Question Answers on Welding for CSWIP 3.1 and AWS CWI Exams.

Q1. Which welding process utilizes a non consumable electrode?

1. SAW
2. MMA
3. TIG
4. MIG

(Explanation: In TIG welding, a tungsten electrode is used to create an arc, and a separate filler material may be added to the weld pool as needed. The electrode itself is not consumed during the welding process.)

Q2. MMA welding (SMAW) of low alloy steels is more likely to be performed with?

1. Rutile electrodes
2. Cellulosic electrodes
3. Neutral electrodes
4. Basic hydrogen controlled electrodes

(Explanation: Basic hydrogen controlled electrodes electrodes are often preferred because they provide good mechanical properties and are effective in preventing the formation of hydrogen-induced cracking, which is a common concern when welding low alloy steels. Examples are;

• E7018: This is a commonly used basic hydrogen-controlled electrode for welding carbon and low alloy steels. It provides good mechanical properties and is known for its versatility.
• E7016: Another basic hydrogen-controlled electrode suitable for welding carbon and low alloy steels. It is often used in applications where higher penetration is required.
• E7015: This electrode is also basic-coated and low hydrogen. It is used for welding carbon and low alloy steels in various applications.)

Q3. Which of the following can be used as a shielding gas in TIG Welding?

1. Argon
2. Helium
3. Nitrogen
4. All the above

(Explanation: For TIG welding, the primary gases which are used are; Argon, Helium and Hydrogen. However, Sometimes a mixture of Argon and Nitrogen (up to 5%) is also used for back purging of duplex stainless, austenitic stainless steels and copper alloys. Nitrogen gas is not used for mild steels because it can cause age embrittlement).

Q4. MIG welding tends to be susceptible to lack of fusion problems. This is because of:

1. Poor maintenance of equipment
2. Incorrect settings
3. Poor inter run cleaning
4. All of the above

(Explanation: Lack of fusion in welding can be caused by poor equipment maintenance, like faulty wire feeders or worn contact tips. Incorrect settings, such as voltage or wire speed, can also lead to insufficient heat. Additionally, not cleaning between welding passes can result in issues due to spatters, or contaminants.)

Q5. What is the correct procedure for handling electrode E6010 (AWS A5.1)?

1. Bake for 1 hour
2. Baking not required
3. Baking for 1 hour at 100ºC and stored at 70ºC
4. Baking for 1 hour at 180ºC

(Explanation: Usually Low-hydrogen electrodes like E7018 require baking. E 6010 (AWS A5.1) fall outside the low-hydrogen category. However, special attention is required for drying and storing these electrodes to prevent moisture absorption. Always follow the manufacturer’s recommendations for proper handling.)

Q6. What issues could arise when making MMA (SMAW) welds with damaged electrode coatings?

1. Porosity
2. Undercut
3. Excessive penetration
4. Excessive bead height

(Explanation: Damage electrode coating can lead to contamination and the release of gases during welding, resulting in porosity in the weld. Porosity is the formation of small cavities or voids within the weld metal, and it can weaken the weld and adversely affect its mechanical properties.)

Q7. Which defect would you expect to get in TIG welds in non-deoxidised steel?

1. Undercut
2. Porosity
3. Tungsten inclusions
4. Linear misalignment

(Explanation: In non-deoxidized steel, porosity can occur due to the presence of oxygen and other contaminants in the weld zone, leading to gas entrapment during solidification. Proper welding techniques and the use of suitable shielding gases (such as argon) are essential to minimize the risk of porosity in TIG welding.)

Q8. The static output characteristic required for MIG/MAG welding would be

1. Constant current
2. Constant voltage
3. Constant polarity
4. Constant amperage

(Explanation: A constant voltage (CV) output characteristic is typically preferred in MIG/MAG due to;

• Stable Arc: A constant voltage power source helps maintain a stable arc by providing a consistent voltage level across the welding arc.
• Wire Feed Control: With a constant voltage power source, changes in arc length do not significantly affect the current, making it easier to control the wire feed speed and, consequently, the heat input.
• Penetration Control: Constant voltage allows for better control over the penetration depth of the weld. This is important in achieving the desired weld profile and ensuring proper fusion between the base metals.

While constant current (CC) sources are suitable for SMAW, constant voltage is generally more appropriate for MIG/MAG welding due to the specific requirements of the process.)

Q9. You notice manual metal arc electrodes, stripped of flux, are being used as filler wire for TIG welding. You would object because:

1. It is too expensive
2. The wire would be too thick
3. The metal composition may be wrong
4. The wire is too short

(Explanation: Using manual metal arc electrodes stripped of flux as filler wire for TIG welding is not recommended because the composition of the filler material may not be suitable for the specific requirements of TIG welding. Manual metal arc electrodes are designed for a different welding process (shielded metal arc welding or SMAW), and their composition may not match the metallurgical needs of TIG welding. For TIG welding, it’s important to use filler materials that are specifically designed for the process and compatible with the base metal being welded.)

Q10. A common gas / mixture used in MIG welding nickel alloys to combine good levels of penetration with good arc stability would be:

1. 100 % CO2
2. 100% Argon
3. 80% Argon 20% CO2
4. 98% Argon 2% Oxygen

(Explanation: For welding nickel alloys, including those with high chromium content like Inconel, 100% argon is a common choice for shielding gas to ensure good arc stability and minimize oxidation.)

