Hot-press forming(HPF) steel can be applied successfully to auto parts because of its superior mechanical properties. However, its resistances to aqueous corrosion and the subsequent hydrogen embrittlement(HE) decrease significantly when the steel is exposed to corrosive environments. Considering that the resistances are greatly dependent on the properties of coating materials formed on the steel surface, the characteristics of the corrosion and hydrogen diffusion behaviors regarding the types of coating material should be clearly understood. Electrochemical polarization and impedance measurements reveal a higher corrosion potential and polarization resistance and a lower corrosion current of the Al-coating compared with Zn-coating. Furthermore, it was expected that the diffusion kinetics of the hydrogen atoms would be much slower in the Al-coating, and this would be due mainly to the much lower diffusion coefficient of hydrogen in the Al-coating with a face-centered cubic structure. The superior surface inhibiting effect of the Al-coating, however, is degraded by the formation of local cracks in the coated layer under severe stress conditions, and therefore further study will be necessary to gain a clearer understanding of the effect of cracks formed on the coated layer on the subsequent corrosion and hydrogen diffusion behaviors.

The driving efficiency in vehicles depends on a weight lightening of wheels. Lightweight aluminum wheel research has been widespread over the years. Carbon wheels reduce weight by 50% compared to aluminum wheels and have high tensile strength and low heat absorption. This study was investigated to apply the carbon fiber of molding pressure to produce the carbon wheel. Carbon wheel of mold structure analysis was performed.

In this paper, research development about a bladder press forming system has been carried out for sheet metal forming. The bladder press forming system consists largely of three units as follows forming process unit, driving unit and hydraulic power unit including bladder. Structural analysis of frame of total system by the ANSYS program, flow analysis of bladder by CFX version 14 and hydraulic circuit analysis by AMESim were carried for basic design of bladder press forming system. We can get a good forming results from bladder press system. Developed bladder press forming system will be largely used in aircraft manufacturing industry field.

The objective of this study is to predict the formability of sheet metal for the bladder press. The static implicit finite element method is applied effectively to analyze bladder forming processes using AutoForm software. The material used for forming analysis is AL2024, and the thickness of the plate is 1.6mm, 1.8mm and 2.0mm. Forming force is shown by 101.92kN～87.22kN. The result from the simulation analysis was applied to the bladder press system.