Nitric acid exposure, intergranular corrosion

Test method for determining the susceptibility to intergranular corrosion of 5XXX series aluminium alloys by mass loss after exposure to nitric acid (NAMLT test) Practice for liquid sodium corrosion testing of metals and alloys... 

Fig. 7.57 Effect of carbon and nickel content on intergranular corrosion penetration rate of 1 8 wt% Cr-base stainless steels. Alloys sensitized for 100 h at 550 °C. Immersion in boiling 65% nitric acid. Pds., periods (48 h) of exposure. Redrawn from Ref 84...

ASTM Standard G 67, Standard Test Method for Determining the Susceptibility to Intergranular Corrosion of 5XXX Series Aluminum Alloys by Mass Loss After Exposure to Nitric Acid, Annual Book of ASTM, 1999, 03.02. 

ASTM A-262 [7.21] has standardized five different methods for testing intergranular corrosion of austenitic stainless steels, after Streicher (two), Huey, Warren and Strauss. The Warren test, using exposure to nitric acid-fluoric acid, is particularly suited for molybdenium-alloyed steels. 

A rather unique mass loss test method, ASTM G 67 (Test Method for Determining the Susceptibility of Intergranular Corrosion of 5xxx Series Aluminum Alloys by Mass Loss After Exposure to Nitric Acid [NAMLT Test]) has been developed to provide a quantitative measure of the intergranular susceptibility of 5xxx series Al-Mg and Al-Mg-Mn allo3rs. The technique is useful to determine whether material has become sensitized by exposure to elevated temperature. Development of the test is reported in Ref 23. 

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