This paper presents previously unavailable constants for the Sellars and Tegart constitutive model for hot metalworking. The materials considered are aluminium alloys 2024, 5083, 6061, 7050, 7075 and 356, carbon steel 1018, stainless steel 304, titanium alloy 6Al–4V, and magnesium alloys AZ31 and AZ61. These materials and their mechanical properties at high temperature are of great interest for latest generation manufacturing processes involving deformation to accomplish solid state joining, such as friction stir welding, cold spray and magnetic impulse welding. The results are also useful to model established processes, such as hot rolling, forging and creep. The methodology used to obtain the constants consists on non-linear regressions based on partial data sets as it was conducted previously. The input data were obtained from published values for hot compression experiments. All regressions presented here have a coefficient of determination R2>0·95. When possible, the results obtained were compared to previous published regressions.
1 October 2011 in Materials Science and Engineering: A
The development of titanium foams with a low elastic modulus has increased their scientific and technological relevance due to the evident need to avoid stress shielding problems. In this work, we studied the synthesis and characterization of Ti-13Zr-13Ta-3Nb (wt.%) alloy foams which present high potential for biomedical applications. A Ti-Nb-Ta-Zr mixture was produced by mechanical alloying using a planetary mill. Ti alloy foams were obtained using NaCl as a space-holder (40, 50, and 60 v/v %) that was mixed with the metallic powders and compacted under 420 MPa stress. NaCl particles were removed from the green compacts by submerging samples in distilled water at 60 °C. The green compacts were sintered at 1300 °C for 3 h in Ar atmosphere. Powders and foams were characterized by SEM and optical microscopy. The results showed that Ti-based foams with a tailored heterogeneous pore distribution can be obtained using the space holder method. The elastic modulus (E) of foams was estimated and measured between 5 and 25 GPa using theoretical and finite element analysis (FEA) models which are close to the E values measured experimentally. The results showed that foams with 50% and 60% porosity are potential bone replacement materials because their E value is closer to the E value of human bone.
4 November 2023 in Materials Science and Engineering: A