3 minute read
Hot-rolled high-strength steels brought to the next level
The results show that wear on the discs made from the new steel is 13% lower than on those of the grade currently in use. This increased durability represents a significant improvement of the discs’ lifetime.
Laura Moli Sanchez
The Amstrong® Ultra grades are well suited for the yellow goods and heavy transport sector, where they are used for trailers, truck chassis and crane booms (amongst other things). They combine ultra-high-strength with excellent formability, good toughness, and fatigue resistance. On top of that, these hot strip products are a cost-effective alternative to the quench and tempered plate products that are frequently used in this market.
The use of higher strength grades allows for longer crane booms, for example; and, thanks to reducing the machinery’s weight, its loading capacity increases, which results in energy-savings. Driven by customer requirements and the general trend towards reducing weight, Amstrong® grades (minimum yield strength of 240-620MPa) are being replaced more and more by higher-strength products of the Amstrong® Ultra (minimum yield strength of 650-1100MPa) range. This ongoing shift to higher-strength grades requires continual product improvement and extension of the dimensional feasibility.
To serve the European market, R&D is being called in to facilitate the production of Amstrong® Ultra 700MC(T) at several ArcelorMittal sites, taking into account the various layouts and possibilities of all plants involved. In this exercise, the OCAS metallurgy team evaluated currently used concepts and initiated a transition to the more cost-effective and more robust concepts for each mill. This will enable ArcelorMittal to serve markets from southern to eastern Europe with a short supply chain, reduce transportation costs (and thus its CO2 footprint), shorten lead times, improve service levels, and ramp up volumes. By expanding the Amstrong® Ultra product range up to very heavy gauges as well as down to thin gauges and extra-wide formats, differentiation on the market was achieved. With a shift to larger, state-of-the-art laser cutting tables at customer sites, wider sheets will help improve nesting and thereby reduce scrapping as well. In addition to the dimensional feasibility, the product offer of these ultra-high-strength grades is being further improved with regard to surface quality and galvanisability. Excellent flatness, as well as improved low cycle fatigue, are also being taken into account in our striving for continuous improvement.
The ongoing shift to higher-strength grades needs continual product improvement and extension of the dimensional feasibility. It is highly rewarding to be able to satisfy our customers.
Rolf Berghammer
CO-DEVELOPMENT OF DURABOR® SATISFIES CUSTOMERS
The ArcelorMittal Durabor® offer covers part of the green goods market. In that domain, the latest innovative products have been realised in close collaboration with customers. Actually, thanks to the interactions between ArcelorMittal’s Customer Technical Team, the mill, and the OCAS lab, a suitable solution for La Piña’s customer was developed quickly with a significant improvement of the in-use properties (strength and wear performance). The OCAS team used its own competencies on computational software to design a new quenchable boron grade with the right chemistry for ArcelorMittal’s Durabor® range. ArcelorMittal Sestao produced coils of the newly designed steel within weeks and sent them to La Piña for evaluation and qualification. Prototyped plough discs were manufactured at La Piña and sent to both the customer and OCAS for testing. “Our customer was highly satisfied with the results and began a twoyear field test,” says Alejandro Amà, export director at La Piña. Meantime, OCAS has tested on full scale bench two sets of discs (reference Durabor and new development) for an equivalent working distance of 240 kilometres in synthetic soil. Results show that the new grade’s wear performance is outstanding.
