Neu-Ulm, Germany
Neu-Ulm, Germany

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Klumper-Westkamp H.,Stitung Institute For Werkstotechnik | Gaus J.-H.,Nabertherm GmbH | Bischof S.,Rohde Schutzgasofen GmbH | Rohde J.,Rohde Schutzgasofen GmbH | Winter K.-M.,Process Electronic GmbH
HTM - Journal of Heat Treatment and Materials | Year: 2013

Plasma nitriding and nitrocarburizing has been established in industrial production since many years. his thermochemical surface treatment is applied to various steel components in order to enhance wear resistance, corrosion resistance and fatigue resistance. he process is done at the state of art in a pulsed discharge technique in the region of anomalous glow discharge in a conventional heated furnace. By adjusting the gas composition and plasma parameters diferent compound layers with diferent thickness, composition, hardness and morphology can be produced. Up to now applications run under constant gas and plasma parameters, which have to be investigated and evaluated before. A lot of expert knowledge and experience is necessary to get the right parameters for the production of the intended compound layer speciication and to secure the reproducibility. Further inluencing aspects on the compound layer formation as batch size, batch surface, batch cleanliness, jigging, temperature distribution, cleanliness and leak rate of the plant are diicult to take into account and can cause large deviations. To overcome these disadvantages a new concept for controlled processing is developed. Investigations in analyzing the exhaust gas of the plasma nitriding process gas showed a signiicant amount of ammonia, although no ammonia is added to the process. Based on process gas analysis together with plasma process parameters and thereof derived speciic characteristic numbers a closed loop control for deined nitriding and nitrocarburizing of well deined layer characteristics is invented.


In recent years, nitriding and nitrocarburizing have gained more and more importance in the heat treatment of components. While only a few years ago, it has been common to perform these processes with fixed set temperatures and gas flows, today so-called potential control became state of the art. Consequently, besides appropriate temperature uniformity nowadays also permissible tolerances in atmosphere potential control are required. The article uses the example of the American aerospace specifications SAE AMS2759/10 and 2750D on the extent to how the therein required tolerance bands allow for staying within the specified tolerances of e.g. compound layer thickness. Intensive experiments were conducted using pure iron, carbon steels AIS11018 and 1070, the high-tensile steel AISI4140 and the hot work tool steel AISIH13, where potentials and temperatures have been varied over a wide range in order to make qualified conclusions.


Winter K.-M.,Process Electronic GmbH | Hoja S.,IWT - Foundation Institute of Materials Engineering | Klumper-Westkamp H.,IWT - Foundation Institute of Materials Engineering
HTM - Haerterei-Technische Mitteilungen | Year: 2011

The process of gaseous nitriding is considered to be fully controllable by temperature and the nitriding potential. Most of the commercially used control systems are based on the Lehrer Diagram showing the relation between nitrogen-iron phases, temperature and the partial pressure ratio of ammonia and hydrogen. This is also reflected in the measuring equipment used to determine the nitriding potential. Lehrer's phase diagram was created out of the reactions between set gas mixtures of ammonia and hydrogen and pure iron powder. In industrial nitriding cycles, dealing with real materials and real parts, the results often do not match the expectations. This paper will try to explain the parameters that have to be taken into account and how to measure, set and control the nitriding and carburizing potentials by giving an overview of the available equipment. © 2012 Carl Hanser Verlag, München.


Zurecki Z.,Air Products and Chemicals Inc | Winter K.-M.,Process Electronic GmbH
ASM International - 27th Heat Treating Society Conference 2013 | Year: 2013

Due to the absence of oxygen-containing gas components, nitrogen-based atmospheres offer a low-cost alternative to the case hardening treatments typically carried out using vacuum furnaces and, in several local economies, may cost less than the traditional atmospheres. When activated at the furnace inlet with electric plasma, nitrogen mixed with just a few percent of hydrocarbon, e.g. methane or propane, is effectively carburizing, and nitrogen mixed with ammonia and some hydrocarbon can be used to carbonitride lean steels within the high, austenitic temperature range, as well as nitride stainless steels in the low-temperature ranges. While offering quality advantages such as intergranular oxide-free cases, critical for non-machined surfaces or diverse near net shape products, the nitrogen atmospheres are non-equilibrium, i.e. require different sensing and process control techniques than the endothermic or methanol atmospheres. This paper provides an update on recent developments concerning process control of nitrogen-based carburizing atmospheres. Copyright © 2013 ASM International®. All rights reserved.


