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 (a _c) and the true relative reduction at fracture φ_f 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 L _C/B at the fracture surface of Charpy samples upon impact bending tests, can be used as the laboratory criteria of crack resistance.     

Microstructure and Properties of Oil and Gas Range Pipe Steel Subjected to Improvement

Metallurgist - The effect of alloying on the properties of highly tempered steels used for production of a range of petroleum pipes is studied. It is shown that an increase in molybdenum content...     

Structure,Phase Composition and Mechanical Properties of Hot-Extruded Ti–3Al–2.5V Pipe After Vacuum Annealing

Metallurgist - The structure and properties of the hot-extruded Ti–3Al–2.5V pipe 90.0 × 20.0 mm in cross section subjected to vacuum annealing are studied using methods of macro-,...     

Hardening of Large Forgings in Water-Air Mixture

A double-stage mode of accelerated controlled hardening of large forgings from structural steels with relatively low hardenability in a water-air mixture with subsequent high-temperature tempering is described. Special features of the decomposition of supercooled austenite in these steels under continuous cooling are considered. The structure and properties of forgings after hardening by the recommended regime are studied.     

Study of Low-Carbon Pipe Steel Strain Ageing

Metallurgist - Strain aging of pipe steels 06G2FB and 07G2MFB with ferrite-pearlite and ferrite-bainite structures is investigated. It is established that a ferrite-bainite structure is more...     

Normalization of the Cold Shortness of Plate Steel: I. Set of Temperature Thresholds

The results of estimating the ductile–brittle transition temperature range for structural steels are compared using direct and indirect toughness characteristics (work, force, strain, type of fracture) for different testing schemes. The critical cold-shortness thresholds determined from different toughness characteristics for the same material are shown to differ by a few hundred degrees Celsius. An approach is formulated to choose a testing scheme and an effective toughness criterion.     

Structure and mechanical properties of the welded joints of large-diameter pipes

The structure and mechanical properties of the technological welded joints of large-diameter pipes of strength class K60 produced by two companies are studied. Along with standard mechanical properties (σ_0.2, σ_u, δ, ψ), specific work of deformation a (tensile toughness) and true rupture strength S _f are estimated from an analysis of the stress-strain diagrams constructed in true coordinates. The mechanical behavior is found to be different for samples cut from different zones of a welded joint (central weld, heat-affected zone, and base metal). The mutual correlation between parameters a, S _f, and impact toughness KCV is considered.