Solidification Crack Evolution in High-Strength Steel Welding Using the Extended Finite Element Method

Abstract

High-strength steel suffers from an increasing susceptibility to solidification cracking in welding due to increasing carbon equivalents. However, the cracking mechanism is not fully clear for a confidently completely crack-free welding process. To present a full, direct knowledge of fracture behavior in high-strength steel welding, a three-dimensional (3-D) modeling method is developed using the extended finite element method (XFEM). The XFEM model and fracture loads are linked with the full model and the output of the thermo-mechanical finite element method (TM-FEM), respectively. Solidification cracks in welds are predicted to initiate at the upper tip at the current cross-section, propagate upward to and then through the upper weld surface, thereby propagating the lower crack tip down to the bottom until the final failure. This behavior indicates that solidification cracking is preferred on the upper weld surface, which has higher weld stress introduced by thermal contraction and solidification shrinkage. The modeling results show good agreement with the solidification crack fractography and in situ observations. Further XFEM results show that the initial defects that exhibit higher susceptibility to solidification cracking are those that are vertical to the weld plate plane, open to the current cross-section and concentratedly distributed compared to tilted, closed and dispersedly distributed ones, respectively.

Toughening and Hardening Limited Zone of High-Strength Steel through Geometrically Necessary Dislocation When Exposed to Electropulsing

“…Since the plastic strain was experimentally inaccessible, numerical simulation was utilized here as an alternative through thermo-mechanics in the ANSYS package by coupling the thermal results listed in Table 1 . The thermo-mechanical constitutive model of FH690 steel was referred to in [ 30 ]. The simulated plastic strain at point A in three EP sub-cases was extracted and is shown in Table 4 .…”

Experimental and Nonlinear Analysis of Cracking in Concrete Arch Dams Due to Seismic Uplift Pressure Variations

“…The (XFEM) emerged from the cohesive segments method [40,41]. When it is employed in unison with the phantom node technique [42][43][44], it is possible to replicate crack initiation and proliferation in an indiscriminate direction. This is because the crack propagation is not bound to mesh-based element peripheries.…”

Eliminating the Brittleness Constituent to Enhance Toughness of the High-Strength Steel Weld Heat-Affected Zone Using Electropulsing

“…The mechanical behavior of an MA constituent is different from that of the matrix, which creates a local inhomogeneous strain, promoting the nucleation of microvoids at the MA interfaces and degrading the HAZ’s fracture toughness. According to the classical Griffith theory [ 2 , 3 ], a brittle fracture occurs once the area of MA constituents reaches a critical value, such as 1 μm 2 [ 4 ]. This local brittle fracture remains ineffectively suppressed by narrowing the HAZ region with decreased heat input in in situ welds [ 1 ].…”