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

Ke Yang,Zhishui Yu,Lijun Yang,Huan Li,Fei Wang,Bo Xia,Chuanguang Luo,Dingshan Duan,Wang Li

doi:10.3390/ma14174898

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.

Highlights

As a rising star in the machinery industry, construction machinery has developed rapidly in recent years and has become an important part of the machinery industry [1,2].Construction machinery includes large excavators, cranes, shovel trucks, forklifts, industrial vehicles and so on
When the cooling rate was less than 2 ◦ C/s, the microstructure of the heat affected zone (HAZ) coarse-grained region was mainly granular bainite (GB)
Taking the triple-wire pulse welding of Q960E high-strength steel as example, this article proposes a method for predicting the HAZ microstructure and hardness by combining the welding thermal simulation and numerical calculation

Summary

Introduction

As a rising star in the machinery industry, construction machinery has developed rapidly in recent years and has become an important part of the machinery industry [1,2].Construction machinery includes large excavators, cranes, shovel trucks, forklifts, industrial vehicles and so on. The quality of welding greatly determines the safety of the equipment, and the efficiency of welding is closely related to the processing cost of the equipment [4,5]. There are two major requirements for the welding of construction machinery: First, the welding of high strength steel. For the welding of high strength steel, a lot of current research has focused on the process windows of different welding methods [11,12,13,14,15], the influence of alloying elements on weldability [16,17,18], the matching and upgrading of welding wire [19,20,21], and the failure of welded joints [22,23,24,25]

Methods

Results

Conclusion