Method for welding 16MnDR low-temperature pressure container pot body closing end splicing welding line

Abstract

The invention provides a method for welding a joint welding seam of a sealing head of a tank body of a 16MnDR low-temperature pressure vessel and relates to a method for welding the joint welding seam of the sealing head of the tank body of the pressure vessel. The method solves the problem that indexes of tensile strength and impact toughness at the joint of the sealing head of the tank body are reduced in the normalizing temperature state in the prior welding process. The method comprises the following steps: 1, opening a Y-type groove on a joint end face of two joint plates of a 16MnDR sealing head; 2, welding one side of the Y-type groove; 3, gouging and chipping back; 4, welding the welding seam on the back; 5, carrying out normalizing temperature treatment at a charging temperature of between 200 and 400 DEG C and a heat preserving temperature of between 900 and 930 DEG C, and keeping the temperature for 10 to 75 minutes; and 6, carrying out annealing treatment at a charging temperature of between 20 and 390 DEG C and a heat preserving temperature of between 600 and 640 DEG C, and keeping the temperature for 40 to 50 minutes and the temperature dropping speed of between 1.0 and 6.7 DEG C /min. Step 2 and step 4 adopt automatic submerged arc welding, wherein the welding wire brand is H09MnDR, the welding wire diameter is Phi 4 millimeters and the flux brand is SJ305, and the drying is performed for 1 to 2 hours at a drying temperature of between 340 and 360 DEG C. The welding current is 650 to 710A, the electric arc voltage is 34 to 36 V, and the welding speed is 48 to 50 cm/min. The method can improve the tensile strength and the low-temperature impact toughness of the welding seam at the joint of the sealing head after the normalizing temperature treatment.

Description

Technical field [0001] The invention relates to a splicing welding seam welding method for the head of a pressure vessel body. Background technique [0002] Due to the splicing and welding of the heads of 16MnDR low-temperature pressure vessels, after welding, it needs to be normalized at 900~930℃, and then treated at 600~640℃ to eliminate welding stress. The test proves the tensile strength and low-temperature impact of the welds at the joints of the heads. Toughness decreases. In order to meet the performance of the 16MnDR low-temperature pressure vessel body, conventional submerged arc welding wire and flux were used in the previous welding process, and the submerged arc automatic welding process was first used for welding. After normalizing treatment, the original weld was gouged out. Then use the electrode arc welding to re-weld this weld again. It needs to be welded twice, and the original weld is removed once. This not only causes a certain economic loss to the manufacture...

AI Technical Summary

Problems solved by technology

[0002] Due to the splicing and welding of the head of the 16MnDR low-temperature pressure vessel, it needs to be normalized at 900-930°C after welding, and then treated at 600-640°C to eliminate welding stress. The test proves that the weld seam tensile strength and low-temperature impact of the head splicing Reduced toughness

In order to meet the service performance of the 16MnDR low-temperature pressure vessel tank, conventional submerged arc welding wire and flux were used in the previous welding process, and the submerged arc automatic welding process was first used for welding. After normalizing, the original weld was planed off. Then use electrode arc welding to re-weld the weld again. It needs to be welded twice, and the original weld should be planed off once. This will not only cause a certain economic loss to the manufacturer, but also increase the labor intensity of the workers and increase the manufacturing cycle. , which increases the production cost of the product

In addition, there is also the problem that the tensile strength and impact toughness index of the splicing part of the tank head in the normalized state decreases, which makes it difficult to meet the use requirements