Welding Process Principles Flashcards

What distinguishes flux-cored arc welding (FCAW-S) 'self-shielded' from FCAW-G 'gas-shielded'?

Answer: FCAW-S generates its own shielding from the flux core without external gas; FCAW-G requires an external shielding gas

FCAW-S electrodes contain compounds in the core that produce sufficient shielding gases and slag when decomposed, eliminating the need for an external gas supply, making it better suited for outdoor/field welding.

In resistance spot welding, the weld nugget forms primarily due to:

Answer: Resistance heating at the faying surfaces between the workpieces

Heat is generated by the electrical resistance at the faying (contact) surfaces between the workpieces; combined with electrode force, this melts the base metal to form the nugget.

What is the purpose of 'preheating' before welding high-carbon or alloy steels?

Answer: Reduce the cooling rate to minimize hydrogen cracking and hard HAZ formation

Preheat slows the cooling rate of the weld and heat-affected zone, reducing the risk of hydrogen-induced cracking and the formation of brittle martensite in hardenable steels.

Which of the following is a characteristic feature of laser beam welding (LBW)?

Answer: Extremely high power density producing a narrow, deep weld with minimal heat input

LBW focuses an extremely high power-density beam onto a small spot, enabling deep, narrow welds with a very small heat-affected zone and minimal distortion.

A welder is producing a multipass groove weld. Between passes, the inspector requires the welder to remove slag. Why is inter-pass slag removal critical?

Answer: Slag inclusions will form if slag is not removed before depositing the next pass

If slag is not completely removed between passes, it can become entrapped in subsequent weld beads, creating slag inclusion discontinuities that reduce weld integrity.

In oxyfuel gas welding (OFW), a 'carburizing' flame is identified by:

Answer: An excess acetylene feather visible beyond the inner cone

A carburizing (reducing) flame has excess acetylene, producing a visible intermediate feather or acetylene cone between the inner cone and the outer envelope.

What is 'interpass temperature' and why is it controlled in welding procedures?

Answer: The temperature of the weld and base metal before depositing a subsequent pass; controlled to limit heat input and maintain mechanical properties

Interpass temperature is the temperature measured in the weld zone immediately before welding the next pass; exceeding the maximum can over-temper the HAZ and reduce toughness or strength.