AWS Welding Techniques 1 — Questions and Answers

Question 1: Which welding process uses a continuously fed wire and shielding gas?

TIG Welding
Stick Welding
MIG Welding (Correct answer)
Oxy-Acetylene Welding

Correct answer: MIG Welding

MIG welding, or Gas Metal Arc Welding (GMAW), uses a continuously fed wire electrode that is consumed during the welding process. A shielding gas (typically argon, CO2, or a mix) is simultaneously fed to protect the molten weld pool from atmospheric contamination, making it efficient and versatile for various metals and applications.

Question 2: Which welding process does not require external shielding gas?

TIG Welding
MIG Welding
Stick Welding (Correct answer)
Plasma Cutting

Correct answer: Stick Welding

Stick welding, or Shielded Metal Arc Welding (SMAW), uses a consumable electrode coated with flux. When the electrode melts, the flux coating decomposes, creating a gaseous shield around the weld pool and forming a protective slag layer. This internal shielding mechanism means no external shielding gas cylinder is required, making it highly portable.

Question 3: What is the main advantage of TIG welding?

High deposition rate
Suitable for thick steel only
Highly portable
Produces high-quality precise welds (Correct answer)

Correct answer: Produces high-quality precise welds

TIG welding (Gas Tungsten Arc Welding, GTAW) is renowned for its ability to produce extremely clean, high-quality, and precise welds. It uses a non-consumable tungsten electrode and a separate filler rod, allowing for excellent control over the heat input and weld puddle. This makes it ideal for critical applications and thin materials where aesthetics and integrity are paramount.

Question 4: What does the flux coating on a stick electrode do?

Increases the electrode temperature
Acts as a filler metal
Creates shielding gas and slag (Correct answer)
Conducts electricity more efficiently

Correct answer: Creates shielding gas and slag

The flux coating on a stick electrode serves multiple crucial functions. As it burns, it produces a shielding gas that protects the molten weld pool from atmospheric oxygen and nitrogen. It also forms a protective slag layer over the cooling weld, which further shields it and helps shape the bead, before being chipped away after solidification.

Question 5: Which welding process is best for welding aluminum?

Stick Welding
TIG Welding (Correct answer)
Flux Core Welding
Submerged Arc Welding

Correct answer: TIG Welding

TIG welding is generally considered the best process for welding aluminum due to its ability to produce very clean and high-quality welds. The use of AC current in TIG welding helps to break up the tenacious aluminum oxide layer, which is crucial for achieving good penetration and a strong, defect-free weld. This precision is vital for aluminum's properties.

Question 6: Which component is essential for Gas Metal Arc Welding (GMAW)?

Chipping hammer
Shielding gas (Correct answer)
Foot pedal
Filler rod

Correct answer: Shielding gas

Gas Metal Arc Welding (GMAW), commonly known as MIG welding, relies heavily on shielding gas to protect the molten weld pool from atmospheric contamination. Without shielding gas, oxygen and nitrogen from the air would react with the molten metal, leading to porosity, brittleness, and a weak weld. It is a critical component for weld integrity.

Question 7: What type of current is typically used in Stick Welding (SMAW)?

AC only
DC only
DC or AC (Correct answer)
Neither AC nor DC

Correct answer: DC or AC

Stick welding (SMAW) can be performed using either Direct Current (DC) or Alternating Current (AC). The choice of current type depends on the specific electrode being used and the material being welded. Many electrodes are designed for either AC or DC, while some are versatile for both, offering flexibility to the welder in various environments.

Question 8: What is porosity in a weld caused by?

Excess heat
Poor shielding gas coverage (Correct answer)
Too much filler rod
Excessive arc length

Correct answer: Poor shielding gas coverage

Porosity in a weld occurs when gases become trapped within the solidifying weld metal, forming small voids. This often happens due to insufficient or improper shielding gas coverage, which fails to protect the molten weld pool from atmospheric contaminants like oxygen and nitrogen. These absorbed gases are then released as bubbles, leading to these internal cavities.

Question 9: What does the term 'undercut' refer to in welding?

A type of electrode
An arc start technique
Groove that weakens the weld joint (Correct answer)
Weld cooling method

Correct answer: Groove that weakens the weld joint

Undercut refers to a groove melted into the base metal adjacent to the toe or root of a weld, which is left unfilled by weld metal. This defect reduces the thickness of the base metal, creating a stress concentration point that significantly weakens the weld joint. It can lead to premature failure under load.

AWS Welding Techniques 1

Which welding process uses a continuously fed wire and shielding gas?