The objective of the study described here is to elucidate the effect of carbon and niobium on the microstructure, precipitation behaviour, and mechanical properties of 0?09C-0?11Ti (%) steel and 0?05C-0?025Nb-0?11Ti (%) steel under ultra fast cooling condition. The strengthening mechanisms are also discussed. The ferrite grains size and the size of precipitates in Ti and Nb-Ti steels were measured respectively. The mechanical properties obtained in Ti steel were similar to Nb-Ti steel with yield stress .700 MPa, elongation .20%, and good low temperature impact toughness. The study underscores that addition of higher carbon content by 0?04% under controlled rolling and ultra fast cooling conditions, we can achieve similar strength in the absence of micro-alloying element, niobium.

No abstract

The implicit parametric method was briefly discussed in this paper. An implicit parametric 3D solid model and a finite element (FE) model of a body-in-white (BIW) were built up by this method. Low order natural vibration frequencies and modes, bending and torsional stiffness of the BIW were analyzed by FE calculation. A good agreement was acquired by comparing the prediction results with the test values. Results indicated that the implicit parametric model of the BIW established could be used for design and development of the BIW in concept design stage of the BIW.

No abstract