The book considers the simplified method of hardness and microstructure prediction at the core of any steel part configuration based on Jominy standardized test. The calculated cooling curve at the core of complicated steel part is compared with the cooling curves of Jominy standard probe and computer program chooses the specific distance where cooling curve at the core of steel part of any configuration and cooling curve at specific distance are similar that allows core hardness and microstructure prediction. Along with hardness and microstructure prediction, the book explains in detail the poker effect taking place during testing of Jominy probe. The authors came to conclusion that discovered poker effect can be used to measure accurately physical properties of a material. A suggestion is made by authors on using Jominy tests both for hardness - microstructure prediction and physical properties of steel evaluation. For this purpose the hyperbolic heat conductivity equation withthe appropriate boundary conditions should be solved taking into account electrical forces of the double electrical layer.