Corrosion-Fatigue Crack-Growth Resistance of Steel of the Frame of a Sprayer Boom

We construct diagrams of fatigue crack growth for St3ps steel placed in demineralized water and in saturated solutions of the Nurelle D insecticide and UN-32 complex liquid fertilizer and evaluate the corresponding values of threshold and critical stress intensity factors. It is established that, in a Nurelle D solutions, the fatigue crack-growth rate increases, whereas in UN-32 solutions, it decreases as compared with its value in air. For the demineralized water, there exists a characteristic value below which the crack-growth resistance of steel increases and above which it decreases. The obtained results may serve as a basis for the numerical analyses aimed at prediction of the serviceability and residual service life of the frames of sprayer booms.