Can The Crane Hook Be Repaired With Cracks?

 Crane hooks are the most used spreaders for cranes. Most types of cranes use hooks as lifting spreaders, which are one of the necessary parts of cranes. Because the hook has to bear gravity, in order to ensure safety, when the hook has cracks or is severely worn, it must be replaced and cannot be repaired .

So why can’t it be welded? There are two reasons why the crane hook cannot be repaired:

First, it is difficult for repair welding to meet the original quality standards.

Second, the high temperature of repair welding will reduce the temperature of the hook.

Disadvantages of repair welding of hook group

It is difficult for hook repair welding to meet the principled quality standards. Repair welding is the whole process of partial melting, fusion and solidification of metal. During repair welding, due to heat conduction, part of the base metal is heated and cooled to different degrees due to the heat conduction effect of the hook matrix close to the repair welding. It is like a heat treatment of this part, which changes the structure and performance of this part. Welding is all aimed at the worn and recessed part of the hook, and the recess is on the same line as the vertical dangerous section. Repair welding causes the metal structure of the hook to be refined and the sequence of metal fibers is destroyed, which destroys the toughness of the hook, thereby reducing the performance of the hook.

Crane hook material

The crane hook material is made of high-quality low-carbon killed steel or low-carbon alloy steel, such as 20 high-quality low-carbon steel, 16Mn, 20MnSi, 36MnSi, which is annealed after forging. When the hook is subjected to impact load at work, sufficient strength and toughness of the hook group can be ensured.

Production process of crane hook

The hook head is made by heat treatment after forging. The forging process is a method of metal thermal processing. The forging process is the process of refining the metal structure and arranging the metal fibers. The heat treatment is to eliminate internal stress and further improve the mechanical properties of the metal (it can be simply understood as making the metal internal Organization is more compact).

Since it is difficult to completely avoid casting defects in the casting process, casting hooks are generally not allowed; because the stress concentration and possible cracks caused by welding cannot be prevented, welding is not allowed to make hooks, nor is it allowed to repair hooks by repair welding.