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Welding technology of P92 steel submerged automatic arc welding for power station boiler

A technology for automatic submerged arc welding and power station boilers, applied in arc welding equipment, welding media, welding equipment, etc., can solve the problems of reduced production efficiency, prolonged single pause time, frequent pauses in the welding process, etc., to improve the welding seam. Toughness, the effect of improving welding efficiency

Inactive Publication Date: 2014-08-13
DONGFANG BOILER GROUP OF DONGFANG ELECTRIC CORP
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Studies have shown that when the interlayer temperature exceeds 300 °C, the probability of cracks increases significantly (Li Zhenshan, Yan Zheng, Liu Zhiming, et al., Nondestructive Testing and Defect Prevention of P91 / P92 Steel Pipeline Factory Prefabricated Welded Joints, 2009). The temperature is generally controlled within 280°C (Mao Min, Xu Zailin, Zhang Yanfei, et al., P92 Steel Welding Quality Control of Ultra (Ultra) Critical Units, 2009), but the interlayer temperature is limited below 280°C, which makes the welding process stop frequently and single-shot The pause time is obviously extended, which seriously reduces the production efficiency

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  • Welding technology of P92 steel submerged automatic arc welding for power station boiler
  • Welding technology of P92 steel submerged automatic arc welding for power station boiler

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Embodiment

[0014] One, technological principle of the present invention is based on following considerations:

[0015] (1) The hot crack tendency of P92 submerged arc welding seam is large and the toughness is low, which is mainly due to improper selection of welding materials. At present, the welding wire whose composition is equivalent to that of P92 steel is generally selected, typical grades such as 9CrWV and Thermanit MTS616 submerged arc welding wire. This type of wire has a high C content (typically 0.11wt.%), and the addition of about 0.5-0.8 wt.% Ni element suppresses the formation of δ-ferrite. The disadvantage is that the high C content of the welding wire increases the thermal crack sensitivity of the weld, and the addition of Ni appears to be insufficient at high temperatures, resulting in the formation of δ-ferrite in the weld, but continue to increase the addition of Ni in the welding wire make A again C1 Excessive reduction will affect the selection of post-weld heat tr...

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Abstract

The invention relates to a welding technology of P92 steel submerged automatic arc welding for a power station boiler. According to a specific method, welding wires are selected, wherein the content of C is 0.06-0.08wt%, the content of Co is 0.9-2.0wt%, the contents of other elements are the same as that of a base material, and the diameters of the welding wires are 2.4mm; the specific welding method comprises the following steps: firstly preheating; beginning to weld until the temperature is 200-250 DEG C by preheating, wherein the welding speed is constantly kept to be 13-22 m / h, and the interlayer temperature is controlled to be 300-350 DEG C; stopping welding when the temperature is over 350 DEG C, and going on welding when the temperature is reduced to be lower than 350 DEG C and not lower than 200 DEG C. Therefore, the welding technology has the advantages that the crack sensitivity of weld joints is reduced and the formation of delta-ferrites is inhibited by selecting a low-carbon Co-alloying welding material, so that the tenacity of the weld joints is improved. According to the technology, the upper limit of the interlayer temperature can be promoted to be 350 DEG C, and thus the welding efficiency is greatly improved.

Description

[0001] technical field [0002] The invention relates to a submerged arc automatic welding process, in particular to a submerged arc automatic welding process for P92 steel used in power station boilers. Background technique [0003] P92 steel is a new type of martensitic heat-resistant steel widely used in thick-walled pipes such as ultra-supercritical boiler main steam pipes and headers. The welding of the main body of the P92 header is completed in the factory, and the submerged arc automatic welding method with high efficiency and stable quality is generally used. However, the heat input of submerged arc welding is larger than that of electrode arc welding, and the thermal conductivity of P92 steel is lower than that of low alloy steel, so that the temperature between welding layers is at a high level (continuous welding can reach above 450 ° C). Deteriorating the toughness of the weld, but the layer temperature limit is too low and the welding process has to stop frequ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B23K9/18B23K35/24
CPCB23K9/18B23K35/24
Inventor 王学潘乾刚曾会强刘洪刘洪伟杨建明
Owner DONGFANG BOILER GROUP OF DONGFANG ELECTRIC CORP
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