Abstract
The hydrogen-induced fracture of linepipe steel is characterized by the formation of internal blisters caused by hydrogen precipitation at an inclusion-matrix interface, followed by the formation of blister-crack array by linking the region connecting them under the combined action of internal hydrogen pressure and external force.
The manner of extension of the hydrogen-induced fracture of this type is considerably influenced by the presence of external force, i. e., in the absence of it the fracture develops by stepwise linking the blisters. while in the presence af it the fracture develaps by linking the blisters which are formed in stacked arrays out of the plane approximately perpendicular to the external stress axis. The shear stress distribution induced around the blister is sensitively influenced by external force applied parallel to the blister. therefore it is expected that the manner of extension of the blister-induced fracture should be influenced by the external force.
In the present paper the above-mentioned change due to external force of the manner of extensi the hydrogen-induced fracture is explained on the basis of the stress analysis around the hydrogen gas pressurized crack-like cavity under stress.
