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Welding history

Classification of welding

Effect of welding speed

Welding defects

Types of welding joints

Welding position

Welding electrodes

Types of welding flame

Welding flux

Welding techniques

Welding symbol

Welding edge preparation

Advantages of welding joints

Thermal properties of metal

Welding safety

Types of welds



Effect of welding speed

     The welding time, the rate of advance is not as rapid as that assumed when filling with molten metal, so that, an area expanding and an area contracting as showing in picture A and picture B in the parent metal. In the picture A showing the condition when welding speed relatively slow speed. In this case, the expanding zone (which is marked green color) is small in compression to the width of the contraction zone (which is marked gray color). Therefore the contraction area is the predominating factor, because the plates to close-up ahead of the arc. The distortion of the plates being in the same direction as indicates by the line (which is shown in red dotted line).

The picture B showing the condition when welding is relatively high-speeds. In this case the expanding area (which is marked green color) relatively large and wide. It is the predominating factor and causes the plates to open up ahead of the arc. The distortion being in the direction indicated by the line (which is shown in red dotted line).

In the above cases, after welding has been completed and the plate has cooled to room temperature, the filler weld metal and parent metal in the yellow zone (which is shown in picture) which is subjected to plastic flow and its trying to contraction. But it is restricted by the base metal outside the plastic flow zone. The residual stress is happened during the arc welding. This residual stress can be measure by the strain gauge.

The weld filler metal and the base metal within the plastic flow zone (which is shown with yellow color) is in tension longitudinally, and the just outside of the base metal the plastic flow area is in compression stress longitudinally.

Welding speed picture diagram

Welding speed effect

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Welding speed effect