Electroslag welding

January 13, 2020

Electroslag welding is not a major welding process because its line energy produces coarse weld metal particles, and heat affected zones can cause poor fracture toughness. Toughness can only be improved by post-weld heat treatment. Introduction Electroslag welding is the use of electrical resistance generated by current through the slag as a heat source to melt the filler metal and the parent metal, and solidify to form a solid connection between the metal atoms. At the beginning of welding, the welding wire is short-circuited with the welding groove, and a small amount of solid flux is continuously added, and the heat of the arc is used to melt it to form liquid slag. When the slag reaches a certain depth, the feeding speed of the welding wire is increased, and The voltage is reduced, the welding wire is inserted into the slag pool, the arc is extinguished, and the electric slag welding process is transferred.

Electroslag welding mainly includes nozzle electric slag welding, non-melting nozzle electroslag welding, filament electroslag welding, and plate electroslag welding.

Its shortcoming is that the input heat is large, the joint stays at high temperature for a long time, the weld near the weld is easy to overheat, the weld metal is coarsely crystallized as-cast structure, the impact toughness is low, and the weldment generally needs to be normalized and returned after welding. Heat treatment by fire.
Production practice

In the manufacturing industry, the electroslag welding process has been used for post-weld normalizing of thick-walled pressure vessels and for welding components that are used above ambient temperatures, such as blast furnace shells and long steel bars. It is also widely used for welding at railway sites.

Current important issue

In the 1970s, many people expressed interest in electroslag welding when investigating and studying methods that could increase the speed of welding. It is seen as an important parameter for improving productivity and a method of reducing line energy to improve the heat-affected zone and weld metal impact characteristics.

But since then, the development of electroslag welding has achieved little success. These developments are limited to parameter adjustment and tailoring techniques for certain applications.

advantage

☆The speed of the joint is completed, usually 1m seam/hour, regardless of thickness;

☆ no angle change;

☆The corner deformation is limited to 3mm / m weld;

☆ Forming high quality welds;

☆ Simple joint preparation, such as flame cutting right angle edge;

☆ Large repairs can be easily carried out by cutting all welds and repeating welds.

risk

Electroslag welding is not a major welding process because its line energy produces coarse weld metal particles, and heat affected zones can cause poor fracture toughness. Toughness can only be improved by post-weld heat treatment. In addition, the parallel faces of the weld are combined with the coarse metal particles, making it difficult for standard ultrasonic non-destructive testing equipment to identify defects on the melt boundary.

The electroslag welding process has great potential for increasing productivity. However, due to insufficient understanding of the importance of electroslag welding processes and fracture toughness values, its use has been limited to certain special applications. Therefore, the use of the electroslag welding process is limited to a few suitable applications.
Http://news.chinawj.com.CN Editor: (Hardware Business Network Information Center) http://news.chinawj.com.cn

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