Effect of Retrogression and Re-Aging Treatment on the Organization and Properties of Cast Aluminum Alloys

Abstract

In this paper, Samples are subjected to tensile test, metallographic microscope observation, scanning electron microscopy (SEM) analysis for exploring the effect of different retrogression and re-aging (RRA) treatments on the organization and properties of casting aluminum alloy. Results show that after aging at 170°C for 10h ,then regression at 230°C for 10min ,finally aging at 170°C for 10h, tensile strength of the sample is 430.19MPa, elongation is 6.18%, compared with the sample aged at 170°C for 10h (The tensile strength was 426.78MPa, elongation was 3.68%). It demonstrated that through the RRA process, strength of sample can effectively maintain at a similar high level as the samples processed single-stage aging. Meanwhile, the elongation of the sample increase nearly 67.9%. The microstructure characterizations indicate that RRA treatment induced the formation and growth of rod-like T phase, and the T phase homogeneously dispersed in the matrix of alloy. This process is proposed to be the major reason for the improvement of ductility.