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In this study, to confirm the practical advantages and acceptability of galvannealed TS800MPa grade dual-phase steel (DP800), crashworthiness and spot weldability as important properties in practical use were investigated and compared with conventional galvannealed TS440MPa grade and microalloyed TS600MPa grade steels, which are currently used for frame parts. The results have shown that DP800 has high absorbed energy on crash tests, and has almost the same acceptable weldability as comparative steels.

A 2001 SAE paper et al. [1,2] compared the formability aspects of six different grades of galvanealed steel [IF (270E), C-Mn (440W-1), low C - high Mn (440W-2), HSLA440 (440R), HSLA590 (590R) and DP590 (590Y)]. This study has been expanded to evaluate five additional advanced galvanealed steel grades [Low yield type DP780 (780YL), High yield type DP780 (780YM), DP980 (980Y), TRIP590 (590T), and TRIP780 (780T)]. The study presents material properties, forming characteristics in several lab tests and spring back characteristics. The study provides the actual and relative performance of these eleven steels and conclusions on the advantages these grades provide in cost-effective and mass-effective solutions to the manufacturing and performance requirements of the automotive body.

In this paper a computer simulation study on the effects of steering parameters on lateral dynamics of the guideway bus to contribute to a development practice of designing optimum steering control system are dealt with. A stability limit of vehicle lateral motion is analyzed and an emphasis is laid on the effects of moment of inertia of a conventional steering wheel and lateral elasticity of the guide rail which have proven to reduce the critical vehicle speed. It is pointed out conclusively that a normal bus equipped with additional simple guidance equipments can be guided smoothly on a simple guideway at adequately high vehicle speed.

To develop ultra high strength ERW tubing for the door beams of passenger cars using cold rolled steel sheet, an FEM analysis was performed using a tubing deformation model which simulated door beam testing. In the elastic and plastic FEM analysis, the effects of the yield strength and tensile strength of the steel sheet on tubing properties were investigated. The results showed that the tubing peak load in three-point bending increases with an increase in tensile strength. An increase in yield strength enhances the endurance load in the early stages of deflection while it slightly accelerates buckling. The analysis resulted in the production of TS 1470N/mm2 grade cold rolled sheet to be manufactured into ERW tubing. A 0.22%C-0.4%Si-2.4%Mn-0.03%Nb cold rolled steel with a thickness of 2mm was processed in a continuous annealing line which employed water quenching.

TS590N/mm2 hot rolled steel showing a good balance of stretch formability and stretch flangeability has been newly developed for manufacturing high strength automotive parts. A laboratory study revealed that an introduction of a small amount of martensite in ferrite · bainite microstructure remarkably improves uniform elongation of ferrite · bainite steel giving little influence on its good localized elongation. Characteristics in ductile property of this “Tri-Phase” type steel were confirmed in press forming tests.