Metallographic examinations of samples and failure analysis of failed components

Vacuum heat treatment offers numerous persuasive advantages. Quality, consistency and not least environmental compatibility represent the current state of the art.

Carburizing is introduction of carbon into the surface layer of a steel that has a low carbon content. The process is carried out by heating the components in a solid liquid, or gaseous carbon containing medium. The depth of penetration of carbon into the surface is controlled by the time and temperature of the treatment. After carburising it is necessary to harden the components by heating to a suitable temperature and quenching.

The purpose of nitriding is to increase the surface hardness of the steel and improve its wearing properties. This treatment takes place in a medium (gas or salt) which gives off nitrogen. In nitriding, nitrogen diffuses into the steel and forms hard, wearresistant nitrides. This results in an intermetallic surface layer with good wearing and frictional properties.

Nitrocarburising, generally of shorter duration (30 minutes - 5 hours), involves enrichment of the surface with both nitrogen and carbon to impart a thin iron-carbonitride “compound layer” supported by a nitrogen-bearing “diffusion zone”. Conducted at temperatures of 560-580°C (“ferritic nitrocarburising”) or 590-720°C (“austenitic nitrocarburising”), the process may be completed by quenching

Oxidation(Fe3O4) process increases the corrosion resistance. Degreasing must be applied prio rto oxidation process. After oxidation, parts must be greased with a thin oil. Thickness of Fe3O4 film is about 2-4µm.

Cryogenic Society of America defines the “cryogenic temperatures“ as temperatures below - 140°C. Goal of this process is to proceed with martensitic transformation by decreasing the temperature and by so reducing the amount of retained austenite.

Boronizing (also known as boriding) is a thermo-chemical surface hardening process in which boron atoms are diffused into the surface of a work piece to form complex borides (i.e. – FeB/FeB2) with the base metal.

HARDENABLE ALUMINIUM ALLOYS 2xxx Series Alloys: %4,5 Cu, %1,5 Mg and %0,6 Mn 6xxx Series Alloys: %1,0 Mg, %0,6 Si, %0,3 Cu 7xxx Series Alloys: %5,6 Zn, %2,5 Mg, %1,6 Cu ve %0,25 Cr