Magnetic Properties of Malleable Irons

Abstract

Standard or ferritic malleable iron is satisfactory for use as a cast, soft magnetic material. It is made by heat-treating white iron. In addition to its magnetic properties, it can be readily cast into intricate shapes and is one of the most machinable ferrous metals. By merely changing the heat-treatment, pearlitic or martensitic malleable iron can be produced from the same white iron. Like all soft, magnetic materials, ferritic malleable iron is mechanically soft. On the other hand, pearlitic malleable and martensitic malleable irons are graphitic steels and exhibit a range of hardness and strength. They have the same availability as ferritic malleable and much of its machinability. Ordinarily, carbon steels are not used for magnetic applications, but because the pearlitic and martensitic malleables have the advantages outlined above, there is some idea that they might be used as a compromise by giving up some magnetic quality to gain mechanical properties. This paper supplies the magnetic properties necessary for such compromise. Magnetically, pearlitic and martensitic malleables behave like steels if allowance is made for the graphite which is present.