Super-clean steel for automotive springs

Paul Boughton

Automotive spring-grade wire rod from Corus is being used to manufacture transmission springs for the first time.

The super-clean, high-performance grade of rod has been undergoing rigorous fatigue tests for approval to be processed into valve springs with leading wire drawers and spring manufacturers.

Automotive springs such as valve, transmission and suspension springs are among the most demanding applications for any steel, and the approval and testing procedures are extremely arduous.

One of Europe's leading specialist oil-tempered spring wire manufacturers, Haldex-Garphyttan, has conducted lengthy trials with the Corus material, which have given it the confidence to commence regular orders of the steel for transmission spring applications. Haldex is now keen to extend the market for Corus transmission spring wire to other spring manufacturers.

Corus ventured into automotive spring steels after its success in producing super-clean steel for tyre cord, which is now supplied into markets around the world. Few steel manufacturers are able to produce material that meets the stringent quality requirements of automotive spring applications, and Corus is establishing a reputation in this niche market.

Corus Sales Manager, John Morrisroe, says: “Our development of a grade of steel for transmission springs has been a process of continual, incremental improvement. Every cast we have rolled has involved some refinement or process improvement to ensure we deliver the quality of material demanded by the automotive industry.

“We are delighted that, by working closely with Haldex, we have gained approval for the use of our steel in this new market for us. Haldex is now regularly producing wire from our rod that is approved for transmission spring applications.”

Transmission springs are used in gearbox mechanisms, controls and clutches and have to perform under demanding temperature and vibration conditions. In clutch assemblies, for example, springs play an important role in improving torque fluctuations transmitted down the driveline by the engine, thereby helping to reduce noise and vibration, resulting in a better driving environment for vehicle occupants.

Following its trial successes to date, Corus is extending the reach of its super-clean steel grades, and is now working on suspension spring trials with leading players in the industry. Major investment at the company's rod mill is helping to secure its future in these high-value markets.

Morrisroe adds: “We are confident that the improvements we are implementing in casting and rod mill processes will enable us to deliver even greater product quality and consistency for these most demanding automotive applications.”

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