How to test non-metallic inclusions in forging?


In order to test the nature, shape, size, quantity and distribution of non-metallic inclusions in forgings, metallographic microscope is usually used for microscopic inspection, that is, to determine the grade or content of non-metallic inclusions in steel by comparison or calculation with metallographic microscope.

Correlation method. Comparison method is a method to compare the classification, size, quantity, shape and distribution of inclusions with the standard pictures of similar inclusions with the same magnification after polishing the metallographic samples to be examined.

Calculation method. The calculation methods mainly include linear cutting method and grid method. The calculation method is to use a certain length of lines or a certain area of the mesh on the microscope eyepiece, will be tested sample inclusions and straight line or mesh overlap, calculate the number of inclusion intercepted, so as to quantitatively analyze the purity of the forging.

Imager method. The image analyzer analysis of inclusions is the most modern analysis method in quantitative metallography. It has the advantages of fast analysis speed, high precision and functional integrity, so it is widely used. Image analyzer obtains geometric information from images and makes quantitative analysis by using stereological concepts. It can be determined in the quantitative analysis of inclusions.

The percentage of area and volume of inclusions in forgings can be determined according to the different gray scale or shape of inclusions.

Statistical distribution of inclusions in steel, that is, the area and perimeter of each inclusion in a certain area, and statistical parameters or histograms such as mean, maximum, minimum and standard deviation can be obtained.

Inclusion shape factors, such as inclusion aspect ratio, spherical coefficient, etc.