Lean alloy steels with improved machineability will enable the automotive gearbox industry to control and predict the level of distortion in the manufacture of transmissions.

Corus, the international metals company, has developed a range of lean alloy steels that will enable the automotive gearbox industry the ability to control and predict the level of distortion in the manufacture of transmissions. This will help the industry produce gearboxes and shafts with improved noise vibration and harshness (NVH) characteristics, and importantly, help both to reduce costs through improved machine-ability and allow for more environmentally- friendly production processes. The automotive gearbox industry today faces the challenge of manufacturing transmissions that not only meet growing consumer demands for improved refinement and performance but also meet more stringent legislation affecting production and service.

Distortion of material in the manufacture of gearboxes is usually caused by heat treatment after machining.

This is inevitable and is a major contributor to increased NVH, together with a reduction in performance.

However, given the ability to predict the levels of distortion, manufacturers now can allow for its effect and design their processes accordingly.

Utilising its extensive material knowledge and experience of working with the gearbox industry, Corus Engineering Steels has developed a range of new low alloy gear steels that gives manufacturers this ability to control distortion and limit its impact.

Corus' low alloy gear steels feature unique chemical compositions tailored to produce a tightly controlled and repeatable hardenability response, a critical property for ensuring that fatigue and performance requirements in transmissions are met.

Importantly, these leaner alloy steels display comparable hardenability to the more highly alloyed steels previously available.

Although the new gear steels will be of particular benefit to manufacturers of high volume passenger car and CV gearboxes, Corus Engineering Steels' extensive database of chemical compositions will also enable them to design low alloys steels for specific applications - for example, high-load niche motorsport transmissions.

Controlled distortion in gearbox production allows less machining, resulting in a reduction in manufacturing time and therefore reduced costs.

Corus' lean alloys can also be used in the latest more efficient, low pressure carburising processes which offer manufacturers further cost reduction and important environmental benefits.

In addition, the steels can take advantage of new gas quenching techniques which provide more opportunity for improvements in distortion and, by removing the need to use oil quenchants, brings environmental gains as well.

David Milbourn, manager product technology Corus Engineering Steels, said: 'The development of our new range of low alloy steels is yet another example of Corus' commitment to support the automotive industry by providing the latest material innovations that help manufacturers reduce costs whilst improving performance.

It is further evidence of our capabilities which extend far beyond material development and supply into fundamental application engineering.' Jon King, director, Corus Automotive said: 'This is another important supply chain initiative from Corus.

As the industry moves towards the latest generation of smaller, six speed transmissions this will increase the power density and loading on gearboxes.

It is anticipated that this is turn will lead manufacturers to seek more collaborative help from material suppliers such as Corus in finding new and sophisticated material solutions needed to meet the challenges they face.' Corus Engineering Steels currently supplies gear steels to many of the industry's leading manufacturers including BMW, Daimler Chrysler, Eaton, Ford, GM, Scania, Volvo and ZF.