A linear imperfection in a crystalline array of atoms. Two basic types are recognized: (1) an edge dislocation corresponds to the row of mismatched atoms along the edge formed by an extra, partial plane of atoms within the body of a crystal; (2) a screw d ...

Corrosion that occurs under organic films in the form of randomly distributed threadlike filaments or spots. In many cases this is identical to filiform corrosion.

Same as strain hardening.

A chromate conversion coating produced on magnesium alloys in a boiling solution of sodium dichromate.

The property of a material by virtue of which deformation caused by stress disappears upon removal of the stress. A perfectly elastic body completely recovers its original shape and dimensions after release of stress.

The condition of an electrode when the rate of anodic dissolution just balances the rate of cathodic plating.885

Deforming metal plastically under conditions of temperature and strain rote that induce strain hardening. Usually, hut not necessarily, conducted at room temperature. Contrast with hot working.

(1) Water having salinity values ranging from approximately 0.5 to l7 parts per thousand. (2) Water having less salt than seawater, but undrinkable.

Material placed in a drilled hole to fill space around anodes, vent pipe, and buried components of a cathodic protection system.

The electrode of an electrolytic cell at which reduction is the principal reaction. (Electrons How toward the cathode in the external circuit.) Typical cathodic processes are cation' taking up electrons and being discharged, oxygen being reduced. and the ...

The maximum stress that a material is capable of sustaining without any permanent strain (deformation) remaining upon complete release of the stress.

A surface treatment at elevated temperature, generally carried out in pack, vapor, or salt bath, in which an alloy is formed by the inward diffusion of chromium into the base metal.

The lowest value of oxidizing potential at which pits nucleate and grow. It is dependent on the test method used.

Heating a metal or alloy to such a high temperature that its properties are impaired. When the original properties cannot be restored by further heat treating, by mechanical working, or by a combination of working and heat treating, the overheating is kno ...

A factor of proportionality representing the amount of substance diffusing across a unit area through a unit concentration gradient in unit time.

Any interruption in the normal physical structure or configuration of a part, such as cracks, laps, seams, inclusions, or porosity. A discontinuity may or may not affect the usefulness of the part.

The relative humidity above which the atmospheric corrosion rate of some metals increases sharply.

A metastable aggregate of ferrite and cementite resulting from the transformation of austenite at temperatures below the pearlite range but above M

(1) Reduction of corrosion rate by shifting the corrosion potential of the electrode toward a less oxidizing potential by applying an external electromotive force. (2) Partial or complete protection of a metal from corrosion by making it a cathode, using ...

(1) An iron mineral crystallizing in therhombohedral system; the most important oreof iron. (2) An iron oxide, Fe,O,, corrcsponding to an iron content of approximately 70%.