Correlation between Weld Metal Microstructure Evolution and Welding Process Parameters of Low Alloy Ferritic Steel Weldments

Abstract

This study attempts to propose a convenient method to adjust the welding process parameters window with the aim of high volume fraction of acicular ferrite in the weld metal (WM). The samples are directly extracted from the deposition zone of two low alloy ferritic steel dissimilar welded joints (DWJs) that manufactured using different consumables, and their microstructural evolution is controlled using thermomechanical simulation technique. The results show that it is hard for the low‐alloyed WM to obtain high amount of acicular ferrite no matter how to control the cooling process, meaning that the welding consumable with only a small amount of alloying elements is not suitable for welding this DWJ. However, for the high‐alloyed WM, the acceptable window of the cooling process is determined within 10–22 °C s−1 to achieve aimed microstructure. In situ observation shows that the preexisting bainitic laths significantly reduce the growth space of acicular ferrite plates. The average lengthening rate of acicular ferrite plates is ranged from ≈5 to ≈68 μm s−1 at a cooling rate of 3 °C s−1.

Multi-Objective Optimization of Laser Cleaning Quality of Q390 Steel Rust Layer Based on Response Surface Methodology and NSGA-II Algorithm

“…In the construction of nuclear power plants, the use of embedded steel rebar and steel plate components is ubiquitous, and among these components, Q390 steel plates are commonly used [1,2]. There is typically a loose rust layer on the surface, and in the welding process, water absorbed by the rust layer decomposes and produces a large amount of hydrogen, which cannot be discharged in time during the cooling process of the weld.…”

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

“…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 ].…”

“…Deng used two CCT diagrams in a welded joint by considering different prior austenite grain sizes (PAGSs) [ 14 ]. Zhang et al also used a dilatometry to attain a CCT diagram and analyzed the difference in phase transformation temperature and behavior during welding according to the difference between low-alloyed and high-alloyed steel [ 15 ].…”