M. B. D. Ellis

Bio: M. B. D. Ellis is an academic researcher. The author has contributed to research in topics: Fusion welding & Aluminium. The author has an hindex of 1, co-authored 1 publications receiving 8 citations.

Hot cracking behaviour of an autogenously laser welded Al-Cu-Li alloy

Abstract: AA2198 is a relatively new light-weight and high-performance Al-Cu-Li alloy considered for aviation and space applications. However, Al-Cu-Li alloys generally exhibit severe weldability problems for all fusion-welding techniques, such as laser-beam welding. In particular, porosity formation and hot cracking are observed for the laser-beam welding of these alloys. A common remedy for hot cracking is the use of an appropriate filler wire with a high Si content. In the present study, three different approaches for improving the hot cracking susceptibility of AA2198 laser beam welded without any filler material are presented. For this purpose, pre-heating of the weld samples to elevated temperatures, pre-loading of the weld samples perpendicular to the welding direction, or an optimization of the laser-beam welding parameters were conducted. The autogenously welded samples were assessed with regard to the resulting total crack length and their mechanical properties. It was demonstrated that all of the presented approaches led to a reduction of hot cracking. However, the largest effect was observed for the use of low levels of laser power and welding velocity. The mechanical properties of the optimised autogenously welded samples are only marginally inferior as for the samples laser welded with the Al-Si filler wire AA4047.

Tensile and fracture behavior of pulsed gas metal arc-welded Al-Cu-Li

Abstract: Thick plates of Al-Cu-LiMg-Ag-Zr-type alloy were butt-joint welded with pulsed gas metal arc welding (GMAW-P). The joints were made at different pulse frequencies but using one drop detachment per pulse (ODPP) condition. Effect of pulse frequency on microstructure, microhardness, tensile strength, and crack growth resistance as well as fracture path were studied. Some laser-welded joints of the same material were also made for comparison purposes. It was observed that the mechanical properties of the joints made with GMAW-P were comparable to the laser welded joints as well as the ones reported in the literature. At the same time, the GMAW-P joints showed reduction in yield strength with increase in pulse frequency. The fracture path also was found to be different with specimens made at different frequencies.

Numerical and experimental analysis for the GMAW process

Abstract: iii

Research on Narrow Gap Welding Parameters Optimization

Abstract: The effects of welding voltage, welding current and weld heat input on the A105 steel weld formation quality using submerged-arc welding (SAW) with small diameter welding wire were experimentally researched. Through lots of experiments of surface overlaying on flat plates, the optimal parameters were obtained sequentially using numerical regression analysis. The calculated results were compared with experimental data to verify the accuracy of the proposed model. And the optimal variation ranges were obtained. The relationship of the weld heat input with the weld width was qualified to assure the optimal weld appearance quality. At last, the optimal parameters were validated experimentally with narrow gap SAW.