The last centimeter of welding of any weld must be completed in a special way, otherwise in the future such an incorrect seam may crack along.
To prevent you from having such a problem, in today's article I will quickly show you what and how.
In the photo above, I put 2 welds as an example. The electrode shows the end of the left seam, this is an incorrect completion of the weld.
The seam here ends with a small fossa, this fossa is called the seam crater. This crater turned out because at the end of the welding I simply abruptly removed the electrode, this is not possible.
When the electrode is on, a liquid metal weld pool is boiling underneath. By the pressure of the arc of the electrode, this weld pool is formed into a pit. If you stop welding abruptly, the metal will freeze sharply and this pit-crater will remain.
The seam and the adjacent metal have mutual stress. We can say that the weld metal pulls on the metal of the heat-affected zone (by the way, this is why there are welding deformations).
In the crater itself, the weld metal from the electrode has a small thickness, one might say a very thin flake. Therefore, under the action of stress forces, this flake can burst and the crack will go along the entire seam.
Therefore, the crater must always be melted. Do not abruptly stop welding and remove the electrode at the end of the seam.
It is necessary to weld the crater in such ways - you can return from the very end of the seam without stopping welding 5-10 mm back to the main seam. It is also possible, at the end of the seam, to simply melt the metal into a crater several times with a separation, which always forms on the last centimeter of the seam.
Here in the photo above the crater is fused, this is how it will be correct to complete the welding.
Friends, I shot a short video where I showed everything in detail on this topic. Let's see that you never have this problem.