For a customer from the steel industry, HS Schoch, the specialist in machine attachments and wear components, was contracted to regenerate a loading shovel used in a steelworks The shovel is used to mix up to 1000° C hot slag and load it into special trucks for transport from the steelworks for further processing (Fig. 1).
When man, machine and materials do not harmonize with each other perfectly, then the result can be burnout – that was the case with the shovel described above. To make the equipment fit for purpose again, the old 2800-mm-wide cutting edge, base and side edges had to be burnt out and a new base and cutting edges made of Toolox 44 welded to the shovel. Toolox 44 is a product from the Swedish SSAB steelworks and, thanks to its high carbon content, can be easily machined in all standard cutting processes. Excellent high-temperature toughness to combat firing crack formation combined with wear resistance make Toolox 44 ideal for use in steelworks.
As additional protection against wear caused by the extreme heat, the Toolox 44-blades were equipped with special profiles from Borox. To protect the shovel bases against the hot aggressive slag, new composite plates 13 Cromo4/5 and Hardox wear plates are welded into the shovel base (Fig. 2). HARDOX-wear plate prevents premature wear. Thanks to the unique combination of high strength, uniform hardness of up to 600 HBW and excellent absorbed impact energy, performance and availability is improved with the use of Hardox. The combination of pure raw materials, balanced alloying concepts and optimum tempering processes provided the basis for the production of high-quality, wear-resistance HARDOX fine-grain steel plate.
As the tooth-holders at the outside corners are exposed to extreme loads during loading of hot slag, the wear protection expert Mirko Ritter from HS-Schoch and the project managers at the steelworks opted for the Ultralok tooth system from Esco (Fig. 3). The special protection against hot slag was the reason for the selection of this system. In addition cracks formed in the inner curve of the shovel base were removed with a gouger, ground and then welded.