Baumann J.,Process Electronic GmbH
Heat Treatment and Surface Engineering - Proceedings of Heat Treatment and Surface Engineering, HTSE 2013 | Year: 2013

The subject of this presentation is how modern control systems can improve the control of carburizing processes. Using features like online diffusion control, target point control and beta-control within carburizing processes enables to safe process time compared to fixed time controlled processes. Moreover these techniques enable to adopt the process automatically to external influences without changing the result, to reach the result in surface hardness and desired case depth according to the specifications and to apply carbon profiles shaped as an S which gives a horizontal hardness plateau going very deep into the work piece.


Winter K.-M.,Process Electronic GmbH
Journal of Materials Engineering and Performance | Year: 2013

Recent research projects show that retained austenite, if stabilized by nitrogen, has a positive influence on the fatigue strength of work pieces. The combined diffusion profile of carbon and nitrogen applied in a carbonitriding process plays a major role, besides the process temperature. Yet today, only the carbon potential is somehow controlled and even this is not easy to achieve. This paper will present a new system able to measure and control both the carbon potential and the nitrogen potential independently. The knowledge of the activities of nitrogen and carbon in iron and the effect of alloying elements on such activities as well as the solubilities offers a way to apply the potentials on real steels. © 2013 ASM International.


Winter K.-M.,PROCESS ELECTRONIC GmbH
ASM International - 28th Heat Treating Society Conference, HEAT TREATING 2015 | Year: 2015

In the past there have been many attempts to predict nitriding and nitrocarburizing results. Most of the existing scientific work has been focusing on applying thermodynamics on pure iron and binary or ternary alloys with nitride-forming elements and/or carbon. While in pure iron, solubility for nitrogen and interfaces to Fe4N and Fe2-3N nitrides can be derived from the iron-nitrogen phase diagram [1,2,3] and likewise the solubilities for nitrogen and carbon and the resulting interfaces to Fe3C cementite and Fe2-3NC carbonitrides can be derived from the iron-nitrogen- carbon phase diagram [4,5], the presence of nitride and carbide forming elements in real steels has a tremendous influence on the growth kinetics of the diffusion layer as well as of the compound layer. In addition, when treating steel parts, the pre-nitriding condition of the material has to be taken into account. In order to adjust to such a complexity, a more pragmatic approach is used in models that are using a steel database with empirically derived data for later interpolation to predict the outcome in not tested process conditions [6, 7]. This paper will present a new approach were thermodynamic and kinetic effects are calculated based on material composition and pre-nitrided condition. The model is able to simulate up to three-stage recipes with varying temperature and nitriding as well as carburizing potentials, also taking nucleation time into account. The simulation result is giving compound layer thickness, precipitation layer and total diffusion depth and calculates surface hardness, core hardness and effective case depth (core + 50 HV). © 2015 ASM International®.


Although the current crude oil price has fallen by more than fifty percent within a just few months, increasing overall (energy) efficiency is still one of the most important topics in manufacturing of parts and components. This is not only driven by cost but also by social constraints as ultimately we'd like to give our children and grandchildren an existence worth living. To achieve this goal, it needs a stronger focus on engineering and the development of new approaches to production and operations. The article will present some examples of how data is obtained by the "smart" use of sensors and controllers, that allowed following up the optimization of processes and components.


Winter K.-M.,Process Electronic GmbH
ASM Heat Treating Society - 26th Conference and Exposition: Gearing Up for Success | Year: 2011

Making money in heat treating is getting more and more demanding. There is obviously still the economical crisis that has caused the biggest impact on all of us, nevertheless knowing the true dynamic capacity of our - still partially turned down - equipment and being able to squeeze out even the smallest capability will optimize the cost to earnings ratio. Everyone is using computer systems in order to plan their work-flow; however, often a disadvantage of such systems is their missing knowledge of what has to be done with the parts when it comes to breaking down the shop orders into real loads. This article is giving an overview on the existing planning layers and what different methods are used and explains how a consequent planning around bottlenecks will result in an optimized throughput while at the same time trying to minimize the total number of equipment used - hence saving resources. © 2011 ASM International®.


Winter K.-M.,Process Electronic GmbH
ASM Heat Treating Society - 26th Conference and Exposition: Gearing Up for Success | Year: 2011

Late research projects show that retained austenite, if stabilized by nitrogen, has a positive influence on the fatigue strength of work pieces. The combined diffusion profile of carbon and nitrogen applied in a carbonitriding process plays the major role, besides the process temperature. Yet today, only the carbon potential is somehow controlled and even this is not easy to achieve. This paper will present a new system able to measure and control both, the carbon potential and the nitrogen potential independently. The knowledge of the activities of nitrogen and carbon in iron and the effect of alloying elements on such activities as well as the solubilities offers an easy to use method to apply the potentials on real steels. © 2011 ASM International®.

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