Effect of Strain Rate on the Hot Tensile Behavior of Invar Alloy

Authors

• A. Pahlavani
• S.M. Abbasi
• M. Morakabati
• R. Mahdavi

Abstract

       The effect of strain rate on the hot tensile behavior of Invar alloy was studied and determination of fundamental equations by hot tensile tests over temperature range of 850- 1150 °C and at strain rates of 0.01, 0.1, 1 s-1 were carried out. The stress-strain curves and structure of sample after fracture was investigated. It was found that grain boundary sliding was the major mode of intergranular failure in the Invar alloy. In this alloy, increasing the strain rate is found to improve ductility. The experimental data of flow stress were constitutively analyzed and the apparent activation energy of deformation was estimated to be 411.5 kJ/mol.

Keywords

• Invar alloy
• Hot tensile test
• Intergranular failure
• Activation energy

---

References

1- S. Gibb, “An Introduction to Invar”, Graduate Student College of Optical Sciences University of Arizona, 2006.

2- C.E. Guillaume, “Invar and Elinvar”, Nobel Lecture, 1920.

3- Special Metals, “The Nilo and Nilomag, Nickel-Iron Alloys”, 2004.

4- ASM Specialty Handbook: “Nickel, Cobalt, and Their Alloys”, ASM International, Materials Park, Ohio, USA, 2000.

5- H.G. Suzuki and D. Eylon, “Hot Ductility of Titanium Alloy: A Challenge for Continuous Casting Process”, Materials Science and Engineering A, Vol. 243, pp. 126-133, 1998.

6- B. Mintz, S. Yue and J. Jonas, “Hot ductility of steels and its relationship to the problem of transverse cracking during continuous casting”, International Materials Reviews, Vol. 36, pp. 187-217, 1991.

7-علیرضا عبدالهی و علی علیزاده،"تولید نانوکامپوزیت دو جزیی فوق مستحکم زمینه آلومینیومی به روش آلیاژسازی مکانیکی و اکستروژن داغ و بررسی خواص مکانیکی آن"،مجله مواد نوین، جلد 4، شماره 1، صفحه 98-83، 1393.

8- B. Mintz and J. Jonas, “Influence of strain rate on production of deformation induced ferrite and hot ductility of steels”, Materials Science and Technology, Vol. 10, Pp. 721-727, 1994.

9- F.J. Humphreys and M. Hatherly, "Recrystallization and Related Annealing

Phenomena", 1st ed., Pergamon, Oxford, United Kingdom, 1996. 

10- C.M. Sellars, "in Hot Working and Forging Process", C.M. Sellars and C.H.J. Davis, eds., The Metals Society, London, 1979.

11- ASTM E8," Metals Mechanical Testing Elevated and Low Temperature Tests Metallography", ASTM Annual Book,Vol. 03.01, 1999.

12- L. Ben Mostefai, G. Saindrenan, M.P. Solignac and J.P. Colin, “Effect of Interfacial Sulfur Segregation on the Hot Ductility Drop of Fe-Ni36 Alloys”, Acta. metall. Material, Vol. 39, pp. 3111-3118, 1991.

13- M.T. Perrot-Simonetta and A. Kobylanski, “Influence of Trace Elements on Hot Ductility of an Ultra High Purity Invar Alloy”, Journal De Physique, Vol. 5, pp. 323-334, 1995.

14- ح. امیدوار، ب. فلاح قنبری و م. تمیزی‌فر، "رفتار سیلان آلیاژ Ti-6Al-4V تجاری با ریزساختار لایه‌ای در فورج همدما"، مواد پیشرفته در مهندسی، شماره‌ی دوم، از صفحه 23 تا 35، 1390.