defects found in welds definition of welds

defects found in welds

Defects welds

Defects welds – disorders welds , which can destroy the entire structure.

Most of the defects found :

Shapes and sizes of sutures
Macro- and microstructure
The deformation and warping of welded structures
Defects in the shape and size of welds

Violation of shapes and sizes seam often appear due to a sag or sag , undercuts , burn-through and uncertified craters. Essentially weld defects occur due to human negligence in most cases.

Sagging formed – a leakage of the liquid metal into the cold edge of the base metal . The reasons: the large value of the welding current , arc wrong size , wrong position of the electrode , etc.

Undercuts called recess ( groove ) formed in the base metal .

The undercuts may be the cause of the destruction of the joint.

Burn-through – this is the main or penetration weld metal .

How to find Welding defects

defects macrostructure

These defects are detected with increasing no more than 10 times . These include : gas pores, slag inclusions , cracks .

Cause of defect: high carbon content in the base metal , rust , excessive welding speed . The tests of metals in tension can detect many defects .

Slag inclusion – is the result of mediocre parts cleaning parts and welding wire from scale and dirt , over- speed welding. They have different , the shape of the size and location.

Lack of penetration – this is a local lack of fusion of the base metal to weld . Causes: poor cleaning metal joint gap , etc.

When spot and seam welding prerequisite for the lack of penetration is insufficient amount of current , welding time and the amount of pressure , inappropriate work surface electrodes. When is the butt weld , lack of fusion most often occur as a result of delayed shutdown current.

Cracks and lack of fusion – the most dangerous defects in welds .

Cracks are divided into hot and cold . First appearing at 1000-13000 C, and the latter 100-3000 C. Fix all these defects are more difficult than preventing their occurrence , so the artists responsible approach – the key to high-quality welding results .