SEDL / STP / STP656-EB / STP34848S

Intergranular Corrosion Testing and Sensitization of Two High-Chromium Ferritic Stainless Steels

Nichol, TJ
Technical marketing manager and research specialist, stainless and alloy steel metallurgy, Allegheny Ludlum Steel Corporation, Research Center, Brackenridge, Pa.

Davis, JA
Technical marketing manager and research specialist, stainless and alloy steel metallurgy, Allegheny Ludlum Steel Corporation, Research Center, Brackenridge, Pa.

Pages: 18    Published: Jan 1978

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Abstract

The effect of several parameters (alloy chemistry, thermal history, and solution chemistry) on the resistance of two new ferritic stainless steels to intergranular corrosion was investigated. The susceptibility of Types 26-1S and 29-4 to intergranular corrosion depended on the alloy chemistry and the particular test used to evaluate susceptibility. For both alloys, the severity of the standard tests increased in the following order: copper sulfate (CuSO⁴)-16 percent sulfuric acid (H²SO⁴), nitric acid (HNO³)-hydrogen fluoride (HF), CuSO⁴-50 percent H²SO⁴ and ferric sulfate (Fe²(SO⁴)³)-50 percent H²SO⁴. Sensitization was produced in these alloys by either welding or high-temperature annealing followed by air cooling. The most reliable evaluation method was bending of the material combined with optical examination.