Optimization of Heat Treatment Cycles and Characterization of Aluminum Alloy AA7010
- 12 Downloads
Multistage retrogression and reaging (RRA) heat treatment has been carried out on aluminum alloy AA7010. Each of the heat treatment steps for this alloy has been optimized on the basis of preliminary hardness and electrical conductivity measurements. These values were found to be a function of precipitate morphology and distribution. Samples were solution-treated (ST) with three different temperatures and quenching media, further aged at fixed temperature (120 °C) with time ranging from 24 to 120 h. Retrogression and reaging is done at 180-240 °C (for time duration of 2-60 min) and 120 °C (for 24-90 h), respectively. ST at 480 °C followed by warm water quenching (70 °C), aging cycle for T6 and T73 condition: 120 °C/42 h and 170 °C/128 h were found to be optimum. The optimum RRA conditions were achieved at retrogression parameters of 200 °C for 60 min and 240 °C for 60 min along with aging parameters of 120 °C/30 h and 120 °C/36 h, respectively. TEM images showed the presence of uniformly distributed precipitates in the matrix in RRA conditions. Statistical distribution of precipitates showed higher frequency of precipitates for RRA with optimized conditions RA1 (120 °C for 42 h + 200 °C for 60 min + 120 °C for 30 h) and RA2 (120 °C for 42 h + 240 °C for 60 min + 120 °C for 36 h).
KeywordsAA7010 electrical conductivity hardness retrogression and reaging solution treatment
Authors are thankful to HWMD/MMG for heat treatment and characterization support. They thank GM, MMA, DD, MME, VSSC for providing guidance during this work and Director, VSSC, for kind permission to publish the work.
- 4.X.J. Raizenne, M.D. Chen, and W.R. Poon, Thirty Years of Retrogression and Re Aging, in ICAS Congress, 2002, pp. 1–11Google Scholar
- 13.P. Mrudula, K.C. Kshirod, and B.R. Raghavendra, Effect of Retrogression and Reaging Treatment on Properties of 7010 Aluminum Alloy Forgings, in National Conference on Challenges in Research & Technology in the Coming Decades, 2014Google Scholar
- 19.A.K. Mukhopadhyay, K.S. Prasad, V. Kumar, G.M. Reddy, S.V. Kamat, and V.K. Varma, Key Microstructural Features Responsible for Improved Stress Corrosion Cracking Resistance and Weldability in 7xxx Series Al Alloys Containing Micro/Trace Alloying Additions, Mater. Sci. For., 2006, 519–521, p 315–320Google Scholar
- 20.P.L. Srinivasamurthy, B.N. Sarada, B.S. Karthik, and S.H. Shamanth, Effect of Retrogression and Reaging Heat Treatment on Microstructure and Corrosion Properties of Al-7075, Int. J. Innov. Res. Sci. Eng. Technol., 2013, 11, p 6434–6441Google Scholar