Welding Process Fundamentals Flashcards
7 cards from real CWI practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Welding Process Fundamentals flashcards as text
Which of the following welding processes uses a non-consumable electrode?
Answer: GTAW
GTAW (TIG welding) uses a non-consumable tungsten electrode to maintain the arc, with filler metal added separately if needed.
What is the function of 'preheat' when welding high-carbon or alloy steels?
Answer: To slow the cooling rate, reducing the risk of hydrogen cracking and hard brittle microstructures in the HAZ
Preheat reduces the thermal gradient and slows cooling, allowing hydrogen to escape and preventing the formation of brittle martensite in the heat-affected zone.
In friction stir welding (FSW), the joint is made by:
Answer: A rotating non-consumable tool that generates frictional heat and mechanically stirs the plasticized material
FSW is a solid-state process where a rotating probe tool generates heat through friction and mechanically intermixes the plasticized (but not melted) material to form a weld.
What does DCEN (Direct Current Electrode Negative) polarity mean for GTAW?
Answer: The electrode is connected to the negative terminal; electrons flow from electrode to workpiece, concentrating heat in the base metal
In DCEN (straight polarity), electrons leave the negative tungsten and strike the positive workpiece, directing about two-thirds of the heat into the base metal for deep penetration and minimal tungsten heating.
A CWI finds incomplete fusion (lack of fusion) in a groove weld. Which root cause is MOST likely?
Answer: Improper electrode angle or insufficient heat causing the weld pool to fail to fuse to the sidewall or previous pass
Lack of fusion results when the weld pool fails to fuse to the base metal or preceding weld pass, typically due to insufficient heat input, improper technique, or wrong electrode angle.
What is the primary purpose of post-weld heat treatment (PWHT) on pressure vessels?
Answer: To relieve residual stresses and temper hard HAZ microstructures, improving toughness and dimensional stability
PWHT reduces residual welding stresses, tempers brittle microstructures in the HAZ, and is required by codes such as ASME Section VIII for certain materials and thicknesses.
In SMAW, what is the significance of the 'F' number classification for filler metals in AWS D1.1?
Answer: It groups electrodes with similar usability characteristics to qualify welders across grouped processes
F-numbers group filler metals by similar welding characteristics; a welder qualified with one electrode in an F-number group is generally qualified for other electrodes in the same group.