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

Abstract

Low carbon ferrite-bainite pipe steels of the K65 (Kh80) strength grade produced by two manu facturing companies have been studied using different mechanical tests and fractographic analysis of frac tured surfaces. The results demonstrate that the energy capacity a (a c ) and the true relative reduction at frac ture ϕ f upon tensile tests, as well as the level of KCV -40 ≥ 250 J/cm 2 and the relative width of the zone of homo geneous ductile fracture L C /B at the fracture surface of Charpy samples upon impact bending tests, can be used as the laboratory criteria of crack resistance.

Influence of strain aging on the ductility of 05Γ2ΦБ steel in controlled rolling and accelerated cooling

“…Hence, at the beginning of plastic flow (at σ y ), strain aging has no significant influence on the crack resistance of heterophase steels in which failure occurs after extremely large plastic deformation. Thus, in such steels, the impact strength correlates with S cr and ψ and does not depend on σ y (S y ) or σ B (S B ), as shown in [13].…”

Effect of Temperature-Force Factors and Concentrator Shape on Impact Fracture Mechanisms of 17Mn1Si Steel

“…Pipe steel structures are highly sensitive to the technological process of their manufacturing. Variations in technological variables result in considerable scatter of properties along the pipelines, increasing the probability of sudden damage and failure [5,6]. Main detrimental factors affecting the strength and crack resistance of pipe steel are attributed to tensile stresses and corrosion of the outer surface of pipes arising in underground conditions due to delamination or rupture of protective coating and localized corrosion of the inner surface [7].…”

“…Furthermore, analysis of the literature data [4][5][6][7][8] shows that modern low-carbon steel structures produced by thermomechanical processing of the initial sheet have different sensitivity to the concentrator shape and temperature/force loading parameters. It is therefore important to understand 2 Advances in Materials Science and Engineering the fracture mechanisms operating at different stress stiffness values.…”