What is the difference between undercut and underfill?

So how do we differentiate undercut from underfill? In a nutshell, undercut occurs in base metal adjacent to the weld, and underfill occurs in the weld metal. Although undercut can occur on both grooves and fillets, underfill will occur only on grooves.

What are the causes of underfill?

Basically, Underfill is undersized welding.

LACK OF PENETRATION (INCOMPLETE PENETRATION):
Root gap too small.
Fast travel speed.
Low heat input.
Too large an electrode diameter.
Proper joint preparation i.e. providing a suitable root gap.
Proper heat input.
Correct travel speed.

What is undercut welding?

In welding, undercutting is when the weld reduces the cross-sectional thickness of the base metal. This type of defect reduces the strength of the weld and workpieces. Another reason is if a poor technique is used that does not deposit enough filler metal along the edges of the weld.

What is concave weld?

Definition: A fillet weld that has excessive concavity or convexity. Main Causes: (1) Too fast electrode manipulation, using too high. welding amperage (Concave fillet weld)

What is porosity in welding?

Porosity is the presence of cavities in the weld metal caused by the freezing in of gas released from the weld pool as it solidifies.

What is slag inclusion?

Slag inclusions are nonmetallic particles trapped in the weld-metal or at the weld interface. Slag inclusions result from faulty welding technique, improper access to the joint, or both. Sharp notches in joint boundaries or between weld passes promote slag entrapment.

What is underfill PCB?

Underfill is a type of liquid polymer applied to the printed circuit board (PCB) after it has been subjected to the reflow process. In this process the underfill encapsulates the bottom side of the silicon chip, covering the fragile interconnected pads between the chip’s bottom side and the PCB’s top side.

What are the 5 essential of welding?

Travel speed is influenced by the type of welding current (DCEN, DCEP or AC), amperage, welding position, electrode melt rate, material thickness, surface condition of the base metal, type of joint, joint fit up and electrode manipulation.

What is overlap welding?

Overlap. Overlap occurs when molten metal flows over the surface of the base material and then cools without fusing with the base material. A typical cause of overlap is the supply of too much weld metal due to low welding speed. Overlap in fillet welds is caused by the droop of excessive molten metal due to gravity.

What is convex weld?

Convexity is defined in AWS A3. 0:2010, Standard Welding Terms and Definitions, as “the maximum distance from the face of a convex fillet weld perpendicular to a line joining the weld toes.” Figure 1, which is adapted from Fig. An analogous dimension in a groove weld would be weld reinforcement height.

What causes wormholes in welds?

Wormhole porosity typically occurs during the flux cored arc welding process (FCAW) on both self shielded and gas shielded applications. The common cause of this condition is the nitrogen getting trapped as it tries to escape the puddle during the solidification process.