Innovative solution for uncommon cold
Based north of the Arctic Circle in Kiruna, the mining capital of Sweden, Kiruna Wagon produces heavy-duty equipment designed for use in harsh conditions. In an exceptionally cold environment, corrosion and cracked welds pose challenges for rail wagons formed from carbon steel. Add to that the challenge of loads of ore that refuse to release, and it was clear that Kiruna needed an innovative solution.
Today, Kiruna is building 50 new wagons from Outokumpu Forta LDX 2101, a duplex stainless steel. The material’s good weldability and malleability characteristics make it a natural choice for innovative solutions.
Quality rooted in innovation
Working with Forta LDX 2101 cold-rolled coil, Kiruna Wagon needs to be able to join two plates to reach the desired width. When traditional welding techniques proved less than ideal, Kiruna Wagon partnered with Outokumpu to devise a unique plasma welding solution.
Rarely used in Sweden, plasma welding required creation of new equipment for the application. Outokumpu developed a machine capable of delivering the quality Kiruna Wagon depends on. “The method we’ve chosen is unusual,” admits Outokumpu’s Site Manager Mladen Perkovic from Plate Service Center Nordic in Degerfors. “But we needed to make sure the welds will not crack.”
For the Kiruna Wagon project, 2-meter wide material is produced at Outokumpu’s Avesta mill and subsequently processed at its Plate Service Center Nordic in Degerfors. Tight tolerances are the primary requirement, but consistent material quality is also important. Outokumpu conducts X-ray tests to ensure the material and the welds have no inclusions that could jeopardize wagon strength and performance.
A highly functional polish
Kiruna Wagon’s order for 100 tonnes of Forta LDX 2101 was delivered earlier this year. The fully recyclable material is a perfect fit for a renewal program in which existing undercarriages will be reused and topped with new “baskets” formed of a high-strength, corrosion-resistant duplex stainless steel.
With traditional carbon steel wagons, some mining materials hold so tight to the walls that air hammers are often used to release the contents. Wagons formed of duplex stainless steel represent significant innovation. “From the beginning, this is a really good surface,” Perkovic says. “With a polished surface, the wagons should be easier to empty.”