Corrosion fatigue is a phenomenon that occurs when materials are weakened over time due to a series of stresses experienced as the result of being in a corrosive environment. Most often associated with metals, this type of damage begins to accelerate when the protective coating on the materials is damaged in some manner, and exposure to various elements begins to break down the composition of the metal. Corrosion fatigue can occur to many different types of metal products, ranging from heavy equipment to the metal panels used in construction and shipbuilding.
One of the main causes of corrosion fatigue is the repeating or cycling stress that occurs due to changes in temperature and humidity in the setting where the metal equipment is in use. Depending on the frequency of these alternating or cycling shifts, the stress level on the metal can be substantial. Over time, the changes can begin to weaken the protective coating on the metal. This in turn makes it easier for the elements to begin breaking down the surface of the metal and lead to increased fatigue.
When corrosion fatigue occurs, cracking begins to occur along the surface of the metal as it begins to degrade and lose strength. As exposure to alternating or cyclic stress continues, those cracks increase in number and size, eventually creating a network of corrosion along the surface of the metal. If left unchecked, the degradation continues to occur, eventually rendering the metal object unfit for its original use.
The process of corrosion fatigue may be readily apparent in the earliest stages. Typically, the small cracks in the protective coating are difficult to detect at first, and may not be visible until the process of corrosion is well underway. Depending on the type of metal involved, it may be possible to cleanse the material and repair the protective coating. While this does nothing to restore the metal to its former strength, this type of action can slow the progression of the fatigue and make it possible to extend the life of the metal to some degree.
Since no metal is capable of withstanding constant exposure to alternating environmental factors, the type of protective coating applied to the material is extremely important to slowing the rate of corrosion fatigue. In recent decades, various types of resins are sometimes used to coat or seal metal objects, making it possible for them to remain strong and stable for longer periods of time. Many types of paints designed for use with metals also contain protective properties that help to reduce the damage that occurs due to exposure to various types of stress. One common example is the use of a protective coating on metal lawn furniture. As long as the coating is maintained, the damage or corrosion that occurs to the underlying material is minimized and the useful life of the lawn furniture is extended.
By Malcolm Tatum