PSI - Issue 17

Garan Martin et al. / Procedia Structural Integrity 17 (2019) 514–519 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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Fig.1 Metallographic analysis of the steel pipeline structure (17Mn4) after multi-year operation. Double grain boundaries are the sites of nitride segregation.

Fig.2 The Charpy hammer impact fractures - gradual embrittlement of the material: ductile fracture (see left), brittle fracture on the part of the fracture surface (see middle), brittle fracture on the most part of the fracture surface of the steel 17Mn4 (see right).

original ductility

Fig.3 Tensile diagram – reduced steel ductility of the steel 17Mn4 after the multi-year operation.