Accession Number : ADA579023


Title :   Corrosion Mechanisms in Brazed Al-Base Alloy Sandwich Structures as a Function of Braze Alloy and Process Variables


Descriptive Note : Final rept. 27 Mar 2006-31 Dec 2012


Corporate Author : VIRGINIA UNIV CHARLOTTESVILLE OFFICE OF SPONSORED PROGRAMS


Personal Author(s) : Scully, John R


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a579023.pdf


Report Date : 01 Feb 2013


Pagination or Media Count : 61


Abstract : 14 AA 6061 (UNS A96061) and AA4047 (UNS A94047) were brazed to construct a tapered modelbraze joint with variable braze clearance. Isolated AA 6061 T6 was also exposed to the thermal cycle of a typical dip brazing process without applying filler metal. The braze, mixed, and heat affected zones were modeled by thermochemical computations and characterized experimentally. Corrosion exposures were conducted in accordance with BS 11846 Method B for detection of intergranular corrosion (IGC). Each zone developed its own corrosion morphology traced to the unique chemical composition and metallurgical characteristics. The brazing thermal cycle promoted IGC of isolated AA 6061. Moreover, the Al-Si braze and AA 6061 joint promoted additional intergranular corrosion in the Si containing mixed zone exacerbated by grain boundary Q (AI4Cu2Mg8Si7) and phases as well as eutectically formed Sineedles at solidification boundaries. Pitting occurred in the Al-Si braze zone.


Descriptors :   *BRAZING ALLOYS , *CORROSION , BRAZING , CHEMICAL COMPOSITION , COMPUTATIONS , DETECTION , EXPOSURE(GENERAL) , FILLERS , GRAIN BOUNDARIES , GRANULAR MATERIALS , METALLURGY , METALS , MIXING , SOLIDIFICATION , THERMAL CYCLING TESTS , THERMOCHEMISTRY , VARIABLES


Subject Categories : Metallurgy and Metallography


Distribution Statement : APPROVED FOR PUBLIC RELEASE