Prediction of HAZ Microstructure and Hardness for Q960E Joints Welded by Triple-Wire GMAW Based on Thermal and Numerical Simulation

Abstract

Since heat affected zone (HAZ) is the weak area of welded joints, this article proposes a method to predict the HAZ microstructure and hardness for the triple-wire gas metal arc welding (GMAW) process of Q960E high strength steel. This method combines welding thermal simulation and numerical simulation. The microstructures and hardness of Q960E steel under different cooling rates were obtained by thermal simulation and presented in a simulated HAZ continuous cooling transformation (SH-CCT) diagram. The cooling rate in HAZ were obtained by numerical simulation with ANSYS software for the triple-wire welding of Q960E thick plates. By comparing the cooling rate with the SH-CCT diagram, the microstructure and hardness of the HAZ coarse-grained region were accurately predicted for multiple heat input conditions. Further, an ideal heat input was chosen by checking the prediction results. This prediction method not only helps us to optimize the welding parameters, but also leads to an overall understanding of the process-microstructure-performance for a complex welding process.

A Methodology for Predicting the Phase Fraction and Microhardness of Welded Joints Using Integrated Models

“…A method commonly used for verifying the welding heat transfer model is to compare the thermal cycle or weld bead morphology via experiments and simulations [ 12 , 21 , 36 , 37 ]. To evaluate the accuracy of the heat transfer model for case 1, the experimentally obtained thermal cycle and weld bead morphology were compared with those from simulations.…”

“…Wu et al studied the microstructure and microhardness of a simulated HAZ subjected to various peak temperatures and established the continuous cooling transformation (CCT) diagram of the coarse-grained HAZ (CGHAZ) for a peak temperature of 1350 °C [ 11 ]. Di et al simulated inter-critical HAZ (ICHAZ), which is known as the weak area of a weld, and studied the relationship between the microstructure and toughness for peak temperatures of 750, 780, and 800 °C [ 12 ]. To analyze the microstructure and physical properties of a welded joint at a desired location or welding condition, experimental studies are appropriate.…”

“…CCT diagrams are useful for predicting the microstructure of welded joints because they provide information about the phase transformation during cooling. Numerous studies have been conducted to predict phase fraction using CCT diagrams [ 12 , 13 , 14 , 15 ]. Yang et al proposed a model that combines experiments and numerical simulations to predict the microstructure and microhardness of the HAZ [ 12 ].…”

“…Numerous studies have been conducted to predict phase fraction using CCT diagrams [ 12 , 13 , 14 , 15 ]. Yang et al proposed a model that combines experiments and numerical simulations to predict the microstructure and microhardness of the HAZ [ 12 ]. A thermal simulator reproduces a thermal cycle with the same peak temperature but different cooling rates.…”

Heat source modeling, penetration analysis and parametric optimization of super spray MAG welding

“…If the heat input is too large, it is easy to cause problems such as coarse grains, root defects, decline of mechanical properties, etc. 24 , 25 . This paper presents an analysis of the heat flow distribution in Super Spray MAG Welding using FEM simulation.…”