CSWIP 3.1 Multiple Choice Questions And Answers

Hard stamping involves using a stamp or die to imprint identification marks on a material. In high integrity applications, such as those involving critical components or safety-critical parts, hard stamping may not be allowed because it has the potential to damage the material. This can compromise the structural integrity and performance of the material, which is undesirable in such applications. Therefore, alternative methods of material identification that do not pose a risk of damage are preferred in these cases.

High heat input welding refers to a welding process that requires a significant amount of heat energy to be inputted into the weld joint. In this case, 5KJ/mm is the only option that meets this criteria, as it represents a high heat input of 5 kilojoules per millimeter. The other options, 550J/mm, 55J/mm, and 5.5J/mm, have significantly lower heat inputs and would not be considered high heat input welding.

A crack running along the centreline of a weld bead can be caused by a weld bead that is too deep and very narrow. When the bead is too deep and narrow, it creates a high amount of stress concentration in the centerline, making it more susceptible to cracking. This is because the excessive depth and narrow width restrict the ability of the weld to properly distribute stress and strain, leading to the formation of cracks.

The correct answer is pWPS. A pWPS, or Preliminary Welding Procedure Specification, is the initial document prepared for a Weld Procedure Qualification test. It outlines the essential variables and parameters for the welding procedure, such as welding process, materials, joint design, and preheat temperature. The pWPS serves as a guideline for the actual welding process and is subjected to testing and evaluation to ensure it meets the required standards before a final WPS (Welding Procedure Specification) is established.

Preheating a low alloy steel prior to welding helps to minimize the risk of heat-affected zone (HAZ) cracking. The HAZ is the area surrounding the weld that experiences high temperatures during the welding process. This rapid heating and cooling can lead to the formation of brittle microstructures in the HAZ, which increases the likelihood of cracking. By preheating the steel, the temperature of the HAZ is raised, reducing the thermal gradient and allowing for a slower cooling rate. This helps to prevent the formation of brittle structures and decreases the risk of cracking in the HAZ.

Solidification cracking in the weld metal is associated with SAW (Submerged Arc Welding) more often than it is with MMA (Manual Metal Arc) welds. Solidification cracking occurs when the weld metal cools and solidifies, and it is more likely to happen in SAW due to its high heat input and slower cooling rate. MMA welds, on the other hand, have a faster cooling rate, reducing the likelihood of solidification cracking.

To measure arc voltage accurately, it is recommended to connect the voltmeter across the arc and as near as practical to the arc. This is because the arc voltage is the voltage drop across the arc itself, and measuring it as close as possible to the arc ensures that any voltage drop in the circuitry or cables is minimized. By measuring the voltage across the arc, it provides a more precise measurement of the voltage specifically at the point of the welding operation. Connecting the voltmeter across the power source terminals or anywhere else in the circuit may introduce additional resistance or voltage drop that can affect the accuracy of the measurement.

Agglomerated submerged arc welding flux is susceptible to moisture pick-up. This is because agglomerated flux consists of small particles that are bonded together, leaving spaces between them where moisture can be trapped. Moisture in the flux can lead to porosity and other defects in the weld, affecting its quality and strength. Therefore, proper storage and handling of agglomerated flux is necessary to prevent moisture absorption and ensure optimal welding results.

The STR test is specifically used to measure the through-thickness ductility of a steel plate in the Z direction. This test helps determine the ability of the steel plate to withstand deformation or stretching perpendicular to its surface. It provides valuable information about the material's strength and its ability to resist cracking or breaking when subjected to forces applied in the Z direction. Therefore, the correct answer is through-thickness ductility of a steel plate (the Z direction).

Using back-step welding is a technique where the welder starts at the end of the joint and welds towards the start, moving back and forth along the joint. This helps to distribute the heat evenly and reduces the risk of distortion in thin plates. By welding in this manner, the heat-affected zone is kept small, minimizing the amount of shrinkage and distortion that can occur.

The correct answer is "All of the above." Preheat temperatures should be checked before welding starts or restarts, on both the shell and nozzle, and at points at least 75mm from the joint edge. This is important to ensure that the temperature is appropriate for the MMA welding process and to prevent any potential issues or defects in the weld.

Agglomerated SAW flux is susceptible to breaking down into fine particles during circulation. Agglomerated flux contains larger particles that are held together by a binder. However, during circulation, the binder can break down, causing the flux to disintegrate into smaller particles. This can lead to issues such as poor weld quality and increased spatter.

A large grain size in the Heat Affected Zone (HAZ) of a C-Mn Steel weld joint may result in low toughness. This is because larger grain sizes can lead to reduced resistance to crack propagation and increased brittleness, resulting in lower toughness. This means that the material is more prone to fracture and less able to absorb energy before breaking. Therefore, a weld joint with a large grain size in the HAZ may have lower toughness compared to one with a smaller grain size.

The presence of iron sulphides in a weld bead can cause solidification cracking. Solidification cracking, also known as hot cracking or hot tearing, occurs during the solidification process of the weld when the material contracts and experiences high stresses. Iron sulphides have a low melting point and can form liquid films or pockets during solidification. These liquid films act as crack initiation sites, leading to the formation of solidification cracks. Therefore, the presence of iron sulphides increases the likelihood of solidification cracking in a weld bead.

The typical temperature used for normalizing a C-Mn steel plate is 880-920ºC. Normalizing is a heat treatment process that involves heating the steel plate to a temperature above its critical point and then cooling it in still air. This process helps to refine the grain structure of the steel, improve its mechanical properties, and relieve internal stresses. The temperature range of 880-920ºC is commonly used for normalizing C-Mn steel plates to achieve the desired results.

