Упражнения

Упр.1. Найдите в тексте английские эквиваленты:

1. Загрязнение, 2. валик шва, 3. соотношение, 4. способствовать расслоению, 5. вогнутый, 6. поглощать, впитывать, 7. чувствительный, 8. конструкция, 9. подрезка, 10. растягивающее напряжение, 11. пластичность, 12. прочность соединения, 13. напряжение сжатия, 14. выравнивать, 15. уязвимый

Упр.2. Переведите на РЯ следующие слова и словосочетания из текста:

1. Welding sequence, 2. segregation, 3. to be prone, 4. transverse strain, 5. hydrogen induced cracking, 6. fabrication, 7. to diffuse, 8. tensile stress, 9. the toe of the 10. lamellar tearing, 11. transverse direction, 12. butt weld, 13. fillet weld, 14. fusion boundary, 15. ductile material

Упр.3. Переведите на РЯ:

1.Уменьшение зазоров между деталями помогает избежать образования усадочных трещин. 2. Рекомендуемое соотношение глубины и ширины шва равно 0.5-1. 3. Слишком большое соотношение глубины и ширины шва может привести к расслоению и избыточной поперечной напряженности. 4. Недостаточное заполнение кратера приведет к появлению вогнутой формы шва. 5. Некоторые материалы склонны к усадочному растрескиванию больше, чем другие. 6. Индуцированный гидрокрекинг возникает при варке металла или производстве изделия. 7. Водород поглощается сварочной ванной и проникает в горячую зону. 8. Гидрокрекинг может быть вызван действием на шов растягивающего напряжения. 9.Подрезка уменьшает прочность соединения. 10. Расслоение обычно имеет место в низкокачественной стали.

Unit 17. DETECTION OF WELDING DEFECTS

Visual inspection

Prior to any welding, the material should be visually inspected to see that they are clean, aligned correctly; that machine setting and filler selection are checked etc.

At the first stage of inspection of all completed welds, visual inspection under good lighting should be carried out. A magnifying glass and a straight edge may be used as a part of this process. Undercutting can be detected with the naked eye and, provided there is access to the reverse side, excess penetration can often be visually detected.

Liquid penetrant inspection

Serious cases of surface cracking can be detected by the naked eye but for most cases some type of aid is needed and the use of dye penetrant methods is quite efficient when used by a trained operator. This procedure is as follows:

- Clean the surface of the weld and the weld vicinity

- Spray the surface with a liquid dye that has good penetrating properties

- Carefully wipe all the dye off the surface

- Spray the surface with a white powder

- Any cracks will have trapped some dye which will weep out and colour the white coating and be clearly visible.

X-ray inspection

Sub-surface cracks and inclusions can be detected by X-ray examination. This is expensive, but for safety critical points e.g. in submarines and nuclear power plants – 100% X-ray examination of welded joints will normally be carried out.

Ultrasonic inspection

Surface and sub-surface defects can also be detected by ultrasonic inspection. This involves directing a high frequency sound beam through the base material and weld on a predictable path. When the beam strikes a discontinuity some of it is reflected back. This reflected beam is received, amplified and processed and from the time delay the location of the flaw is estimated. Porosity, however, in the form of numerous gas bubbles causes a lot of low amplitude reflections which are difficult to distinguish from the background noise. Results of any ultrasonic inspection require skilled interpretation.

Magnetic particle Inspection

This process can be used to detect surface and slightly sub-surface cracks in ferro-magnetic materials. It can not therefore be used with austenitic stainless steels. The process involves placing a probe on each side of the area to be inspected and passing a high current between them. This produces a magnetic flux at right angles to the flow of the current. When these lines of force meet a discontinuity, such as a longitudinal crack, they are diverted and leak through the surface, creating magnetic poles or points of attraction. A magnetic powder dusted onto the surface will cling to the leakage area more than elsewhere, indicating the location of any discontinuities. This process may be carried out wet or dry, the wet process is more sensitive as finer particles may be used which can detect very small defects. Fluorescent powders can also be used to enhance sensitivity when used in combination with ultraviolet illumination.

Repair

Any detected cracks must be ground out and the area re-welded to give the required profile and then the joint must be inspected again.

VOCABULARY

Visual inspection – внешний осмотр

With the naked eye – невооруженным глазом

Liquid penetrant inspection – капиллярная дефектоскопия, дефектоскопия ме-

тодом проникающих жидкостей

Dye penetrant inspection – цветная дефектоскопия

Dye – краска, краситель, красящее вещество

Sub-surface defect – внутренний, под-поверхностный дефект

Ultrasonic inspection – ультразвуковая дефектоскопия

X-ray inspection – рентгеноскопия

Discontinuity – разрыв, нарушение однородности

Amplify – усиливать, увеличивать

Time delay – задержка во времени

Amplitude – амплитуда

Probe – щуп, пробник

Magnetic particle inspection – магнитопорошковая дефектоскопия

Longitudinal crack – продольная трещина

Divert –отклонять, отводить

Cling - прилипать

Fine – тонкий, мелкий

Predictable path – заданная траектория

Background noise – фоновые помехи

Magnifying glass – увеличительное стекло

Straight edge –поверочная линейка