Tension-Compression Asymmetry in Ultrafine-grained Commercially Pure Ti Processed by ECAP

Abstract

A homogenous microstructure of ultrafine-grained (UFG) commercially pure (CP) Ti characterized by equiaxed grains/subgrains with an average grain size of about 150 nm and strong prismatic fiber texture were obtained after 4 passes of equal channel angular pressing (ECAP). Tension–compression asymmetry in yield and work hardening behavior of UFG CP Ti were investigated by uniaxial tension and compression tests. The experimental results reveal that UFG CP Ti exhibits a relatively obvious tensioncompression asymmetry in yielding and work hardening behavior. The basal and prismatic <a> slip are suppressed either for tension or compression, which is the easiest to activate. The tension twin system $\{10\bar{1}2\}<\bar{1}011>$ is easily activated in compression deformation due to the prismatic fiber texture based on the Schmidt factor, consequently resulting in a lower yield strength under compression than tension. ECAP can improve the tension-compression asymmetry of CP Ti due to grain refinement. The interaction among the dislocations, grain boundaries and deformation twins are the main work hardening mechanisms for compression deformation, while the interaction between the dislocations and grain boundaries for tension deformation. Deformation twins lead to the higher work hardening under compression than tension.

Keywords

ultrafine-grained commercially pure Ti / equal channel angular pressing / tension-compression asymmetry / texture / twinning

References

[1] Ma T H, Chang L, Guo S, et al. Comparison of Multiaxial Low Cycle Fatigue Behavior of CP-Ti under Strain-controlled Mode at Different Multiaxial Strain Ratios[J]. Int. J. Fatigue, 2020, 140: 105 818.

[2] Gu Y X, Ma A B, Jiang J H, et al. Simultaneously Improving Mechanical Properties and Corrosion Resistance of Pure Ti by Continuous ECAP Plus Short-duration Annealing[J]. Mater. Charact., 2018, 138: 38-473.

[3] Bosh N, Müller C, Mozaffari-Jovein H. Deformation Twinning in CP-Ti and Its Effect on Fatigue Cracking[J]. Mater.Charact., 2019, 155: 109 810.

[4] Fintová S, Kubĕna I, Palán J, et al. Influence of Sandblasting and Acid Etching on Fatigue Properties of Ultra-fine Grained Ti Grade 4 for Dental Implants[J]. J. Mech. Behav. Biomed. Mater., 2020, 111: 104 016.

[5] Masrouri M, Faraji G, Pedram M S, et al. In-vivo Study of Ultrafine-grained CP-Ti Dental Implants Surface Modified by SLActive with Excellent Wettability[J]. Int. J. Adhes. Adhes., 2020, 102: 102 684.

[6] An B L, Li Z R, Diao X O, et al. In Vitro and in Vivo Studies of Ultrafine-grain Ti as Dental Implant Material Processed by ECAP[J]. Mater. Sci. Eng., 2016, C67: 34-41.

[7] Lin P, Hao Y G, Zhang B Y, et al. Tension-compression Asymmetry in Yielding and Strain Hardening Behavior of CP-Ti at Room Temperature[J]. Mater. Sci. Eng., 2017, A707(7): 172-180.

[8] Tuninetti V, Gilles G, Milis O, et al. Anisotropy and Tension-compression Asymmetry Modeling of the Room Temperature Plastic Response of Ti-6Al-4V[J]. Int. J. Plast., 2015, 67: 53-68.

[9] Vinogradov A, Orlov D, Danyuk A, et al. Deformation Mechanisms underlying Tension-compression Asymmetry in Magnesium Alloy ZK60 Revealed by Acoustic Emission Monitoring[J]. Mater. Sci. Eng., 2015, A621: 243-251.

[10] Li Y F, Zeng X G. Dynamic Tensile Behavior and Constitutive Modeling of TC21 Titanium Alloy[J]. J. Wuhan Univ. Technol. -Mat. Sci. Ed., 2019, 34(3): 707-716.

[11] Lee S I, Kim J S, Park S J. Evolution of Tension and Compression Asymmetry of Extruded Mg-Al-Sn-Zn Alloy with Respect to Forming Temperatures[J]. Mater. Des., 2016, 110(15): 510-518.

[12] Zhao M J, Jin L, Dong J, et al. Influence of Twinning Behavior on Mechanical Property of Pure Zinc Deformed at Room Temperature [J]. Trans. Nonferr. Met. Soc. China, 2018, 28(9): 1808-1815.

[13] Huang G H, Li X, Yin D D, et al. Effect of Extrusion Parameters and Y Content on the Microstructure and Tension-Compression Deformation Behavior of Extruded Mg-Y Alloy Bars[J]. Rare Metal Mat. Eng., 2018, 47(9): 2861-2868.

[14] Lv C L, Liu T M, Liu D J, et al. Effect of Heat Treatment on Tension-compression Yield Asymmetry of AZ80 Magnesium Alloy[J]. Mater. Des., 2012, 33: 529-533.

[15] Bohlen J, Dobron P, Swiostek J, et al. On the Influence of the Grain Size and Solute Content on the AE Response of Magnesium Alloys Tested in Tension and Compression[J]. Mater. Sci. Eng. A, 2007, 462(1–2): 302-306.

