Not all case-hardening treatments are equal. RÜBIG’s R.CARB+® processes have been used in the heat treatment sector for decades and still add optimum value. Tight tolerances and highest reproducibility are a given. Other advantages of R.CARB+® treatments by RÜBIG include uniform hardness and dimensional stability.
Case hardening is a combination of a carburisation and hardening process including tempering. This results in a carburised edge surface with a carbon content of 0.6 - 0.8%. The carbon content decreases continuously towards the core.
The result of the hardening process is an edge with a high hardness and a soft, tough core. Materials suited for the carburisation process are so-called case-hardened steels with a carbon content below 0.25 weight by weight.
Advantages of case hardening R.CARB+®:
Inert gas hardening is a complete hardening process during which the components are protected within a reactive atmosphere against negative impacts of the edge zone (e.g. decarburisation). During the inert gas hardening, an oil bath is used for quenching purposes. This method is also applied to completely harden unalloyed and low-alloy steels.
With a subsequent tempering treatment, the characteristics (strength, toughness, wear resistance, ...) can be achieved within a broad range.
Advantages of inert gas hardening:
Carbonitriding differs from case hardening in respect to the addition of nitrogen, i.e. the edge zone is concentrated with nitrogen in addition to carbon. This is followed by a hardening process incl. tempering in order to achieve the desired characteristics. In comparison to case hardening, the carbonitriding procedure provides the advantage that the hardenability is increased due to the nitrogen. Thus, unalloyed steels (construction steels) can be treated as well.
As is the case with the case hardening, a hard, wear resistant edge surface with a high strength and a tough core is the result of the carbonitriding procedure.
Advantages of carbonitriding:
A special version of the carbonitriding is the "High Carb" procedure which results in a better hardenability and in particular in a tempering resistance due to a special process control.
During the carburisation procedure, the edge layer of a steel (normally case-hardened steels) is concentrated with carbon and not hardened subsequently in order to not achieve an increased hardness. This method allows the components to be processed which is followed by the actual hardening process. An advantage of this procedure is that it is possible with this sequence to manufacture components with different case depths.
Materials suited for the carburisation process are case-hardened steels with a carbon content below 0.25 weight by weight.
The term 'quench and temper' refers to a combination of a complete hardening procedure (e.g. vacuum or inert gas hardening) followed by a tempering procedure at high temperatures.
Quench and temper is also known under the abbreviation "QT". The tempering treatment is performed at high temperatures of up to 700°C in order to achieve a good ratio of strength and toughness. Therefore, the quench and temper procedure is particularly suited and required for dynamically stressed components.
Advantages of the quench and temper procedure:
Refrigeration is particularly advantageous or required if components must meet the following requirements:
Refrigeration is normally performed at a temperature of -120°C and with dwell times of several hours.
Another method is the so-called cryotreatment. During this procedure, the temperature is cooled down to -196°C and the dwell time exceeds the traditional heat penetration time by far.
More informations on request: ht.office[at]rubig[dot]com