STRATEGY FOR COST-EFFECTIVE ALLOY DESIGN OPTIMIZATION FOR STRENGTH AND DUCTILITY PROPERTIES OF STRUCTURAL STEELS
Jose Maria Rodriguez-Ibabe, Houxin Wang, Douglas Glenn Stahlheim, Ronaldo Antonio Neves Marques Barbosa
Alloy, labor, and energy made up for major costs in the production of flat and long commodity-grade structural steel products. Flat and long commodity-grade structural steels such as ASTM A36, ASTM A527Gr50, S235, S275, S355, and other equivalent world societal standards represent over 500 million annual tons worldwide. Carbon, manganese, and silicon constitute the minimum base of alloying elements for the commodity structural steels. This base can be then supplemented with microalloying elements of either vanadium or niobium. Since 2016 raw material costs for two of the five alloying elements in these commodity-grade structural steels, FeMn and FeV, have risen significantly and/or have become volatile. This is making difficult to maintain stability in profitability. For steel plants producing hundreds of thousands and in some cases over a million tons annually of these common structural steel grades, because of the significant alloy cost increase for Mn and V, alloy additions have squeezed profitability. Commodity-grades usually represent the base loading for cost controls in most steel plants. Hence a significant cost increase or volatility in two of the five elements used for these grades will have a negative effect on overall production costs. However, with a proper strategy for alloy design working in conjunction with the mills’ existing processing capabilities to achieve the desired end metallurgy/mechanical properties, alloy costs and operational efficiencies can be realized.
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