Table of Contents
- 1 What is the difference between weld defect and discontinuity?
- 2 What is arc welding discontinuity?
- 3 What are the 12 most common discontinuities?
- 4 What determines if a discontinuity is acceptable?
- 5 Why is weld overlap bad?
- 6 Is a discontinuity a defect?
- 7 What do you call interruptions in a weld?
- 8 When do inclusions occur in a weld what happens?
What is the difference between weld defect and discontinuity?
Welding Defects If a discontinuity renders a weld incompetent or lowers its quality, it would be classified as a defect. Defects make the product risky to use or substandard. It is up to the quality control to decide whether the discontinuity qualifies as a defect or not.
What is arc welding discontinuity?
A lack of local physical material continuity at or near the weld is called a discontinuity or flaw. Such a feature has to be detected and evaluated to determine if it is a harmless imperfection or an intolerable defect that must be removed because of the service the structure will sustain in operation.
What weld discontinuity is most severe?
Cracks
Cracks – Cracks are the most detrimental discontinuity for the integrity of a welded connection.
What is defect and discontinuity?
discontinuity: a lack of continuity or cohesion; an intentional. or unintentional interruption in the physical structure. or configuration of a material or component. defect, n—one or more flaws whose aggregate size, shape, orientation, location, or properties do not meet specified.
What are the 12 most common discontinuities?
What Are Some Common Welding Discontinuities?
- Porosity. Porosity occurs when gas becomes trapped in the weld pool, forming permanent bubbles as the metal cools from a liquid state back to a solid.
- Inclusions.
- Inadequate Joint Penetration.
- Incomplete Fusion.
- Arc Strikes.
- Overlap.
What determines if a discontinuity is acceptable?
Welding Discontinuities Evaluation of the discontinuity will determine if the discontinuity is a defect or an acceptable condition: Undercut – A groove melted into the base metal adjacent to the weld toe or weld root and left unfilled by weld metal.
What is convexity in welding?
The maximum distance from the face of a convex fillet weld perpendicular to a line joining the weld toes.
What causes underfill in welding?
Fig. Definition: The protrusion of weld metal beyond the weld toe or weld root Main Causes: (1) Too low welding amperage (2) Too slow electrode manipulation (3) Too short arc length, or too low arc voltage (4) Electrode travel and work angles are inappropriate.
Why is weld overlap bad?
Using too much electric current causes an overlap. Too much current leads to over-melting of the weld material and a consequential overflow above the metal.
Is a discontinuity a defect?
A discontinuity is not necessarily a defect. or product unable to meet minimum applicable acceptance standards or specifications. the term designates rejectability. Engineering Problems?
What are the basic welding symbols?
The skeleton of a welding symbol has an arrow, a leader line (attached to the arrow), a horizontal reference line, a tail, and a weld symbol (not to be confused with welding symbol, which refers to the whole thing. See symbol 1). Hold on, if you’re already lost, don’t panic. It’ll all start making sense soon.
When do discontinuities in welding become weld defects?
Discontinuities, as stated above, are not necessarily weld defects. They become weld defects when they exceed specified maximums of the code or customer specifications. This means that you can have weld discontinuities and still have an acceptable weld. However, we always want welds free of discontinuities whenever possible.
What do you call interruptions in a weld?
Interruptions or flaws in the physical, mechanical or metallurgical properties of a weld are called discontinuities. The number or extent of the discontinuities that is acceptable for a given product depends on its standards.
When do inclusions occur in a weld what happens?
Inclusions occur when slag, oxides or other nonmetallic materials become trapped between the bases metal and the weld, between the beads of the weld or in the weld metal. The structural integrity of the weld can be compromised by the presence of inclusions. 3.
What are the effects of unacceptable Weld profiles?
Unacceptable weld profiles can cause a reduction in base material thickness, reduction in weld size, or stress concentrations on the weld or plate surface. These types of weld discontinuities often seriously detract from the overall performance of a welded component in service.