The Numerical Modelling Approach with a Random Distribution of Mechanical Properties for a Mismatched Weld

Abstract

The aim of this work was to include a local variation in material properties to simulate the fracture behaviour in a multi-pass mis-matched X-weld joint. The base material was welded with an over and under-match strength material. The local variation was represented in a finite element model with five material groups in the weld and three layers in the heat-affected zone. The groups were assigned randomly to the elements within a region. A three-point single edge notch bending (SENB) fracture mechanics specimen was analysed for two different configurations where either the initial crack is in the over or under-matched material side to simulate experimentally obtained results. The used modelling approach shows comparable crack propagation and stiffness behaviour, as well as the expected, scatter and instabilities of measured fracture behaviour in inhomogeneous welds.

Experimental and Numerical Analysis of Fracture Mechanics Behavior of Heterogeneous Zones in S690QL1 Grade High Strength Steel (HSS) Welded Joint

“…where σYW and σYB represent the yield strength of the weld metal (WM) and the yield strength of the base metal (BM), respectively. In this welded joint, mismatch factor M = 1.16 (Table 2) which indicates the slightly over-matching (OM) weld metal, with M > 1 [8,31]. In general, HSS steel grades can be welded using various matching filler metals.…”

“…In scope of welded joint testing, such round specimens can capture the BM, WM and only general HAZ properties. The possibility of testing tensile properties along the linear direction (e.g., transverse welded joint direction) is successfully demonstrated by implementation of mini tensile specimens (MTS) [8][9][10][11]. This testing approach enables capturing the HAZ specific segments properties.…”

“…The tensile properties along the transverse welded joint line are determined using two sets of mini tensile specimens (MTS) [8][9][10]. Using this substandard sized tensile specimens is required due to limitations of the material test volume inside the welded joint in order to determine the stress-strain curves for each characteristic weld zone.…”

“…Numerical representation of SENB test specimen and test setup is prepared in twodimensional environment. Such numerical representation is developed based on the SENB specimen, notch and crack modelling approaches, previously established by Starčevič et al [8] and Štefane et al [15]. As the reference indicates, the authors also used other approaches of numerical modelling SENB specimens and corresponding cracks, carried out by various researchers, described in the available literature [38][39][40][41][42].…”

Yield Load Solutions for SE(B) Fracture Toughness Specimen with I-Shaped Heterogeneous Weld

“…The application of the SINTAP procedure is based on the implementation of the yield load solution in the failure assessment diagram (FAD) to determine the safe operation of the assessed structure. There are a number of studies dealing with various aspects of the fracture behavior of homogeneous welds with strength mismatch compared to the base metal, including recent ones [ 4 , 5 , 6 , 7 , 8 , 9 ], as well as a number of studies dealing with heterogeneity in welds with strength mismatch [ 10 , 11 , 12 , 13 , 14 , 15 , 16 ].…”