Super duplex stainless steels (SDSS) are widely used in marine and energy industries owing to their excellent combination of strength and corrosion resistance. However, achieving both high productivity and desirable phase balance in additively manufactured SDSS remains challenging. This work establishes an in-process thermo-mechanical pathway for microstructure engineering by integrating high-productivity cold-wire gas metal arc wire-directed energy deposition with interlayer high-pressure rolling and targeted solution treatment. The coupled deformation and thermal cycles promote recovery, partial recrystallisation and the δ→γ transformation, resulting in a refined heterogeneous duplex microstructure with improved phase balance. While the as-deposited material remains slightly ferrite-rich, solution treatment restores the ferrite–austenite balance to the industrially accepted range while preserving the deformation-refined ferrite structure. Consequently, the proposed route delivers an excellent combination of strength and ductility, achieving an ultimate tensile strength of 1020 MPa in the as-deposited condition and 880 MPa, 660 MPa yield strength and 30% elongation after solution treatment. The proposed thermo-mechanical pathway provides a practical strategy for simultaneously improving productivity, microstructure control and mechanical performance in additively manufactured SDSS.
2024
Sensors
Study of Residual Stress Using Phased Array Ultrasonics in Ti-6AL-4V Wire-Arc Additively Manufactured Components
Joseph Walker, Brandon Mills, Yashar Javadi, and 7 more authors
This paper presents a study on residual stress measurement in wire-arc additively manufactured (WAAM) titanium samples using the non-destructive method of phased array ultrasonics. The contour method (CM) was used for the verification of the phased array ultrasonic results. This allowed for a comparison of measurement methods to understand the effects on the distribution of residual stress (RS) within Ti-6Al-4V samples and the effectiveness of measurement of residual stress using phased array ultrasonics. From the results of the experiments, the phased array ultrasonic data were found to be in good agreement with the CM results and displayed similar residual stress distributions in the samples. The results of the individual elements of the phased array were also compared and an improvement in accuracy was found. From per-element results, anomalies were found and could be mitigated with the ability to average the results by using phased array ultrasonics. Therefore, based on these results, there is a strong case for the benefits of using phased array ultrasonics as a method of residual stress measurement for WAAM Ti-6Al-4V components over other existing residual stress measurement techniques.
@article{sensors_2024,author={Walker, Joseph and Mills, Brandon and Javadi, Yashar and MacLeod, Charles and Sun, Yongle and Taraphdar, Pradeeptta Kumar and Ahmad, Bilal and Gurumurthy, Sundar and Ding, Jialuo and Sillars, Fiona},title={Study of Residual Stress Using Phased Array Ultrasonics in Ti-6AL-4V Wire-Arc Additively Manufactured Components},journal={Sensors},volume={24},year={2024},number={19},article-number={6372},url={https://www.mdpi.com/1424-8220/24/19/6372},issn={1424-8220},doi={10.3390/s24196372},}
2019
Development and testing of an antenna deployment system for nanosatellite applications
C. Malde, S. Gurumurthy, and R. Diwan
Proceedings of the International Astronautical Congress(IAC), Washington D.C., 2019
@article{IAC_2019,title={Development and testing of an antenna deployment system for nanosatellite applications},journal={Proceedings of the International Astronautical Congress(IAC), Washington D.C.},year={2019},author={Malde, C. and Gurumurthy, S. and Diwan, R.},}
Dynamic Active Thermal Control of a LEO Nanosatellite Based on its Mode of Operation
Sundar Gurumurthy and Chintan Malde
Proceedings of the 33rd AIAA-USU Smallsat conference, Logan, Utah, 2019
@article{AIAA_2019,title={Dynamic Active Thermal Control of a {LEO} Nanosatellite Based on its Mode of Operation},howpublished={\url{https://www.base-search.net/Record/76e571816a3d2618dc41f6e5e604bda26a57061e95e9fb6b8cac6a70f943912f}},journal={Proceedings of the 33rd AIAA-USU Smallsat conference, Logan, Utah},author={Gurumurthy, Sundar and Malde, Chintan},year={2019},}
