Now showing 1 - 2 of 2
No Thumbnail Available
Publication

Solidification of GTA aluminum weld metal: Part 1 - Grain morphology dependent upon alloy composition and grain refiner content

2014 , Schempp, P. , Cross, C.E. , Pittner, A. , Oder, G. , Neumann, R.S. , Rooch, H. , Dörfel, I. , Österle, W. , Rethmeier, M.

The solidification conditions during welding strongly influence the weld metal microstructure and mechanical properties of a weld. In the first part of this study, the grain morphology of gas tungsten arc (GTA) bead-on-plate welds was investigated for the aluminum Alloys 1050A (Al 99.5), 6082 (Al Si1MgMn), and 5083 (Al Mg4,5Mn0.7). The experiments revealed that increasing welding speed and alloy content allow the growth of small, equiaxed grains, particularly in the weld center. Furthermore, increasing grain refiner additions led to a strong reduction of the weld metal mean grain size and hence facilitated the columnar to equiaxed transition (CET). In addition, wavelength dispersive X-ray spectroscopy (WDS) and transmission electron microscopy (TEM) analysis revealed in the weld metal TiB2 particles that were surrounded by Al3Ti. This suggests the duplex nucleation theory for nucleation of aluminum grains in GTA weld metal.

No Thumbnail Available
Publication

Weld metal grain refinement of aluminium alloy 5083 through controlled additions of Ti and B

2011 , Schempp, P. , Schwenk, C. , Rethmeier, M. , Cross, C.E.

The refinement of the weld metal gram structure may lead to a significant change in its mechanical properties and in the weldability of the base metal. One possibility to achieve weld metal grain refinement is the inoculation of the weld pool. In this study, it is shown how additions of titanium and boron influence the weld metal grain structure of GTA welds of the aluminium alloy 5083 (Al Mg4.5Mn0.7). For this purpose, inserts consisting of base metal and additions of the master alloy Al Ti5Bl have been cast, deposited in the base metal and fused in a GTA welding process. The increase of the Ti and B content led to a significant decrease of the weld metal mean grain size and to a change in grain shape. The results provide a basis for a more precise definition of the chemical composition of commercial filler wires and rods for aluminium arc welding.