Ultra-long cycle fatigue of high-strength carbon steels part I: review and analysis of the mechanism of failure

Laboratory Study on Evolution Mechanisms of Non-metallic Inclusions in High Strength Alloyed Steel Refined by High Basicity Slag

“…[2][3][4][5][6] Hard, large and angular inclusions should be avoided because they could not be deformed together with steel matrix during hot rolling and could easily result in stress concentrations at steel/inclusion interface. [7][8][9][10][11][12][13][14] Inclusions with low temperature T m /2 (T m stands for melting temperature) have better deformability 15) and exist as liquid which tend to be spherical in morphology and much easier to be removed from steel. Therefore, inclusions of relative lower melting points, smaller in size and spherical in morphology would be better for the improvement of fatigue resistance properties.…”

Formation of MgO·Al₂O₃ Inclusions in High Strength Alloyed Structural Steel Refined by CaO–SiO₂–Al₂O₃–MgO Slag

“…Chapetti et al found that internal inclusions contribute to the ultra-long cycle fatigue of high-strength steel. 1,2) Further, there is still another viewpoint that small, globular and uniformly distributed MgO · Al 2 O 3 inclusions are practically harmless to fatigue and other properties of the steel. [3][4][5][6] In fact, MgO · Al 2 O 3 spinel inclusions have been widely discussed in recent years.…”

A two-parameter model to predict fatigue life of high-strength steels in a very high cycle fatigue regime

“…It has been shown that almost all of the fatigue life in the VHCF regime is consumed to form FGA [21][22][23][24][25], so it is reasonable to approximate the fatigue life N FGA consumed in FGA as the total fatigue life N f . From the expression of β , it should be at least a function of σ a /σ Y , so that N Thus, a two-parameter model for the fatigue life of highstrength steels with fish-eye mode failure in a VHCF regime is derived as…”

“…It was shown that the stress intensity factor range at the front of the FGA was a constant and was close to the threshold value of the crack propagation K th . In crack initiation and early growth stage of VHCF, the crack growth rate is much lower than 10 −10 m/cycle [13,[17][18][19][20], and more than 90 % of fatigue life is consumed to form the FGA [21][22][23][24][25]. Therefore, it is essential to develop a model to predict the fatigue life in relation to FGA.…”

“…Therefore, it is essential to develop a model to predict the fatigue life in relation to FGA. Some methods have been proposed to predict the fatigue life or fatigue strength of high-strength steels in the VHCF regime by incorporating the effect of inclusion size at the crack origin [21,[26][27][28]. For example, Wang et al [29] incorporated fatigue life into Murakami's model [30] and proposed where β = 3.09 − 0.12 log N f for interior inclusions or defects and β = 2.79 − 0.108 log N f for surface inclusions or defects for four low-alloy high-strength steels.…”