Svetsaren_nr2 definitief (Page 1) - Esab

partly with the SAW two-wire process with solid wire as
described above. FILARC PZ6166 was introduced
after a test programme was successfully completed,
showing that requirements relating to mechanical
properties and hydrogen levels could be fulfilled.
However, other important aspects included weldability
features, such as good penetration, excellent wetting
and low spatter, ensuring a minimum of post weld
cleaning, grinding and repair. The consumption for the
metal-cored wire is estimated at roughly 7-10 tonnes
per runner.
Another Chinese company, the Dongfang Electric
Machine Company as a subcontractor in the Voith
consortium, has also considered metal-cored wires (in
combination with solid wires) as a possible solution for
the production of turbine runners. A smaller Francis
turbine runner was therefore successfully produced,
using the FILARC PZ6166 metal-cored wire, as a prefabrication
test to evaluate the suitability of this
consumable for the Three Gorges project.
Final comments
Close co-operation between ESAB and GE Energy
proved fruitful when it came to finding a complete
package solution. The development of a new wire/flux
combination made it possible to comply with the
requirements relating to consumable weldability and
productivity, in combination with the stringent requirements
imposed on the mechanical and metallurgical
properties of the weld metal. This combination proved
to be very successful and it is now the standard combination
for the SAW of hydro-turbines in 410NiMo
martensitic stainless steels. The development of the
new, compact welding head, which was necessary for
welding in the limited space available and is capable of
following the complicated joint geometry, was greatly
facilitated by input from GE Energy.
Depending on the preferences of the manufacturing
facility and the selected technical solutions, different
degrees of mechanisation and, consequently, different
choices of welding method and consumable, will
produce the optimum combination of productivity and
cost. A combination of different solutions is often
applied, as a complex object, such as a turbine runner,
may be partly well suited to mechanisation, whereas
other joints can be more economically welded using
manual methods. In the Three Gorges project, GMAW
welding with metal-cored wires has been chosen as
either the preferred welding method or the best
method to complement mechanised SAW welding.
Acknowledgements
The authors wish to thank Trond Multubakk (GE
Energy, Norway) for providing illustrations and for
permission to publish information relating to test
results and requirements for the Three Gorges project.
Figure 6. Section of a Francis turbine runner welded with
the metal cored wire FILARC PZ6166.
About the authors
Nils Thalberg is Global Marketing Manager for
the Power Generation segment. He is located in
Gothenburg.
Solveig Rigdal, MSc, EWE, joined ESAB in
1982 and has since then been working with
product development and market support within
the R & D department in Gothenburg. During
the last years, her main focus has been submerged
arc welding of stainless and high alloyed
steels and strip cladding.
Dr. Leif Karlsson joined ESAB's R&D department
in 1986, after receiving a Ph.D. in materials
science from Chalmers University of Technology.
He currently holds a position as Manager
Research Projects at ESAB AB in Sweden,
focussing on projects dealing with corrosion
resistant alloys and high strength steels.
John van den Broek is Application Engineer
working within the Shipbuilding and Offshore
Group of ESAB Europe. He is located in
Utrecht, The Netherlands.
Herbert Kaufmann, M. El. Sc. and M. Mech. Sc.,
joined ESAB in 1988 as Technical Director at
ESAB Automation Inc., USA. He is currently
working as Project Manager within the
Engineering Department of ESAB Welding
Equipment in Laxå Sweden.
8 • Svetsaren no. 2 • 2002