Combined finite element and phase field method for simulation of austenite grain growth in the heat-affected zone of a martensitic steel weld

Abstract

Engineering components operating at high temperature often fail due to the initiation and growth of cracks in the heataffected zone adjacent to a weld. Understanding the effects of microstructural evolution in the heat-affected zone is important in order to predict and control the final properties of welded joints. This study presents a combined finite element method and phase field method for simulation of austenite grain growth in the heat-affected zone of a tempered martensite (P91) steel weld. The finite element method is used to determine the thermal history of the heat-affected zone during gas tungsten arc welding of a P91 steel plate. Then, the calculated thermal history is included in a phase field model to simulate grain growth at various positions in the heat-affected zone. The predicted mean grain size and grain distribution match well with experimental data for simulated welds from the literature. The work lays the foundation for optimising the process parameters in welding of P91 and other ferritic/martensitic steels in order to control the final heat-affected zone microstructure.

Edge Microstructure and Strength Gradient in Thermally Cut Ti-Alloyed Martensitic Steels

“…In the plasma cut specimens (Figure 4), no significant variation in grain structure with the position was observed by SEM in both steels. Formation of complex phase balance in HAZ was reported previously for welded martensitic steels [34] and analyzed using an integrated microstructure modelling approach [35].…”

Phase-Field Simulation of Grain Boundary Evolution In Microstructures Containing Second-Phase Particles with Heterogeneous Thermal Properties

“…Large thermal gradients in a material lead to the development of large thermal stresses, and additional mechanical driving forces for grain boundary evolution due to elastic deformation 26,27 . Simplified approaches for incorporating the effects of second phase particles in larger length scale simulations also exist, however these approaches, which generally consider different thermal activation energies for grain structures with the presence and absence of second phase particles, do not explicitly consider the particles, and consequently the perturbation of the thermal field due to the particles is not captured 28 .…”

Prediction of prior austenite grain growth in the heat-affected zone of a martensitic steel during welding

“…In [22] an overview of multi-scale multi-physics modelling [21]. (a) process model [23], (b) microstructure evolution model [24], (c) property prediction model [20].…”

“…Analytical solutions for predicting grain growth in HAZ have been reported [34,35,36]. In our previous work, application of the existing analytical solutions show poor prediction of grain growth in the HAZ of a precipitation strengthened martensitic steel, such as P91 [24]. This is because the existing analytical solutions do not consider the dissolution of precipitation at high temperature (above 1373 K), which is the determinant factor for final austenite grain size during welding of P91 steel.…”

“…To date, there are limited studies investigating the influence of thermal cycles on PAG growth in the HAZ of P91 welds [24]. Pandey et al [37,38] has studied the influence of post-weld heat treatment (PWHT) on microstructure evolution in various zones of gas tungsten arc welded P91 pipe weldments.…”