CORUS DEVELOPS NEW ULTRA-CLEAN STEELS FOR IMPROVED DIESEL FUEL INJECTION SYSTEMS
23 October 2003 - Corus Automotive

Diesel passenger car sales have risen steadily across Europe over the last ten years thanks to consumer demands for better fuel economy and growing pressure on vehicle manufacturers to reduce CO2 emissions. This trend is set to continue with some industry reports predicting diesel passenger car sales in Europe reaching a market penetration of 50 per cent by the year 2005. Coupled with the growth in diesel car sales has been the demand from motorists for improvements in performance, driving characteristics and refinement, resulting in vehicle manufacturers turning increasingly towards new diesel engine technology to help them meet the engineering challenges.

The introduction of common rail fuel injection systems, which work at higher pressures to improve atomisation of fuel for more power output and better engine performance, is one example of the latest advances. However, the use of new technology to make diesel engines more efficient is placing even greater challenges on the materials specified for critical components such as injectors.

Injector bodies and nozzles are required to work at high injection pressures and are therefore subject to high fatigue loading as well as being required to respond well to higher heat tolerances. In addition to these demanding requirements, the components are also produced in large volumes and therefore must be easily machined.

To help improve the durability and performance of injector components, Corus has worked closely with diesel injection system manufacturers to develop a range of new, extremely clean steels with far fewer non-metallic inclusions. In addition, system manufacturers have benefited from Corus’s extensive and proven track record in market sectors such as bearings and aerospace, which also require high quality high performance steel products.

Key benefits of Corus’s clean steels for diesel injectors include a consistent heat treatment response and excellent machinability. These features are paramount to meet the demands of the high injection pressures present in the close tolerance gun-drilled holes of the fuel delivery system.

In the case of steels for injector nozzles, Corus products exhibit extremely high cleanness, consistent hardenability and increased fatigue resistance, which importantly, help improve the life expectancy of diesel injector components. In addition, all of these attributes are required to enable fuel to be delivered to the ignition chamber at high cyclical pressures through laser-drilled spray holes, often as small as 0.1mm in diameter.

Commenting on the development of these new steels, Martin Read, senior metallurgist, Corus Engineering Steels said: By working closely with us, the diesel injection system manufacturers have not just benefited from our proven material technology but also our well-established and world class clean steel manufacturing processes that ensures the production of a consistently high quality material.

Corus clean steel manufacturing practice involves careful control of steelmaking to casting, from raw material to product, via well defined procedures established over many years by Corus’ experts in market sectors such as bearings and aerospace, with particular attention being given to oxygen content. Corus’s automotive customers, including injection system manufacturers, are now benefiting from this practice.

Mr Read added: Corus is continuing to work closely with diesel injection manufacturers to help provide material solutions to the new challenges ahead. These include tougher future environmental legislation which will require diesel engines to be even more efficient and the need to reduce vehicle component weight placing even greater demand on materials used within the engine system.

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