Key points of construction technology of steel bar welding

Update:22 Feb 2020

In the construction of modern buildings, the welding of […]

In the construction of modern buildings, the welding of steel bars is widely used. Common welding methods for steel bars include flash butt welding, arc welding, and electroslag pressure welding. The welding quality of steel bars is related to the weldability of the steel and the welding process. This article briefly discusses the construction technical points of steel bar welding.
Welding process
The welding process includes arc initiation, stabilizing arc, electroslag, and top pressure. Before welding, the rust in the end of the steel bar should be removed within about 120mm, the clamp should be clamped on the lower steel bar, and the upper steel bar should be straightened. Hold firmly in the moving electrode and fill the flux box with flux.
When manual electroslag electric pressure welding is used, the direct arc initiation method can be used. First, the upper and lower steel bars are contacted. After the welding power is turned on, the upper steel bar is lifted by 2 to 4 mm immediately to ignite the arc; Several millimeters of steel, after the arc is stably burned, it is gradually sent down as the steel is melted, and it is transferred to the electroslag process. After the steel has been melted to a certain level, the welding power is cut off and the pressure is quickly pressed and cooled 1 ~ After 3 minutes, you can open the flux box, retract the flux, remove the jig, and knock out the slag.
Problem and cause analysis
1.Quality issues and phenomena
The length of the weld is not enough, the surface of the weld is uneven, and there are large depressions and welding knobs. The welding seam has undercuts, the electrode does not meet the requirements, the welding skin is not knocked off, and the axes of the two reinforcing bars are not consistent.
2.Cause analysis
(1) The welder is unskilled and has not obtained a welder examination certificate.
(2) The weld core length of the inflatable core mold is not measured after welding is completed.
(3) The electrode is unqualified, or the specification of the electrode is incorrect.
(4) After welding is completed, care is not taken to knock off the inflatable core mold welding skin.
(5) The overlapped ends of the two welded bars are not pre-bent.