• Transactions of Materials Processing
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• v.17 no.8
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• pp.600-606
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• 2008

In closed-die hot forging, a billet is formed in dies such that the flow of metal from the die cavity is restricted. Some parts can be forged in a single set of dies, whilst others, due to shape complexity and material flow limitations, must be shaped in multi sets of dies. The purpose of a performing operation is to distribute the volume of the parts such that material flow in the finisher dies will be sound. This study focused on the design of preforms, flash thickness and land width by theoretical calculation and finite element analysis, to manufacture the super hot forging product, 70MC type piston crown used in marine engine. The optimal design of preforms by the finite element analysis and the design experiment achieves adequate metal distribution without any defects and guarantees the minimum forming load and fully filling of the cavity of the die for producing the large piston crown. The maximum loads obtained by finite element analysis are compared with the results of experiments. The loads of the analysis have good agreements with those of the experiment. Results obtained using DEFORM-2D enable the designer and manufacturer of super hot forging dies to be more efficient in this field.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.05a
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• pp.479-482
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• 2005

To improve the efficiency of fossil power plant, the higher steam temperature and pressure are required. Ultra super critical(USC) system meets very well this requirement. The HIP rotor is one of the most important parts of turbine in USC system and its material is easy to crack during hot forging. In this study, the upsetting and cogging process far $12\%Cr$ ESR ingot was analyzed and it is suggested a optimum process to avoid surface crack. The results were verified by test product with 4,200 tonnage press.