STP728: Effects of Iron on the Corrosion Resistance of Titanium

    Covington, LC
    Chief corrosion engineer and research engineer, Henderson Technical Laboratories, Timet Division, Titanium Metals Corp. of America, Henderson, Nev.

    Schutz, RW
    Chief corrosion engineer and research engineer, Henderson Technical Laboratories, Timet Division, Titanium Metals Corp. of America, Henderson, Nev.

    Pages: 18    Published: Jan 1981


    Abstract

    This paper presents the results of extensive laboratory tests and experience in industrial applications to explain the effects of iron on the corrosion resistance of titanium.

    In the great majority of cases where titanium is being used in corrosive environments, the effect of iron at the levels normally found in unalloyed titanium (⋍0.1 percent) is insignificant and has not led to any problems. However, in some cases, high solid-solution iron levels have been blamed for premature failures due to pitting or hydrogen embrittlement. Tests conducted at TIMET, Henderson, Nev., suggest that solid-solution iron has little, if any, effect on susceptibility to pitting or hydrogen embrittlement.

    Iron particles embedded in the surface of unalloyed titanium are very deleterious. They serve as initiation sites for pitting and also as entry points for hydrogen.

    Ferric ions in the corrosive solution are beneficial and serve as an excellent passivating agent for titanium. Iron oxide deposits on the surface of titanium also have a passivating effect.

    Galvanic coupling of titanium and iron can lead to accelerated corrosion of the iron and, in some environments, to hydrogen embrittlement of the titanium. The magnitude of the effect is dependent on surface area ratios and the characteristics of the environment. Titanium, however, is being widely used successfully in applications where galvanic coupling with iron exists, with comparatively few problems being reported.

    Keywords:

    titanium, iron, corrosion, industrial applications


    Paper ID: STP28066S

    Committee/Subcommittee: B10.01

    DOI: 10.1520/STP28066S


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