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Quality-cost analysis of modern carburising technology implementation in the production cycle of cog elements for the aviation industry

Pawęta S., Pietrasik R.

Archives of Materials Science and Engineering

2017

Vol. 87, nr 2

75--84

Purpose: The aim of the study was to analyse the possibility of introducing vacuum carburising technology with pre-nitriding in the aviation industry. Design/methodology/approach: The samples have been tested with new technology and the planet gear requirements for aviation applications were determined. The effect of pre-nitriding technology used before vacuum carburising was also investigated for antidiffusional surface protection. A cost analysis of replacing the conventional technology with a new low-pressure carburising technology has also been introduced. Findings: Structural characteristics of the obtained layers were determined in terms of carbon concentration distribution, effective and total thicknesses, hardness of the surface and core, structure, grain size, residual austenite content and lack of decarburization and internal oxidation. The degree of degradation of various forms of anti-diffusion protections in the form of pastes and coppering and their effect on the surface layer have also been investigated. The comparative economic analysis of the use of conventional and vacuum technologies, namely the carburization in a function of the required thickness of the hardened layer and temperatures of processes, has also been made. Research limitations/implications: Basing on the studies and analyses carried out in this work, it can be concluded that the introduction of pre-nitriding carburising technology instead of conventional carburising technology in endothermic atmosphere is justified qualitatively and economically alike. Practical implications: The analysis of the test results confirms that it is possible to meet the requirements of the aviation industry through high temperature pre-nitriding vacuum carburising. The results of anti-diffusion protection tests confirm that it is possible to use anti-fouling pastes instead of electrolytic copper. Cost analysis confirms the economic benefits of implementing a new technology. The implication of the above is the willingness of the proposed technology to allow testing in the aviation industry. Originality/value: The research confirming the fulfilment of quality requirements set for hardened layers in aviation applications which also have an economic advantage.

Wyznaczenie wytrzymałości zmęczeniowej na zginanie stali 17CrNi6-6 po procesie nawęglania niskociśnieniowego

Dybowski K., Kula P., Lipa S., Pietrasik R.

Inżynieria Materiałowa

2010

Vol. 31, nr 4

939-941

Technologia nawęglania próżniowego sukcesywnie wypiera konwencjonalne metody nawęglania gazowego. Związane jest to z szeregiem zalet, które posiada. Najistotniejszą z nich jest możliwość skrócenia czasu nawęglania, głownie dzięki znacznemu podwyższeniu temperatury procesu. Wyższa temperatura obróbki wiąże się jednak z rozrostem ziarna. Można temu zapobiegać przez wprowadzanie we wstępnej fazie procesu azotu do warstwy wierzchniej stali. W artykule porównano wytrzymałość zmęczeniową na zginanie stali nawęglanej próżniowo z i bez wstępnego nasycania azotem.

Conventional methods of gaseous carburising are successfully replaced by the low pressure carburising process. This is the result of numerous advantages of that method. The most important one is the shortening of the carburising time, mainly due to increased temperature of the process. However, higher temperature causes the growth of grains. It can be limited by the nitrogen introduction into surface layer during heating. In this paper bending fatigue strengths of steel after low pressure carburising with and without preliminary nitrogen saturation were compared.

Surface modification of aluminium - lithium alloy using prenitriding option and SixNy coating deposition

Kaczmarek Ł., Sawicki J., Kyzioł K., Siniarski D., Jonas S., Stegliński M., Kołodziejczyk Ł., Tkacz-Śmiech K.

Journal of Achievements in Materials and Manufacturing Engineering

2009

Vol. 37, nr 2

282-285

Purpose: EU directive of CO2 emission reduction causes many applied technologies to become unprofitable considering environmental protection. Due to that, there is an urgent need to create new or modify existing technological solutions - especially in the field of materials engineering. One of the options to reduce CO2 emission is replacement of parts made of steel by Aluminum -Lithium alloys mainly in such branches like automotive and aircraft industry. Design/methodology/approach: Prenitriding option was carried out in low pressure plasma discharge mode, at a substrate temperature below 200şC followed by the deposition of 500 nm thick SixNy coating. Morphology and mechanical properties were compared with substrate without prenitriding treatment. Findings: In this paper, first promising results of surface treatment with the use of prenitriding option of Al-Li alloy are presented. The results showed that the wear resistance of the Al-Li alloy may be modified by application of plasma enhanced CVD [1-4]. Two different types of surface modification were applied. Research limitations/implications: In case of vehicles’ parts, subjected to wear or/and contact fatigue a use of light weight alloys gives rise to many difficulties, caused by their low surface parameters. The aluminium alloys applied for elements operated in wear contact even with the best possible mechanical properties at the moment, it is limited due to still not enough tribological properties. The research in this field may bring another reduction of vehicles total weight. Practical implications: At present, ultra light materials with high durability are elaborated for components, e.g. in automotive industry mainly to realize a light gearbox. Originality/value: Functional Gradient Coatings (FGC) was deposited below temperature which could cause destruction of “tailored” structure of the substrate.