Corrosion Control
Corrosion Control is a serious concern for all manufacturers, especially those using a "closed-loop" cooling system for injection molds. The microstructure and heat treatment of tool steels are carefully controlled to optimize corrosion resistance. The joining of dissimilar metals presents a never-ending battle with corrosion.
Terminology
The following terms relate to Corrosion Control:
- Alloy
- A substance that has metallic properties and is composed of two or more chemical elements of which at least one is a metal.
- Corrosion
- The deterioration of a metal by chemical and/or electrochemical reaction with its environment. Surface oxidation is a common form of corrosion.
- Corrosion Embrittlement
- The embrittlement caused in certain alloys that are susceptible to intergranular corrosion attack when they are exposed to a corrosive environment.
- Corrosion Resistance
- The ability of some metals to form a protective oxide or passive layer which renders them more resistant to corrosion.
- Intergranular Corrosion
- A type of galvanic corrosion that progresses along the grain boundaries of an alloy. The grain boundaries become anodic to the grains and deteriorate, usually causing failure of the part.
- Oxidation
- (1) Surface oxidation of a metal caused by thermal exposure in air. (2) A reaction in which there is an increase in valence resulting from a loss of electrons. (3)A corrosion reaction in which the metal combines with oxygen to form an oxide. In steels, an oxidized surface is manifest by discoloration from a straw to a dark blue/black brittle and flaky scale.
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