SEDL / STP / STP656-EB / STP34850S

Intergranular Corrosion in 12 Percent Chromium Ferritic Stainless Steels

Lula, RA
Assistant to the vice president of research and research specialist, stainless and alloy steel metallurgy, Research Center, Allegheny Ludlum Steel Co., Brackenridge, Pa.

Davis, JA
Assistant to the vice president of research and research specialist, stainless and alloy steel metallurgy, Research Center, Allegheny Ludlum Steel Co., Brackenridge, Pa.

Pages: 15    Published: Jan 1978

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Abstract

Intergranular corrosion of Types 409, 405, and 410 stainless steels was evaluated in the heat treated and welded condition. Standard ASTM Method A 262 corrosion tests are too severe for 11 to 13 percent chromium steels, and two modified tests were developed: 65 percent nitric acid at 49°C (140°F) and 50 percent sulfuric acid-cupric sulfate at 49°C (140°F). Type 409, a titanium stabilized ferritic steel, shows intergranular corrosion in nitric acid but is immune in the cupric sulfate test. Type 405 with a duplex structure shows intergranular corrosion in both tests. Type 410 with a martensitic structure does not exhibit intergranular corrosion. The behavior of these steels is explained based on their microstructure.