Strain Hardening and Stretch Formability Behavior of Triple Phase (TP) Steel Strips




Triple Phase (TP) steel, Bainite, martensite, ferrite TP Steel, Double quenching treatment, Strain Hardening rate, Stretch Formability


The current work explores the strain hardening and stretches formability behaviour of the developed Triple Phase (TP) steel. Double quenched TP steel strips posse three distinguished stages of strain hardening on tensile forming. 1st stage represents the highest n-value reflecting resistance to homogeneous deformation, where steel can be safely stretched. 2nd and 3rd stage reveals lower n-values, where localized thinning exist. On Erichsen testing, the relationship between punch forming force and punch stroke exhibits two forming regions. The 1st region is delineated by a straight line showing an ultra-high strain-hardening rate, which represents a reversible elastic stretch forming.  The 2nd forming region continues to a higher Erichsen punch stroke than that of the 1st region and presents the permanent plastic stretch forming behaviour.  It is found that bainite and martensite clusters created, by double quenching, in TP-steel exaggerated the elastic stretch forming limit 10 times higher than the as-hot rolled condition. 7 min. holding time of strips in the salt bath is considered the most effective for the creation of a useful volume fraction of the bainite phase. However, 21 min. holding time in salt bath grows martensite laths through the bainite aggregates, affecting negatively on stretch formability.

Author Biography

Taher El-Bitar, Professor in the Plastic Deformation Department at Central Metaurgical R&D Instiute (CMRDI) - Egypt

Professor Taher Ahmed El-Bitar is working at Central Metallurgical R&D Institute (CMRDI) since 1980, where he conducted and published many scientific researches in the field of alloy development and thermo-mechanical processing for many alloys. Furthermore, he is a holder of a license for practicing a profession consultant in the field of Metal forming and Heat treatment.

On the practical side, Dr. Taher El-Bitar worked as a consultant for Multi-M Group company at El-Khanka, Kandil Steel Complex at 10th of Ramadan city, and Galva Metal Company at El-Obour City.

He has presided and participated over many international industrial projects with the German Niobium Products Company. Nationally, he chaired many projects funded by the Academy of Scientific Research and projects funded by the Science and Technology Development Fund (STDF), as well as industry.

On 2004-2006, He was pioneer in introducing the applications of  Niobium as a micro-alloying element in steel processing units containing continuous casting of compact slabs and direct hot flat rolling. These projects were succeeded to process  different API steel grades, where grade X52 was developed at the Alexandria Iron and Steel Company in Dekheila. Grades X60 & X70 were processed at Ezz Flat Steel (EFS) Company at El- Ain  El-Sokhna in Suez.

2014-2016 Professor El-Bitar got  a fund from STDF for implementation of a project dealing with the development of Bainitic Dual Phase steel sheets. 2015-2017, he got a fund from STDF for another project dealing with the development of Si-steel thin sheets for electric power transformation.

On 2015, professor Taher chaired and implemented the project of processing armor steel 500B. The project was funded by the National Authority for Military Production (Military Factory 100).

Professor T. El-Bitar was a member of the Industry Research Committee of the Academy of Scientific Research since 2005 to 2010.

Officially, Professor El-Bitar occupied a chair on the Board of Directors of the Central Metallurgical R & D Institute (CMRDI) in the period 2005 - 2012. He was also a member of the Promotion Committee at CMRDI in addition to his work as an evaluator for Promotion of the Mining, Petroleum and Metals Engineering in the Egyptian Universities.

Of course, Professor Taher organized and delivered lectures in many conferences, seminars and workshops. In the field of international cooperation, he participated and prepared the cooperation agreement between the CMRDI and the University of Blida in the Republic of Algeria for 6 years. Recently, on October 2019, he participated and prepared the cooperation agreement between the CMRDI and the Russian University of Belarus.




How to Cite

ElMeligy, M., & El-Bitar, T. (2021). Strain Hardening and Stretch Formability Behavior of Triple Phase (TP) Steel Strips . Acta Metallurgica Slovaca, 27(3), 152–156.