Effect of Hydrogenation and Plastic Predeformation on the Crack Growth Resistance of Structural Steel

摘要

The synergistic effect of hydrogenation and plastic predeformation (PPD) on the fracture toughness and fatigue crack growth resistance in the tempered 0.4-1Cr-1Ni steel was studied. In the no hydrogenated state, PPD of steel slightly decreases its fracture toughness and increases considerably the fatigue crack growth resistance in the near threshold region of da/dN - ΔK diagram. Crack closure is responsible for the latter effect. Hydrogenation of the material drastically decreases the fracture toughness and intensifies the fatigue crack growth, especially in the middle region of da/dN - ΔK diagram. The synergistic effect of PPD and hydrogenation of the investigated steel causes the maximum decrease of crack growth resistance, both under static and cyclic loading. The possible consequences of such effect from the point of view of structural strength of drill pipe string are analyzed.