About steel pipe weld strength

1.When welding according to welding material code and industry standard, what strength can the typical structural weld between steel plates reach?

The weld can maintain high strength, exceeding the strength required by the welding material code and application. In many cases, this weld strength can not be identified by the welding material code itself.

2.Why is the strength of welded joint of structural steel higher than that of base metal in typical welding state?

There are two reasons.

(1) The metal core of the electrode is high quality steel, and its performance is better than that of the base metal.

(2) In the welding process, molten metal is well protected. Compared with EAF steel, electrode coating has the function of deoxidizer and purifier.

3.What is the effect of welding defects on the strength of the weld?

(1) Although there are serious undercut defects in the weld, but under the tensile action of static load, the failure is not the weld, but the metal plate.

(2) The size of the fillet weld is 75% of the thickness of the welded metal plate. When the size of the fillet weld is reduced to 6.4 mm, the weld metal will fracture under the pressure of 220 kPa / mm.

(3) Before the tensile test, the weld should be smooth. When the necking of the weld is reduced to 31% of the thickness of the whole sample, the whole weld will fracture.

4.How many pores in the weld will affect the weld strength?

When the porosity in the weld is greater than 7% of the whole weld, the tensile strength, plasticity and impact strength of the weld change greatly.

Working weld and contact weld

According to the load transfer, the weld on the welded structure can be divided into two types.

Working weld: the weld and connected components are in series, which can transfer load. After fracture, the structure will fail.

Contact weld: the weld and connected components are in parallel, playing the role of interconnection between components. Once broken, the structure will not immediately fail.

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