy steel shafts, used in the manufacture of steam turbine, are produced by ingot making, forging and heat treatemtn processes. The numerical analysis techniques are introduced to analyze and design the working conditions in each process. The solidification of a steel ingot is studied through the finite element method. The open die press forging and quenching process are simulated by viscoplastic and elastic-plastic finite element method, respectively. Thus numerical analysis techniques are very useful tools to study favorable working conditions for better and more desirable product quality.