Development and application of advanced high-strength steels in lightweight cars for heavy-duty mining dump trucks

With the rapid development of the automobile industry in China, energy consumption and environmental pollution problems have become increasingly serious issues, and therefore, lightweight vehicles have received more and more attention. Shougang Group has developed advanced high strength steels (AHSS) of NM450 and Q690CF (crack-free) grades by using a Nb-Mo-B microalloyed design and two-stage rolling with quenching and tempering processing. Whilst maintaining the high strength, the toughness and weldability of the AHSS were improved by reducing the carbon equivalent. For the high strength wear-resistant NM450 grade, the yield strength is higher than 1100 MPa, the tensile strength is higher than 1350 MPa, the elongation is greater than 15%, and the low temperature (-40 °C) Charpy impact energy value is not less than 60 J. The abrasion resistance of NM450 is five times that of the typical Q235 grade. For the high-strength structural steel (Q690CF), the yield strength is greater than 750 MPa, the tensile strength is above 800 MPa, the elongation is higher than 20%, and the low temperature (-40 °C) Charpy impact energy value is more than 200 J. These AHSS grades are successfully applied in Shougang’s SGE150® heavy dump body tub, resulting in a reduction of body weight, an improvement of the lifespan of the mine car and a reduction of the transportation costs. (AU) Copyright © 2018 Companhia Brasileira de Metalurgia e Mineração (CBMM) All rights reserved