The effect of low temperatures on the fatigue crack growth of S460 structural steel

Study on fatigue failure mechanism at various temperatures of a high-speed railway wheel steel

“…Below the fatigue ductile-brittle transition temperature, a further temperature decrease, caused an increased fatigue crack growth rate due to the enhanced cleavage bursts [9] and the intergranular fracture was the primary mode of failure at low temperatures. According to Walters et al [7], the main mechanism that caused the fatigue ductile-brittle transition was the result of two competing effects. On one side, an increase of the stress necessary for plastic flow occurrence was observed as the temperature was lowered.…”

“…The Fatigue Ductile-Brittle Transition (FDBT) is a phenomenon similar to the ductile to brittle fracture transition, 3 where the fracture mode of the fatigue cracks changes from ductile transgranular to cleavage and/or grain boundary separation. The fatigue at temperatures below the FDBT displays a quite different crack growth rate than the fatigue beyond that temperature [7,8]. Moody et al [9] reported that the crack growth rates were observed to decrease initially as the temperature decrease for all alloys.…”

“…presents the fracture surface morphology in stage I for various stress amplitudes under -40 o C. At high stress amplitude, the fatigue step could be observed along the crack propagation direction, whereas a high number of wear facets could be observed at low stress amplitude. According to Walter et al[7], an increase of the stress amplitude necessary for the plastic flow occurrence was observed, whereas the local plastic deformation increased, resulting in a crack growth speed increase in stage I. Consequently, at high stress amplitude along with high crack growth speed, the fatigue step was observed as dominant on the fracture surface. At low stress amplitude along with low crack growth speed, the crack was subjected to a repeated opening and closure and the interaction time of the cracks with the external environment was long, providing a good explanation for the wear facets formation, as observed on the fracture surface.…”

Fatigue crack propagation for Q345qD bridge steel and its butt welds at low temperatures

“…Below the fatigue ductile-to-brittle transition temperature, fatigue crack propagation rate increases with the decreasing temperature. [16][17][18][19] Other research efforts have studied the effects of welding residual stress, the deteriorated fracture toughness, and the inhomogeneity of materials 20-23 on the fatigue crack propagation in welded joints under a low temperature. 16 The assessment of the low-temperature fatigue failure requires a quantitative relationship between the ductile-to-brittle transition temperatures for fatigue and fracture.…”

Temperature‐dependent characteristics of DH36 steel fatigue crack propagation

“…The temperature at which this transition occurs is known as the fatigue transition temperature (FTT). 28 On the one hand, an increase of the stress necessary for producing plastic flow is observed as the temperature is lowered: Its thermal component (effective stress), which is and expression for the short-range barriers that mobile dislocations must overcome, 29 is inversely proportional to the temperature such that plastic deformation is hindered as temperature is decreased. Below the FTT, higher fatigue crack propagation rates are encountered.…”