1, macro inspection
The chemical composition is decisive for ensuring the performance of the steel, but the composition is qualified and cannot comprehensively explain the performance of the steel. Due to the non-uniformity of the internal organization and composition of the steel, the macro inspection supplements this deficiency to a large extent.
Macroscopic inspection can observe the crystallization of the steel, the continuity of the steel and the non-uniformity of some components.
Standard "Structure Steel Low-Degree Organization Defect Rating Chart" GB1979
There are 8 kinds of macro defects: segregation, loosening, inclusions, shrinkage holes, bubbles, white spots, cracks, and folds.
Mold picture
Mold picture
2.1, assessment of annealing organization
The purpose of annealing is to reduce the hardness of the steel, facilitate machining, and also prepare for subsequent heat treatment.
Carbon tool steel annealing organization according to GB1298 rating chart of the first rating.
2.2, carbide inhomogeneity
Cr12-type benessllite steel contains a large amount of eutectic carbides in the structure. The non-uniformity of carbides has a very important influence on the service performance, so the distribution of carbides must be strictly controlled.