Macrostructure of steel
For heterogeneity analysis, caused by pressure or heat treatment, a standard macrosection is prepared. Cm. macroslice.
Inhomogeneity of steel structure from pressure treatment
Fiber direction, created by processing pressure, well detected by a standard reagent in the composition 85 g of copper chloride and 58 g of ammonium sulphide per 1000 ml of water. This is because, what metal fibers, especially their border areas, differ in structure and content of impurities and therefore have unequal etching properties.
Thickness of the hardened steel layer
The thickness of the hardened layer is set by the type of fracture: it is finer grained, and when quenched without overheating - porcelain. To more accurately set the thickness of this layer, the sample is ground along the fracture (perpendicular to axis) and poison during 3 minutes in 50 %-ny hydrochloric acid solution at 80 ºS. In this case, the hardened layer acquires a darker color..
Thickness of carburized steel layer
The outer cemented and hardened layer also has a finer grain in the fracture, and when carburizing and quenching without overheating - matt porcelain (silky) view. The thickness of this layer is used to judge the depth of cementation.
More precisely, the thickness of the cemented layer is determined by grinding the fracture site (perpendicular to axis) and etching in a reagent composition 2 g of copper sulfide and 1 ml of hydrochloric acid per 100 ml of alcohol for 1-2 minutes. In this case, the soft uncemented core becomes covered with a reddish coating of copper due to its displacement by iron from the reagent, and the cemented layer remains intact.
Source: Metallurgy and heat treatment of steel