Investigation of the quenching sensitivity of forged 2A14 aluminum alloy by time-temperature-tensile properties diagrams

To guide the design of quenching technologies for forged 2A14 aluminum alloys, the quenching sensitivity of this material was investigated with time-temperature-tensile properties (TTP) diagrams. The TTP diagrams were determined by interrupted quenching experiments followed by tensile testing. The microstructures were observed with TEM and EDX. The results indicate that the quenching sensitivity temperature range is from 300 to 390 degrees C and the nose temperature is about 350 degrees C. The tensile strength and yield strength decrease rapidly in the quenching sensitivity temperature range, and they decrease most rapidly at the nose temperature. In addition, the yield strengths decrease faster than the tensile strengths with increasing isothermal holding times. At the nose temperature of 350 degrees C, quench-induced rod-shaped theta ' particles precipitate and grow rapidly because of the high diffusion rate of the solute and the high phase-nucleation rate. The amount and size of the rod-shaped theta ' particles increase when the holding time is prolonged. This increase results in a decrease of supersaturated solid solution after the quenching, which reduces the density of the needle-shaped fine age-induced precipitates theta ' and theta '' (strengthening particles) and increase the breadth of precipitate free zone (PFZ) after the aging treatments. (C) 2017 Published by Elsevier B.V.