1 Subject Content and Application Scope
This standard specifies evaluation method, evaluation principles and Structure characteristics for metallurgical phases of steel free cementite, and pearlite, zonal structure and widmanstatten structure of low-carbon deformed steel.
This standard is applicable to microstructure determination (evaluation) of low-carbon and medium-carbon steel plates, strips and sections; other type of steels may reference this standard for determination in accordance with the related standards and arrangements.
2 Normative References
GB/T 13298 Metal － Inspection method of microstructure
3 Cutting and Preparation of Test Samples
The cutting and preparation of test samples shall be taken in accordance with the relevant regulations of GB/T 13298.
4 Determination of Microstructure
4.1 The magnification for determinating free cementite and pearlite is 400 X (360 ~ 450 X allowable); the magnification for determinating zonal structure and widmanstatten structure is 100X (95~110X).
4.2 The Standard field number is 80 mm.
4.3 The method of comparing with corresponding standard Grading figure shall be adopted in determination.
4.4 Two surface layers which the depth is 10% of steel plate thickness may not be inspected.
4.5 The determination shall be selected on the positron with the highest viewing field.
4.6 The results of Grading are indicated by grade. If the class characteristic is between two grades, half grade may be added. If necessary, Series letter shall be indicated, like 1A and 3B.
GB/T 13299-1991 The following standards are cited：
