The types of Surface Heat treatment

Chemical Heat Treatment-a heat treatment process in which a metal or alloy is placed in an active medium at a certain temperature so that one or more elements penetrate into its surface to change its chemical composition, structure, and properties. Common Chemical Heat Treatment Process: carburizing, nitriding, carbonitriding, aluminizing, boronizing and so on. The aim of the chemical heat treatment is to improve the hardness, wear resistance, corrosion resistance, fatigue strength and oxidation resistance of steel surface.

Surface hardening — the process of rapidly heating the surface of a piece of steel above a critical point, but cooling it quickly before the heat reaches the heart, so that the surface layer is quenched in martensite But the heart does not have the phase change, this has realized the surface hardens but the heart department invariable goal. Suitable for medium carbon steel.

Surface Heat treatment is generally divided into two categories: one is called surface quenching, which changes the structure of the surface layer without changing its chemical composition It includes flame heating surface quenching, high medium frequency heating surface quenching, contact electric heating surface quenching, electrolyte heating surface quenching, laser electron beam heating surface quenching, etc. It changes both the surface chemical composition and the surface structure, including carburizing, nitriding, cyanidation, boronizing, metal infiltration and so on. In addition, there is a new surface hardening technology, is on the surface of metal materials covered with special hardening layer, such as Chemical vapor deposition (CVD) and Physical vapor deposition (PVD), as well as plasma spraying.

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