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Lcf loop shape in near pearlitic steels – influence of temperature

Johan Ahlström (Institutionen för material- och tillverkningsteknik, Materialteknologi)
Proceedings of 7th International Conference on Low Cycle Fatigue, Aachen, Germany, September 9–11, 2013 p. 81-86. (2013)
[Konferensbidrag, refereegranskat]

Specimens of near pearlitic railway wheel steels have been exposed to isothermal, uniaxial low cycle fatigue tests at constant total strain amplitudes from 0.4 – 1.0%. Temperatures have been varied from -60°C to 500°C. The data recorded has been analysed by fitting polynomial expressions to different parts of the loop. A technique used for extracting the unloading stiffness was presented at the previous conference, LCF6 in Berlin 2008. This procedure has now been extended to characterize the entire loop. The degree of micro plasticity and its effect on unloading stiffness, the strain energy and the cyclic stress development have been characterized. An increased cyclic hardening during the main part of the fatigue life was identified on cycling at 300°C at total strain amplitude of 0.6%. At 500°C the viscous behaviour dominates over the cyclic strain hardening yielding decreasing stress amplitude.

Nyckelord: LCF loop shape, hysteresis loop analysis, unloading stiffness, cyclic softening, micro plasticity, temperature effects

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Denna post skapades 2013-10-10. Senast ändrad 2014-09-02.
CPL Pubid: 185072