[16] Yu X, Li Y L, Wei Q M, et al. Microstructure and Mechanical Behavior of ECAP Processed AZ31B over a Wide Range of Loading Rates under Compression and Tension[J]. Mech. Mater., 2015, 86: 55-70.

[17] Qu S, Huang C X, Gao Y L, et al. Tensile and Compressive Properties of AISI 304L Stainless Steel Subjected to Equal Channel Angular Pressing[J]. Mater. Sci. Eng., 2008, A475(1–2): 207-416.

[18] Wang J W, Duan Q Q, Huang C X, et al. Tensile and Compressive Deformation Behaviors of Commercially Pure Al Processed by Equal-channel Angular Pressing with Different Dies[J]. Mater. Sci. Eng., 2008, A496(1–2): 409-416.

[19] Beyerlein I J, Alexander D J, Tome’ C N. Plastic Anisotropy in Aluminum and Copper Pre-strained by Equal Channel Angular Extrusion[J]. J. Mater. Sci., 2007, 42: 1733-1750.

[20] Haouaoui M, Karaman I, Maier H J. Flow Stress Anisotropy and Bauschinger Effect in Ultrafine Grained Copper[J]. Acta Mater., 2006, 54: 5477-5488.

[21] Yapici G G, Karaman I, Luo Z P. Mechanical Twinning and Texture Evolution in Severely Deformed Ti-6Al-4V at High Temperatures[J]. Acta Mater., 2006, 54(14): 3755-3771.

[22] Meredith C S, Khan A S. Texture Evolution and Anisotropy in the Thermo-mechanical Response of UFG Ti Processed via Equal Channel Angular Pressing[J]. Int. J. Plast., 2012, 30–31: 202-217.

[23] Hu H J, Liu Y, Zhang D F, et al. The Influences of Extrusion-shear Process on Microstructures Evolution and Mechanical Properties of AZ31 Magnesium Alloy[J]. J. Alloys Compd., 2017, 695: 1088-1095.

[24] Bednarczyk W, Wątroba M, Kawałko J, et al. Determination of Room-temperature Superplastic Asymmetry and Anisotropy of Zn-0.8Ag Alloy Processed by ECAP[J]. Mater. Sci. Eng., 2019, A759: 55-58.

[25] Jäger A, Gärtnerova V, Tesař K. Microstructure and Anisotropy of the Mechanical Properties in Commercially Pure Titanium after Equal Channel Angular Pressing with Back Pressure at Room Temperature[J]. Mater. Sci. Eng., 2015, A644: 114-120.

[26] Wang G J, Zhao X C, Yang X R, et al. Texture Evolution in Commercially Pure Titanium after Equal Channel Angular Pressing at Room Temperature[J]. Mater. Sci. Tech., 2013, 29(8): 961-967.

[27] Christian J W, Mahajan S. Deformation Twinning[J]. Prog. Mater. Sci., 1995, 39: 1-157.

[28] Ishiyama S, Hanada S, Izumi O. Orientation Dependence of Twinning in Commercially Pure Titanium[J]. J. Jpn. I. Met. Mater., 1990, 54(12): 976-984.

[29] Munroe N, Tan X, Gu H. Orientation Dependence of Slip and Twinning in HCP Metals[J]. Scripta Mater., 1997, 36(12): 1383-1386.

[30] Lutjering G, Williams J C. Titanium[M], 2007 Second edition Berlin Heidelberg: Springer.

[31] Hazell P J, Appleby-Thomas G J, Wielewski E, et al. The Shock and Spall Response of Three Industrially Important Hexagonal Close-packed Metals: Magnesium, Titanium and Zirconium[J]. Phil. Trans. R. Soc., 2014, A372(2023): 20130204

[32] Xin Y C, Zhou X J, Liu Q. Suppressing the Tension-compression Yield Asymmetry of Mg Alloy by Hybrid Extension Twins Structure[J]. Mater. Sci. Eng., 2013, A567: 9-13.

[33] He J J, Liu T M, Xu S, et al. The Effects of Compressive Pre-deformation on Yield Asymmetry in Hot-extruded Mg-3Al-1Zn Alloy[J]. Mater. Sci. Eng., 2013, A579: 1-8.

[34] Coghe F, Tirry W, Rabet L, et al. Importance of Twinning in Static and Dynamic Compression of a Ti-6Al-4V Titanium Alloy with an Equiaxed Microstructure[J]. Mater. Sci. Eng., 2012, A537: 1-10.

[35] Luo J, Li M, Yu W. The Variation of Strain Rate Sensitivity Exponent and Strain Hardening Exponent in Isothermal Compression of Ti-6Al-4V Alloy[J]. Mater. Des., 2010, 31(2): 741-748.

[36] Song Y Q, Guan Z P, Pinkui M A. Theoretical and Experimental Standardization of Strain Hardening Index in Tensile Deformation[J]. Acta Metall. Sin., 2006, 42(7): 673-680.

[37] Salem A A, Kalidindi S R, Semiatin S L. Strain Hardening due to Deformation Twinning in a-Titanium: Constitutive Relations and Crystal-plasticity Modeling[J]. Acta Mater., 2005, 53(12): 3 495-3 502.