Longer life wear parts water quenched versus Creusabro® Steels
Abraservice Introduce the Creusabro® Range of Steels at BULK 2013
Presented by: Gilles Gros, Product Manager & Nick Taylor, Sales Director, Abraservice Group.
Over 2 million tonnes of specialist steels are used globally each year for the production of wear resistant parts, and the most commonly used materials are water quenched steels produced by a wide variety of suppliers with known brand names such as Hardox® from SSAB, Dillidur from Dillinger Hütte, Raex® from Ruukki, Abrazo® from Tata, Xar® from Thyssen Krupp, Durostat® from Voestalpine and Abro from Abraservice, who are part of the distribution network of Industeel, a whollyowned subsidiary of ArcelorMittal Group.
In the fight against wear phenomena, the hardness of a material is a key factor, so in addition to specialist steels, other potential materials are also available such as white cast iron, chromium carbide overlay, nitriding steel and ceramics with hardness's ranging from 400 - 600 HB for wear resistant steels up to 1600 - 2500 HV for ceramics. However, to produce the wear part geometries required, the materials need to undergo processing such as flame cutting, welding, rolling, bending, drilling, machining or tapping and for this to be successful materials need to be ductile with a minimum of 10 - 12 % elongation. So ceramics can give excellent wear properties but are brittle and difficult to work with, whilst rubbers offer easy working conditions but poor wear resistance at temperatures <800C. The optimal combination of high strength with elongation is provided by the Creusabro® range, an alternative grade of steel where hardness is intentionally limited at delivery stage for easy processing but the hardening effect occurs (+70 HB) once the parts are subjected to impact or pressure which causes spontaneous atomic rearrangement of the microstructure, known as the TRIP effect.
In addition, by comparison to water quenched steels which can only work up to 250C before significant softening occurs, Creusabro® grades, due to the significant presence of Cr and Mo, can also maintain their wear resistant mechanical properties up to 450C, making them suitable for higher temperature applications.
Case Study 1 - Creusabro® 8000 vs industry standard water quenched 450 HB
Location: Chromium Mine, Eti Krom City, Turkey.
A comparative test program was designed to compare the cost of investment for replacement wear edges with the wear life achieved from the components to prove the cost benefits of specialist steel Creusabro® 8000. Mining excavator buckets were fitted with identical bucket wear edges, 30mm in thickness, produced in the two different steels. They were then tested under very harsh abrasive conditions in a side by side comparison program focussing on areas of impact, dragging and sliding within crushed aggregate in two areas mining for chromite (FeCr2O4) and ferrochrome alloy (FeCr).
Results: A 20% investment in higher cost wear resistant bucket edges provided an increase in wear life of components of up to an outstanding +92% depending upon the size and density of the aggregate being mined, as well as reducing downtime and significantly increasing periods between maintenance.
Case Study 2 - Creusabro® 4800vs industry standard water quenched 500 HB
Location: Coal Fire Power Station, Germany.
Wear resistant Creusabro® 4800Phas been approved for the manufacture of the injection system and the pipe work which transports the coal powder to the power station furnace. The main square pipe work and the elbows positioned upstream from the burner are manufactured in the same material as the intentionally limited mechanical properties of the Creusabro® 4800 allows the processing and shaping of the geometries required as well as providing the necessary temperature resistance required for the application from 300 - 500C.
Results: Water quenched materials cannot operate above 250C, so the wear resistance, ease of processing and working temperature of Creusabro® 4800 all meet the application requirements. As a result of this Creusabro® 4800 has been approved and is in use with power suppliers EON (Germany), ENEL (Italy) and EDF (France).
® Creusabro is a registered trademark of Industeel ArcelorMittal.