Millwright Welding and Cutting Processes Flashcards
6 cards from real Millwright Certification practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
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Which welding process uses a non-consumable tungsten electrode and a separate filler metal?
Answer: Gas Tungsten Arc Welding (GTAW)
GTAW, also known as TIG welding, is characterized by its non-consumable tungsten electrode which creates the arc. A separate filler rod is manually fed into the weld pool, and an inert shielding gas protects the weld from atmospheric contamination.
Which thermal cutting process is most suitable for cutting non-ferrous metals like aluminum and stainless steel?
Answer: Plasma arc cutting
Plasma arc cutting uses an ionized gas jet to melt and expel material, making it effective on any electrically conductive metal. Oxy-fuel cutting relies on the oxidation of iron and is therefore not effective on stainless steel or aluminum.
A weld bead exhibits a groove melted into the base metal adjacent to the weld toe that is not filled by weld metal. What is this defect called?
Answer: Undercut
Undercut is a common weld defect caused by excessive current, incorrect electrode angle, or too fast of a travel speed. It creates a stress concentration point at the toe of the weld, which can lead to cracking.
When setting up an oxy-acetylene torch, what is the maximum safe working pressure for acetylene?
Answer: 15 psi
Acetylene becomes unstable and can decompose explosively at pressures above 15 psi. For safety, it should never be used at a pressure exceeding this limit in its free state.
In Shielded Metal Arc Welding (SMAW), what is the primary function of the flux coating on the electrode?
Answer: To provide a shielding gas, deoxidizers, and a slag covering
The flux coating serves multiple purposes: it vaporizes to create a shielding gas that protects the molten weld pool from the atmosphere, it contains elements that clean and deoxidize the weld metal, and it forms a protective slag layer over the solidifying weld.
Before welding two pieces of thick carbon steel plate with a full penetration groove weld, what is the most critical preparation step?
Answer: Preheating the material
Preheating thick sections of carbon steel is crucial to slow the cooling rate of the weld and the heat-affected zone (HAZ). This helps prevent the formation of brittle microstructures like martensite and reduces the risk of hydrogen-induced cracking.