Statistical Analysis to High-Cycle Fatigue Property in Very Long-Life Regime of High Strength Steel SNCM439
Details
In order to investigate the fatigue properties of high strength steels in the very long-life range (N〓1×10^7), the cantilever type rotating bending fatigue tests were carried out for high strength steel SNCM439. We conducted the statistical analysis to high-cycle fatigue properties using the fatigue life date of 15 institutions. As a result, from the P-S-N curve using the fatigue life data of 15 institutions, it was found that the dispersion of the fatigue life data of slope part in 'surface crack origin type' area is smaller than the dispersion of the fatigue life data of slope part in 'internal crack origin type' area. The fatigue life data of 'surface crack origin type' over σa=1300MPa follow the 2-parameter Weibull distribution and but those below σa=1300MPa don't follow the 2-parameter Weibull distribution and nearly follow the mixed Weibull distribution or the composite Weibull distribution. The fatigue life data of 'internal crack origin type' almost follow the 2-parameter Weibull distribution. The dispersion of the fatigue life data of 'internal crack origin type' is almost larger than that of 'surface crack origin type'.
