Annealing is a key process. For stainless steel welded pipes

Annealing is a heat treatment process of stainless steel welded pipes. The purpose is to eliminate residual stress, stabilize the size, and reduce the tendency of deformation and cracking.

It is difficult to distinguish whether the stainless steel welded pipe is annealed with the naked eye, so there are some methods that can be used to help you identify this.

Here I will introduce you to some of this knowledge.

1.The pipe can be judged by echo

Tap the welded pipe with a little more force, and listen to the echo at the mouth of the attached ear.If the echo is loud and sharp, it means that it has been annealed.

So why does the annealed stainless steel pipe produce a higher echo? It is caused by the relatively uniform and dense crystals inside the annealed part. Without the annealing, there will be more tissue defects and it will absorb most of the acoustic energy, so the echo is relatively small. If possible, you can use sonar to detect.

2.Use a digital multimeter with better accuracy

Measure the resistance per unit length (such as 2 meters). The resistance of stainless steel is relatively large, and the resistance value after annealing is smaller than that without annealing.

Note: there must be no liquid left on it before testing.

Not all stainless steel welded pipes produced by all manufacturers will undergo the annealing process, so you must learn to distinguish between annealed stainless steel welded pipes and unannealed stainless steel welded pipes using the above methods.