Research on Three-Roll Screw Rolling Process for Ti6Al4V Titanium Alloy Bar

Xiaoming Ding,Xu Huang,Zhiwei Zhao,Liyuan Sun

doi:10.1515/htmp-2016-0215

Xiaoming Ding, Xu Huang + Show 2 more

Open Access

https://doi.org/10.1515/htmp-2016-0215

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Abstract

Abstract The effects of both the microstructure and the original grain size on three-roll screw rolling process of Ti6Al4V titanium alloy bar were studied in the present work. The microstructure of Ti6Al4V titanium bar had a great influence on the mechanical properties of the rolling bar. When the original size was large, the grains were apparently refined but the microstructure was uneven. But for semi-finished titanium bar composed of fine equiaxed grains, the grains after rolling were fine and uniform. During the rolling process, the Ti6Al4V titanium alloy microstructure changed from equiaxed structure to the basket-weave one. After annealing at 800℃ for 1.5 hours and then cooling in air, the average tensile strength decreased from 984 MPa to 964 MPa; while after annealing at 950℃ for 1.5 hours and then cooling by water, and aging at 540℃ for 6 hours then cooling by air, the average tensile strength increased from 979 MPa to 1107 MPa.

Highlights

Material and experimental proceduresTi6Al4V titanium alloy displays an excellent combination of high strength, corrosion resistance and low density
The effects of both the microstructure and the original grain size on three-roll screw rolling process of Ti6Al4V titanium alloy bar were studied in the present work
The microstructure of Ti6Al4V titanium bar had a great influence on the mechanical properties of the rolling bar

Summary

Introduction

Ti6Al4V titanium alloy displays an excellent combination of high strength, corrosion resistance and low density. They play an important role in modern industry and are widely used for many applications, especially in the field of aeronautics and astronautics and biomaterial [1,2,3]. Ti6Al4V is the most common material in this class, which is well known for its desirable mechanical properties and corrosion resistance. The mechanical properties and microstructure characteristics of Ti6Al4V depend on the variables of the microstructure of semi-finished states, hot rolling processes and post-deformation heat treatments. Ti6Al4V was received as hot forged bars with Ф 60 mm, its composition(in wt%) was of 6.37 aluminum, 4.16 vanadium, 0.17 oxygen, 0.19 iron, 0.005 carbon, 0.001 hydrogen, 0.004 nitrogen and balance titanium. The beta transus-temperature was approximated 985°C measured by thermal dilation method [7]

Experimental procedures

Results and discussion

Conclusions