Mechanical-technological and fracture mechanical properties of the high grade pipeline-steel X80 with results of different pipeline-projects

Nowadays already a lot of large onshore-projects have been implemented for the steel X80 with, as it seems, fully satisfactory results. A lot of money is spent worldwide in finding the right joining process for the circumferential welds of these pipes and so a worldwide central collection of welding variaBles and efficient processing could result in a prediction of the mechanical properties and fracture mechanical values out of the data of the preceding joining process, and would save a lot of trial and error and therefore costs. This paper deals with the mechanical properties, as yield strength, tensile strength, impact energy, and hardness, and the fracture mechanical values, as CTOD- (Crack Tip Opening Displacement-) values, out of the parameters, as for example heat input, of the joining process. The problems in determining and predicting these mechanical properties are discussed in detail, and the results are compared. Finally the different resulting values are compared with each other, with the values of the base material, and with the values out of numerous references. The tested materials were the base material, the weld metal, and the heat-affected zone of welds, using different welding processes, as for example manual metal arc welding, gas metal arc welding, gas tungsten arc welding, or submerged arc welding, of the pipeline steel X80 according to API 5L (L 555MB according to OENORM EN 10208-2).