Wear of nickel superalloy tools during friction stir welding of commercially pure titanium

Employees of the Laboratory for Quality Control of Materials and Structures and the Laboratory of Local Metallurgy in Additive Technologies of the Institute of Physics and Mathematics and Metallurgy of the SB RAS conducted a study of the wear of tools made of heat-resistant nickel superalloys during friction stir welding of commercially pure titanium.

Traditional methods of welding titanium alloys do not always make it possible to obtain high quality joints due to high residual stresses. Friction stir welding may be a possible solution to this problem. However, friction stir welding of titanium alloys is complicated by severe tool wear due to high loads and temperatures during the process. Previously, tools made of heat-resistant nickel superalloy ZhS6U performed well, but tool life still needs to be improved. In this work, the wear of a tool made of the ZhS32 heat-resistant alloy was studied, and the effect of liquid cooling of a tool made of the ZhS6U alloy on its wear was also investigated. Was shown, that liquid cooling significantly reduces tool wear. In particular, the tool service life has increased by 1.75 times.

The work proposes a diagram of the adhesion-diffusion mechanism of tool wear. The rotating tool is immersed in a titanium alloy, which heats up due to friction and becomes plastic. As a result of adhesion, the plasticized material sticks to the tool and moves with it. In the transfer layer, mutual diffusion of the tool material and titanium occurs. When the critical mass of the transfer layer increases, it breaks away from the tool, resulting in wear.

The study was carried out within the framework of the state assignment of the Institute of Physical Problems and Problems of the Siberian Branch of the Russian Academy of Sciences FWRW-2021-0006. The study results were published in the journal Lubricants (IF: 3.639, Q2 according to SJR).

Amirov, A.; Eliseev, A.; Beloborodov, V. Wear of Ni-Based Superalloy Tools in Friction Stir Processing of Commercially Pure Titanium. Lubricants (2023), 11, 307.
https://doi.org/10.3390/lubricants11070307