Submerged arc welding and gas shielded welding butt joint tests were carried out on domestic Q345 qE weatherproof steel.Mechanical properties and metallographic structure were observed and analyzed after welding. The results show that the weldability of Q345 qE weatherproof steel is good

without preheating welding

and the toughness of heat affected zone is good

but the heat input has an effect on the impact performance. In practical application

the heat input should be controlled to be less than or equal to 35 kJ/cm;the metallographic structure of weld seam is B+F+P

and the mechanical properties are good;the tensile and bending properties of welded steel sheet are qualified at room temperature. The weldability of Q345 qE weathering steel and the toughness of heat affected zone can be improved indirectly by using low carbon composition.