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Graphical abstract Highlights • Experimental analysis of residual stresses in pipes using standardized methods. • Influence of residual stresses to the fracture behavior of PRNB specimens. • Numerical analysis of PRNB specimens with and without the residual stresses. • Numerical results validated experimentally. Abstract This paper focuses on analysis of the influence of residual stresses on the fracture behavior of PRNB specimens, with the aim to estimate the differences in fracture behavior of PRNB specimens with and without the residual stresses. The residual stresses are estimated experimentally for four different pipe types by using three methods: incremental hole drilling method, X-ray diffraction, and Splitting method. In order to estimate the influence of residual stresses on the fracture behavior of the newly proposed PRNB specimens, there are load-displacement curves obtained experimentally and numerically and then compared. In order to obtain more detailed analysis of residual stresses' influence, J – integral versus thickness of the specimen curves are presented for the specimen with and without residual stresses and for various loading pin displacements. Obtained results show a very good correlation between experimentally and numerically obtained load-displacement curves. The J – integral analysis leads to the conclusion that residual stresses do not have significant influence on fracture behavior of PRNB specimens made from investigated pipes. [ABSTRACT FROM AUTHOR]

• Experimental and numerical analysis of Pipe Ring Notched Bend specimen (PRNB) • Influence of torsion effect in crack plane to the fracture behavior of PRNB specimen. • Numerical analysis of PRNB specimen with and without the torsion effect influence. • Numerical results validated experimentally. Through the time, researches realize the problem of inability to measure the fracture toughness of pipe material in some cases, because of inability of producing standard specimens from pipe wall. This problem is especially expressed in thin walled pipes. In that sense, a lot of alternative procedures and nonstandard specimens are proposed but with no notable success. One of the latest and the most convenient one is Pipe Ring Notched Bend specimen (PRNB) proposed by Gubeljak and Matvienko (Patent No. RU 2564696 C1, 10.10.2015.: Matvienko Y.G. and Gubeljak N., Model for Determination of Crack – Resistance of the Pipes). Lot of research are made on the PRNB specimen and this paper presents further analysis of such a specimen. Due to the specific geometry of PRNB specimen and loading which is three – point bending, torsion effect occurs in the region of crack. This paper deals with analysis of influence of this torsion effect on fracture behavior of PRNB specimen. In order to obtain more detailed analysis of torsion effect influence, J – integral versus thickness of the specimen curves are presented for the specimen with and without torsion effect and for various a / W ratios. Further, comparison of maximal J – integral values (at half of wall thickness B /2) for specimens with and without torsion effect in relation to the a / W ratio has been analyzed. [ABSTRACT FROM AUTHOR]