Elemental segregation during resistance spot welding of boron containing advanced high strength steels

Abstract

The partitioning behaviour of carbon, phosphorous and boron during the solidification of a resistance spot weld pool was studied using experimental simulations and a phase field model. Steels with varying carbon, phosphorous and boron contents were designed and subjected to a range of resistant spot welding thermal cycles. Mechanical properties were evaluated by hardness and cross tension tests and correlated with the weld microstructure. Phase field modelling results and experimental predictions show that the phosphorus concentration in the last area in the weld pool to solidify can reach about 0.38 wt% for a steel with a bulk concentration of 0.08 wt%. Elemental analysis indicates that in the absence of boron, the grain boundaries of columnar grains in the weld pool are decorated with phosphorous. As a result, a complete interface failure occurs during cross tension testing. With the addition of boron, apart from an increase in weld strength and plug diameter, the failure mode switches to a complete plug mode, resulting from the phosphorous depletion at the grain/inter-phase boundaries.

Hot cracking investigation during laser welding of high-strength steels with multi-scale modelling approach

“…Simulations were carried out on a two-dimensional 400 × 200 grid with a grid spacing of 0.5 μm. The energy parameters for the phase interaction [18] used in this simulation are listed in Table 2.…”

Transient Softening at the Fusion Boundary of Resistance Spot Welds: A Phase Field Simulation and Experimental Investigations for Al–Si-coated 22MnB5

“…In the past decades, phase-field modeling has been widely used for the simulation of microstructure evolution in the solidification process [13] and for high-speed processes as RP-welding [14,15]. The progress of the phase evolution is dependent to minimizing the free energy functional.…”

The microstructural evolution and elemental distribution of a 3rd generation 1 GPa advanced high strength steel during double pulse resistance spot welding

“…The presence of a relatively high percentage of alloying elements in combination with the high cooling rates of the welding process leads to the formation of a martensitic microstructure that influences the mechanical properties of the welds. Alloying elements like silicon, manganese and phosphorous tend to segregate to the grain boundaries during solidification [6,7]. Furthermore, the formation of nonmetallic and complex inclusions is reported in the fusion zone of welded AHSSs [8][9][10].…”