TECHNOLOGY
As Enrique Matey says: “That’s especially true in environments with extremely high temperatures, where the wear resistance of many materials drops away, leading to premature failure. The alloy maintains its performance at elevated temperatures – its hardness is three times higher than other materials at 800°C.”
The need for flux-cored welding wire “Because of its capabilities, we have had a long-held ambition to produce EnDOtec 6070N as a flux- cored welding wire for MIG and TIG welding, offering major advantages over MMA,” Enrique Matey explains. From an economic point of view, MIG and TIG welding have a higher deposition rate, therefore can cut the duration of repairs. In turn, this can reduce cost and/or enable faster return of critical equipment to service after a repair. These processes are also compatible with automatic and robotic welding. They also use material more
efficiently by producing less slag and there’s less need to throw out tips, as is the case with stick electrodes. In practice, a welder might be able to deposit 980 g out of every kilogram of wire, but only around 600 g with stick electrodes. When it comes to operational life, it
is possible to achieve a better surface finish with a flux-cored wire than with a stick electrode. Smoother surface and smaller ridges are important for wearfacing coatings as ridges may catch the material being processed, creating friction or higher pressure that raises stress locally inside the component, leading to premature failure.
Material developments Producing this alloy as a welding wire was impossible for many years due to limitations in raw materials and production methods. The 6070N alloy achieves its
performance thanks to high levels of alloying elements such as vanadium, niobium, molybdenum, chromium and carbon. These are distributed evenly throughout the alloy’s microstructure, giving it consistent high strength and hardness. However, there are practical
limitations on how much alloying content can be included in a flux- coated welding wire. A welding wire has a mild steel strip around which many single wires made of different materials are wrapped. During the welding process, the wires and strip melt together into the weld pool and form the required alloy. “The challenge for highly alloyed
materials like 6070N is that as the alloying content increases,” states Enrique Matey, “the number and size of the wires increases. However, the space inside the wrapper is limited, meaning that flux cored wires are usually restricted to a maximum of 35% alloying content. Because 6070N contains more alloying elements, we were not able to produce it in the form of a wire. “However, in 2021 we learned about
new developments in raw materials that created an opportunity. We immediately established a research team to develop the welding wire version of the product, including researchers at our laboratory and manufacturing facility in Dublin, Ireland, with support from experts in Madrid and Belgium, and our customer testing workshop in Austria.” With the new approach, it is possible
to combine the raw materials to include all the required alloying elements for 6070N into a flux-cored wire. Instead
40 / WELDING WORLD MAGAZINE - ISSUE 01 - January 2024
of mild steel, the new product uses a strip that contains alloying materials. However, this created a challenge since the strip is less straightforward to draw and handle, meaning that it can only be produced on the advanced machines at Castolin Eutectic’s manufacturing facility in Ireland. The company produced the first
1.7-tonne batch for testing and customer evaluation. The new wire underwent extensive testing at a specialist metallurgy laboratory in Vienna, Austria to ensure that it achieved the required levels of quality and consistency. “Launching it onto the market in
March 2023 was an important milestone as we could then offer it to customers. However, industrial companies always act with care as they need to carry out their own evaluation when introducing new materials and new products into their critical equipment – so in many ways the product launch is only the start of the story,” Enrique Matey says. He adds: “We are now working
with customers across a range of industries to test the EnDOtec 6070N flux-cored wire against comparable products. We see it as having huge potential for wearfacing coatings in the toughest environments.”
Potential applications Some potential applications are at room temperature, for example in mixing and crushing processes. However, the alloy is also useful at higher temperatures, such as in the Banbury mixers used in the rubber industry to create evenly-mixed rubber blends. Its extreme high temperature capability means that 6070N alloy is also suitable for sinter crusher bars and rotors and coke crushing wheels in the steel industry, as well as in the furnace feed screws in waste-to-energy plants. Ultimately, the new wire creates
an opportunity for professional welders to help industrial companies extend the life of critical components that experience heavy wear from a combination of abrasion, corrosion and high temperature. In turn, operators will be able to extend maintenance intervals and keep equipment in service for longer.
www.castolin.com
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