A Coupled Thermo-Mechanical-Metallurgical Model Capturing Essential Transformations in the Welding of High Strength Low-Alloy Steels

Um Modelo Termo-Mecânico-Metalúrgico Acoplado Capturando Importantes Transformações na Soldagem de Aços de Alta Resistência e Baixa Liga

Abstract:

A well-known challenge is to predict the transformations occurring during the metal alloys welding aiming to control the weldment properties. Thus, this study presents a Thermo-Mechanical-Metallurgical model to numerically predict the thermal history, the solid-state phase transformations, the solidification microstructure and the hardness distribution during and after the welding of high strength low-alloy steels. The model was numerically implemented in an in-house computational code based on the Finite Volume Method, which allowed to dynamically track and calculate the volume fractions of ferrite, pearlite, bainite and martensite at the heat-affected zone, besides the formation and determination of dendrite arm spacing at the fusion zone, whereas the hardness distribution at the heat-affected zone was calculated by applying the phase mixture rule. For this, single-pass autogenous Gas Tungsten Arc Welding welds were numerically simulated and experimentally carried out on high strength low-alloy AISI 4130 steel samples, including their preheating to evaluate the effectiveness of the proposed model to simulate the workpieces welding in different initial thermal conditions and a close agreement between the calculated and experimental results were obtained.

Key-words:
High strength low alloy steels; Welding; Thermo-Mechanical-Metallurgical model; Numerical simulation; Thermal history; Phase transformations; Hardness