Improving Mechanical Properties of Ultrafine-Grained Titanium Produced through Warm ECAP Using a Novel Lubrication System

Document Type : Research Article

Authors

1 Faculty of Mechanical and Mechatronics Engineering, Shahrood University of Technology Shahrood- Iran

2 Assistant Professor Faculty of Mechanical and Mechatronics Engineering, Shahrood University of Technology Shahrood- Iran

Abstract

In this research, warm equal channel angular pressing of grade 2 pure titanium was investigated. A new design was proposed for tooling with 90º channel angle, which eliminated problems such as the undesired flow of material between the two die halves, increased forming load and sticking of the sample in the die. A lubrication system consisting of copper foils and molybdenum disulfide was found to be effective after some trials. Using this lubrication system, 4 passes of equal channel angular pressing at 260 ºC was completed successfully. Tensile test results, demonstrated after the 4th pass, ultimate tensile strength increased by 57% while the reduction of area decreased by 14%. Reducing the process temperature and using appropriate lubrication, and ultimate tensile strength of 799 MPa was achieved which is well above the values already reported from similar researches. The microstructure and fracture surface of the equal channel angular pressing titanium were investigated using a scanning electron microscope. The results show that the initial grain size of 18 μm reduces to 729 nm after four passes. In addition, the fracture surface of the sample shows the formation of fine uniformly distributed dimples, indicating a homogenous structure of the samples.

Keywords

Main Subjects

References

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Amirkabir Journal of Mechanical Engineering
Volume 51, Issue 5
November and December 2019
Pages 1047-1056

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