International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056 Volume: 11 Issue: 06 | Jun 2024
www.irjet.net
p-ISSN: 2395-0072
Effect Of Nitriding Time and Surface Contaminants On Case Depth Of CRDI Nozzle. Madhuri Thombre1, Rajeev Arora1, Prasanth Karakavalasa1 1Cummins Technologies India Private Limited, Cummins India Office Campus, Balewadi, Pune-411045,
Maharashtra, India. ---------------------------------------------------------------------***--------------------------------------------------------------------1.INTRODUCTION Abstract - The fuel-injector nozzle is a vital component in diesel engine, profoundly influencing engine performance. Enduring extreme conditions like high temperatures and pressures up to 3,000 bar during operation, it demands high strength, wear resistance, and fatigue strength, achievable through careful material selection and precise heat treatment. Despite extensive research on gas nitriding process parameters and their impact on nitriding properties across steel grades, understanding the effects of surface structure, composition, and contaminants on the process remains challenging. In the current study, an attempt was made to understand effect of surface contaminants on effective case depth of injector nozzle subjected to zero-flow gas nitriding process which offers precise process control compared to the double component gas nitriding process. While zero-flow technology has been successfully demonstrated in car applications for diesel engine fuel injector nozzles, its adoption in high-end diesel engine applications like trucks and tippers is still limited. In this study, high-end injector nozzles made of H13 steel was subjected to zero-flow gas nitriding at 500±50℃ for varying time intervals. Nozzles with RP oil stains, cutting oil stains, and clean surfaces were subjected to gas nitriding to assess the impact of surface contaminants on nitriding properties. Nitriding properties were assessed using optical microscopy and a microhardness tester. The results show that longer nitriding times increases effective case depth, but surface contaminants reduces it by impeding nitrogen diffusion, resulting in non-uniformity. Optimizing these factors significantly enhances nozzle performance, underscoring the importance of thorough surface preparation in gas nitriding processes.
The common rail diesel injection (CRDI) fuel injection system stands as a critical component in diesel engines employed in on-highway applications like trucks and tippers. Its primary function is to inject fuel into the engine cylinders through a singular, shared line known as the common rail. This common rail is interconnected with all fuel injectors. Operating as an accumulator, the common rail plays a pivotal role in ensuring a constant fuel pressure delivery to the fuel injectors up to 3000 bar [1][3]. A fuel injector is an electronically controlled valve supplied with pressurized fuel by the fuel pump, that sprays pressurized fuel as a fine mist for efficient combustion in an engine [2][3]. Hence injector nozzle is a vital component of diesel engine for the performance and emissions of modern diesel engines. With key design parameters such as the injector seat, sac, and nozzle hole size and shape significantly influencing combustion characteristics, emissions stability, performance consistency, and injector durability over time [2][3]. The fuel injector nozzle operates under extreme conditions, enduring high pressure and temperatures during the combustion process in an internal combustion engine which makes them susceptible to accelerated wear and defects. Therefore, the design of fuel-injection nozzles must prioritize adequate strength, impact resistance, fatigue resistance, and abrasion resistance [6]. For high end application such as trucks and tippers wherein injection pressures are beyond 2000 bar, Gas nitriding has emerged as an optimal heat treatment process capable of imparting these essential properties to the nozzle, ensuring durability and performance under extreme conditions. It involves the formation of a robust nitride layer on the surface of the nozzle which significantly enhances the surface resistance to wear and erosion [4]. It imparts good dimensional stability to the component and is considered a low-temperature process, typically conducted at ~ 500°C±50℃. Furthermore, the surface hardness achieved through gas nitriding imparts sufficient fatigue strength to the nozzle. The formation of a white layer during the process enhances the wear resistance and corrosion resistance of the nozzle and serves as an additional protective barrier against the challenging conditions encountered during engine operation.
Key Words: Kn, Effective Case Depth, Surface Hardness, Surface Contaminants, Nitrogen Diffusion. Abbreviations: CRDI Common Rail Diesel Injector EDS Electron Dispersive Spectrum Kn Nitriding Potential RP Rust Preventive SEM Scanning Electron Microscopy ECD Effective Case Depth DOE Design of Experiment GN Gas Nitriding VHT Vacuum Hardening & Tempering
© 2024, IRJET
|
Impact Factor value: 8.226
In the present work, zero flow nitriding technology was used to nitride hot working tool steel H13 fuel injector
|
ISO 9001:2008 Certified Journal
|
Page 772