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What are the Different Types of Wear?

October 26, 2017

When faced with a decision on what kind of hardfacing product to use, one of the first questions you should be asking is “what kind of wear am I up against?”. Keep in mind – you will often encounter more than one type of wear at a time.

While there are many types and combinations of types of wear. The most typical modes (and factors) encountered are:

  1. Abrasion
  2. Impact
  3. Adhesion/Galling
  4. Erosion
  5. Corrosion
  6. Heat
  7. Cavitation

What is abrasion?

Abrasion is the wearing away of a surface by means of friction – often grinding or scraping. Abrasion is the most common type of wear encountered, and can be broken up into three categories:

  1. Low stress abrasion – is when a metal surface is worn away by an abrasive media that polishes the surface, removing surface material. An example would be sand sliding across a surface at a low angle of attack.
  2. High stress abrasion – is when a metal surface is worn away by an abrasive media that polishes the surface, removing material. An example would be a grinding operation with forces high enough to crush minerals that are hard enough to scratch and cut the hardest materials.
  3. Gouging abrasion – is when a metal surface is worn away by conditions of high stress, usually caused by impact loading. An example would be a rock crushing application having a combination of high impact and abrasion.
Crushing large chunks of rock into smaller pieces which will be used for road bed on a new road construction project. Shallow dof with focus on gravel leaving conveyor belt.

Close up of rock crusher in action. A good example of gouging abrasion.

What is impact wear?

Impact wear is when a metal surface is worn away by forces high enough to cause metal to deform, leading to metal fatigue and cracking.

Close up of bucket teeth with tungsten carbide to protect against impact and abrasion

Bucket teeth and other ground engaging tools often see both impact and abrasion.

What is galling wear?

Galling wear is an extreme version of adhesion wear. It occurs when there is a transfer of material between sliding metallic surfaces – particularly when there is a lack of lubrication. An example of this would be a bearing surface with low or no lubricant on a steel mill processing roll.

  

What is erosive wear?

Erosive wear is when a surface is worn away by abrasive particles suspended in air or liquid. An example of this kind of wear is sand and water flowing through a pipe.

Slurry pipes are used to transport slurry (a mixture of ore concentrate and water) from a mineral processing plant after the ore has been processed.

Slurry pipes

What is corrosive wear?

Corrosive wear is the deterioration of metal as a result of a chemical reaction.

Severe corrosion taking place in a salt mine in Poland

Salt mine in Poland

Heat – softens metal causing accelerated wear when combined with any of the above.

Cavitation – is vapor bubbles in a liquid collapsing under pressure that over time will fatigue and cause the metal surface to spall.

Determining the type of wear and the most suitable hardfacing can be challenging and may require trial and error. Feel free to contact one of our technical experts here at Polymet for assistance in selection.


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