In recent years, there has been an increasing demand to reduce weight of automotive suspension springs reflecting a trend for light weight automobiles to reduce the amount of fuel consumption. To satisfy such demands springs can be made with an increased design stress specification. However, if existing spring steel grades are employed under high operating stress conditions this can lead to problems related to durability and sagging of the spring in application. Consequently, the length of the spring will be lowered due to sagging and accordingly,the height of the vehicle will be decreased leading to possible safety problems and changes in handling condition. Thereto re, these needs necessitated the development of new spring steel materials which possessed combined sagging resistance and improved fatigue strength over conventional spring steels. Over the last few decades researchers have focussed their efforts on the application of microalloying technology, effective heat treatments and mechanical treatments like shot-peening for improving the desired properties of suspension springs.
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