Jan 052014

The technical usage of steel is for one reason based on the fact that a various number of possible heat treatments lead to different properties of one certain material. These different properties are adjustable due to allotropic modification of the steel lattice.
Steels without a α/γ-transformation like austenitic of ferritic steels are neither hardenable nor able to normalize. The various heat treatments can be divided into annealing, hardening and quenching/tempering.
heat tratament
The reason for annealing a material is to create a certain pro-cessability (for example: cold forming, cutting properties). The changing of material properties is done by the following:
-Transformation of structures
-Transformation of grain size, arrangement,
-Stress relieving
The different ways of annealing are seperated in heating up to a certain temperature (set-point), holding at this temperature and cooling down to the room temperature. During the heating of a material the appearance of an increasing tension between outer and inner areas of the material might cause problems. Therefore the thickness of the material as well as the thermal conductivity should be noticed to avoid for example stress cracking. The same could appear during the cooling process of the material.

Removal of Non-Uniform Structures: Diffusion Annealing, Normalizing
Increasing of Workability: Coarse-Grain Annealin, Soft Annealing, Recrystallization Annealing, Crystal Recovery Annealing
Reducing of Stresse: Stress-Relief Annealin, Stress-Relieving Treatment
Transformation of Structure: Tempering
Special Cases: Controlled Cooling:Quenchin, Bainitic Transformation

heat tratament 2

The purpose of hardening is to obtain a hard structure. There are various processes of hardening as normal or surface hardening which all rely on the material.

Normal Hardening: Hardening from Hot-Forming HeatBroken Hardening, Martempering
Surface Hardening: Flame Hardening, Induction Hardening, Dip Hardening, Case Hardening, Nitriding, Gas-Nitro Carbonising.

heat tratament3

The characteristic of a hardened material is the hardness which on the other hand leads to a reduced toughness. To get a hard but tough material another heat treatment has to be done which is called quenching and tempering. 

Alte articole asemanatoare
A Time-Temperature-Transformation (TTT) diagram describes the decomposition of the austenite (after prior heating) and the structure generated by this. In order to set up a TTT diagram for continuous cooling rod-shaped ...
mai multe
ISO 857-2 defines processes of soldering and brazing as well as related terms. Soldering and brazing Joining process in which molten solder is used with a liquidus temperature lower than the solidus ...
mai multe
As T = 0 K, the heat capacity approaches zero, thus, it is assumed that the atoms do not oscillate at their lattice points. By means of supplying heat, the atoms ...
mai multe
This technique (autogenous (lat.) = self working) means working with materials or heating of workpieces by means of a flame. The term "Autogenous Technique" includes different processes, where the process ...
mai multe
Time-Temperature-Transformation Diagram
Soldering and brazing. Definitions for Soldering According to
Processes During Heating and Cooling
The autogenous technique

 Leave a Reply



You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>