Effect of low temperatures on the fatigue strength of structural steels

Abstract

1. The transition of the steel from the ductile to the brittle state with decreasing temperature does not sharply affect the temperature dependences of the values of σ−1, σ−1n,σ−1/σb, q, or Kσ. These dependences retain a monotonic character of change in the direction of an increase in the above characteristics. 2. In the case of the ductile-brittle transition, there is a sharp decrease in the relative duration of crack propagation Nc.p/Nf both at stresses close to the endurance limit and at stresses corresponding to an endurance of about 104 cycles. At fixed values of stress amplitude, longer specimen life (within the scatter of endurances) corresponds to a longer absolute duration of crack growth, despite the fact that here the relative duration of crack growth decreases.