Q11. In order to calculate arc energy, it is necessary to know:

1. Current and Voltage
2. Current, Voltage, and Travel speed
3. Current , Voltage, and weave width
4. Wire feed, Voltage, and burn-off time

(Explanation: To calculate arc energy, you would typically need to know the following parameters:

• Current: The amperage or current flowing through the welding arc.
• Voltage: The electric potential difference across the welding arc.
• .Travel speed: The speed at which the welding process progresses along the joint.

Formula for arc energy is (Volts X Amps)/Travel Speed x 100. Units are; Arc energy: kjJ/mm and travel speed: mm/sec)

Q12. Which of the following weld defects is most likely to be caused by poor welding technique when using the MMA welding (SMAW) process?

1. Hydrogen Induced Cold Cracking
2. Crater cracks
3. Plate laminations
4. Copper inclusions

(Explanation: Crater cracks occur at the end of a weld bead. They are typically caused by inadequate welding techniques, such as sudden termination of the welding arc without proper crater filling.  This can result in stress concentrations and cracking in the crater region. Proper techniques, such as backstepping or ensuring complete crater fill, can help minimize the occurrence of crater cracks.)

Q13. In MMA welding (SMAW) what parameter is used to control the penetration into the base material?

1. Voltage
2. Welding speed
3. Iron powders in the coating
4. Current

(Explanation: Current plays a significant role in controlling the depth of penetration during welding. Increasing the current generally leads to greater heat input and deeper penetration, while decreasing the current can result in shallower penetration.)

Q14. For TIG welding of austenitic stainless steel pipe, why is argon gas backing employed?

1. Prevent oxidation
2. Prevent underbead cracking
3. Prevent undercut
4. None of the above

(Explanation: The argon gas creates an inert atmosphere around the weld area, shielding it from atmospheric oxygen. This is crucial because exposure to oxygen during welding can lead to oxidation, which can result in poor weld quality and a decrease in corrosion resistance.)

Q15. Which gas is the most suitable gas for GMAW for 304L and 316L stainless steel?

1. 100% Argon
2. 70% Argon + 30% He
3. Argon + 20% Hydrogen
4. Argon + 1% O2

(Explanation: Argon with 1% oxygen (Option 4) is chosen for GMAW of 304L and 316L stainless steels to enhance arc stability. The controlled addition of oxygen improves weld characteristics without causing excessive oxidation. However, for applications where oxidation is a concern, 100% Argon (Option 1) remains a suitable choice.)

Q16. Movement of the arc in MMA welding (SMAW) by magnetic forces is called:

1. Arc deviation
2. Arc misalignment
3. Arc blow
4. Arc eye

(Explanation: Arc blows in MMA welding when the welding arc is pushed or pulled due to magnetic forces, causing unwanted deviation. Adjusting electrode position and welding parameters helps control this phenomenon.)

Q17. MIG/MAG welding has a tendency to give lack of sidewall fusion when…..

1. Spray transfer condition are used
2. 100% CO2 shielding gas is used
3. Pulsed current is used
4. Dip transfer conditions are used

(Explanation: In dip transfer conditions, the welding wire is fed to the weld pool in a series of short-circuits (the wire touches the metal, melts a bit, jumps back, and repeats). This mode is often associated with lower energy input. In such conditions, achieving proper sidewall fusion can be challenging, leading to potential issues with the fusion along the sides of the weld joint.)

Q18. Why is the arc shielded when using an arc welding process ?

1. To eliminate hydrogen from the arc region
2. To exclude the atmosphere from the arc region
3. To retard the cooling rate
4. All of the above

(Explanation: The arc needs to be shielded from the surrounding atmosphere. The purpose of the shielding is to prevent the molten metal from reacting with atmospheric elements such as oxygen and nitrogen. If not shielded, it could lead to issues like oxidation, porosity, and other weld defects.)

Q19. Which of the following variables will be most affected by variations in arc length when MMA welding (SMAW)?

1. Travel speed
2. Amperage
3. Polarity
4. Voltage

(Explanation: Arc length is the distance between the tip of the welding electrode and the surface of the workpiece. As the arc length changes, the voltage will also vary. When the arc length increases, the voltage tends to increase and vice versa. This relationship is described by Ohm’s Law (V = I * R), where V is voltage, I is current (amperage), and R is the resistance of the arc. Changes in arc length affect the resistance of the arc, leading to variations in voltage.)

Q20. Which of the following defects is more common to welds deposited by CO2 welding than welds deposited by MMA?

1. Slag inclusions
2. Excess penetration
3. Lack of sidewall fusion
4. Tungsten inclusions

(In CO2 welding (GMAW with CO2 shielding gas), the welding characteristics and heat input may sometimes result in a higher likelihood of insufficient sidewall fusion compared to MMA welding. Lack of fusion in MIG welding can also be caused by poor equipment maintenance, like faulty wire feeders or worn contact tips. Incorrect settings, such as voltage or wire speed, can also lead to insufficient heat. Additionally, not cleaning between welding passes can result in issues due to spatters, or contaminants)