Metallographic test

Metallographic test plays an important role in the fracture failure analysis of LIDS. In some failure analyses, the nature and cause of the accident can be determined by metallographic test. The reason of failure can often be determined by metallographic test for damage caused by process cracks and material defects caused by improper hot processing (casting, forging, welding and heat treatment) and fracture failure caused by environmental factors.

The metallographic test can be used to identify whether the metallographic structure of the material of the cup stacking machine is qualified, whether the inclusion and microstructure segregation are in conformity with the regulations, whether there is decarburization, carburization, intergranular corrosion and other phenomena. For stress corrosion cracking, thermal fatigue damage, creep fracture and other fracture failure accidents, the cracks and micro-cracks in the fracture pieces have special morphological characteristics, so the metallographic test can often determine these types of fracture failure.

There is usually a thick layer of oxide in the fracture of creep fracture failure, so the oxide must be removed in fracture analysis, which often damages the fracture. It is difficult and not reliable to determine creep fracture by fracture analysis. There must be a large number of intergranular cracks near the fracture or main crack of the creep fracture, and there must be early creep crack at a certain distance from the fracture site, so the creep fracture can be determined by metallographic test.