Finite Element Prediction of Temperature Variation of Material and Dies in Aluminum Forging

Investigation into behaviors of aluminum alloy to be metal formed at the room temperature is conducted in this study. An index is used to evaluate the sensitivity of temperature, that is, index of relative normalized temperature rise to steel called normalized temperature rise index per steel which helps researchers to obtain some insight on new materials based on experiences of steel forging. An investigation to an aluminum alloy shows that the index is quite high, implying that temperature effect as well as rate-dependence effect on the forming processes of aluminum alloy at the room temperature cannot be neglected. Some details of thermomechanical predictions of a relatively high-speed automatic multi-stage forging process of a yoke with highly deformed region are given to reveal the importance of temperature and/or strain rate even in cold forging of aluminum alloy parts with high speed and high strain. All manuscripts must be in English, also the table and figure texts, otherwise we cannot publish your paper. Please keep a second copy of your manuscript in your office. When receiving the paper, we assume that the corresponding authors grant us the copyright to use the paper for the book or journal in question. Should authors use tables or figures from other Publications, they must ask the corresponding publishers to grant them the right to publish this material in their paper. Use italic for emphasizing a word or phrase. Do not use boldface typing or capital letters except for section headings (cf. remarks on section headings, below).

Comparison of Hot Deformation Behavior Characteristics Between As-Cast and Extruded Al-Zn-Mg-Cu (7075) Aluminum Alloys with a Similar Grain Size

The hot compressive behavior and processing maps of as-cast and extruded 7075 aluminum alloys with a similar grain size (320–350 m) were studied and compared, which allows us to directly observe the effect of segregated phases in the as-cast microstructure on the deformation behavior and hot workability of 7075 alloys. In the as-cast alloy, the compound phases segregated along the interdendritic interfaces within the interiors of original grains provided the additional sites for continuous dynamic recrystallization via the particle stimulation nucleation mechanism. As a result, the as-cast alloy exhibited higher fractions of recrystallized grains and smaller grain sizes than the extruded alloy after compression. The stress exponent values of the as-cast alloy were smaller than those of the extruded alloy. In the processing maps, the domain associated with high power dissipation efficiencies (≥35%) occurred in a wider temperature range in the as-cast alloy compared to the extruded alloy. The segregated phases that remained undissolved in the as-cast alloy after compressive deformation could be effectively eliminated during the solid solution treatment (753 K for 2 h) for T6 aging applied after hot compression. The current results suggest the possibility and advantage of omitting the extrusion step when preparing 7xxx aluminum forging or extrusion feedstocks for hot working. The proposed method can be applied to other precipitation hardenable aluminum alloys.

Pressure Temperature Ratings of Aluminum Alloy Flanges

ASME B31.3 Appendix L provides the pressure and temperature ratings of forged aluminum flanges. The flanges are from NPS 1/2 to NPS 24 in three rating Classes 150, 300 and 600 with two grades of aluminum alloys: ASTM B247 3003-H112 and 6061-T6. However, B31.3 does not provide any technical information on the basis of the pressure and temperature ratings. A review of the historical development of ASME B16.5 indicated that the aluminum flanges had the same technical basis for pressure and temperature ratings as the ferrous alloy flanges in ASME B16.5. The 1960 Addenda of the 1957 Edition B16.5 included both aluminum flanges and ferrous alloy flanges. A new Code Case 2905 has been recently approved to allow B31.3 Appendix L aluminum flanges in fabricating Section VIII Division 1 pressure vessels as B16.5 flanges on the basis that both flange specifications have the same safety margin. In this paper, the technical basis of the pressure and temperature rating of aluminum flanges is revisited. Based on the same principle, the pressure ratings are extended to Class 900 and Class 1500 for the two aluminum alloys using the same analysis. Since ASTM B247 5083-H112 is another common grade of aluminum forging alloy, the pressure and temperature ratings are proposed for 5083-H112.

Effects of Die Temperature on Microstructure Evolution of 7A85 Aluminum Forging

The free forging process of medium scale specimen was carried out to study the effects of the die temperature on the microstructure evolution of 7A85 aluminum forging. The results show that with the increase of die temperature, the size of the grains and the distribution of dislocations and precipitates of free forging tend to have a high degree of uniformity. Considering the effects of die temperature, the isothermal forging process was applied for the deformation of complex aviation forging. The metal flows smoothly during the isothermal forging process and thus there is little possibility of forming unfill, crack and other defects. The dislocations are evenly distributed during the isothermal forging process. Consequently, there is a relatively uniform distribution of precipitated phases of the aviation forging.

Investigation of Fatigue Properties for Welded Aluminum Forging Preforms

While welded forging preforms offer potential benefits for producing forged parts, work to date has mainly been concentrated on assessing static mechanical properties. As dynamic properties are an important consideration, the objective in the current study was to assess the high cycle fatigue properties of 6061-T6 aluminum forging performs which were prepared using friction welding. Monolithic and friction welded specimens were prepared and hot worked using a laboratory press. Fatigue data was then generated using a rotating beam test machine and a metallurgical evaluation of the weld zone performed. The results showed that, in general, forged preforms demonstrated superior fatigue life when compared to as-friction welded preforms in the same temper condition. Fatigue performance was also found to be comparable to that obtained from monolithic forging preforms which had an identical processing history.