Method for controlling and regulating the primary nucleation of iron melts

A method for controlling solidification of cast iron from a melt having an intrinsic crystallisation ability, by determining and modifying that ability, said method comprising the steps of:

• (a) providing a sampling vessel having at least one thermoelement and containing a calibrated quantity of an inoculating agent based on FeSi and sufficient to produce a maximum inoculating effect in a given-quantity sample of a base iron melt.
• (b) obtaining said given-quantity sample and placing said sampling vessel in thermic equilibrium with said given-quantity sample prior to commencement of solidification of said sample;
• (c) allowing said sample to solidify in said vessel while recording temperature changes of said sample per unit time as sensed by said at least one thermoelement;
• (d) from the temperature changes sensed and recorded in step (c), determining;
• the difference between the minimum temperature in an undercooling phase present in said solidifying sample,
• the maximum temperature in an eutectic reaction phase present in said solidifying sample, and
• the eutectic equilibrium temperature T.sub.e of said solidifying sample;
• and
• (e) adding to said base melt thermodynamically stable particles of at least one spinel, oxide or oxysulphide of at least one element selected from the group consisting of magnesium, aluminium, potassium, zirconium, strontium, titanium and a rare earth metal, when the difference between the eutectic equilibrium temperature and the minimum temperature in the undercooling phase, as determined in step (d), exceeds 10.degree. K. and the difference between the eutectic equilibrium temperature and the maximum temperature in the eutectic reaction phase, as determined in step (d) exceeds 5.degree. K.