LOW STRAIN-RATE PLASTICITY OF CONTINUOUSLY CAST CARBON-STEELS

By a special plastometric method, the straightening operation of a ver tically cast strand of two carbon steels was simulated. The temperatur e dependence of the low strain rate plasticity of both the steels exam ined is analogous although caused by very different reasons. As to the plain carbon steel, the amount of ferrite and its location is of prim e importance, whereas in the case of eutectoid steel various modes of fracture and the influence of temperature on the relative plasticity o f type II MnS inclusions are influencial. To avoid transverse cracking , it seems to be suitable to keep the strand at a rather high temperat ure (above 900 degrees C). Temperature cycling seems to be fundamental as to the structural changes taking place in the strand (grain size r efining, ferrite fraction if any), whereas analogous influences of str aining are more or less inexpressive. Of course, the results obtained are of quality only since the practical and laboratory conditions diff er significantly. The knowledge obtained could be applied in regulatin g the intensity of strand cooling with the aim of lowering the waste p ortion and improving the surface quality of worked products.