Issue 37

D. Angelova et alii, Frattura ed Integrità Strutturale, 37 (2016) 249-257; DOI: 10.3221/IGF-ESIS.37.33 253 (a) (b) A and B spring steels  = 6171,8N f -0,1465 R 2 = 0,8509  = 1829,7N f -0,0449 R 2 = 0,9973  = 39085N f -0,3347 R 2 = 0,992 0 200 400 600 800 1000 1200 1400 1600 1800 1000 10000 100000 1000000 10000000 Number of cycles to failure, N f [cycles] Stress range, [MPa] EN 10270-1 SH; Air, 11 Hz; rotating-bending BS 250 A53; Air, 5 Hz, fully reversed torsion BS 250 A53; 0.6M NaCl, 5 Hz, fully reversed torsion Figure 4 : Wöhler curves: (a) Steel A and characteristic areas with short cracks on the hourglass specimen surfaces, corresponding to given number of cycles. The higher curve shows in-air fatigue, 136 .0 86.9   f N  , and the lower curve - corrosion fatigue, 368 .0 31.73   f N  ; (b) comparison between Wöhler curves of both steels.