| Summary: | 碩士 === 國立交通大學 === 機械工程系所 === 105 === Energy saving and carbon reduction are the main goals of industries all over the world. Automotive industry aims at cutting carbon dioxide emissions under the premise of the vehicle safety standards by utilizing the ultra high strength steels. However, the forming of the ultra high strength steels in room temperature will induce some problems such as the tendency to springback and fracture. In order to overcome these defects, the hot stamping process has been developed. High temperature in hot stamping process are able to soften the steel and solve the defects. The tensile strength of hot stamped steels can exceed 1500MPa by transforming the ferritic-pearlitic microstructure to the high strength martensitic microstructure. With the development of high-strength steels, each country establishes higher vehicle safety standards. The design of vehicle parts pursues not only high strength but also the ability to absorb impact energy. Thus, the tailored blanks are applied to meet those demands.
The research uses the finite element analysis software DEFORM to establish the tailor die quenching process model for the hat-shape part which has B-pillar’s characteristics, and the influence of the process parameters on the strength of the hot stmap product was discussed. The design parameters of the die heating system were also discussed.
The previous results are introduced into the U-shaped model for tailor die quenching process, and compare the result with constant die temperature model. The results show that the hot stamp product of die heating system got uniform hardness distribution, which is similar to the hot stamp product of constant die temperature model. Only the width of transition zone is increased. The result shows that the die heating system design parameters in this study are able to improve the strength distribution of tailor die quenching product and can be used as a initial die design reference.
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