Materials Science and Engineering A 527 (2010) 5033–5037 Contents lists available at ScienceDirect Materials Science and Engineering A journal homepage: www.elsevier.com/locate/msea Quench sensitivity of 2219-T87 aluminum alloy plate Murat Tiryakio˘ glu a,∗ , Ralph T. Shuey b a Robert Morris University, Department of Engineering, 6001 University Boulevard, Moon Township, PA 15108, United States b Alcoa Technical Center, 100 Alcoa Drive, Alcoa Center, PA 15069, United States article info Article history: Received 9 November 2009 Received in revised form 17 April 2010 Accepted 19 April 2010 Keywords: Quench Aging Heat treatment abstract The quench sensitivity of 6.4 mm thick 2219-T87 plate was investigated by using the improved quench factor analysis method and the data of Swartzendruber et al. (NBSIR 80-2069, National Bureau of Stan- dards, 1980). This study was exceptional for the breadth and quality of the investigations. The close integration of the quench factor analysis (QFA) with such a broad and deep independent study of commercial material, was significant in establishing awareness and credibility of QFA. The report by Swartzendruber et al., by the very breadth and depth, exposed some limitations of the QFA. The report did not include emphasizing these limitations nor attempting a remedy. The intention of the present paper is to demonstrate how the QFA can be extended to deal with the limitations implicitly exposed by Swartzendruber et al. The quench sensitivity of the alloy’s yield strength was modeled by three C-curves which represented loss of solute by precipitation of (i)  phase on grain boundaries, (ii)  phase in the matrix, and (iii)  ′ phase on matrix dislocations, which is consistent with previous findings reported in the literature. The model and the implications of the results are discussed in the paper. © 2010 Elsevier B.V. All rights reserved. 1. Introduction 2219 is an aluminum–copper alloy used primarily in high tem- perature applications. Like all heat-treatable aluminum alloys, 2219 loses its capacity to develop the maximum strength as rate of cooling from the solution temperature is decreased. This sensi- tivity to the quench path is attributed primarily to loss of solute by heterogeneous nucleation and growth of quench precipitates which do not provide strengthening during subsequent aging. Although it is desirable to cool the parts from solution treatment to room temperature at the maximum possible cooling rate, the highest cooling rate is often not employed because of the ten- dency for thin products to distort and thick pieces to develop high levels of residual stress. Consequently the cooling path during quenching needs to be designed with a commercially accept- able balance between properties and distortion/residual stress. Quench factor analysis (QFA) was developed by Evancho and Staley [1] to quantify the quench sensitivity of the alloy for this pur- pose. QFA requires that a time–temperature–property curve, alter- natively called C-curve, be available so that properties attainable after quench and age can be predicted as a function of the cooling path. Coefficients defining C-curves typically have been obtained by fitting data on strength or hardness developed after interrupted ∗ Corresponding author. Fax: +1 412 397 2593. E-mail address: tiryakioglu@rmu.edu (M. Tiryakio˘ glu). and/or delayed quench [2]. Review of coefficients by the authors has shown that: • Coefficient sets obtained for similar products or different proper- ties are typically very different. This has prevented using trends to adapt coefficients to incremental changes in composition, fab- ricating path and/or temper. • Coefficients have not been tied to phases nucleating heteroge- neously during the quench. This paper builds on the changes made recently [3] to the QFA equations and demonstrates that properties for different tempers and from different tests can be modeled from the microstructure at the end of the quench. 2. Background The QFA equations predict how a property (primarily yield strength), , of aged product is affected by relation of tempera- ture to time during quench. The decay in attainable strength with time is described as [4]: d dt =  -  min t c (1) where  min is the property after precipitate growth has reached its limit at the particular temperature, and t c is the critical time related to duration of the quench precipitates to nucleate and grow. The 0921-5093/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.msea.2010.04.060