K-Alloy (A304) B117 Salt Spray Test Results
The following photos of K-Alloy (A304) and A360 Alloy are after 30 days of ASTM B117 salt spray chamber testing utilizing cycles of salt, heat and vibration.
Photo 1 illustrates a cast A360 aluminum part (an alloy that has a good rating for corrosion resistance) showing signs of severe corrosion over many areas after 30 days of B117 salt spray testing.
In high magnification shown in photo 2, the same A360 casting exhibits severe signs of corrosion on the corners (which have been rounded). In addition the casting surface shows signs of surface degradation.
After removing the top cover (Photo3) the surface of the A360 casting which contained a pour-in-place gasket, exhibits signs of water intrusion leading to product failure. Corrosion to the edge of the casting was pronounced. The raised area on the perimeter of the casting showed signs of aggressive corrosion. This casting had indications of water around the entire sealing surface. Surface pitting was visible on all casting surfaces.
To clarify the corrosion damage the above A360 casting was lightly bead blasted to remove the adhesive and aluminum oxide from the sealing surface. Photo 4 clearly shows that the aluminum material had been removed by the salt spray process. Pitting on the casting surface was uniform across the casting. The raised perimeter was completely missing in some places.
Photo 6 is a housing manufactured from BorgWarner K-Alloy. This casting was exposed to the same 30-day salt spray cycle as above. Pronounced deterioration of the screw fasteners is evident from the white ring around the contact point on the casting. The casting itself did not show signs of corrosion.
Photo 7 is the same K-Alloy casting as Photo 6 with the top lid removed. The sealed surface was still intact and showed no sign of water intrusion. The housing showed no sign of surface corrosion.
Photo 8 is the same K-Alloy casting as Photo 6 after is had been lightly blasted with glass beads to remove salt residue and dispensed adhesive material on the sealing surface. The casting shows no visual damage from corrosion or metal loss due to salt spray reaction.
