Effect of Groove Cutting Method on Microstructure and Properties of Argon Arc Welded Joints of 12CrMoV Steel

The “V” groove was processed on 12CrMoV steel plates by laser cutting and flame cutting, and then the plates were connected by argon arc welding. The effect of groove cutting method on the microstructure and properties of joints was studied. The results show that the weld under the two groove cutting methods was well formed, but there were slag clamp defects in the weld under the flame cutting method, and no obvious defects in the weld under the laser cutting method. The microstructure of the coarse-grained heat affected zone of the joint under the two groove cutting methods was mainly composed of granular bainite and ferrite; the ferrite content under the flame cutting method was higher, and the alloying element content was about 0.49% lower than that under the laser cutting method. The hardness of the joints under the two groove cutting methods both met the standard requirements, but the hardness distribution in the heat-affected zone of the joint under the laser cutting method was more uniform. The tensile properties of the joints met the standard requirements and the weak positions were located at the base metal. The room temperature impact absorption energy of heat-affected zone of the joint under the flame cutting method did not meet the standards and that under the laser cutting method met the standards. After the bending test, continuous cracking occurred in the joint under the flame cutting method, while no obvious defects were found in the joint under the laser cutting method. For unimportant structures or low service performance requirement structures, welding directly after laser cutting groove could be considered, while for some important bearing structures, the groove still needed to be processed before welding.