Weld Discontinuities & Defects Flashcards

Which discontinuity is most likely to occur when welding austenitic stainless steel with excessive heat input?

Answer: Hot cracking

Austenitic stainless steels are susceptible to hot cracking (solidification cracking) when high heat input causes low-melting impurity films to form along grain boundaries.

A weld exhibiting 'wagon tracks' on a radiograph most likely contains which discontinuity?

Answer: Slag inclusions

Wagon tracks on a radiograph are parallel lines of slag inclusions typically found between weld passes in multi-pass welds.

Which condition is the PRIMARY cause of lamellar tearing in structural weldments?

Answer: Low through-thickness ductility of the base metal

Lamellar tearing occurs when through-thickness shrinkage stresses exceed the low through-thickness ductility of base metal containing planar inclusions.

A welder notices a groove melted into the base metal adjacent to the weld toe that is not filled by weld metal. This is called:

Answer: Undercut

Undercut is a groove melted into the base metal at the weld toe or weld root that is left unfilled by weld metal.

Which nondestructive testing method is MOST effective for detecting subsurface porosity in a thick weld section?

Answer: Radiographic testing (RT)

Radiographic testing (RT) is most effective for detecting internal volumetric discontinuities like subsurface porosity in thick sections.

What type of crack typically initiates at the weld toe and propagates into the heat-affected zone?

Answer: Toe crack

Toe cracks initiate at the geometric stress concentration at the weld toe and propagate into the heat-affected zone, often caused by hydrogen-induced cracking.

Which welding parameter change would MOST effectively reduce the risk of burn-through on thin sheet metal?

Answer: Increase travel speed

Increasing travel speed reduces heat input per unit length, preventing excessive melt-through (burn-through) on thin base materials.