CSWIP Question 6

The side bend test would be the most suitable for detecting lack of interun fusion on a 25mm thick carbon steel butt weld. In this test, the weld is bent to a specified angle, and any lack of fusion between the weld and base metal can be easily identified on the side of the bend. The face bend test examines the face of the weld, the root bend test examines the root of the weld, and the longitudinal bend test assesses the overall integrity of the weld along its length. However, for specifically detecting lack of interun fusion, the side bend test is the most appropriate.

Rimming steel is a type of steel that has a high amount of carbon and low amounts of other elements. This composition leads to the formation of gas bubbles or porosity during the arc welding process. The high carbon content causes the steel to have a higher affinity for oxygen, which can result in the formation of gas pockets. This makes rimming steel more prone to porosity compared to other types of steel.

Mild steel is considered to be the easiest material to weld because it has a low carbon content, which makes it more malleable and easier to work with. It also has good weldability and can be welded using various welding processes, such as MIG, TIG, and stick welding. Additionally, mild steel has good heat conductivity, which helps in achieving a strong and durable weld.

The Charpy Vee notch test is a destructive test that measures the impact toughness of a material, including the weld metal, parent metal, and heat-affected zone (HAZ). This test involves striking a notched specimen with a pendulum and measuring the energy absorbed during fracture. The higher the energy absorbed, the tougher the material. Therefore, the Charpy Vee notch test is used to determine the toughness value of the weld metal/parent metal and HAZ.

If the welding travel speed is doubled but the amps and volts remain the same, the heat input value will be reduced by 50%. This is because heat input is directly proportional to the welding travel speed. When the travel speed is doubled, the time for which the heat is applied is reduced by half, resulting in a decrease in the overall heat input. Therefore, the heat input will be reduced by 50% in this scenario.

If arc strikes were found on a component made of a high tensile strength material, it would be important to have the area checked for possible cracking. This is because arc strikes can cause localized heating and stress concentrations, which may lead to cracking in high tensile strength materials. Therefore, it is necessary to inspect the area for any signs of cracking to ensure the integrity and safety of the component.

Welds made with high heat inputs show a reduction in toughness. When high heat inputs are used during welding, it can lead to the formation of coarse grains and the presence of residual stresses, which can decrease the toughness of the welded joint. Toughness is the ability of a material to absorb energy and deform plastically before fracturing, and a reduction in toughness can make the weld more susceptible to cracking or failure under stress. Therefore, high heat inputs can negatively affect the toughness of welds.

A reduction in-service temperature to sub zero-conditions can increase the likelihood of a brittle fracture in steels because at lower temperatures, the steel becomes more brittle and prone to fracture. This is due to the decreased mobility of atoms, which leads to a decrease in the material's ability to deform and absorb energy before fracturing.

The correct heat input can be calculated by multiplying the current (in amps), voltage (in volts), and travel speed (in mm/minute), and then dividing by 1000 to convert the units from J/mm to KJ/mm. Therefore, the correct heat input is 2.16 KJ/mm.

All of the above need to access the welding procedure (WPS). Welders need to access the WPS in order to understand the specific requirements and techniques for welding a particular job. Inspectors need to access the WPS to ensure that the welding is being done correctly and according to the specified procedures. NDT tech's (Non-Destructive Testing technicians) also need to access the WPS to understand the welding techniques and requirements for conducting their testing.

The correct answer is WPS. WPS stands for Welding Procedure Specification, which is a document that provides instructions to the welder. It outlines the specific welding parameters, techniques, and procedures that should be followed to ensure the desired quality and integrity of the weld. The PWPS (Preliminary Welding Procedure Specification) and WPAR (Welding Procedure Approval Record) are related documents, but they do not directly provide instructions to the welder like the WPS does.

Silicon is needed in the coating of an electrode to prevent the formation of porosity when welding rimming steel. Silicon acts as a deoxidizer, which means it removes oxygen from the weld pool. This is important because oxygen can cause the formation of porosity, which weakens the weld. By adding silicon to the coating, it helps to remove any oxygen present during the welding process, resulting in a stronger and more reliable weld.

Normalizing is a heat treatment process in which steel is heated above the critical temperature and then allowed to cool in air. This process helps to refine the grain structure of the steel, improve its mechanical properties, and relieve internal stresses. Unlike other heat treatment processes like annealing, tempering, and stress relieving, normalizing involves cooling the steel in air from the austenite region, making it the correct answer.

To produce hydrogen induced cold cracking, several criteria are necessary. Firstly, hydrogen must be present. Additionally, the material must have a grain structure that is susceptible to cracking. Stress is also required for the cracking to occur. Lastly, the temperature must be below 200°C. These conditions create an environment where hydrogen can cause cracks in the material, leading to hydrogen induced cold cracking.

