Laboratory criteria of crack resistance of high-strength steels for gas main pipelines

Low-carbon ferrite-bainite pipe steels of the K65 (Kh80) strength grade produced by two manufacturing companies have been studied using different mechanical tests and fractographic analysis of fractured surfaces. The results demonstrate that the energy capacity a (ac) and the true relative reduction at fracture φf upon tensile tests, as well as the level of KCV−40 ≥ 250 J/cm2 and the relative width of the zone of homogeneous ductile fracture LC/B at the fracture surface of Charpy samples upon impact bending tests, can be used as the laboratory criteria of crack resistance.