Measuring linear contraction of alloys

Conclusions

• 1. The study of the linear contraction process by means of standard instruments produced by our industry provides simultaneously a highly accurate recording of both contraction and cooling processes of several samples at a time on a single instrument.

• 2. A rise in the eutectic pause of the temperature curve with an increased sample diameter results in a proportional increase in the time taken by the initial expansion, thus indicating an extended grey iron graphitization process. This holds for grey iron smelted both in ordinary and electric furnaces without the addition of any magnesium, and for cast iron modified by magnesium alone or by magnesium and 75% ferrosilicon.

• 3. It is known from literature that a rise in the thickness of the case walls reduces the strength of the iron and increases the graphite deposit. In this instance a reversed relationship is observed between the eutectic temperature pause, the duration of the precontraction expansion, the graphite deposit, and the mechanical properties' indices of the grey iron of the above composition. This result requires experimental verification.

• 4. The total linear contraction of grey iron samples decreases with a rising diameter.