Effect of Microstructure of Welded Joints HG785D on Impact Toughness
The microstructure and impact toughness of joints of HG785D high strength steel welded by metal active gas shielded arc welding (80%Ar+20%CO2) was observed and analyzed. The result showed that the microstructure of weld seam was mainly composed of acicular ferrite, the impact energy of which was better. While the microstructure of HAZ with large size bainite and M-A island. Using the method of EBSD, it's also found that the effective grain size of weld seam was similar with fine grain HAZ. However the proportion of high-angle grain boundary in weld seam was much larger than that of HAZ. As a result, it could arrest propagating cracks and enhance the toughness.
Hun Guo, Taiyong Wang, Dunwen Zuo, Zijing Wang, Jun Li and Ji Xu
Q. Zhang et al., "Effect of Microstructure of Welded Joints HG785D on Impact Toughness", Key Engineering Materials, Vol. 693, pp. 740-746, 2016