A loss in ductility accompanied by an increase in hardness and strength that occurs when low-carbon steel (especially rimmed or capped steel) is aged following plastic deformation. The degree of embrittlement is a function of aging time and temperature, o ...

Current flowing through paths other than the intended circuit.

Corrosion resulting from direct current flow through paths other than the intended circuit. For example, by an extraneous current in the earth.

The intensity of the internally distributed forces or components of forces that resist a change in the volume or shape of a material that is or has been subjected to external forces. Stress is expressed in force per unit area and is calculated on the basi ...

A multiplying factor for applied stress that allows for the presence of a structural discontinuity such as a notch or hole; Kt equals the ratio of the greatest stress in the region of the discontinuity to the nominal stress for the entire section. Also ca ...

Changes in contour or discontinuities in structure that cause local increases in stress.

The algebraic ratio of two specified stress values in a stress cycle. Two commonly used stress ratios are: (1) the ratio of the alternating stress amplitude to the mean stress. A = Sa/Sm and (2) the ratio of the minimum stress to the maximum stress. R =Sm ...

Heat treatment carried out in steel to reduce internal stresses.

A cracking process that requires the simultaneous action of a corrodent and sustained tensile stress. This excludes corrosion-reduced sections that fail by fast fracture. It also excludes intercrystalline or transcrystalline corrosion, which can disintegr ...

A scaling factor, usually denoted by the symbol K, used in linear-elastic fracture mechanics to describe the intensification of applied stress at the tip of a crack of known size and shape. At the onset of rapid crack propagation in any structure containi ...

In fatigue, the variation in the stress-intensity factor in cycle, that is, Kmax-Kmin.

Also called postweld heat treatment cracking, stress-relief cracking occurs when susceptible alloys are suhjected to thermal stress relief after welding to reduce residual stresses and improve toughness. Stress-relief cracking occurs only in metals that c ...

A fatigue fracture feature, often observed in electron micrographs, that indicates the position of the crack front after each succeeding cycle of stress. The distance between striations indicates the advance of the crack front across that crystal during o ...

Formation of isolated particles of corrosion products beneath a metal surface. This results from the prcferential reactions of certain alloy constituents to inward diffusion of oxygen, nitrogen, or sulfur.

The reaction of a metal or alloy with a sulfur-containing species to produce a sulfur compound that forms on or beneath the surface on the metal or alloy.

Brittle failure by cracking under the combined action of tensile stress and corrosion in the presence of water and hydrogen sulfide. See also environmental cracking.

A surface-active agent; usually an organic compound whose moleculei contain a hydrophilic group at one end and a lipophilic group at the other.

An electrode when polarized frequently yields a current potential relationship over a region which can be approximated by:h=

Surface discoloration of a metal caused by formation of a thin film of corrosion product.

(1) In heat treatment, to reheat hardened steel or hardened cast iron to some temperature below the eutectoid temperature for the purpose of decreasing hardness and increasing toughness. The process is also sometimes applied to normalized steel. (2) In to ...