Welding process for improving CTOD performance of thick plate high-strength steel in extremely cold environment

The invention relates to a welding process for improving CTOD performance of thick-plate high-strength steel in an extremely cold environment. The welding process is characterized by specifically comprising the following steps that S1, a movable heat preservation shed is manufactured; s2, material taking; s3, base metal cleaning; s4, preheating before welding; s5, anti-oxidation welding; S6, post-heating after welding; s7, ultrasonic flaw detection; the welding process is simple in step, safe, reliable, good in stability, good in forming and free of non-welding and crack defects; through strict preparation before welding and treatment after welding, the grade of a welding seam is the first grade of full penetration welding, and in a low-temperature environment, the mechanical property of a welded test piece can reach the acceptance inspection effect, so that the welding efficiency is ensured, and the expected requirement is met; when the welding environment is lower than 0 degree but not lower than-10 degrees