Liekkilämpökäsittelyyn

Liekkilämpökäsittely, often referred to as flame hardening in English, is a surface hardening heat treatment process. It involves rapidly heating the surface of a ferrous metal, typically medium or high carbon steel, to its critical temperature using a flame. Immediately after heating, the surface is quenched in a suitable medium such as water, oil, or brine. The rapid heating and quenching create a hard, wear-resistant surface layer while the core of the material remains relatively tough and ductile.

The flame used for this process is typically generated by an oxy-fuel gas torch, such as oxyacetylene or propane. The intensity and speed of the flame are carefully controlled to heat only the desired surface layer without affecting the underlying material. The depth of the hardened layer can be adjusted by controlling the heating time, flame temperature, and quenching rate. Liekkilämpökäsittely is a cost-effective method for hardening components that require localized wear resistance, such as gears, shafts, cams, and cutting edges.

The advantages of flame hardening include its speed, relatively low equipment cost, and the ability to treat large or irregularly shaped parts. It is a versatile process that can be applied to a wide range of steel grades. However, it requires careful control to avoid distortion or cracking, and the hardened layer is typically shallow compared to other surface hardening methods like induction hardening. The microstructure of the hardened layer consists of fine martensite, which provides excellent hardness and wear resistance.