The tee joint (fillet welded) would normally require the highest preheat temperature because it involves welding a fillet weld at the intersection of two pieces of metal. The fillet weld requires more heat to ensure proper fusion and penetration between the two pieces of metal. In contrast, the edge joint, lap joint, and butt joint (single-V) typically have less surface area to be welded and therefore require lower preheat temperatures.

A transition joint is used when two different materials are to be welded together. This type of joint allows for a smooth transition between the two materials, ensuring a strong and durable bond. It is commonly used in industries such as automotive and aerospace, where different materials may be required for specific purposes. The term "composite joint" refers to a different type of joint that involves combining different materials to create a composite material, while "compound joint" is a more general term that can refer to any joint made up of multiple components.

The heat-affected zone (HAZ) is the area of the base metal that has undergone a microstructural change due to the heat input during welding. This region typically has lower toughness compared to the parent metal and the weld metal. Therefore, the test piece taken from the HAZ is most likely to have the lowest toughness.

In the martensitic grain structure, hardness would be expected to increase. This is because the martensitic structure is characterized by a high level of hardness due to its unique arrangement of atoms. Martensite is formed through a rapid cooling process, which leads to the transformation of the crystal structure of the material. This transformation results in a hard and brittle microstructure, which increases the hardness of the material.

Austenitic stainless steels have a high coefficient of thermal expansion, meaning they expand and contract more with changes in temperature. This, combined with their low thermal conductivity, makes them more susceptible to distortion. When heated or cooled, the uneven expansion and contraction of the steel can cause it to warp or deform. Additionally, the low thermal conductivity means that heat is not evenly distributed throughout the steel, further contributing to distortion.

Preheating is applied in welding to reduce the chance of a brittle grain structure and to reduce the chance of hydrogen entrapment. Preheating helps in reducing the cooling rate of the weld, which allows for slower solidification and reduces the likelihood of the formation of brittle grain structures. Additionally, preheating also helps in driving out moisture and reducing the presence of hydrogen, which can cause hydrogen embrittlement. By reducing the chance of a brittle grain structure and hydrogen entrapment, preheating improves the overall quality and integrity of the weld.

An increase in travel speed will most likely require the preheat temperature to be increased because when the travel speed is increased, the welding process becomes faster and the heat input to the material decreases. To compensate for this decrease in heat input, the preheat temperature needs to be increased to ensure proper fusion and weld quality.

A transverse tensile test is used to measure the ultimate tensile strength, elongation, and yield strength of a material. This test helps determine the maximum amount of stress a material can withstand before breaking, the amount of deformation the material can undergo before breaking, and the point at which the material starts to permanently deform under stress. Therefore, all of the given options are correct as they represent different aspects of the material's behavior during the test.

Hydrogen cracking in the Heat Affected Zone (HAZ) is most likely to occur when welding carbon manganese steels. This is because carbon manganese steels have a higher susceptibility to hydrogen cracking compared to other types of steel. The presence of carbon and manganese in these steels creates a higher risk of hydrogen being absorbed into the material during the welding process. This hydrogen can then accumulate in the HAZ and lead to cracking, especially under high stress conditions. Austenitic stainless steel, micro alloyed steel (HSLA), and low carbon steel have lower susceptibility to hydrogen cracking compared to carbon manganese steels.

All of the above are considerations for the selection of a preheat temperature. The preheat temperature is determined by factors such as the arc energy, material thickness, hydrogen scale, and carbon equivalent. These factors are important to consider as they can affect the quality and integrity of the weld joint. The arc energy refers to the heat input during the welding process, which can influence the preheat temperature required. Material thickness affects the rate of heat transfer and can determine the need for preheating. The hydrogen scale and carbon equivalent are indicators of the potential for hydrogen cracking and can influence the preheat temperature needed to prevent this issue.

A carbon equivalent (CE) of 0.5% indicates a high carbon content in carbon manganese steel. This high carbon content can lead to increased susceptibility to cracking during welding. Therefore, it may be necessary to preheat the steel to a temperature over 100°C in order to minimize the risk of cracking and ensure a successful weld.

Tensile specimens are usually measured in pounds per square inch (psi). This unit is commonly used to measure the amount of force or stress applied to a material per unit area. It is a measure of the material's ability to withstand tension or stretching without breaking. Newton per square inch (N/in²) is not a commonly used unit for measuring tensile specimens. Joules (J) is a unit of energy and is not directly related to measuring tensile specimens. Therefore, the correct answer is a) Pounds per square inch.

