What is the difference between flash butt welding and electroslag pressure welding of steel bars?

​ ​First of all, Xinxing Steel Barflash butt weldingIt is a 0-degree horizontal butt joint, and electroslag pressure welding is a 90-degree vertical joint. Their principles and processes are also different.

1. Different principles
Rebar flash butt welding is a welding method in which two steel bars are placed horizontally in the left and right electrodes, current flows through the ports of the two steel bars, and the resistance heat of the steel bars itself is used to melt the metal at the contact point, causing strong splashing to form a flash, and then quickly applying upsetting force to complete.

Steel bar electroslag pressure welding is a pressure welding method in which two steel bars are placed vertically butted together. The welding current flows through the end faces of the two steel bars, forming an arc process and an electroslag process under the flux layer, thereby generating arc heat and resistance heat, melting the steel bars, and then pressing to complete the process.

2. Different processes

1. Welding process of steel bar flash butt welding
It can be divided into continuous flash welding, preheated flash welding and flash-preheated flash welding, etc., which are selected according to factors such as steel bar type, diameter, welding machine power, and welding location.

1) Continuous flash butt welding process:
Close the circuit → flash (the end faces of the two steel bars are in slight contact) → → continuous flash heating to near the melting point (the end faces of the two steel bars slowly move and contact) → electrified upsetting → → electroless upsetting

2) Preheat flash butt welding process:
Close the circuit → intermittent flash preheating (the end faces of the two steel bars are alternately contacted and separated) → - + continuous flash heating to near the melting point ( the end faces of the two steel bars slowly move into contact) - + charged upsetting → → electroless upsetting

3) Flash/preheat flash butt welding process:
Closed circuit - +- Flash flash flat end face (end faces of two steel bars are in slight and slow contact) → → Intermittent flash preheating (end faces of two steel bars alternately contact and separate) → Two consecutive flashes to heat to near melting point (end faces of two steel bars slowly move and contact → Belt forging - → → Electroless upsetting 3.2

2. Steel bar electroslag pressure welding process

The process of electroslag pressure welding includes: arc starting, arc, electroslag and top pressure processes

(1) Arc ignition process: The iron wire arc ignition method should be used, or the direct arc ignition method can be used.
The iron wire arc ignition method is to place the iron wire loop between the ends of the upper and lower steel bars, with a height of about 10mm. The current passes through the contact points between the iron wire loop and the end surfaces of the upper and lower steel bars to form a short-circuit arc.
The direct arc striking method is to quickly lift the upper steel bar after powering on, so that the distance between the two ends is 2~4mm to strike the arc. When the ends of steel bars are mixed, they are not conductive
When arc ignition is difficult due to electrical material or excessive smoothness, the upper steel bar can be moved down several times to short-circuit the lower steel bar and then be lifted up to achieve the purpose of arc ignition.
(2) Arc process: The high temperature of the arc continuously burns the protruding part of the steel bar end; at the same time, the flux around the joint is fully melted to form a slag pool of a certain depth.
(3) Electroslag process: After the slag pool forms a certain depth, slowly insert the upper steel bar into the slag pool. At this time, the arc is extinguished and the electroslag process begins. Since the current passes directly through the slag pool, a large amount of resistance heat is generated, causing the temperature of the slag pool to rise to nearly 2000C, melting the ends of the steel bars quickly and evenly.
(4) Pushing process: When the end of the steel bar reaches full cross-section melting, quickly push the upper steel bar downward to squeeze out all impurities such as molten metal, slag and oxides from the joint surface. At the same time, cut off the power supply, and the welding is completed.

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