Titanium alloys have been a popular choice in the aerospace and medical industries due to their excellent strength-to-weight ratio and high corrosion resistance. However, understanding the tensile behavior of titanium alloys under different stress conditions has always been a challenge for scientists and engineers. The present work attempts to shed some light on this mystery by exploring the effect of stress relaxation on the tensile behavior of two commercially pure titanium alloys of different strength levels.
In this research, the alloys, Grade 1 and Grade 4, were subjected to tensile tests at room temperature and the stress relaxation tests were performed by interrupting the tensile tests at regular strain intervals of 5% in the plastic region of the tensile curve. The results were then compared to the monotonic tensile tests performed at different strain rates ranging from 10^-4 to 10^-1s^-1. To understand the effect of anisotropy, samples were taken along 0° and 90° to the rolling direction (RD) for both the alloys.
The results of the study showed that the introduction of stress relaxation steps improved the ductility of both alloys at all the strain rates, compared to the monotonic tests. However, there was not much change in the flow stress or the strain hardening behavior of the alloys. The true stress-true strain curves of Grade 4 samples taken in 90° to RD exhibited a yield-point elongation (YPE) after the yield point, which is a discontinuous yielding phenomenon.
The improvement in ductility of the titanium alloys can be linked to the recovery process that occurs during the stress relaxation steps. The repeated interrupted tensile tests resulted in improved ductility after each test. The paper summarizes the results of the stress relaxation tests for the two different alloys, providing new insights into the tensile behavior of titanium alloys under different stress conditions.
In conclusion, this work provides valuable information for the aerospace and medical industries, where titanium alloys play a crucial role in the design and fabrication of high-strength, lightweight components. The results of this research will help engineers to design better titanium components and improve their mechanical properties.
Reference:
[1] Eipert I, Sivaswamy G, Bhattacharya R, Amir M, Blackwell P. Improvement in Ductility in Commercially Pure Titanium Alloys by Stress Relaxation at Room Temperature. KEM 2014;611–612:92–8. https://doi.org/10.4028/www.scientific.net/kem.611-612.92.
