Apparatus for Stress Corrosion Tests in Boiling Magnesium Chloride Solutions

Time-to-failure in stress corrosion tests on stainless steels and related alloys depends on the temperature of the boiling magnesium chloride test solution. Small losses of water vapor and condensate from solutions in the range of 40 to 46 wt % MgCl₂ lead to rapid increases in boiling temperature. Components of a three-part test apparatus – flask, condenser, and trap – have been designed to reduce losses of water vapor and condensate to negligible proportions. With this apparatus the temperature of the boiling magnesium chloride solution can be held constant, e.g. at 155 C ±1 C (311 F ± 1.8 F), for periods of 100 days or more. This apparatus for reducing vapor and condensate losses may also be useful for other solutions whose boiling points are significantly affected by such losses. Design details are given for a 1-liter Erlenmeyer test flask, condenser, and vapor trap. In addition, dimensions are provided for two stress corrosion specimens, a U-bend and a bent-beam, together with holders for these specimens, which fit a 1-liter test apparatus.