A MIG/MAG welding plant typically consists of a transformer and rectifier that provide a constant voltage power supply. This type of welding plant is commonly used for MIG (Metal Inert Gas) and MAG (Metal Active Gas) welding processes, where a continuous wire electrode is fed into the weld pool. The constant voltage power supply ensures a stable arc and allows for better control of the welding process.

The purpose of microscopic examination of a weld is to determine the number and type of defects present and to determine the grain size. By examining the weld under a microscope, any defects such as cracks, porosity, or inclusions can be identified and quantified. Additionally, the grain size can be measured, which can provide information about the strength and integrity of the weld. Therefore, both options a) and b) are correct.

The main reason for qualifying a welding procedure is to demonstrate that the welded joints meet the requirements of the specification. This ensures that the welding process is capable of producing the desired results and that the final product will meet the necessary standards. Additionally, qualifying a welding procedure helps to determine the welder's ability, check if acceptance criteria can be met, and show that the fabricator has good welding control.

The correct answer is that a Charpy test is a dynamic test used to determine a material's notch toughness in the weld region. This test involves striking a notched specimen with a pendulum and measuring the energy absorbed during fracture. It is commonly used in the welding industry to assess the impact resistance of materials and to ensure the quality of welded joints.

The correct answer is d) Both a and b. This means that the HAZ (Heat Affected Zone) associated with a fusion strength cannot be avoided and usually has the highest tensile strength.

Macro specimens should be inspected both after etching and after cutting and before etching. Inspecting the specimen after etching allows for the examination of the microstructure and the identification of any defects or anomalies. Inspecting the specimen after cutting and before etching allows for the evaluation of the surface condition and any visible defects or irregularities that may affect the subsequent etching process. Therefore, both inspections are necessary to ensure a thorough examination of the macro specimen.

In the Charpy test, a small specimen is subjected to an impact load to measure its resistance to fracture. This test is commonly used to determine the ductile to brittle transition temperature of a material. The transition temperature is the temperature at which a material changes from being ductile (able to deform plastically) to brittle (more prone to fracture). By comparing the results of Charpy tests at different temperatures, the ductile to brittle transition curve can be plotted, providing valuable information about the material's behavior under different conditions.

A carbon steel weld (CE 048) welded without preheat may have a narrow heat affected zone and hardness value in excess of 400HV. This is because welding without preheat can result in rapid cooling of the weld zone, leading to a smaller heat affected zone. Additionally, the rapid cooling can also cause an increase in hardness, resulting in hardness values exceeding 400HV.

A Single-U butt with backing would normally be considered for a mechanical welding process because it provides better control and stability during the welding process. The backing material helps to support the weld and prevent distortion, ensuring a stronger and more reliable weld joint. The U shape also allows for better access and visibility during welding, making it easier to achieve a high-quality weld.

The EN499 standard refers to covered electrodes for MMA (Manual Metal Arc) welding. This standard provides specifications and requirements for the composition, mechanical properties, and testing of these electrodes. MMA welding, also known as stick welding, is a commonly used welding process that involves using a consumable electrode coated in a flux to create the weld. The EN499 standard ensures that the covered electrodes used in MMA welding meet certain quality and performance standards.

The EN278 standard refers to welder approval. This means that it provides guidelines and criteria for approving welders based on their skills and qualifications. This standard ensures that welders have the necessary knowledge and expertise to perform welding tasks effectively and safely. By following the EN278 standard, companies can ensure that their welders meet the required standards and can produce high-quality welds.

The answer is a) A lower heat input and higher degree of grain refinement. This is because a smaller electrode diameter (4mm) will result in a lower heat input compared to a larger electrode diameter (6mm). The lower heat input leads to less heat being transferred to the material, resulting in less distortion. Additionally, the smaller electrode diameter allows for a higher degree of grain refinement, as it provides better control over the welding process and allows for finer grain structure to be formed.

Carbon has the greatest effect on creep strength when added to steel. Carbon is a strong carbide former and it forms carbides with iron, which helps to strengthen the steel. These carbides act as obstacles to dislocation movement, which increases the resistance of the steel to creep deformation. Additionally, carbon also improves the hardness and wear resistance of steel, making it an important alloying element in steel production.

The tensile test can be used to give a quantitative measurement of weld zone ductility. This test involves applying a tensile force to a specimen until it breaks, and measuring the amount of deformation and the force required to cause the break. By analyzing the results of the tensile test, including the elongation and reduction in area, the ductility of the weld zone can be determined. The bend test and Charpy V notch test are not specifically designed to measure ductility, but rather to assess other mechanical properties such as toughness and impact resistance.