Теоретичний тест з дисципліни "Технологія зварювання"

Dealing with defects that exceed permissible norms is necessary because they reduce the strength of welded joints in the structure under dynamic loads.

The methods used to detect internal defects are radiographic and ultrasonic. These techniques involve using radiation or sound waves to penetrate the material and create images or detect abnormalities within it. The radiographic method uses X-rays or gamma rays to produce images, while the ultrasonic method uses high-frequency sound waves to detect changes in the material's density or structure. These methods are commonly used in industries such as manufacturing, construction, and aerospace to ensure the quality and integrity of materials and products.

Starting a weld at a tack weld is not recommended because it can lead to the formation of cracks in the tack welds. Cracks can weaken the overall weld joint and compromise its structural integrity. Therefore, it is important to avoid starting a weld at a tack weld to ensure the quality and strength of the welded connection.

The correct answer is "б) повністю видалити прихватки механічним способом" which translates to "completely remove the defects mechanically". This means that if there are defects in the grips, they should be removed using a mechanical method. This could involve using tools or equipment to physically eliminate the defects from the grips.

The correct answer is а) литу, стовпчикову. This means that the metal of the weld has a predominantly cast, columnar structure.

The correct answer is б) внутрішнього шва кутового з'єднання (internal corner weld). When welding an internal corner joint, the protective gas is more effectively contained within the joint, reducing the amount of gas consumed. This is because the surrounding material acts as a barrier, preventing the gas from escaping and creating a more efficient shielding effect.

The width of the welding heat-affected zone (ЗТВ) depends on both the welding method and mode, as well as the composition and thickness of the metal. Therefore, answer в) which states that the width of ЗТВ depends on both the answers а) and б), is correct.

The number and length of the handles are determined by the diameter and thickness of the part.

If the welding current is too low, it can result in incomplete fusion or lack of penetration, which can lead to the formation of unwelded areas or incomplete welds.

The main parameters of TIG welding include the length of the arc and the welding current. These parameters directly affect the quality and efficiency of the welding process. The length of the arc determines the heat input and penetration depth, while the welding current controls the amount of heat generated. By adjusting these parameters, the welder can achieve the desired weld bead shape, fusion, and overall weld quality.

The most dangerous defects in welding are the brittleness of the welded joint and the presence of hot and cold cracks. These defects can compromise the structural integrity of the welded component and lead to catastrophic failures. Brittle welded joints are prone to fracture under stress, while hot and cold cracks can propagate and weaken the joint over time. It is crucial to detect and address these defects during the welding process to ensure the quality and safety of the final product.

When welding pipes, it is necessary to perform clamps in pairs at diametrically opposite points on the pipe. This ensures that the pipe is evenly secured and prevents any distortion or misalignment during the welding process. Performing the clamps sequentially or in any other order does not provide the same level of stability and may result in uneven welding or structural issues.

The correct answer is "в) ЗТВ є при всіх видах зварювання плавленням." This means that the thermal influence zone (ЗТВ) is present in all types of fusion welding. The thermal influence zone refers to the area surrounding the weld where the base metal undergoes heat treatment and experiences changes in its microstructure and mechanical properties. This zone is a result of the high temperatures reached during fusion welding processes, regardless of the welding parameters or the conductivity of the steel being welded.

The correct answer is "а) стикове" (butt joint) because this type of welding joint provides the highest strength to the base metal. In a butt joint, two pieces of metal are placed end to end and welded together along the seam. This creates a strong bond as the entire cross-sectional area of the joint is fused, resulting in maximum strength. Other types of joints, such as lap joints or T-joints, may not provide the same level of strength as they have less contact area between the metals being joined.

The correct answer is в) те й інше. This means "other reasons" in English. The question is asking about the cause of porosity in a weld. The options provided are a) incorrect choice of filler material, b) insufficient protection of the welding pool, and c) other reasons. The correct answer is c) other reasons because there can be various factors that contribute to porosity in a weld, such as improper shielding gas, contamination, or incorrect welding parameters.

The correct answer is б) 2,5 - 3 діаметра електрода. When sharpening a tungsten electrode for welding, the length of the cone should be 2.5 to 3 times the diameter of the electrode. This ensures that the electrode has a proper shape and angle for effective welding. A cone that is too short or too long can result in poor weld quality and difficulty in striking an arc. Therefore, the recommended length range helps to achieve optimal welding performance.

The correct answer is "б) «кутом назад»". This means that in order to achieve a higher melting of the base metal, TIG welding should be performed with a "backwards angle". This technique involves directing the welding torch towards the previously welded metal, which helps to create a deeper penetration and better fusion between the base metal and the filler material. Welding with a "forwards angle" («кутом вперед») or using a vertically positioned torch (при вертикально розміщеному пальнику) would not provide the same level of heat concentration and fusion.

Before welding, it is necessary to clean the edges and adjacent surfaces to a width of at least 15-20 mm on the face side and at least 10 mm on the root side. This ensures proper fusion and penetration of the weld.

The correct answer is "а) круто спадаючу зовнішню вольт-амперну характеристику (ВВАХ)". This is because for TIG welding, the power sources need to have a steeply falling external volt-ampere characteristic (V-A curve). This characteristic allows for better control of the welding process and ensures stable and precise arc formation.

The correct answer is б) аргон, гелій і їх суміші. This is because argon and helium are inert gases that do not react with the metal being welded, providing a stable and protective atmosphere around the weld pool. Using a mixture of argon and helium can further enhance the welding process by improving heat transfer and reducing the risk of porosity in the weld.

The correct answer is б) багатопрохідному. This means that the plastic properties of the welded metal are better when using a multi-pass welding technique. This is because multi-pass welding allows for more control over the heat input and allows for better distribution of the heat throughout the weld, resulting in improved plastic properties of the welded metal.

The correct answer is в) постійним струмом прямої полярності і змінним струмом. This means that TIG welding can be performed using both direct current with straight polarity and alternating current.

The correct answer is в) приблизно 90º. The question is asking about the angle between the axis of the burner and the attachment rod. The word "присадний" in Ukrainian means "attachment". The word "повинен" means "should" or "must". Therefore, the angle between the axis of the burner and the attachment rod should be approximately 90º.

In the melting space, both the electrode (additive) material and the base material undergo melting and crystallization.

It is recommended to perform the clamping of low carbon steel parts with the use of filler material.

The correct answer is "а) про в'язкість матеріалу" because testing samples for bending allows one to assess the material's viscosity.