WE Seminar: Andres Fischdickacuna and Jiarui Kang

Ultrasonic assisted tensile test of pure Cu

Jiarui Kang
Advised by Dr. Xun Liu

Abstract

Incremental sheet forming (ISF) is a sheet forming technique where a sheet is formed by serials of incremental deformations by a tool piece. Compared with conventional forming, the forming cost per piece can be significantly reduced since there is no die needed. However, it is challenging to form sheets incrementally on hard metals with high yield strength where a large deflection of tool is observed. One potential solution is to soften the material using ultrasonic vibration during deformation. In this study, the softening effect of ultrasound on pure copper is investigated in small-scale tensile test. The flow stress drops immediately with the application of ultrasound. Results show that a larger reduction of flow stress is observed at higher vibration amplitude. Micron-scale digital image correlation (DIC) analyses were conducted, showing that the application of ultrasound changes the strain field distribution along the sample. Strain is localized near the source of ultrasound while it is uniform along the sample when there is no ultrasound.

Bio

Jiarui Kang received his B. Eng in 2016 and M. Eng in 2018 from Harbin Institute of Technology at Weihai, where he focused on brazing of alumina and the wettability of Sn-Ti alloy on it. He is now working with Dr. Xun Liu on small-scale ultrasonic assisted tensile tests. Outside of work, he enjoys skiing, ice skating and stargazing.

Weld Metal Analysis of the Tubesheet Welds from Electrical Heaters of a Pre-salt FPSO

Andres Fischdickacuna
Advised by Dr. Antonio Ramirez

Abstract 

Oil and Gas industry has an extent list of heat exchanger applications. Some of the critical ones are on heating gas received from the oil filed extraction. This application subjects the equipment to high pressure, cyclic stress and temperature loads. The tubesheet-tube are highly demanded due to the nature of the construction, a thin noble metal welded to a thick tubesheet in some cases less alloyed material. A failure occurred during operation due to gas leakage. In this demanding and productive environment a fast failure analysis response is essential. The study presented investigated the soundness of the tubesheet-tube weld as one of possible failure causes. The autogenous GTA welds on a dissimilar (carbon steel to austenitic stainless steel) produced a martensitic weld metal not ideal for service loading conditions. The not proper design combined uncontrolled welding process, pores and high travelling speeds was one of the causes for gas leakage, which culminated in flashing and explosion of part of equipment.

Bio

I obtained my bachelor degree as Mechanical Engineer on Universidade Federal do Rio Grande do Sul in 2008 and on the same year join Petrobras (Brazilian National Petroleum Company) as equipment engineer working in Research and Development of pipelines. In 2010 I took a welding engineering specialization in Petrobras corporate university. From the specialization on my research was focused on advanced welding process for pipelines as Hybrid laser welding, radial friction welding and friction stir welding.

In 2013 my daughter was born to change my life and since everything was changing, in December we moved to Columbus in order to take my masters at OSU WE. On my master’s second year son was born, a Buckeye to the family. I really enjoyed my time in Columbus spending most of my time with my family and mountain biking on Alum Creek trails. I have finally graduated in 2016 with my thesis on Hybrid laser welding for API X65 and X70 steels and returned to Brazil to continue my career at Petrobras as researcher for the whole company structure, onshore and offshore facilities, refineries and thermal plants. On the beginning of 2017 my third and last son was born and with that we start to plan another change to finally in 2019 return to OSU as GRA to extend my education to a PhD on welding of Hyper-duplex Steels.