Oil quenched malleable iron,the strength of an old material in a "green cast" development

Malleable iron lost the interest and the development stopped in the turbulent seventies of tremendous developments of new technologies.The personal computer,emission spectrometer,thermal analysis,cold-box core system and automatic vertical moulding were introduced into the foundry industry.Experience shows that these new technologies do not always match up with malleable iron.Solidification and mould filling simulation programs are not always capable to handle a low carbon equivalent iron like malleable iron.Recent developments show however by using these new technologies and combined with practical experience,it is possible to increase the casting yield of malleable iron to the same level as ductile iron.The mechanical properties,especially the yield strength of malleable iron according to the standard are equivalent to those of ductile iron,however the yield strength of oil quenched malleable iron is significantly higher than that of ductile iron.An extensive investigation is made between ductile iron,air quenched and oil quenched malleable irons based on the properties of more than 350 test bars produced under the same conditions.The results are compared with the existing international standards and discussed.Other properties like fatigue strength and response to surface treatments as induction hardening are also discussed.The costs of malleable iron are reviewed and compared with other ferro alloys.These recent developments in increasing the casting yield,the understanding of the strength,makes malleable iron competitive with ductile iron and cheaper than the first grade of ausferritic ductile iron,or steel qualities.It is possible to design lighter and save weight which is essential in the automotive industry.An example of"green cast"development for typical applications,used in automotive transmissions and engines are shown.