Entwicklung von Niederdruck-Carbonitrierprozessen zur Festigkeitssteigerung hochbelasteter Bauteile

Low pressure carburizing offers the ability to produce bright-metallic surfaces without unwanted internal oxidation known from carburizing at atmospheric pressure but with lower consumption of hydrocarbon Grä01 . The expected increase in fatigue life of low pressure carburized parts compared to gas-carburized parts could not be achieved due to other side-effects than internal oxidation Cla03 . Case-hardening steels of the grades 18CrNiMo7-6, 20MoCrS4 and 20CrMo4 were tested with different approaches to dilute or even prevent these side-effects. Two types of furnaces were used to derive results, which are instantly applicable in industrial scale production. The first one was set up for research at the IWT in Bremen, Germany (Brand: Ipsen, type: RVTC). The second one is in use in industrial scale production and property of Wegener Härtetechnik GmbH located in Homburg, Germany (Brand: ALD, type: ModulTherm). In this paper the development of process strategies is presented, which exploit the potential of low pressure carburizing that could not be obtained in the past. Additionally, results relevant for operators are presented to show the assignability between the two types of furnaces and to give examples of conditioning and interdependencies in low pressure carbonitriding processes.