Research on Solution Strengthened Ferritic Ductile Iron (SSFDI) Structure and Properties Using Different Treatment and I
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Copyright 2020 American Foundry Society https://doi.org/10.1007/s40962-020-00469-4
Abstract A market review of solution strengthened ferritic ductile iron (SSFDI or SSF) is provided as a backdrop for research work conducted by Elkem over the past 5 years. This research included trials that were specifically designed and conducted on SSF materials to better understand how these irons behave when varying magnesium ferrosilicon (MgFeSi) and inoculating materials are used. During this research, three extensive trials were conducted during which 20 treatment ladles were made to study the effect of five different MgFeSi alloys, nine different types of inoculants, and two cover materials. In addition, the influence of separate antimony (Sb) additions
made during inoculation was tested to see if this element enhanced the structure and reduced the risk of forming chunky graphite. The results of this research demonstrated the effect of these variations on the thermal analysis, microstructure, mechanical properties, and shrinkage tendency with emphasis on some of the differences between regular and SSF ductile irons.
Introduction
enhanced materials are continuously researched and developed to meet these demands.
Keywords: ductile irons, solution strengthened ferritic irons, solid solution, strengthening mechanisms, casting, cover materials, MgFeSi, inoculants, antimony, bismuth
Early SSF Developments Both academic research and industrial research are continually developing new materials having improved properties and lower weights without compromising design integrity or service reliability. In fact, lightweight designs are central to improving efficiency and optimizing energy consumption. For these reasons, it is imperative that
This paper is an invited submission to IJMC selected from presentations at the 6th Keith Millis on Ductile Iron held October 23–26, 2018, at the Sonesta Resort, Hilton Head Island, SC. It is published in the IJMC by permission of the DIS (Ductile Iron Society).
International Journal of Metalcasting
Much of this interest has been focused on various generations of high-silicon ductile iron that were originally published in Swedish standards and subsequently by EN 1563:2011. These grades are also known as ferritic–pearlitic and solution strengthened ferritic (SSF) ductile iron. These SSF grades contain elevated levels of Si, typically between 3 and 4.5%. They are particularly important because of their inherent capability to cast complex shapes that provide excellent mechanical properties at relatively low cost. The use of these iron grades was initially studied by Volvo in the early 1980 s.
Within the ferritic/pearlitic DI grades, varying cooling rates normally caused by different section thicknesses promote differing levels of pearlite and very different microstructures. These structural changes create significantly greater variations in hardness and mechanical properties than are found in a purely ferritic structure. The development of the SSF grades has provided a solution to this challe
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