Research on Effects of Uneven Macrostructure to Mechanical Properties in TC21 Forging

Abstract:

The microstructure, tensile properties, fracture toughness, fatigue crack growth rate and fatigue limit of different macrostructure regions in TC21 open-die forging were investigated. The results show that the microstructure is also uneven corresponding to non-uniform macrostructure. The ultimate tensile strength (UTS) and yield strength (YS) of coarse-grained zone are that UTS1070MPa, YS960MPa, which can meet the requirement of technical standard, whereas the strength of fine-grained zone drops more than 100MPa. The fracture toughness of this forging is that K_IC90MPa·m^1/2, being equivalent to the normal one. But when K=11MPa·m^1/2, the fatigue crack growth rate is that da/dN=2.488758×10^-5mm/cycle, higher than the normal TC21 open-die forging for an order of magnitude. The fatigue limit of fine-grained zone drops about 40MPa compared with coarse-grained zone. Uneven macrostructure and microstructure lead to a decline of tensile and fatigue property in TC21 forging.

• Periodical: Materials Science Forum (Volumes 747-748)
• Pages: 823-827
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.747-748.823
• Online since: February 2013
• Authors: Jun Li, Zhi Shou Zhu, Xin Nan Wang, Yue Fei, Guo Qiang Shang, Li Wei Zhu
• Keywords: Mechanical Property, Open-Die Forging, TC21 Alloy, Uneven Macrostructure

References

[1] Y.L. Zhao, B.L. Li, Z.S. Zhu, et al., The high temperature deformation behavior and microstructure of TC21 titanium alloy, Materials Science and Engineering A. 527 (2012) 5360-5367.

DOI: 10.1016/j.msea.2010.05.076

[2] Y.H. Fei, L. Zhou, H.L. Qu, et al., The phase and microstructure of TC21 alloy, Materials Science and Engineering A. 494 (2008) 166-172.

DOI: 10.1016/j.msea.2008.04.017

[3] Y.C. Zhu, W.D. Zeng, J.L. Liu, et al., Effect of processing parameters on the hot deformation behavior of as-cast TC21 titanium alloy, Materials and Design. 33 (2012) 264-272.

DOI: 10.1016/j.matdes.2011.07.018

[4] Z.S. Zhu, X.N. Wang, G.Q. Shang, et al., Research and development of damage tolerance titanium alloys for aeronautical use in China, The 12th World Conference on Titanium, Beijing, (2011).

[5] X.N. Wang, Z.S. Zhu, L. Tong, et al., The influence of forging processing on fatigue crack propagation rate of damage-tolerant titanium alloy, Rare Metals Letters. 27 (2008) 12-16. (in Chinese).

[6] H.L. Qu, Y.G. Zhou, L. Zhou, et al., Relationship among forging technology, structure and properties of TC21 alloy bars, Transactions of Nonferrous Metals Society of China. 15 (2005) 1120-1124.

[7] Z.S. Zhu, X.N. Wang, L. Tong, et al., Studies of new-type titanium alloys for aviation industry application in China, Titanium Industry Progress. 24 (2007) 28-32. (in Chinese).

[8] Z.S. Zhu, X.H. Zhou, W.G. Ma, et al., A new β forging processing for high strength and damage tolerance titanium alloys, Rare Metal Materials and Engineering. 34 (2005) 539-542. (in Chinese).

[9] S.J. Ma, X.R. Wu, J.Z. Liu, et al., Influence of microstructures on mechanical properties for TC21 titanium alloy, Journal of Aeronautical Materials. 26 (2006) 22-25. (in Chinese).

[10] Y.C. Zhu, W.D. Zeng, F. Feng, et al., Characterization of hot deformation behavior of as-cast TC21 titanium alloy using processing map, Materials Science and Engineering A. 528 (2011) 1757-1763.

DOI: 10.1016/j.msea.2010.11.015