Although galvanic corrosion is not commonly encountered, it may occur if these, Cold water is the most commonly used quenching medium for many hard, aluminum alloys (2xxx, 6xxx and 7xxx). Effect of quenching rate on the properties of 7075-T6 sheet, plate and forging. The linear £ow velocity was calculated using the volume £ow from the pump, and the cross-sectional area of the sleeve and the probe. Statistical models for quench factor and predicted, yield strength were developed using standard multiple linear regression analysis, techniques to determine the signi¢cant variables relative to the modeled response, cross-section size for (a) 6061; (b) 2024-T3 and T-4; and (c) 7, The contour plot shown in Fig. However, it must be remembered that the particular C-curves obtained, for an alloy are composition-dependent. , March 10^12, 1997, St. Louis, MO, (T. Bains and D. S. MacKenzie, , (H. Walton and R. Wallis, eds. However, the quenchant may undergo slow con-, tamination, such as metal ion build-up, or even a slow molecular weight, degradation process. 46, following this value horizontally until it intersects the diagonal, line representing a ¢lm coef¢cient of 0.21. value for the maximum thickness that can be expected to be properly quenched. sequent heating must not be suf¢cient to affect the tensile properties [95]. In such. the workpiece to the quenchant is controlled by events occurring in three stages: ¢lm boiling, nucleate boiling and convective heat transfer. ess’’, Hrterei-Tech. Wedge specimen and cooling rates at various locations in the specimen. 68. This process may. 33^40. thick AA, F water; (b) Effect of surface preparation on mid-plane cooling, (a) Wetting sequence for a cylindrical specimen quenched in distilled water at, f an AlMg5 sample in distilled water at 80, C. Both probes were cleaned with 600 grit abrasive paper before, ) were extremely short. ), 1991, The Minerals, Metals and Materials Society, pp. G. E. Totten & Associates, Inc., Seattle, Washington, U.S.A. If an alloy is slowly cooled from an elevated temperature, alloying elements are, precipitated and diffuse from the solid solution to concentrate at the grain, boundaries, small voids, on undissolved particles, at dislocations, and other. using a data sheet such as the one shown in Fig. 47 and properties of AA7075-T73 aluminum plate as a function of water tempera-, Quench factor charcterization of quenching media can provide a valuable insight, into the quenching of aluminum alloys with water [54]. Schuler reported that, the critical cooling rates (cooling rates between 750^550, intergranular corrosion [90]. The properties in plate were higher than in forged and quenched, specimens as illustrated in Fig. Laboratory test procedure and the quenching of production parts are described. Heat transfer is fastest. Elements are kept. offered significant, often dramatic, advantages in residual stress and distortion reduction. However, cold water, hot water and aqueous polymer solutions, are the most frequently used throughout the world to process aerospace aluminum, If the diffusion process is suf¢ciently fast during quenching, alloying elements and, compounds may precipitate in the grain boundaries. during quenching be suf¢ciently fast to minimize precipitation during cooling. Intergranular corrosion occurs, in aluminum-copper alloys; Al-Cu-Mg (2xxx), Al-Zn-Mg-Cu (7xxx) and Al-Mg, series aluminum alloys is caused by the loss of copper or suf¢cient magnesium. The dis-, tortion reduction advantages of PAG quenchants relative to both cold and hot water, are illustrated in Fig. 2, July 1998; pp. Illustration of a typical analytical data log sheet. Thick parts of high–strength aluminium alloys usually undergo a drastic quench which gives rise to thermal stresses and may cause distortion of products. Up to bath, process always began at the surface that was geometrically lower in the bath. 7075 aluminum alloy plate quenched into different con-, C). The, boiling mechanism is stabilized by increas. 43^47. solution is dependent on an inverse solubility mechanism as illustrated in Fig. factor analysis. The overaged alloy AA7075-T73 was quite resistant to stress corrosion. aluminum alloys are provided in Table 6 [37,38]. alloys have been published. The large temperature difference creates a, high thermal stress which often causes plastic deformation in the web. Wärmeübergangszahl) berechnet. Aluminum’’, Adv. index is affected by oil and metallic salts. Cooling curves for 1 in. The, is then calculated for each average temperature using the above equation. 62 [71] or the quenchant can be replaced if salt con-, Although thermal separation may be performed by simply heating the, quenchant in the tank until separation occurs, this process is not applicable for larger, tanks. tempers which can be used in quench factor calculations [37,38]. To satisfy this need, a process to quantitatively measure the rewetting process of, standard quenched aluminum probes was developed [52,53]. Mitt., 1987, 42(3), pp. Heat Mass Transfer, 1981, Hemisphere Press, Washington, D.C., pp. Thermal conductivity (, of various materials is provided in Table 5. Figure 43 illustrates the superposition of a cooling curve on a C-curve [37]. ing through the membrane. B. Übergangstemperatur vom Film- zum Blasensieden (LEIDENFROST-Punkt) und Abkühlgeschwindigkeiten). 1, the fraction transformed equals the fraction represented by the C-curve. )