Oil Quenched Malleable Iron, the Strength of an Old Material in a Green CastDevelopment and a New Future
Malleable iron is the oldest ductile iron since its development started in 1720 by R. A. F. de Reamur in Europe and in 1831 by Seth Boyden in the United States of America. 1 Until the invention of ductile iron in 1948 by Keith Millis in the USA and Henton Morrogh in England, malleable iron was the most important ductile cast iron used, first in the agriculture-, rAllway-and later the automotive industry. 2 Due to the development of ductile iron and the energy crisis in the late seventies malleable iron castings became more and more in discredit, and the world production dropped to a one and a half million tonnes in 2008, of which half a million tonnes is produced in China. 3 The increase in ductile iron production was also related to the low investments iron foundries had to make to produce a ductile high strength iron. Malleable iron lost the interest and the development stopped, in the same 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 in the foundry industry. Experience shows that these new technologies not always match with malleable iron. The digital thermal analysis for instance, shows phenomena which are difficult to understand. Solidification-, mould filling simulation programs are not always capable to handle a low carbon equivalent iron like malleable iron is. Recent developments shows however by using these new technologies and combined with practical experiance, it is possible to increase the casting yield of malleable iron to the same level as of ductile iron. The mechanical properties, specific 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, Alr quenched-and oil quenched malleable iron based on the properties of more then 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 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 then 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.
Cornells J. van Ettinger
Gieterij Doesburg, The Netherlands
国际会议
69th World Foundry Congress(第69届世界铸造会议 WFC 2010)
杭州
英文
427-435
2010-10-16（万方平台首次上网日期，不代表论文的发表时间）