(EN) A method for enhancing the strength and toughness of a welded joint formed on Q890DQP steel comprises: placing an under-matched 50 kg welding wire at the root of a weld seam, and performing welding with an even-matched 90 kg welding wire serving as a filler for the weld seam and a material for a cap; using a mixed gas containing Ar+20％ CO 2 and performing gas shielded welding, where the welding energy ranges from 12 to 16 KJ/cm; for mid-level restriction conditions, performing a welding process without preheating, and for high restriction conditions, preheating until the temperature reaches 50°C before welding the weld seam, and controlling an interlayer temperature to be 100-150°C. The method enhances the strength and toughness of a welded joint, such that the welded joint has in-use performance matching the in-use performance of a Q890DQP base material, and exhibits favorable mechanical performance. The invention can reduce the temperature to be reached by preheating before a welding process, reduce production costs, improve the welding environment, and effectively enhance production efficiency.
