Abstract
When analyzing the places of the destruction of welded samples of thermally hardened steels and the relative transverse narrowing, it was found that in the range of relative thicknesses of the “soft” layer τ <0.6–0.8, when the strength of the welded samples is at the level of thermally hardened base metal. Destruction occurs both on the base metal at a distance from the weld, and along the weakened area in the heat-affected zone. At large values of τ, the destruction of the welded samples occurs, as a rule, along the weakened area near the weld. A characteristic feature of fracture of welded samples in a weakened section is a decrease in the relative transverse narrowing ψ compared to the case when the fracture occurs on the thermally hardened base metal at a distance from the weld. However, as is known, the value of ψ for thermally hardened metal is lower than for normalized. Based on the results of theoretical and experimental studies, as well as taking into account the basic principles of fracture mechanics, recommendations were developed on the choice of hydra model parameters impact testing of the pipeline on a section of 266-505 km in the Tyumen region. The obtained values of the crack depth l cr = 3.9–4.3 mm correspond to the acts of technical failures of the pipeline in section 335–337 km.
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