Papers by Keyword: Drawability

Abstract: A feasibility study has been made to produce the Mg alloy sheet of high tensile strength and formability by strip casting and an optimized rolling process. 4mm thickness AZ31 and AZ91 strips were cast successfully. While the microstructure of the cast AZ31 strip consisted of columnar zones, the cast AZ91 strip consisted of fine, equiaxed dendrite and fine precipitations. All samples were rolled to 0.5 mm thickness using an optimized finish-rolling schedule, and their grain size was around 4μm. The ultimate tensile strength (UTS), yield strength (YS) (0.2% offset) and elongation (EL) of the rolled AZ31 sheet were higher than those of commercial AZ31B sheet, and the UTS and YS of the rolled AZ91 sheet were 30% higher than commercial AZ31B sheet. The press formability of the rolled AZ31 and AZ91 sheet was equal or superior to commercial AZ31B sheet.

Abstract: The investigation was focused on the detailed description of precipitation/formation processes of TiN, TixSy, Ti4C2S2, TiC, and (Fe,Ti)P particles occurring in the production of thin sheets of titanium-bearing interstitial-free steels. The knowledge concerning this reactions was gained based on the thermodynamic calculation and physical simulations conducted on Gleeble 3800 thermal – mechanical simulator. The formation process of titanium carbosufide of Ti4C2S2 is the crucial reaction for the thin sheets properties. The investigation confirmed the in-situ mechanism of this phase formation, involving carbon diffusion in the TiS and TixSy sulfides’ crystal lattice. Thus, the precipitation of the substantial fraction of these sulfides is a prerequisite for further intense carbosulfide formation. Titanium sulfides are formed at the rough rolling stage of the transfer bar rolling process. The most intense precipitation of the sulfides occurs at around 1000°C. Besides the effect on the carbosulfide formation, it was found out that the sulfides substantially retard the recrystallization and grain growth in the IF steels. The most favourable Ti4C2S2 formation conditions prevail in the temperature range of approximately 950 - 920°C, which corresponds to the plate finish rolling stage. Both reactions, i.e. sulfides and carbosulfide formation, are deformationinduced processes.

Abstract: To examine the formability of a magnesium-based alloy AZ31 sheet, a temperature and strain rate related constitutive model for AZ31 sheet was developed based on tensile experiments. The relative parameters were obtained by fitting the equation to the experimental data. The comparison between the fitted and the experimental data proved the effectiveness of the model. Based on this model, the deep drawing process has been simulated with the finite element method and the limit drawing ratio (LDR) of AZ31 sheet was numerically studied. The study result was helpful to the application of the stamping technology for the magnesium alloy sheet.