Microporous spots, for corrosion elements gathered themselves together, and it is shallow light color, irregular shape, more smooth and slightly concave spots. According to the segregation of location and shape.
They generally summed up as the following categories:
(1) center segregation Cold Drawn Steel Tubes appeared in the central part, show irregular shape of dark spots.
(2) type ingot segregation: concentrated in a different size, has the original ingot cross section shape (usually is square) the closing of the dark spots, so type ingot segregation also called square segregation.
(3) punctate segregation: generally larger spots, show color is deeper, slightly concave graphics, elliptic or seeds. General distribution, called the general punctate segregation: distributed on the edge of the steel parts, called edge punctate segregation.
Cause: segregation in the ingot casting solidification Cold Drawn Tubes process, caused by crystallization and the diffusion of some elements. Segregation is the general production situation is inevitable. Osteoporosis: steel internal porosity, the pore on the low power sample.
An irregular polygon, apex narrow at the bottom of the pit, often appear in the segregation more spots. Serious, has become the trend of the sponge. Them according to the distribution of the loose situation which center loose loose and divides into two broad categories:
1) center of osteoporosis: the gap in low power is concentrated near the center of the sample and dark dots. Longitudinal fracture on a slight interlining, under the microscope could see pearlite increased, in the center precision welded tubes of osteoporosis center loose in the carbon content increased.
(2) general osteoporosis: organization on low power sample density, scattered with small pore and small black spots. Pore more irregular polygon or graphics, distribution on besides edge part of the whole section. Loose center, generally appear in the ingot head and central, and the general difference between distribution of loose parts rather than in the center of the steel section and cross section as a whole. Generally, the higher the carbon content in steel, the more serious the center loose.