decarburization
Decarburization refers to the process whereby carbon content is reduced from the outside of steel or other carbon-bearing alloys. This is generally ascribed to the high-temperature exposure of steel to an oxygen-rich environment. It leads to changes in mechanical properties of the material, often resulting in a reduction of hardness and strength.
Key Features:
- Causes and Mechanism: If decarburization is said to happen, the process is when steel is being heated in some envelop of gas or atmosphere where oxygen, hydrogen, and carbon dioxide react with the carbon present in the material to diffuse out of the surface of the material.
- Effects to Material Properties: Losing carbon means that the surface layers of the steel get weakened, soft, and easily worn out. However, in some cases, this decarburization is induced intentionally to give enhanced properties.
- Prevention and Control: To impede further unwanted decarburization, we use protective atmosphere, coatings, or methods of controlled cooling in heat treatment processes.
The decarburization, therefore, occupies a significant position in industries, where surface hardness and wear resistance are of utmost importance, i.e., automotive, aerospace, and tool manufacturing. The surface hardness of gears, bearings, and cutting tools is required, which is contrary to decarburization. Therefore, manufacturers use coatings or controlled environments inside the furnace to limit or minimize the losses of carbon. In contrast, for certain welding and forging applications, controlled decarburization will actually enhance ductility. Development of heat treatment technology also leads to improvement in decarburization control that ensure peak performance in engineering application of those materials.