Vol.11, No1, 2011, pp.27-34
UDC 620.17 : 669.15

FATIGUE STRENGTH AND MICROSTRUCTURAL FEATURES OF SPRING STEEL

B. Šuštaršič1, P. Borković1, Wifried Echlseder2, G. Gerstmayr2, A. Javidi2, B. Senčič3

1) Institute of Metals and Technology, Ljubljana, Slovenia

2) Institute of Mechanical Engineering, Leoben, Austria

3) Štore Steel, Štore, Slovenia

Abstract

Knowledge about the local dynamic properties of steel, as well as the local loading conditions is absolutely necessary for the fatigue analysis and life time prediction of spring steel components. Mono-leaf and double-leaf springs of specific geometry made of 51CrV4 spring steel manufactured in the Slovenian steel plant Štore Steel are of interest in this case. Fatigue strength of the selected steel is determined in different loading modes for two different heat treatment conditions and two outmost directions of segregations of alloying elements. Microstructural characterisation of the selected steel is performed, as well as fractographic examination of fractured surfaces. The experimental results enable fatigue life prediction of spring steels using the local stress gradient concept.

Keywords: spring steel, S-N curves, fatigue strength, notch effect, microstructure

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