Papers by Keyword: Melt-Treatment

Abstract: 3003 Al alloy with different metallurgical quality were obtained by different melt-treatment methods, which were deformed by isothermal compression in the range of deformation temperature 300-500°C at strain rate 0.0l-10.0 s^-1 with Gleeble-1500 thermal simulator. The results show that the material is sensitive to positive strain rate. The hot deformation activation energy (Q) bears linear relationship with inclusion content (H) of 3003 Al alloy prepared by different melt-treatment, Q=35.62 H+171.58, the activation energy of 3003 Al alloy prepared by high melt-treatment is the lowest (174.62 KJ×mol^-1), which is beneficial to the material hot plastic deformation. The critical strain of 3003 Al alloy prepared by different melt-treatment methods is investigated through the work hardening rate. Finally, the critical conditions of the investigated alloy were determined to predict the dynamic recrystallization occurrence in the paper.

Abstract: The as-cast microstructure feature of Al sheet with high forming properties used for pressure can manufacturing pre-treated by different melt-treatment technique was observed and analyzed by SEM, EDAX, TEM and selected area electron diffraction (SAED), etc. It was found that the oxide inclusions in Al sheet were mainly γ-Al2O3, and the Fe-rich impurity phases in the sheet mainly Al3Fe, T1(Al12Fe3Si) or (AlFeSiRE). The crystal structure of (AlFeSiRE) phase was too complicated to be determined. The effect of melt-treatment technique on the as-cast microstructure of the sheet was remarkable. There were a number of oxide inclusions in the Al sheet before or after conventional melt-treatment, which distributed non-uniformly and gathered together in larger block shape with the size of about 10-40μm. The Fe-rich impurity phases in the sheet were mainly Al3Fe and T1, and a few of the meta-stable phase Al6Fe existed in the sheet. These Fe-rich impurity phases appeared in a coarse, long needle/flake or skeletal form, and were easily to gather together with oxide inclusions. When the Al sheet was treated by high-efficient melt-treatment, the amout of oxide inclusions was decreased obviously, and these inclusions distributed more uniformly in the tiny granular form (about or less than 4μm). The Fe-rich impurity phases were mainly (AlFeSiRE), and a small amount of Al3Fe phases also existed in the material. The (AlFeSiRE) phases distributed uniformly along grain boundary in tiny group/sphere or short stick form. No congregation of Fe-rich phases with oxide inclusions was found in the material.

Abstract: The Al sheet used for pressure can manufacture (or called Al piece) was prepared by different melt-treatment techniques and using the lower grade commercial purity raw Al (Al99.5). And the influence laws of melt-treatment techniques on the metallurgical quality and mechanical properties of Al piece were investigated. It is found that high-efficient melt-treatment technique improves the metallurgical quality of Al piece remarkably, that is, the rate of removing inclusions and the extent of lowering porosity amount to about 66.6% and 87.0%, respectively, and as-cast mean grain diameter decrease to a great extent, and the coarse and long needle/flake Fe-rich impurity phases transform into complex compounds of tiny, sphere/short stick form, which makes fracture mechanism of the material be transformed into the congregation of transgranular micro-hole, thus raising mechanical properties of this material remarkably. Its metallurgical quality and mechanical properties have reached or exceeded the level of present products. It is feasible that Al piece is made by using the lower grade commercial purity raw Al. The viewpoint that the purification is the fundamental and key process, i.e., the basic of modification and grain refinement processes, has been also further tested and verified.