Editing Forging (section)

== Materials and applications ==

[[File:Industrial_furnace.jpg|thumb|Solid forged billets of steel (glowing incandescently) being loaded in a large industrial chamber furnace, for re-heating]]

=== Forging of steel ===

Depending on the forming temperature steel forging can be divided into:<ref>Doege, E., Behrens, B.-A.: ''Handbuch Umformtechnik: Grundlagen, Technologien, Maschinen'' (in German), Springer Verlag, 2010, p. 7</ref>

* Hot forging of steel
** Forging temperatures above the recrystallization temperature between 950–1250&nbsp;°C
** Good formability
** Low forming forces
** Constant tensile strength of the workpieces
* Warm forging of steel
** Forging temperatures between 750–950&nbsp;°C
** Less or no scaling at the workpiece surface
** Narrower tolerances achievable than in hot forging
** Limited formability and higher forming forces than for hot forging
** Lower forming forces than in cold forming
* Cold forging of steel
** Forging temperatures at room conditions, self-heating up to 150&nbsp;°C due to the forming energy
** Narrowest tolerances achievable
** No scaling at workpiece surface
** Increase of strength and decrease of ductility due to strain hardening 
** Low formability and high forming forces are necessary

For industrial processes steel alloys are primarily forged in hot condition. Brass, bronze, copper, precious metals and their alloys are manufactured by cold forging processes; each metal requires a different forging temperature.

=== Forging of aluminium ===

* Aluminium forging is performed at a temperature range between 350–550&nbsp;°C
* Forging temperatures above 550&nbsp;°C are too close to the solidus temperature of the alloys and lead in conjunction with varying effective strains to unfavorable workpiece surfaces and potentially to a partial melting as well as fold formation.<ref>Doege, E.; Behrens, B.-A.: ''Handbuch Umformtechnik: Grundlagen, Technologien, Maschinen'', Springer Verlag, 2010, pp. 671f.</ref>
* Forging temperatures below 350&nbsp;°C reduce formability by increasing the yield stress, which can lead to unfilled dies, cracking at the workpiece surface and increased die forces

Due to the narrow temperature range and high thermal conductivity, aluminium forging can only be realized in a particular process window. To provide good forming conditions a homogeneous temperature distribution in the entire workpiece is necessary. Therefore, the control of the tool temperature has a major influence to the process. For example, by optimizing the preform geometries the local effective strains can be influenced to reduce local overheating for a more homogeneous temperature distribution.<ref>Stonis, M.: ''Mehrdirektionales Schmieden von flachen Aluminiumlangteilen'' (in German), In: Behrens, B.-A.; Nyhuis, P.; Overmeyer, L. (ed.): Berichte aus dem IPH, Volume 01/2011, PZH Produktionstechnisches Zentrum GmbH, Garbsen 2011.</ref>

==== Application of aluminium forged parts ====

High-strength aluminium alloys have the tensile strength of medium strong steel alloys while providing significant weight advantages. Therefore, aluminium forged parts are mainly used in aerospace, automotive industry and many other fields of engineering especially in those fields, where highest safety standards against failure by abuse, by shock or vibratory stresses are needed. Such parts are for example pistons,{{Citation needed|date=August 2019}} chassis parts, steering components and brake parts. Commonly used alloys are AlSi1MgMn ([[6082 aluminium alloy|EN AW-6082]]) and AlZnMgCu1,5 ([[7075 aluminium alloy|EN AW-7075]]). About 80% of all aluminium forged parts are made of AlSi1MgMn. The high-strength alloy AlZnMgCu1,5 is mainly used for aerospace applications.<ref>Richter, J.; Stonis, M.: ''Qualitätsverbesserung beim Aluminiumschmieden'' (in German), In Aluminium Praxis, Giesel Verlag GmbH, Volume 20 (2015), Issue 6/15, p. 20.</ref>

=== Forging of magnesium ===

* Magnesium forging occurs at a temperature range between 290–450&nbsp;°C<ref name="Papenberg, Nikolaus P 2020">Papenberg, Nikolaus P et al. “Mg-Alloys for Forging Applications-A Review.” Materials vol. 13,4 985. 22 Feb. 2020, doi:10.3390/ma13040985</ref>

Magnesium alloys are more difficult to forge due to their low plasticity, low sensitivity to strain rates and narrow forming temperature.<ref name="Papenberg, Nikolaus P 2020"/> Using semi-open die hot forging with a three-slide forging press (TSFP) has become a newly developed forging method for Mg-Al alloy AZ31, commonly used in forming aircraft brackets.<ref>Dziubińska, A., Gontarz, A., Dziubiński, M., & Barszcz, M. (2016). THE FORMING OF MAGNESIUM ALLOY FORGINGS FOR AIRCRAFT AND AUTOMOTIVE APPLICATIONS. Advances in Science and Technology Research Journal. https://doi.org/10.12913/22998624/64003</ref><ref>Dziubinska, A., & Gontarz, A. (2015). A new method for producing magnesium alloy twin-rib aircraft brackets. Aircraft Engineering and Aerospace Technology. https://doi.org/10.1108/AEAT-10-2013-0184</ref> This forging method has shown to improve tensile properties but lacks uniform grain size.<ref>Dziubinska, A., Gontarz, A., & Zagórski, I. (2018). Qualitative research on AZ31 magnesium alloy aircraft brackets with a triangular rib produced by a new forging method. Aircraft Engineering and Aerospace Technology. https://doi.org/10.1108/AEAT-09-2016-0160</ref><ref>Dziubińska, A., Gontarz, A., Horzelska, K., & Pieśko, P. (2015). The Microstructure and Mechanical Properties of AZ31 Magnesium Alloy Aircraft Brackets Produced by a New Forging Technology. Procedia Manufacturing. https://doi.org/10.1016/j.promfg.2015.07.059</ref> Even though the application of magnesium alloys increases by 15–20% each year in the aerospace and automotive industry, forging magnesium alloys with specialized dies is expensive and an unfeasible method to produce parts for a mass market. Instead, most magnesium alloy parts for industry are produced by casting methods.