Peculiarities of the Destruction of Deformed Cast Irons, Depending upon Type of Thermal Treatment

Abstract

Because of development of the deformed cast irons of bainitic-martensitic type, the investigation of influence of different thermal treatments on their structure, properties and destruction during the shock-dynamic load, is of considerable interest. The above alloys are prospective materials, mainly, for production of gears, crankshafts and other heavy-loaded elements. In the present work the hot-rolled at 900 o C cast irons, with the rates of deformation 20% and 40%, were studied. The following thermal treatments were applied: 1-austenization at 900 o C during 30 min. plus austempering at 400 o C or 270 o C; 2-austenization at 900 o C during 30min. plus water quenching with subsequent austempering at 400 o C or 270 o C. It has been established that the combination of different types of treatment makes it possible to control morphology and distribution of structural components of the cast iron in wide range. The impact strength of the cast iron is changing consequently. The influence of amount and stability of the retained, in the cast iron matrix, austenite on the destruction parameters is also discussed in this work. The influence of substructure of the hot-rolled austenite on the kinetics and the mechanism of structure transformations, at different types of thermal treatment, were studied as well.