gas-shielded welding was used for partial penetration corner welding of Q420qD steel with 16 mm thickness
the welding process of flat
vertical and elevation weld was optimized
and the microstructure and mechanical properties of the welded joints were analyzed. The results showed that the microstructure of the weld metal (WM) and the heat-affected zone (HAZ) was stable under different heat input conditions (13.25~19.77 kJ/cm). The microstructure of the WM was mainly pre-eutectic ferrite and acicular ferrite
the coarse grain zone has a mixed bainite
acicular ferrite and pearlite
the ferrite and pearlite in the fine grain zone were uniformly distributed. The hardness of welded joints varies as follows: HAZ
>
WM
>
base material (BM). The yield strength of welded joints (558~669 MPa) was significantly higher compared to the BM (464 MPa)
and the tensile fracture location all occurred in the HAZ; The impact energy of the WM and HAZ at -20 ℃ was above 69 J
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