Answer: If there is a tendency for intergranular corrosion, metallographic inspection or hammer inspection can be used. During the hammer inspection, use a 0.5~1.0kg hand hammer to knock on both sides of the weld or other parts.
Intergranular corrosion is corrosion that occurs along or close to the grain boundaries of the metal. Common methods for intergranular corrosion inspection include visual inspection (including naked eyes and magnifying glasses), hammer inspection, surface flaw detection inspection and metallographic inspection, among which hammer inspection and metallographic inspection are more commonly used and have better results.
(1) The inherent characteristics of intergranular corrosion make it possible to use hammering and metallographic methods for inspection.
(2) The hammering method is simple, easy to use, and low-cost, and is widely used in boiler inspections; the metallographic method can fully understand the metallographic structure of the corroded area.
(3) The hammer method relies on the sound produced by the object being struck and the degree of rebound of the hammer to determine whether there is a defect in the metal material. The weight and mass of the hammer affect the sound and the degree of rebound, so it is stipulated that a hammer weighing 0.5 to 1.0 kg should be used.
