The contributions of hardening mechanisms in the martensitic structure
include the solid solution substitution element hardening, the precipitation hardening, the primary austenitic grain size hardening and the martensite morphology hardening.
The registered condition of the initial microstructure suggested that this case was the final condition of the chip as the martensitic structure mentioned above showed no subsequent plastic deformation.
The only finding is that the X-ray diffraction method did not show presence of any martensitic structure in the chip samples.
Tempering of the martensitic structure
at approximately 620 deg C leads to the reformation of the finely dispersed austenitic structure.
When these materials are heated the martensitic structure
is changed into austenitic structure.
As emphasized in the theoretical section, the connection between a single variant of martensite and the parent austenitic phase is provided by a twinned martensitic structure
, which is able to satisfy the compatibility conditions both with the austenite (over the habit plane) and with the single variant.
Extendo-Die hot work die steel, with a fully martensitic structure
, has superior wear resistance and toughness when compared with H-13 tool steel, especially in large sections heavier than 3[inches] to 4[inches].
The wear is smaller when the steel has a martensitic structure
The Q-P process is a new kind of heat treatment which gives rise to a martensitic structure
with foliated retained austenite surrounding martensite needles.
The aim of the Q&P process is to achieve a very fine martensitic structure
with foliated retained austenite.
Austempering is valuable because it is stronger and tougher than tempered martensitic structures
obtained with conventional heat treatment of cast iron.
The important demonstrations of surface layers strengthening at dynamical shot are the density and configuration of thermally stable dislocations, dislocations nets, dislocation barriers, density of slip lines, slips and twins, fragmentations of carbides or impurities joined with equiaxed grains properties homogenization levelling, very fine austenitic and martensitic structures
with two or even three times higher wear resistence (Baca, 1995), the creation of beneficient pressure stresses system in surface layer, increasing of hardness and strength in surface layer, the creation of texture in strengthened surface layer, the change of surface quality.