The burn-off rate of the wire in GMAW (Gas Metal Arc Welding) is directly related to the wire feed speed. The wire feed speed determines how fast the wire is fed into the welding arc. A higher wire feed speed results in a higher burn-off rate, meaning that more wire is consumed during the welding process. This affects the deposition rate and the amount of filler metal being added to the weld joint. Therefore, controlling the wire feed speed is crucial in achieving the desired weld quality and ensuring proper penetration and fusion.

The use of low carbon austenitic stainless steels and stabiliser stainless steels helps to minimize the risk of weld decay. Weld decay refers to the corrosion that occurs in the heat-affected zone (HAZ) of stainless steel welds. It is caused by the depletion of chromium in the HAZ, which leads to the formation of chromium carbides and subsequent corrosion. By using low carbon austenitic stainless steels and stabilizer stainless steels, the carbon content and the formation of chromium carbides are reduced, thus reducing the risk of weld decay.

The coefficient of thermal expansion refers to how much a material expands or contracts when subjected to changes in temperature. When welding, the heat from the welding process causes the metal to expand, and as it cools down, it contracts. The coefficient of thermal expansion determines the magnitude of this expansion and contraction, which can lead to significant distortion in the welded structure. Therefore, the coefficient of thermal expansion has the greatest influence on welding distortion.

The Submerged Arc Welding (SAW) process is known for its ability to produce high-quality welds with minimal distortion. By using a single pass per side, the heat input is controlled and evenly distributed, resulting in less distortion compared to other methods. TIG and MMA welds, whether single-sided or double-sided, require more passes and higher heat input, increasing the chances of distortion. Therefore, the SAW weld with one pass per side would be expected to produce the least distortion in a 15mm straight butt weld.

According to EN ISO 5817 (Level C), the limit for the diameter of a single pore in a weld is D

The suitable gas/gas mixture for GMAW (Gas Metal Arc Welding) for aluminum is 100% Argon. Argon is commonly used as a shielding gas for aluminum welding because it provides excellent protection against atmospheric contamination and produces a stable arc. It helps prevent oxidation and ensures a clean weld with minimal porosity. Argon also has good heat transfer properties, which is important for maintaining proper weld penetration and preventing distortion. Therefore, using 100% Argon as the shielding gas is the most appropriate choice for GMAW on aluminum.

If the CEV (Carbon Equivalent Value) is increased, it means that the steel contains a higher amount of carbon and other alloying elements. This increase in carbon content will lead to an increase in the maximum hardness in the Heat Affected Zone (HAZ) of the steel. Higher carbon content can result in the formation of harder and more brittle microstructures such as martensite, which can increase the hardness of the HAZ.

The measured excess weld metal is acceptable in the situation where b = 35 and the measured excess weld metal is 4.5mm. This is because according to the given specification, the limit for excess weld metal (h) on a butt weld is h

Initiating a TIG arc using high frequency spark can potentially damage electronic equipment. This is because the high frequency spark can create electromagnetic interference (EMI) which can disrupt the functioning of sensitive electronic devices. The EMI generated during the arc initiation can interfere with the signals and circuits in electronic equipment, leading to malfunctions or permanent damage. Therefore, it is important to avoid using high frequency spark for TIG arc initiation in order to prevent any harm to electronic equipment.

A macrosection is particularly good for showing overlap in a welding joint. A macrosection is a cross-sectional view of a weld that allows for a detailed examination of the weld's structure and integrity. Overlap refers to the condition where the edges of the base metals being welded do not properly fuse together, resulting in a weak joint. By examining a macrosection, one can easily identify if there is any overlap present in the weld, which is crucial in assessing the quality and strength of the joint.

Argon + 20% CO2 is a suitable shielding gas for FCAW of stainless steels because it provides good arc stability, excellent weld bead appearance, and helps prevent oxidation and contamination during the welding process. The addition of 20% CO2 helps to improve the penetration and weld pool fluidity, resulting in a stronger and more reliable weld.

To improve resistance to service failure caused by cyclic loading, it is good practice to ensure there are no features that give high stress concentration. This means avoiding any design or fabrication elements that could lead to localized stress concentrations, such as sharp corners, notches, or abrupt changes in geometry. By minimizing stress concentration points, the material can better distribute the cyclic loading forces, reducing the likelihood of failure. This practice helps to improve the overall durability and longevity of the structure or component under cyclic loading conditions.

Ultrasonic examination is a technique that can detect internal defects such as laminations or tearing within the steel plates before welding. Ultrasonic waves are used to penetrate the material, and variations in wave reflections can indicate the presence of hidden defects.

The risk of hydrogen cracking is greater when MMA welding low alloy steels for elevated temperature service. This is because low alloy steels contain higher levels of hydrogen, which can become trapped in the weld metal during the welding process. When the temperature of the weld cools down, the hydrogen can cause cracking in the weld. This risk is particularly high in elevated temperature service, as the higher temperatures can increase the mobility of hydrogen atoms, making them more likely to migrate and cause cracking.

When welding a C-Mn steel using MMA, the electrode run-out lengths that are shorter than specified by the WPS can result in lower values of HAZ (Heat Affected Zone) toughness. The HAZ refers to the portion of the base metal that experiences a temperature increase during welding but does not melt. Inadequate electrode run-out lengths can lead to insufficient heat input, causing the HAZ to cool too rapidly. This rapid cooling can result in a brittle microstructure and decreased toughness in the HAZ, making it more prone to cracking and failure.