STP830: Crevice Corrosion of High-Strength Titanium Alloys in Saturated Brine

    Dees, DD
    Development and corrosion chemistOremet Titanium, Albany, Ore.

    Pages: 10    Published: Jan 1984


    Abstract

    The present work in this area is to develop crevice corrosion initiation conditions for Ti-3Al-2.5V, Ti-6Al-4V, Ti-6Al-6V-2Sn, Ti-6Al-2Sn-4Zr-2Mo, and Ti-6Al-2Sn-4Zr-6Mo in saturated sodium chloride (NaCl), as a function of pH and temperature. These high-strength titanium alloys are being used increasingly in corrosive industrial applications.

    The use of titanium and its alloys in aqueous chloride environments can be limited by crevice corrosion at high temperatures and low pH. When crevices are present, titanium and its alloys may exhibit increased localized corrosion under conditions not predicted by general corrosion rates. Temperature, pH, and oxidizing ions are important variables with regard to crevice corrosion in brines. The use of saturated NaCl brine limits the interference of dissolved oxygen on crevice corrosion initiation by decreasing the ability of titanium to form a passive film inside the crevices. Lowering the pH of the saturated NaCl brine has been shown to lower the critical temperature necessary for crevice corrosion to occur.

    Crevice corrosion coupons have been tested in various environments for these alloys. Specimens were bolted together with titanium fasteners and evaluated for possible initiation of corrosion both by discoloration and observance of accelerated corrosion products inside the crevice areas. Various means such as weight loss, surface pitting, and corrosion product identification were used to determine if crevice corrosion had indeed occurred.

    Keywords:

    titanium, titanium alloys, corrosion, corrosion characteristics, corrosion testing, crevice corrosion, corrosion chlorides, pH, industrial applications


    Paper ID: STP32519S

    Committee/Subcommittee: B10.01

    DOI: 10.1520/STP32519S


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