Welding controls must ensure that the weld deposit matches the ferrite/austenite
ratio of the parent material; excess austenite
will make the alloy weaker and excess ferrite will make the alloy more susceptible to hydrogen cracking.
in 17-4 precipitation-hardening stainless steel produced by selective laser melting.
One concrete case would be the nucleation and growth of ferrite from austenite
in an iron-carbon alloy.
During the heating of steel with spherodized cementite in ferrite matrix, the austenite
phase nucleates at the ferrite-cementite boundary.
Some authors claim that the temperature in the wheel-rail area of contact may extend the boundaries of transformation temperature for generation of austenite
(Kout 2001, Mitura 1980) while the subsequent rapid cooling may be the cause for modification into martensite (Jergeus 1992) in a closely delimited area corresponding to the surface.
1) As generally it is assumed that friction in hot rolling is of sticking type, at first sight this decrease in hot strength with higher strains only can be explained by some metallurgical mechanism, like dynamic recrystallization of austenite
-to-ferrite transformation or temperature increase due to forming work.
Since [epsilon]-martensite has a lower corrosion resistance compared with austenite
, this is expected to influence the corrosion behavior of the sample B.
In traditional, slow heat treatments, steel's initial microstructure always dissolves into a homogeneous phase called austenite
at peak temperature, Babu explained.
Suitable parameters of the schedule led to ferrite-bainite microstructure with 15% retained austenite
, ferrite grain size of about 2 um and elongation of about 30%.
With the removal of the load, the martensitic transforms back into the austenite
phase and resumes its original shape (Gumpel et al.
Increase along the layer depth, martensite' size and retained austenite
's volume has significant difference, around graphite,coarse martensite, residual austenite
increased; Away from graphite.
AHSS are primarily multi-phase steels, which contain ferrite, martensite, bainite, and/or retained austenite
in quantities sufficient to produce unique mechanical properties.
For ESC of a hollow ingot from carbon steel a mandrel with a rod from austenite
steel is used.
The mechanism behind it is quite simple: atoms tend to be arranged in several crystallographical configurations having different symmetry groups: higher symmetrical one (referred to as the austenite
phase, typically cubic) has higher thermal capacity while lower symmetrical one (called the martensite phase, typically tetragonal, orthorhombic, or monoclinic) has lower thermal capacity and may exist, by symmetry, in several variants (typically 3, 6, or 12, respectively).
In the case of ferrous materials, the austenite
, which is the original larger and softer crystalline structure, often is transformed to martensite, a smaller and more compact crystal, Stewart says.