Bestimmung des Dehnungsfeldes im schmelzbadnahen Bereich beim Lichtbogenschweißen

• Strain field determination in the vicinity of the molten pool during arc welding

Sharma, Rahul; Reisgen, Uwe (Thesis advisor); Kannengießer, Thomas (Thesis advisor)

Düren : Shaker (2023)
Book, Dissertation / PhD Thesis

In: Aachener Berichte Fügetechnik 1/2023
Page(s)/Article-Nr.: XIII, 14 bis 137 Seiten : Illustrationen, Diagramme

Dissertation, RWTH Aachen University, 2022

Abstract

A wide variety of welding processes use a heat source with high power density that moves over the surface of the component. The temperature field generated by this is highly inhomogeneous and characterized by high spatial gradients. This also leads to an inhomogeneous strain distribution in the material, which can cause material separation at high temperature and residual stresses after cooling. In this work, the thermally induced strain behavior in the region of the molten pool during TIG welding was investigated. The main motivation here was the question of how to quantify the transient strain behavior to understand hot crack initiation near the weld pool in the high temperature range. However, the focus was not on hot cracking itself, but on a specific experimental investigation of the strain behavior of two model materials, pure aluminum Al99.5 and the nickel-based alloy Alloy 625. Here, the focus was on in-situ experiments using neutron diffraction, which were supplemented by conventional strain and temperature measurement methods (image correlation and thermography). The observation was complemented by residual stress measurements by neutron diffraction and the incremental borehole method. The results show that in-situ neutron diffraction can be used to determine the elastic strain field during welding and that the experimental technique provides valid results. At the same time, however, the limitation of a low spatial resolution due to the large measurement volume is also evident. The developed method for temperature determination from diffraction data could significantly facilitate the evaluation of the strain experiment. Future investigations should focus on refinement of the spatial resolution and more accurate determination of the high-temperature material behavior, as the experiments have shown a need for research in this area.

Institutions

• Welding and Joining Institute [417610]